Center for Invasive Species Prevention

Disappearing Floristic Diversity – Should Some of the Attention to Extinctions be Refocused on Invasive Plants?

Sakhalin knotweed (*Fallopia (Reynoutria) sachalinensis*) – an invasive plant widespread in Europe; photo by Katrin Schneider [korina.info] via Wikimedia

There is growing evidence that invasive plants – as distinct from invasive species of animals, microbes, etc. – play a significant role in causing the loss of floristic uniqueness at the local or regional level. I provide full citations of all sources at the end of this blog.

Less Diversity. More Similarity

Several studies show that plant invasions have a bigger impact than extinction in the homogenization of Earth’s flora. A major driver is sheer numbers. Daru et al. point out that 10,138 plant species have become naturalized to a region outside their native ranges while only 1,065 species have gone extinct. Even under a scenario in which all species currently included in IUCN Red List as “threatened” become extinct, non-native plant species naturalizations are by far the stronger contributor to biotic reorganization.

Winter et al. report that in Europe since AD 1500, plant invasions have greatly exceeded extinctions, resulting in increased taxonomic diversity (i.e., species richness) on the Continent but increased taxonomic and phylogenetic similarity among European regions. In other words, floras of individual European countries became phylogenetically and taxonomically impoverished. This situation is likely to worsen in the future because introductions continue.

Winter et al. conclude, more broadly, that a focus on species richness can be misleading because it does not capture the important effects of taxonomic or phylogenetic distinctiveness.

Yang et al. (2021) considered the situation globally. They divided most of Earth’s ice-free land surface into 658 regions. They found that introduction of non-native plants has increased the taxonomic similarity between any two of these regions in 90.7% of the time. Introductions increased phylogenetic similarity in 77.2% of those pairs. Australasia illustrates the situation. The region has a large proportion of endemic species, reflecting its unique evolutionary history and exhibiting high floristic diversity. However, the region has also received large numbers of non-native plants from other regions. The result is that the Australasian flora has lost much of its original uniqueness.

rubbervine (*Cryptostegia madagascariensis*) – one of the worst invasive plants in Australia; photo by Tatters via Flickr

Introduced plant species rarely cause outright extinction of members of the native flora of the receiving ecosystem – at least at the scale of a continent. Winter et al. found that in Europe, extinction usually occurs to plant species with small numbers that are limited to localized habitats. Often, however, the same species continue to thrive elsewhere on the continent. The “losing” country finds its flora becoming more similar to that of other European countries. It loses some uniqueness because it lost one or more components of its flora. However, for Europe as a whole, there is no loss. The homogenization of the “losing” country’s flora is exacerbated by the fact that more than half of plant species listed as invading a particular European country are from other European regions. Winter et al. say a similar pattern has been found in North America.

The picture is more complex for small isolated ecosystems. Carvallo and Castro (2017), writing about isolated volcanic islands in the southeastern Pacific Ocean, introduction of large numbers of non-native plant species has not caused extinction of native plant species. It has, however, resulted in the homogenization of the islands’ floras.

These authors worry that this reduction in phylogenetic diversity could have detrimental impacts for ecosystem function and ecosystem services. (Interestingly, at the level of order or family rather than species or genus, the combined effects of species introductions and extinctions did not change the islands’ taxonomic diversity. They don’t explicitly say whether that fact might mitigate effects on ecosystem function.)

What is the situation in Hawai`i? The Islands are the “capital” of both extinction and invasion. I know the Hawaiian flora has very high levels of endemism and of endangerment. In addition, naturalized non-native plant taxa constitute up to 54% of the archipelago’s flora (Potter et al. 2023). However, it is probably extremely difficult to distinguish the impacts of introduced plants separate from the impacts of the many non-native animals, e.g., feral hogs.

Extinction by Introduction

It has been reported that invasive species have caused the extinction of at least seven species of plants on the Cape of Good Hope and endangered another 14% (Houreld 2024). Unfortunately, the report doesn’t specify whether the non-native species are plants or animals. Either way, this is a tragedy. I remind you that the Cape Floral Kingdom is Earth’s smallest Plant Kingdom in geographic size (78,555 km²), and extremely important in uniqueness. According to the article in The Washington Post, two-thirds of the 20,400 plant species growing in South Africa are endemic – found nowhere else on Earth.

Nearly a decade ago, Downey and Richardson objected to measuring the impact of introduced plant species by considering only total extinction of native plant species. They complain that this approach fails to recognize that plants experience a long decline before reaching extinction. They divide this decline into six “thresholds”. Downey and Richardson say there is abundant evidence of invasive plants driving native plants along this extinction trajectory. For example, increases in non-native plant cover or density that result in decreased native plant species diversity or richness equates, under their hierarchy, to the native species crossing from the first to second threshold. They note there are also examples of species causing “extinction debts”. That is, the extinction occurs long after the invader is introduced and initiates a native species’ decline. They call for conservationists to intervene earlier in that trajectory.

The Global Assessment on Biodiversity and Ecosystem Services was recently published by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. This report notes that there are at least 1,061 invasive plants on Earth. In terrestrial systems, invasive plants are the taxonomic group most frequently reported as having negative impacts, especially in cultivated areas, plus temperate and boreal forests. As I have noted above, non-native plant taxa constitute a particularly high proportion of the flora on islands. The assessment found that the number of non-native plants exceeds the total number of native plants on more than one quarter of the Earth’s islands. However, this report does not distinguish the number of species endangered by plant invasions from the number of species endangered by invasive species of all taxonomic groups.

Tiburon mariposa lily (*Calochortus tiburnensis*) – a federally Threatened species in California; photo by T.J Gehring via Flickr

None of the experts denies the impact of extinction on biodiversity. Extinction represents the loss of phylogenetically and taxonomically unique organisms. This loss is exacerbated if some taxonomic groups are at disproportionately higher risk of extinction. Introduced non-native species compensate for these losses only to a point (Daru et al.). In Europe, Winter et al. found that extinctions usually befall specialized endemic or rare species, often from species-poor families. On the other hand, successful invaders are often ecological generalists with large ranges, often belonging to species-rich families. This results in the pronounced decrease of phylogenetic and taxonomic ß-diversity within and between regions to which the rare species are unique.

All these experts agree that species declines — short of extinction — have severe impacts on ecosystem functions, and even evolution.

Yang et al. emphasize that the rapid and accelerating loss of regional biotic uniqueness changes biotic interactions and species assemblages, with probable impairment of key ecosystem functions. Daru et al. stress that biotic homogenization— declining ß-diversity—reduces trait and phylogenetic differences between regions. Conceding that the consequences of this global biotic reorganization on ecosystems are poorly understood, Daru et al. cite increasing evidence that biotic heterogeneity provides insurance for the maintenance of ecosystem functioning in a time of rapid global change. They assert that declining ß-diversity is a more characteristic feature of the Anthropocene than species loss.

Winter et al. also state that the phylogenetic structure of a species assemblage represents the evolutionary history of its members and reflects the diversity of genetic and thus morphologic, physiologic, and behavioral characteristics. High phylogenetic diversity might enable rapid adaptation to changing environmental conditions.

According to Daru et al., the loss of 14 billion years of evolutionary history has affected some regions particularly. The most disturbed biotas include those of California and Florida; Mesoamerica; the Amazon; the Himalaya-Hengduan region; Southeast Asia; and Southwest Australia. These are regions that experienced spectacular taxonomic radiation over time, and now have both high levels of threat and also species invasion.

Carvallo and Castro, focused on the Pacific islands, call for integrating the two parallel channels of conservation that currently operate separately: those focused on reversing plant extinctions and those focused on reducing invasions. They call for a biogeographical approach that addresses all causes of phylogenetic homogenization.

*Tetragonia tetragonoides* – the most widespread invasive plant on these Pacific islands; photo by Jake Osborn via Flickr

I believe all these experts, in all their papers, have made the case for such integration world-wide.

Invasive plants’ impact on non-plant species

While I have focused here – and in most of my blogs more broadly — on impacts on wild, native plant communities, it is clear that alterations to floristic communities influence other taxonomic groups. A couple of years ago I summarized findings by Douglas Tallamy and colleagues on what happens to insects – and their predators – when a landscape is dominated by introduced plant species.

In short, domination by non-native plants – whether invasive or just widely planted – suppresses the numbers and diversity of native lepidopteran caterpillars. One study cited in the blog found that 75% of all lepidopteran species were found exclusively on native plant species. Non-native plants in the same genus as native plants often support a similar but depauperate subset of the native lepidopteran community. Tallamy and colleagues conclude that a reduction in the abundance and diversity of insect herbivores will probably cause a concomitant reduction in the insect predators and parasitoids of those herbivores – although few studies have measured this impact beyond spiders, which are generalists. Tallamy focuses on birds.

In the same blog I reviewed publications by Lalk and colleagues, which examined interactions between invasive woody plants and arthropod communities more broadly. They decried the insufficient data about most of these interactions.

A few weeks ago I saw a report of an unexpected impact of invasive plants: roots of beach naupaka [beach cabbage or sea lettuce] (Scaevola sericea) are penetrating sea turtle nests so aggressively that they kill the unhatched turtles. Apparently this is happening at several sites in the Caribbean, where the plant is not native (Houreld 2024). I could find no scientific reports of this phenomenon. One reference noted that a related species (S. taccada) can form large, dense stands that might prevent adult sea turtles’ access to nesting areas (Swensen et al. 2024).

Sources:

Daru, B.H., T.J. Davies, C.G. Willis, E.K. Meineke, A. Ronk, M. Zobel, M. Pärtel, A. Antonelli, and C.C. Davis. 2021. Widespread homogenization of plant communities in the Anthropocene. NATURE COMMUNICATIONS (2021) 12:6983. https://doi.org/10.1038/s41467-021-27186-8

www.nature.com/naturecommunications

Downey, P.O. and D.M. Richardson. 2016. Alien plant invasions and native plant extinctions: a six-threshold framework. AoB Plants, 2016; 8: plw047 DOI: 10.1093/aobpla/plw047; open access, available at http://aobpla.oxfordjournals.org/

Houreld, K. 2024. “Parched Cape Town copes with climate change by cutting down trade.”. The Washington Post. February 29, 2024.

Potter, K.M., C.Giardina, R.F. Hughes, S. Cordell, O. Kuegler, A. Koch, and E. Yuen. 2023. How invaded are Hawaiian forests? Non-native understory tree dominance signals potential canopy replacement. Landsc Ecol https://doi.org/10.1007/s10980-023-01662-6

Swensen,S.M., A. Morales Gomez, C. Piasecki-Masters, N. Chime, A.R. Wine, N. Cortes Rodriguez, J. Conklin, and P.J. Melcher. 2024. Minimal impacts of invasive Scaevola taccada on Scaevola plumieri via pollinator competition in Puerto Rico. Front. Plant Sci. 2024; 15: 1281797.

Yang, Q., P. Weigelt, T.S. Fristoe, Z. Zhang, H. Kreft, A. Stein, H. Seebens, W. Dawson, F. Essl, C. König, B. Lenzner, J. Pergl, R. Pouteau, P. Pyšek, M. Winter, A.L. Ebel, N. Fuentes, E.L.H. Giehl, J. Kartesz, P. Krestov, T. Kukk, M. Nishino, A. Kupriyanov, J.L. Villaseñor, J.J. Wieringa, A. Zeddam, E. Zykova. and M. van Kleunen. 2021. The global loss of floristic uniqueness. NATURE COMMUNICATIONS (2021) 12:7290.

https://doi.org/10.1038/s41467-021-27603-y

Winter, M., O. Schweiger, S. Klotz, W. Nentwig, P. Andriopoulos, M. Arianoutsou, C. Basnou, P. Delipetrou, V. Didz.iulis, M. Hejdah, P.E. Hulme, P.W. Lambdon, J. Pergl, P. Pys.ek, D.B. Roy, and I. Kuhn. 2009. Plant extinctions and intros lead to phylogenetic and taxonomic homogenization of the European flora PNAS Vol 106 # 51 December 2009

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm

www.fadingforests.org

Too Many Deer; Too Few Forest Seedlings & Wildflowers

white flowered trillium (Trillium grandiflorum); via PICRYL One of the “charismatic wildflowers” mentioned by Blossey and colleagues

Bernd Blossey, Darragh Hare, and Don Waller have published a plea that America’s federal government take the lead in formulating a new national program on managing deer. Otherwise, they fear that deer populations will not be reduced to ecologically sustainable levels. I find their argument convincing and well-sourced. I agree that Americans need to figure out how to address this threat. (The full citation is at the end of this blog).

First, Blossey and colleagues describe the damage caused by overabundant deer:

severe declines in populations of many native forest herbs and shrubs, probably including disappearing wildflowers;
their replacement by non-native species that are less palatable;
poor regeneration of many canopy hardwood species;
decreased forest resilience, lowering forests’ ability to adapt to stressors, especially climate change;
decreased ability of forests to deliver benefits that are of increasing value to many people;
increased prevalence of wildlife and human diseases associated with the spread and size of growing tick populations; and
people – and deer — killed vehicle accidents on roads.

The widespread impacts of white-tailed deer (Odocoileus virginianus) in forests of the East are well-documented (see my previous blogs for a few examples; scroll below the “Archives” to find “Categories”). Blossey and colleagues note examples of similar impacts in the West, attributed to elk (Cervus elaphus) and black-tailed and mule deer (Odocoileus hemionus).

The authors review the decimation of deer populations in earlier centuries and the efforts of state wildlife agencies to rebuild their populations during the 20^th Century. The problem, in their view, is that federal and — especially — state wildlife agencies have retained their traditional focus on managing wildlife for recreational hunters. However, recreational hunters make up a small and shrinking proportion of all Americans. Many more people now engage in “non-consumptive” enjoyment of wildlife.

lack of regeneration in Rock Creek Park, Washington D.C.; photo by Sam Sheline, NatureServe, via Flickr

State agencies’ narrow focus might partly arise from fragmented authorities. Agencies other than wildlife departments are responsible for addressing some repercussions of overabundant deer. These include threats to human health, loss of agricultural crops.

For several reasons, Blossey and colleagues call for federal leadership. They think that only a national strategy can address, in a holistic way, the interrelated deer, human health, forest, and biodiversity crises. The strategy’s goal should be to protect species that are in decline because of over-browsing by deer and to avoid further declines in environmental and human health.

The authors reason that states are tied to traditional constituencies. Also, they have difficulty acting across jurisdictional boundaries. Second, few state wildlife agencies have authority to protect plant and invertebrate species. Yet these are the taxa most directly affected by overabundant deer. Blossey and colleagues point out that, of the ~1,300 species listed under the federal Endangered Species Act, 942 are plants and 287 are invertebrates.

They point out that deer also suffer the effects of overpopulation. Chronic wasting disease is spreading. It causes a slow, agonizing death of affected animals. Another 2.1 million deer are killed each year in vehicle crashes. [According to the World Animal Foundation, the current number of deer killed in traffic crashes is 1.8 million — 300,000 fewer.) Again, these deaths are often gruesome. Finally, the principal population “control” now is death by starvation in winter. This, too, is cruel.

Blossey and colleagues say that return of large predators, even where feasible, will not result in sufficient reduction in deer populations. Nor will encouragement of greater hunting pressure on does.

They note that the federal government owns nearly 30% of the United States’ terrestrial surface area. Management is divided among many agencies – National Park Service, Fish and Wildlife Service, Bureau of Land Management, USDA Forest Service, Department of Defense, and many smaller agencies. Management approaches vary. However, it would be possible to bring them into agreement – although, in some cases, this would require new legislation.

Another issue requires resolution: federal agencies’ authority to manage wildlife on federal land.. The states have repeatedly claimed constitutional and legal authority to manage (vertebrate) wildlife on the federal lands within their borders. This assertion was countered years ago by Nie et al. (2017):

‘Federal land management agencies have an obligation, not just the discretion, to manage and conserve fish and wildlife on federal lands. … [M]ost states have not addressed the conservation obligations inherent in trust management; rather, states wish to use the notion of sovereign ownership as … a source of unilateral power but not of public responsibility. Furthermore, the states’ trust responsibilities for wildlife are subordinate to the federal government’s statutory and trust obligations over federal lands and their integral resources.’

Blossey and colleagues assert that managing wildlife (typically defined as mammals, birds, and fish) is much broader than establishing hunting seasons or methods. Furthermore, the concept of “public trust resources” means resources should be managed for all citizens, not just the fewer than 10% of US residents who hunt. A growing proportion of society expects this management to support healthy and diverse environments.

The authors stress that reducing deer overpopulations is necessary to meet numerous policy goals. These include fulfilling obligations under international treaties related to climate change, invasive species, and threatened species; restoring and conserving the nation’s forests to provide habitat; and adopting “nature-based” climate adaptations, such as carbon sequestration. They express the hope that recent presidential mandates to better quantify and value natural assets will increase awareness of the harm caused by deer overpopulation. Their proposed national strategy would develop goals and metrics to match specific environmental and human health outcomes.

Of course, management of deer must extend beyond federal property lines. This will require cooperation among states, Tribes, and private landowners.

The paper proposes the North American Waterfowl Management Plan as a model. Under this scheme the US Fish and Wildlife Service works with states, tribal governments, Mexico, and Canada to ensure accurate information on waterfowl populations a to calculate harvest levels. States implement their assigned quotas through their own regulations. Waterfowl hunters purchase Duck Stamps to fund the monitoring efforts. This program has worked well for most species covered by the program. Waterfowl are one of the few bird groups that have not declined dramatically.

Reducing deer populations will probably require lethal control. Studies indicate that at least 60% of does must be removed from a population to reduce herd sizes over time. Other means have been attempted at regional or larger landscape levels, such as sterilization, fertility control. These methods have failed even when paired with recreational hunting. Lethal approaches will probably distress many people. However, Blossey, Hare, and Waller believe the program would be supported if it is understood to be undertaken with the goal of improving the health of both humans and also the environment.

In the end, Blossey, Hare, and Waller say they are not willing to leave the killing to cars, disease, and starvation. They emphasize our moral responsibility to protect humans and the many other species that rely on diverse ecosystems. Our policies and choices created the problem, so we must try to correct it.

SOURCES

Blossey. B., D. Hare, and D.M. Waller, 2024. Where have all the flowers gone? A call for federal leadership in deer management in the US. Front. Conserv. Sci. 5:1382132. doi: 10.3389/fcosc.2024.1382132

Nie, M., C. Barns, J. Haber, J. Joly, K. Pitt and S. Zellmer. 2017. Fish and Wildlife Management on Federal Lands: Debunking State Supremacy. Environmental Law, Vol. 47, no. 4 (2017).

Posted by Faith Campbell

www.fadingforests.org

Forest Regeneration Again … Deer!

I have recently recent blogged several times about threats to regeneration of eastern forests. Most of the underlying studies stress the role of deer browsing as a major driver of suppression of native plant species and proliferation of non-native ones. Most studies discussed at a recent Northern Hardwood research forum (USDA, FS 2023b Proceedings) found that deer browsing overwhelms other disturbances, such as fire and canopy gaps that typically promote seedling diversity. Miller et al. also stressed the importance of the deer-invasive plant complex in interrupting regeneration in National parks. Reed et al. found that, on the Allegheny Plateau of western Pennsylvania, high deer densities at the time stands formed reduced tree species diversity, density, and basal area – changes that were still detectable decades later.

On the other hand, Hovena et al. found that at their study sites in Ohio, interaction between non-native shrubs and soil wetness overshadowed even the impact of deer herbivory on the species richness and abundance of seedlings.

Unlike the others, Ducey et al. don’t mention deer as a factor in their analysis of regeneration in a forest in the northern half of New Hampshire. They focus on the minimal impact of silvicultural management. Its effect is secondary to overall forest development as the forest ages. Is it possible that overabundant deer are not a factor in the Bartlett Experimental forest.

American elm (*Ulmus americana*); photo by F.T. Campbell

Some of the studies acknowledge the impacts of non-native insects and pathogens. The most thorough discussion is in Payne and Peet. They note that specialist pathogens have caused the loss of important tree species, specifically elms and dogwoods plus the impending widespread mortality of ash. Such mortality is resulting in drastic and long-lasting shifts in community dynamics.

Ducey et al. anticipate pest-driven reversals of increases over the decades of eastern hemlock (Tsuga canadensis) and American beech (Fagus grandifolia). Also, they expect that white ash (Fraxinus americana), which has a minor presence, will disappear.

Miller et al. also stressed the importance of emerald ash borer-induced suppression of ash regeneration in some National parks . The authors also noted the threat to beech trees from beech leaf disease in other parks. Hovena et al. state that the interaction between non-native shrubs and soil wetness was more influential than ash mortality in shaping woody seedling communities.

Reed et al. considered the role of non-native earthworm biomass on plant species’ growth.

But too many of the studies, in my view, make no mention of the probably significant role of non-native insects and pathogens.

It is perhaps understandable that they don’t address emerging pests that either have not yet or have barely reached their study sites. For example, Hovena et al. and Yacucci et al. [see below] noted growth of one native shrub, Lindera benzoin, in the face of the challenges presented by deer and invading plants. Neither acknowledges the approach of laurel wilt disease, which has not yet become established in Ohio (it has been detected on the Kentucky-Indiana border). Similarly, neither mentions beech leaf disease, although some of the plots studied by Hovena et al. are just east of Cleveland – where BLD was first detected. The location of the Yacucci et al. study is less than 50 miles away. The North Carolina forests studied by Payne and Peet are apparently too far east to be affected by beech bark disease and beech leaf disease is not yet established nearby.

Less understandable is the failure to mention loss of elms – which were abundant in riparian areas until killed off by Dutch elm disease – which was first detected in Cleveland!); or to discuss the impact of dogwood anthracnose. Their focus on the deciduous forest might explain why they don’t mention hemlock woolly adelgid – which is just now invading the area discussed by Reed et al. I suppose the demise of American chestnut was so many decades ago that it is truly irrelevant to current forest dynamics.

A new study raises anew these questions about whether inattention to the role of non-native pests has skewed past studies’ results. Yacucci et al. compared regeneration in a military installation (Camp Garfield), to the results in the surrounding second-growth forest. This choice allowed them to overcome one drawback of other studies: using deer exclosures that are small and of short durations. The military facility covers 88 km². Inside it, deer populations have been controlled for 67 years at a density of 6.6 – 7.5 deer/km². Outside, deer have been overabundant for decades. Populations have grown to densities estimated (but not measured) to be at least 30 deer/km²– more than four times as high.

These authors established 21 experimental gaps in the low-deer-density area and 20 gaps outside the installation where deer densities are high. Some of the gaps in both low- and high-deer-density environs were located on wetter, seasonally flooded soils, some on drier sites. None of the forest sites had experience fire in recent decades.

Their findings support the importance of deer browsing as driver of changes to forest regeneration.

northern spicebush (*Lindera benzoin*); photo by R.A. Nonemacher via Wikimedia

They found that at low deer densities, gaps develop a vigorous and diverse native sapling layer, including oaks. Total stem density of red and pin oaks was 13 times higher in these gaps than in gaps in high-deer-density locations. Oak saplings were growing into the subcanopy – that is, above deer browse heights. Saplings of other species – i.e., tuliptree (Liriodendron tulipifera), red maple, and ash (Fraxinus spp.) were also flourishing. Also present were dogwood (Cornus florida) and two native shrubs — Lindera benzoin and Rubus allegheniensis. One non-native shrub, buckthorn (Rhamnus frangula), also thrived at low deer densities. Other non-native plant species were far fewer; their cover was 80% lower. Overall, abundance, richness, and diversity of native herbaceous and woody species were 37–65% higher at the low-deer-density study sites. On average tree species were more than twice as tall as in high-deer-density plots.

In high-deer-density plots, non-native species were six times more abundant while native species richness was 39% lower. Diversity was 27% lower. Most native tree species were short in stature and in low abundance. The one exception was black cherry (Prunus serotina), which deer avoid feeding on. The cherry was 95% more abundant in these high-deer-density plots.

There were several surprising results. In most cases, neither years since gap formation nor habitat type (wet vs. dry) had a significant impact on plant diversity, richness, or abundance. The exception was that non-native plant species were more abundant in older gaps where deer densities were high. Yacucci et al. warn that this phenomenon is a potential threat to biodiversity since high deer density is now the norm across eastern forests.

The authors also note that fire has probably never been a factor in these forests, which are primarily beech-maple forests. Certainly there have been no fires over the past 70 years, either inside or outside the military installation.

Yacucci et al. did not discuss past or possible future impacts of non-native insects or pathogens. They did not mention emerald ash borer or dogwood anthracnose – both of which had been present in Ohio for at least two decades when they completed their study. Although they said their study forest was a beech-maple forest, they did not discuss whether beech are present and – if so – the impact of beech bark disease or beech leaf disease. Both of these are spreading in Ohio. The latter was originally detected in 2012 near Cleveland, just 50 miles from the location of Camp Garfield (between Youngstown and Cleveland, Ohio). As noted above, they also did they mention that Lindera benzoin is susceptible to laurel wilt disease.

beech seedlings in Virginia; photo by F.T. Campbell

Proposed solutions to deer over-browsing

Given the combined threat from widespread deer overpopulation and invasions by non-native plants, Yacucci et al. propose enlisting those military posts that regularly cull deer into efforts to conserve and regenerate native plants. Otherwise, they say, the prognosis for regeneration is poor.

Bernd Blossey and colleagues propose a more sweeping solution: implementation of a national policy to reduce deer populations on all land ownerships. They point out that overabundant deer:

disrupt the plant communities of affected forests – from spring ephemerals to tree regeneration;
promote disease in wildlife and people; and
lead to miserable deaths of deer on our highways, through winter starvation, and disease.

They call for federal leadership of coordinated deer-reduction programs. I discuss their proposal in detail in a separate blog.

SOURCES

Ducey, M.J, O.L. Fraser, M. Yamasaki, E.P. Belair, W.B. Leak. 2023. Eight decades of compositional change in a managed northern hardwood landscape. Forest Ecosystems 10 (2023) 100121

Hovena, B.M., K.S. Knight, V.E. Peters, and D.L Gorchov. 2022. Woody seedling community responses to deer herbivory, intro shrubs, and ash mortality depend on canopy competition and site wetness. Forest Ecology and Management. 523 (2022) 120488

Payne, C.J. and R.K. Peet. 2023. Revisiting the model system for forest succession: Eighty years of resampling Piedmont forests reveals need for an improved suite of indicators of successional change. Ecological Indicators 154 (2023) 110679

Miller, K.M., S.J. Perles, J.P. Schmit, E.R. Matthews, and M.R. Marshall. 2023. Overabundant deer and invasive plants drive widespread regeneration debt in eastern United States national parks. Ecological Applications. 2023;33:e2837. https://onlinelibrary.wiley.com/r/eap Open Access

Reed, S.P., D.R. Bronson, J.A. Forrester, L.M. Prudent, A.M. Yang, A.M. Yantes, P.B. Reich, and L.E. Frelich. 2023. Linked disturbance in the temperate forest: Earthworms, deer, and canopy gaps. Ecology. 2023;104:e4040. https://onlinelibrary.wiley.com/r/ecy

United States Department of Agriculture, Forest Service. 2023a. Proceedings of the First Biennial Northern Hardwood Conference 2021: Bridging Science and Management for the Future. Northern Research Station General Technical Report NRS-P-211 May 2023

Yacucci, A.C., W.P. Carson, J.C. Martineau, C.D. Burns, B.P. Riley, A.A. Royo, T.P. Diggins, I.J. Renne. 2023. Native tree species prosper while exotics falter during gap-phase regeneration, but only where deer densities are near historical levels New Forests https://doi.org/10.1007/s11056-023-10022-w

Posted by Faith Campbell

www.fadingforests.org

Funding of tree pest programs through §7721

spotted lanternfly – target of many projects funded by USDA’s Plant Pest & Disease Management & Disaster Prevention Program; photo by Holly Raguza of Pennsylvania Department of Agriculture

I am belatedly reporting on the forest-pest projects funded by annual grants under the Plant Pest & Disease Management & Disaster Prevention Program ( of the Plant Protection Act). As usual, APHIS funded projects totaling $62.975 million in FY24. In total, 353 projects were funded. These projects represented 70% of the 504 project proposals submitted (the total funding sought was $106 M).

APHIS reserved $11 million for responding to P&P emergencies. I applaud this choice since the agency’s annual appropriation provides only a completely inadequate $1 million (or less) to cover emergencies.

APHIS notes that since initiation of the Plant Pest & Disease Management & Disaster Prevention Program in 2009, it has funded more than 5,500 projects with a total of nearly $870 million.

In FY24 the program funded 30 more projects than the 322 projects funded in FY23. blog 320 The FY24 allocation provides more than $1 million more for goal area 1S — Enhance Plant Pest/Disease Survey (from $14.4 million to $15.7 million). This was balanced by small decreases for the other goal areas: enhancing mitigation capabilities received $13.6 million; inspections at domestic sites important in invasive species’ spread received $6.3 million; pest identification and detection received $5.3 million; and outreach and education received $4.1 million. Projects safeguarding nursery production and those improving pest and disease analysis each received about $2 million.

By my calculation – subject to error! – about $7.5 million went to projects clearly dealing with forest pests [12% of total funding]. This is a welcome increase from FY23 – when funding of such projects reached about $6.5 million (a little over 10%). blog 320 Funding for tree pest projects might be higher. Some $1.9 million is allocated to surveys of grapevines and orchards — hosts of the spotted lanternfly (SLF). However, it is not clear whether these projects are focused on detecting and managing SLF; they might have a much broader goal. If we do include these projects, the total for tree-killing pests rises to $9.4 million — nearly 15% of the total.

Over both FY23 and FY24, the majority of funds went to similar topics: survey and management of sudden oak death in nurseries; surveys for bark beetles, Asian defoliators, and forest pests generally; and outreach programs targetting the spotted lanternfly. In FY24, just under $100,000 paid for efforts to develop tools for rapid detection of laurel wilt link to DMF in avocados – that is, in a crop rather than the natural environment.

No projects addressing tree or forest pests were funded in seven states or territories: Guam, Idaho, Nebraska, New Mexico, Rhode Island, South Dakota, and Utah. This was three fewer states than in FY23. In neither year do I know whether these states submitted proposals in this category that ended up not being funded.

In FY24, spotted lanternfly is by far the pest addressed by the most projects. As noted above, I can’t be precise about the number because of the lack of information about the 23 projects that fund pest surveys of grapes and/or tree crops that are SLF hosts. Eleven projects named SLF specifically. A final project (not included in above) is one funding registration of Verticillium nonalfalfae as a biocontrol for Ailanthus altissima – an invasive tree that is the preferred host of SLF.

The District of Columbia, Kansas, Missouri, and Oklahoma each had one tree pest project funded. In the cases of Kansas and Missouri, the single project was surveys for thousand cankers disease of walnut. Three other states — Iowa, Maryland, and Pennsylvania — also obtained funding to survey for TCD.

The single Oklahoma project concerned efforts to ensure that the sudden oak death pathogen(Phytopthora ramorum) is not present in nurseries. (An Oklahoma wholesaler was one of the hubs of this pathogen’s spread to 18 states in 2019). Eleven other states were also funded to survey their nurseries for P. ramorum: Alabama, Kentucky, Louisiana, Nevada, North Carolina, Ohio, Pennsylvania, South Carolina, Virginia, and West Virginia. P. ramorum is a “program pest” in 2024. That is, APHIS had designated it as a regulated pest for which the agency wished to fill knowledge gaps about its distribution. I note that last year APHIS published a risk assessment that downplayed the likelihood that P. ramorum would establish in the eastern states. Is APHIS seeking more information to test this conclusion?

In a separate case, Oregon received $76,000 to evaluating the threat to nurseries and forests arising from the presence in the state’s forests of two strains or lineages of P. ramorum that previously had not been extant in the environment of North America.

Another approximately 53 projects fund surveys for tree pests other than spotted lanternfly; these are often fairly general surveys, such as for woodborers or “Asian defoliators”. About ten projects fund management efforts – including evaluation of the efficacy of emerald ash borer biocontrol programs.

Last year I noted that two states – Mississippi and Nevada — had projects to survey the “palm commodity”. Hawai`i joined this group in FY24. The project descriptions don’t specify which pests are the targets. The South American palm weevil (Rhynchophorus palmarum) seems most probable; it is established in far southern California and neighboring Mexico. APHIS prepared a risk assessment on the species in 2012. link? In Hawa`ii, concern probably focuses on the coconut rhinoceros beetle (Oryctes rhinoceros). link? There are other threats to palms, e.g., the red palm weevil (Rhynochophorus ferrugineus), link? and a deadly Fusarium wilt. link?

native palms in the desert at Anza-Borrego, California; photo by F.T. Campbell

California has native palms (Washingtonia filifera); southern states from Texas to at least South Carolina have native palmettos. Of course, many species of palms are important ornamental plants in these states, and dates are raised commercially.

Another “program pest” that I have blogged about in the past is box tree moth. link to blog 287 In FY24 five projects addressed this pest, including surveys and efforts to develop better control tools.

beavertail cactus (*Opuntia basilaris*) in Anza-Borrego, California; photo by F.T. Campbell

I am pleased by continued funding of projects trying to utilize biocontrol agents to protect two groups of cactus severely threatened by non-native insects: lepidoptera that attack flat-padded prickly pear cacti (Opuntia spp.) link to DMF and the mealybug that attacks columnar cacti of Puerto Rico and the Virgin Islands. link to DMF

vulnerable cactus on St. John, US Virgin Islands; photo by F.T. Campbell

I applaud the decision to fund projects focused on determining the efficacy of biocontrol projects. As noted above, three projects are asking these questions in the case of the emerald ash borer. link to DMF Another project funds production, release, and efficacy evaluation of biocontrol agents targetting Brazilian peppertree in Florida & Texas.

I am also pleased that three projects assist Washington State in its efforts to eradicate the invasion by giant hornets from Asia. link to blogs & Hornet Herald – no detections in 2023 … A company in California also received funding to developing hornet detection tools.

Nineteen projects funded outreach efforts, including continued funding for the “Don’t Move Firewood” program. In addition to those focused on spotted lanternfly, such projects also included other firewood programs, Asian longhorned beetle awareness, and the nursery industry.

I note that while California received funding for 27 projects, none dealt with any of several deadly tree pests extant in the state – goldspotted oak borer, polyphagous and Kuroshio shot hole borers, Mediterranean oak borer, and the palm weevils. Nor did Hawai`i obtain funding to address rapid ohia death. Did no one submit proposals to address any of the many issues impeding management of these killers?

South American palm weevil; photo by Allan Hopkins via Flickr

Posted by Faith Campbell

www.fadingforests.org

Planting Trees to Sequester Carbon – Beware the Wrong Places!

Greater prairie chicken – denizen of the Tallgrass Prairie; NPS photo

In August 2022 I blogged about unwise planting of trees in New Zealand as a warning about rushing to ramp up tree planting as one solution to climate change.

New Zealand has adopted a major afforestation initiative (“One Billion Trees”). This program is ostensibly governed by a policy of “right tree, right place, right purpose”. However, Bellingham et al. (2022) [full citation at end of blog] say the program will probably increase the already extensive area of radiata pine plantations and thus the likelihood of exacerbated invasion. They say the species’ potential invasiveness and its effects in natural ecosystems need more thorough consideration given that the pines

have already invaded several grasslands and shrublands;
are altering primary succession;
are climatically suitable to three-quarters of New Zealand’s land

North American Tallgrass Prairie; photo by National Park Service

A new study by Moyano et al. [full citation at the end of the blog] tackles head-on the question of whether widespread planting of trees to counter climate change makes sense. They focus on plantings in naturally treeless ecosystems, i.e., grasslands, shrublands and wetlands. They find that:

relying on tree planting to significantly counter carbon change in the absence of reducing carbon emissions would require converting more than a third of Earth’s of global grasslands into tree plantations.
Reforestation of areas previously forested has the potential to produce a net increase in carbon sequestration more than twice as great as can be done by afforesting unforested areas.

Moyano et al. conclude that conservation and restoration of degraded forests should be prioritized over afforestation projects. This recommendation confirms points made in an earlier blog. Then I reported that Calders et al. (2022) said temperate forests account for ~14% of global forest carbon stocks in their biomass and soil. They worried that ash dieback link will kill enough large trees that European temperate deciduous forests will become a substantial carbon source, rather than sink, in the next decades. In my blog I pointed out that other tree taxa that also formerly grew large – elms, plane trees, and pines – have either already been decimated by non-native insects and pathogens, or face severe threats now.

Moyano et al. also point out that naturally treeless ecosystems are often at risk to a variety of threats, they provide numerous ecosystem services, and they should be conserved.

Loss of Biodiversity

Tree planting in naturally treeless areas changes ecosystems at the landscape scale. Moyano et al. say these changes inevitably degrade the natural biodiversity of the affected area. For example, grasslands provide habitats for numerous plant and animal species and deliver a wide range of ecosystem services, including provisioning of forage for livestock, wild food and medicinal herbs, + recreation and aesthetic value. Already 49% of Earth’s grassland area is degraded. Restoration of herbaceous plant diversity in old growth grasslands requires at least 100 years.

These obvious impacts are not the only losses caused by conversion of treeless areas to planted forests.

Ambiguous Carbon Sequestration Benefits

Grasslands store 34% of the terrestrial carbon stock primarily in the soil. Tree planting in grasslands can result in so much loss of carbon stocks in the soil that it completely offsets the increment in carbon sequestration in tree biomass. The underlying science is complicated so scientists cannot yet predict where afforestation will increase soil carbon and where it will reduce it. Important factors appear to be

Humid sites tend to lose less soil carbon loss than drier sites;
Soil carbon increases as the plantation ages;
Tree species: conifers either reduce soil carbon or have no effect; broadleaf species either increase soil carbon or have no effect.
Sites with higher initial soil carbon tend to lose more carbon during afforestation.
Afforestation has greater impacts on upper soil layers.

Moyano et al. assert that appropriate management of grasslands can provide low cost, high carbon gains: a potential net carbon sequestration of 0.35 Gt C/ year at a global level, which is comparable to the potential for carbon sequestration of afforestation in all suitable dryland regions (0.40 Gt C/year).

Changes in Albedo

Trees absorb more solar energy than snow, bare soil or other life forms (such as grasses) because they reflect less solar radiation (reduced albedo). Moyano et al. say the resulting warmer air above the trees might initially offset the cooling brought about by increased carbon sequestration in the growing trees’ wood. Only after decades does the increase in carbon sequestration compensate for the reduction in albedo and produce a cooling effect. Furthermore, they say, the eventual cooling effect that afforestation could create is slight, reducing the global temperature only 0.45°C by 2100 if afforestation was carried out across the total area actually covered by crops. As they note, replacing all crops by trees maintained to sequester carbon is highly unlikely.

Eucalyptus-pine plantation burned in Portugal; photo by Paolo Fernandez via Flickr

Increased fire severity

Planting trees in many treeless habitats – deserts, xeric shrublands, and temperate and tropical grasslands – increases fire intensity. This risk is exacerbated when managers choose to plant highly flammable taxa, e.g., Eucalyptus.Already the fire risk is expected to increase due to climate change. These fires not only threaten nearby people’s well-being and infrastructure; they also release large portions of the carbon previously sequestered, thus undermining the purpose of the project. Moyano et al. note that the carbon stored in the soil of grasslands is better protected from fire.

Water supplies reduced

Afforestation changes the hydrological cycle because an increase in carbon assimilation requires an increase in evapotranspiration. The result at the local scale is decreased water yield and increased soil salinization and acidification. Water yield losses are greater when plantations are composed of broadleaf species. Moyano et al. point out that these water losses are more worrying in areas where water is naturally scarce, e.g., the American southwest, including southern California. On the other hand, increased evapotranspiration can enhance rain in neighboring areas through a redistribution of water at the regional scale and increased albedo through the formation of clouds.

Moyano et al. say planting trees also alters nutrient cycles. To my frustration, they don’t discuss this impact further.

Bioinvasion risk

Moyano et al. cite several experts as documenting a higher risk of bioinvasion associated with planting trees in naturally treeless systems. These invasions expose the wider landscapes to the impacts arising from tree plantations, e.g., increased plant biomass carbon sequestration, reduced soil carbon, reduced surface albedo, increased fuel loads and fuel connectivity, reduced water yield, and altered nutrient cycles. Even native ecosystems that are legally protected can be threatened. Thickets of invading trees can exacerbate some of the impacts listed above since the invading trees usually grow at higher densities. On a more positive side, invading stands of trees often are more variable in age; in this case, they can be more like a natural forest than are even-aged stands in plantations. Because of these complexities, the effect of tree invasions on ecosystem carbon storage becomes highly context dependent. This is rarely evaluated by scientists. See Lugo below.

Moyano et al. say woody plant invasions can exacerbate human health issues by providing habitat for wildlife hosts of important disease vectors, including mosquitoes and ticks. I ask whether plantations using unwisely chosen tree species might raise the same risks. They decry the minimal research conducted on this issue.

Assessing the tradeoffs

The goal is to remove CO₂ from the atmosphere by fixing more carbon in plant biomass. Moyano et al. say careful consideration of projects’ potential impacts can minimize any negative consequences. An integrated strategy to address climate change should balance multiple ecological goals. Efforts to increase carbon storage should not compromise other key aspects of native ecosystems, such as biodiversity, nutrient and hydrological cycles, and fire regimes. First, they say, planners should avoid the obvious risks:

don’t plant fire-prone/flammable tree species; do adopt fuel- and fire-management plans.
don’t plant potentially invasive species.
don’t plant forests in vulnerable environments where negative impacts are likely.

In order to both minimize that certain risks will arise and ensure counter measures are implemented if they do, Moyano et al. suggest incorporating into carbon certification standards two requirements:

that soil carbon be measured throughout the whole soil depth.
that plantation owners be legally responsible for managing potential tree invasions.

The authors praise a new law in Chile, which prohibits planting monospecific tree plantations as a natural climate solution.

Furthermore, they advocate for regulators conducting risk analyses rather than accepting groundless assumptions about carbon storage and climate cooling effects.

Recognizing the uncertainty about some effects of introducing trees into naturally treeless areas, and interactions between these effects and the key role of the ecological context, Moyano et al. call for increased study of plant ecology. They specify research on the above-mentioned highly variable impacts on soil carbon as well as albedo.

Role of NIS trees in sequestering /storing carbon in U.S.

According to Lugo et al. (2022; full citation at the end of this blog), in the Continental United States, non-indigenous tree species contribute a tiny fraction of the forests’ carbon storage at the current time: about 0.05%. This is because non-native trees are widely scattered; while individuals can be found in more than 61% of forested ecosections on the continent, they actually occupy only 2.8% of the forested area.

However, non-native tree species are slowly increasing in both their area and their proportion of species in specific stands. Consequently, they are increasingly important in the forest’s carbon sink – that is, the amount of additional carbon sequestered between two points in time. In fact, non-native trees represent 0.5% of new carbon sequestered each year. This is ten times higher than their overall role in carbon storage. In other words, the invasive species play increasingly important ecosystem roles in the stands in which they occur.

neem tree – considered invasive in the Virgin Islands; photo by Miekks via Wikimedia

On the United States’ Caribbean and Pacific islands, non-native tree species are already much more common, so they are more important in carbon sequestration. On Puerto Rico, 22% of the tree species are non-native; link to blog 340 they accounted for 38% of the live aboveground tree carbon in forests. On the Hawaiian Islands, an estimated 29% of large trees and 63% of saplings or small trees are non-native. link to blog 339 Consequently, they store 39% of the mean plot area-weighted live aboveground tree carbon.

SOURCES

Bellingham, P.J., E.A. Arnst, B.D. Clarkson, T.R. Etherington, L.J. Forester, W.B. Shaw, R. Sprague, S.K. Wiser, and D.A. Peltzer. 2022. The right tree in the right place? A major economic tree species poses major ecological threats. Biol Invasions Vol.: (0123456789) https://doi.org/10.1007/s10530-022-02892-6

Calders, K., H. Verbeeck, A. Burt, N. Origo, J. Nightingale, Y. Malhi, P. Wilkes, P. Raumonen, R.G.H. Bunce, M. Disney. Laser scanning reveals potential underestimation of biomass carbon in temperate forest. Ecol Solut Evid. 2022;3:e12197. wileyonlinelibrary.com/journal/eso3

Lugo, A.E., J.E. Smith, K.M. Potter, H. Marcano Vega, and C.M. Kurtz. 2022. The Contribution of NIS Tree Species to the Structure and Composition of Forests in the Conterminous US in Comparison with Tropical Islands in the Pacific and Caribbean. USFS International Institute of Tropical Forestr. January 2022. General Technical Report IITF-54 https://doi.org/10.2737/IITF-GTR-54

Moyano, J., R.D. Dimarco, J. Paritsis, T. Peterson, D.A. Peltzer, K.M. Crawford, M.A. McCary,| K.T. Davis, A. Pauchard, and M.A. Nuñez. 2024. Unintended consequences of planting native and NIS trees in treeless ecosystems to mitigate climate change. Journal of Ecology. 2024;00:1-12

Posted by Faith Campbell

www.fadingforests.org

California bill – model for other states?

invasion of wild/black mustard *Brassica nigra*; photo by carlbegge via Flickr

A California state legislator has proposed a bill to expand state efforts to counter invasive species. Should we support it – and others like it in other states?

The bill is Assembly Bill 2827 introduced by Assembly Member (and former Majority Leader) Eloise Reyes of the 50th Assembly District. She represents urban parts of southwestern San Bernardino County, including the cities of Rialto, Colton, and Fontana.

According to media reports, Reyes was prompted to act by the current outbreak of exotic fruit flies, which as of some months ago resulted in detections in 15 California counties.

The bill is much broader than agricultural pests, however. It would find and declare that it is a primary goal of the state to prevent the introduction, and suppress the spread, of invasive species within its borders. I applaud the language of the “findings” section:

(a) Invasive species have the potential to cause extensive damage to California’s natural and working landscapes, native species, agriculture, the public, and economy.

(b) Invasive species can threaten native flora and fauna, disrupt ecosystems, damage critical infrastructure, and result in further loss of biodiversity.

Paragraph (c) cites rising threats associated with increased movement of goods, international travel, and climate change — all said to create conditions that may enhance the survival, reproduction, and spread of these invasive species, posing additional threats to the state.

(d) It is in the best interest of the state to adopt a proactive and coordinated approach to prevent the introduction and spread of invasive species.

California sycamore attacked by invasive shot hole borer; photo by Beatriz Nobua-Behrmann

The bill calls for

The state agencies, in collaboration with relevant stakeholders, to develop and implement pertinent strategies to protect the state’s agriculture, environment, and natural resources.
The state to invest in research, outreach, and education programs to raise awareness and promote responsible practices among residents, industries, and visitors.
State agencies to coordinate efforts with federal, local, and tribal authorities.

However, the bill falls short when it comes to action. Having declared that countering bioinvasion is “a primary goal of the state”, and mandated the above efforts, the bill says only that the California Department of Food and Agriculture (which has responsibility for plant pests) is to allocate funds, if available, to implement and enforce this article. Under this provision, significant action is likely to depend on holding agencies accountable and providing increased funding.

removing coast live oak killed by goldspotted oak borer; photo by F.T. Campbell

Would this proposed legislation make a practical difference? I have often complained that CDFA has not taken action to protect the state’s wonderful flora. For example, CDFA does not regulate firewood to prevent movement of pests within the State. It has not regulated numerous invasive plants or several wood-boring insects. These include the goldspotted oak borer; the polyphagous and Kuroshio shothole borers; and the Mediterranean oak borer.

On the other hand, CDFA is quick to act against pests that might enter the state from elsewhere in the country, e.g., spongy moth (European or Asian), emerald ash borer and spotted lanternfly.

I hope Californians and the several non-governmental organizations focused on invasive species will lobby the legislature to adopt Assembly Bill 2827. I hope further that they will try to identify and secure a source of funds to support the mandated action by CDFA and other agencies responsible for managing the fauna, flora, and other taxa to which invasive species belong.

I applaud Ms. Reyes’ initiative. I hope legislators in other states will consider proposing similar bills.

Posted by Faith Campbell

www.fadingforests.org

Proposed new surveillance approach: focus on the receiving ecosystem

Whitebark pine – a foundational & keystone species in high elevation mountains of the West; photo by Walter Siegmund

A British scientist has proposed a new way to conduct early pest detection surveillance that she thinks will better serve resource managers: prioritize ecosystems which would suffer the greatest alteration if a non-native plant pest decimated one or more plant species. She says scientists should focus on foundational species and maintaining habitat resilience.

Dr. Ruth J. Mitchell leads the Biodiversity and Ecosystems Group within the Ecological Sciences Department at the James Hutton Institute in Aberdeen, Scotland. The Institute works on issues relevant to sustainable management of natural resources. I provide a full citation of her article at the end of the blog.

Dr. Mitchell’s focus is on protecting biological diversity. She worries that introduced plant pests can drive large-scale declines in native plant species. She mentions several examples, including chestnut blight and ash decline. Those declines, in turn, can cause a range of cascading effects on associated species that use the host plant for feeding, breeding and shelter, and on ecosystem functioning. To be prepared to counter this level of risk, managers of natural habitats need to know which habitats and plants are at greatest risk in order to prioritize surveillance of the most likely human actions and sites; and allocate resources to address the most damaging invasions.

Her proposal: prioritize host plant species or habitats which ecological theory indicates an invasion would have the greatest ecological impact. In other words, focus on “foundational species” — plant species that drive key ecosystem functions; or low (plant) diversity habitats — based on the assumption that diverse communities are more stable and resilient than less diverse communities.

Mitchell notes that ecological theory posits that if a foundation species is lost or declines, its disappearance will have a greater effect on the ecosystem than if non-foundation species are impacted. She believes that although there is no list of foundation species, scientific staff can develop appropriate lists for their site. For her study, she made the simplistic assumption that those species that occur at high abundance are most likely to be foundation species. Regarding the second, habitat-resilience criterion, Mitchell assumed that a pest which eliminates a plant species in a low-diversity habitat is likely to have a greater ecological impact on that habitat’s functioning than would extinction of a species in a high-diversity habitat, which is likely to have redundancies.

Mitchell asserts that these approaches to surveillance take account of an invasion’s impacts on broader associated species and ecosystem functions – on biodiversity broadly. These suggested methods have other advantages, too. They avoid the bias in existing lists of pests, which consist predominantly plants of commercial importance; and they don’t need to be updated frequently.

Mitchell identifies four ways to prioritize surveillance efforts based on the potential host rather than the potential pest. The surveillance monitoring might target:

(1) Plant genera known to host the pests (including pathogens) most likely to establish (Host-pest);

(2) Habitats harboring hosts for the greatest number of pests most likely to establish (Habitat-pest);

(3) Plants classed as foundation species (Foundation-species);

(4) Habitats with low plant species diversity and hence low resilience (Habitat-resilience).

Mitchell analyzed the damage that 91 pest species might cause to plant species which occur at 25% or higher cover in 12 broad habitat types in the United Kingdom. As a case study, she also looked at 22 vegetation communities within one of those habitat types (heathland). (See the article for a discussion of how she derived her list of 91 pests, their hosts, and the entity responsible for designating the habitat types.)

For both hosts and habitats, Mitchell compared results of two approaches: (a) assessment based on lists of known known pests; and (b) assessment based on potential ecological impact. Surveillance based on known risks i.e. lists of plant pests(i.e., the Hosts-pest and Habitat-pest methods) assumes that scientists have a complete list of pests, their risk of establishment, and their impacts. We know that is not the case. As an illustration, Mitchell’s review of the literature identified 142 insects or pathogens hosted by plant genera present on British moorlands that are not listed as pests by the appropriate British authority, the UK Plant Health Risk Register (PHRR).

To conduct a “Foundation-species” surveillance program, one must first identify foundational plant species. Mitchell defined those as species that constitute more than 75% cover in any plant community. (While this is admittedly an oversimplification, Mitchell says that the loss or severe decline of such abundant species will have a major impact on community composition.) One then prioritizes surveillance of these species – regardless of whether they are at risk from a known pest. This method emphasizes attention to potential impact to the habitat or plant community. Furthermore, this approach accommodates detection of the ‘known unknown’ pests.

To conduct a “Habitat-resilience” surveillance program, one must first identify the number of species in each habitat or vegetation community that occur at more than 25% cover. One then prioritizes surveillance of those habitats with the lowest average species diversity.

Differences in results

When basing the analysis on lists of known pests threatening all 12 habitat types, two genera stood out as at particular risk: Prunus and Solanum. Each consists of hosts supporting more than 20 of the 91 pests. Another 17 genera comprised hosts of six or more pests. Many of these genera include species that are important in ornamental horticulture or production forestry. Mitchell considers this a flaw. She points out that different genera ranked highest under this system when the focus narrowed to heathland communities. In heathlands, the genera comprising hosts of the most pests were Calluna, Erica, Festuca and Vaccinium.

American elm – a deserving priority for pest surveillance! Photo by F.T. Campbell

I note that from my perspective – concern about pests that kill native trees – several of the 17 genera included in the “known pests” analysis do raise alarm: Acer, Salix, Ulmus, Fraxinus, Pinus, Quercus, Betula, Viburnum, and Juniperus.

Mitchell then tested the results of focusing on habitat types where the highest number of pests were likely to become established. This method gave highest priority to woodlands – because plants in this habitat type can host 87 of the 91 pests. The second priority should be open habitats (defined as disturbed habitats, arable weed communities, weedy pastures, paths, verges, wasteland and urban habitats). Plants in the “open habitat” type can host 54 pests. (While Mitchell did not specify whether she excluded non-native plant species from her calculations, she does write generally about impacts on native flora – so I believe she did.)

Looking specifically at the 22 heathland vegetation communities, Mitchell identified four communities as able to host the greatest number of pests so deserving surveillance priority.

When she focused on “foundation species”, Mitchell found a range of plant species that occur at 75% or greater cover in each habitat. Again, the highest number (71 species) occur in woodlands; the lowest (11 species) grow in Calcicolous grasslands. In the 22 heathland plant communities, the number of plant species meeting this criterion numbered fewer than five in each. Two communities have no “foundation” species for surveillance since no vascular plant species that occur at 75% cover. In both the habitat and community cases, the surveillance priority of managers of each habitat type would concentrate on the species that fit this criterion for the appropriate biome.

Finally, Mitchell identified those habitats or communities with the lowest species richness / fewest species as being at greatest risk of unravelling if they lose one or more species to an introduced pest. The data indicated these to be the Salt Marsh and Swamps and tall-herb fens systems. At the other end of the spectrum, Mesotrophic grasslands and Woodlands have the lowest priority for surveillance because they are species-rich. Of course, communities within a habitat type vary greatly in their species richness and associated resilience. For example, the one heathland community which has only two species occurring at 25% or greater cover has a higher priority than the communities with more such species.

heath – *Erica carnea* ; photo by H. Zell

Mitchell asserts that prioritizing plant species or habitats for surveillance based on potential ecological impact rather than risk (known pests) provides a less biased process and allows for the detection of the known unknowns pests. The resulting set of priority surveillance targets differs significantly from the set developed by reliance on pest lists. For example, looking at heathland communities, the Host-pest and Foundation-species methodologies share only three of 24 host genera. The differences arise from the PHRR’s bias oflisting predominantly species relevant to agriculture, horticulture, or forestry. None of these genera is listed under the Foundation-species methodology.

Since trade in plants for planting is the main pathway of introduction of non-native pests, Mitchell concedes that plant species in natural habitats that are closely related to species of commercial importance might be more threatened than other species. However, such an approach takes no account of the potential for a pest to jump hosts.

Prioritization based on potential ecological impact rather than known risk has many advantages. The Foundation-species method prioritizes those plant species whose decline would have the greatest impact on wider biological diversity, ecosystem function and service delivery. That is, it incorporates consideration of the wider risks to the whole ecosystem rather than just the risk to a specific plant species. The Habitat-resilience method similarly takes account of the wider ecosystem level impacts, targeting those habitats or communities that might recover less quickly

On a practical level, these approach do not require surveyors (who might be citizen scientists or land manager) to identify specific pests. Instead, the surveyors report signs of unhealthy-looking plants to the relevant authorities, who then identify the cause.

These methods address a universal problem for plant health: the many pests that are previously unknown before their emergence in new regions and on naïve hosts. Mitchell briefly mentions scientists’ continue struggle to identify traits that can forecast potential pest impacts. [See my blogs re: studies by Mech, Schulz, Raffa]

redbay tree killed by laurel wilt disease – a pathogen unknown until it was introduced to southeastern U.S. Photo by F.T. Campbell

Mitchell suggests several ways to adapt these approaches to other countries or improve their targetting. First, scientists can link various pest/host databases (e.g., EPPO or CABI databases) to landcover or biome data and national or regional vegetation classification systems to make the system appropriate for their country or region. Incorporating attention to dirty equipment and movement of soil &/or plants is fitting at sites undergoing habitat restoration.

It is possible to refine the “foundation species” approach by applying a trait-based approach. She names two examples.

Finally, the Habitat-resilience method could be enhanced by integrating metrics of plant phylogenetic and functional diversity to the idea functional redundancy.

Mitchell stresses the need to unite efforts by many agencies and stakeholders within each country, as well as across political boundaries. She asserts that such collaborative efforts are more efficient / less costly, so lessening the restrictions imposed by resource limits. She also advocates reliance on citizen science and “passive surveillance” or chance observations by professionals agents, land-users and owners. These steps can facilitate large-scale surveillance that would otherwise be financially infeasible.

Mitchell highlights the difficulties imposed by the division of responsibilities. Usually the National Plant Protection Organization (NPPO) is responsible for early detection surveillance. The agency’s goal is to detect pests sufficiently early to facilitate eradication – or at least effective control. Its program is linked to regulatory requirements under the international plant health system. link to blogs & FF reports While the NPPO’s responsibilities include both cultivated and uncultivated (wild) plants, in many countries the NPPO prioritizes plants with commercial value. (This is certainly true in the United States – see my previous blogs & the Fading Forest reports – links provided below; and apparently the United Kingdom [Dr. Mitchell’s article] and Australia.) Protecting plant health in habitats is usually the task of conservation organizations. Mitchell calls for unifying these programs. CISP is advocating draft legislation that aims to fix this gap in the U.S. link to Welsh bill

What do you think? Is this approach as promising as Dr. Mitchell believes? Is it feasible?

I certainly concur that pest-based surveillance ignores the various categories of “unknown” pests and focus on commercially important species to the detriment of ecologically important ones. However, can such a system provide “early detection” of introduced pests? We have learned that insects and pathogens causing noticeable damage in natural environments have probably been present in a country or region for years – or decades. Perhaps these ecosystem-based criteria should be applied as guidance for selecting species to be monitored in “sentinel plant” programs. The plantings would be established in situations likely to receive pests early in their invasion process, e.g., warehouse districts (for pests in wood packaging) and ornamental nurseries that import growing stock.

Mitchell says the same issues pertain with regard to wildlife disease. See her article for sources.

SOURCE

Mitchell, R.J. 2024. A host-based approach for the prioritization of surveillance of plant pests and pathogens in wild flora and natural habitats in the UK. Biol Invasions (2024) 26:1125–1137 https://doi.org/10.1007/s10530-023-03233-x

Posted by Faith Campbell

www.fadingforests.org

Europe outlaws “ecocide”

American bullfrog (*Lithobates catesbeianus*); photo by Will Brown via Wikimedia; one of invasive animals deliberately introduced to Europe in the past

In February 2024 the European Parliament approved legislation outlawing “ecocide” and providing sanctions for environmental crimes. Member states now have two years to enshrine its provisions in national law.

The new rules update the list of environmental crimes adopted in 2008 and enhance the sanctions. The goal is to ensure more effective enforcement. Listed among the offenses are:

the import and use of mercury and fluorinated greenhouse gases,
the import of invasive species,
the illegal depletion of water resources, and
pollution caused by ships.

This action followed an in-depth analysis of the failures of the previous EU environmental directive, first adopted in 2008 (Directive 2008/99/EC). The review found that:

The Directive had little effect on the ground.
Over the 10 years since its adoption few environmental crime cases were successfully investigated and sentenced.
Sanction levels were too low to dissuade violations.
There had been little systematic cross-border cooperation.

EU Member states were not enforcing the Directive’s provisions. They had provided insufficient resources to the task. They had not developed the needed specialized knowledge and public awareness. They were not sharing information or coordinating either among individual governments’ several agencies or with neighboring countries.

The review found that poor data hampered attempts by both the EU body and national policy-makers to evaluate the Directive’s efficacy.

The new Directive attempts to address these weaknesses. To me, the most important change is that complying with a permit no longer frees a company or its leadership from criminal liability. These individuals now have a “duty of care”. According to Antonius Manders, Dutch MEP from the Group of the European People’s Party (Christian Democrats), if new information shows that actions conducted under the permit are “causing irreversible damage to health and nature – you will have to stop.” This action reverses the previous EU environmental crime directive – and most member state laws. Until now, environmental crime could be punished only if it is unlawful; as long as an enterprise was complying with a permit, its actions would not be considered unlawful. Michael Faure, a professor of comparative and international environmental law at Maastricht University, calls this change revolutionary.

Another step was to make corporate leadership personally liable to penalties, including imprisonment. If a company’s actions cause substantial environmental harm, the CEOs and board members can face prison sentences of up to eight years. If the environmental harm results in the death of any person, the penalty can be increased to ten years.

Financial penalties were also raised. Each Member state sets the fines within certain parameters. Fines may be based on either a proportion of annual worldwide turnover (3 to 5%) or set at a fixed fine (up to 40 million euros). Companies might also be obliged to reinstate the damaged environment or compensate for the damage caused. Companies might also lose their licenses or access to public funding, or even be forced to close.

Proponents of making ecocide the fifth international crime at the International Criminal Court argue that the updated directive effectively criminalizes “ecocide” — defined as “unlawful or wanton acts committed with knowledge that there is a substantial likelihood of severe and either widespread or long-term damage to the environment being caused by those acts.”

Individual member states also decide whether the directive will apply to offences committed outside EU borders by EU companies.

Some members of the European Parliament advocate for an even stronger stance: creation of a public prosecutor at the European Union level. They hope that the Council of Europe will incorporate this idea during its ongoing revision of the Convention on the Protection of the Environment through Criminal Law. To me, this seems unlikely since the current text of the Convention, adopted by the Council in 1998, has never been ratified so it has not come into force.

The Council of Europe covers a wider geographic area than the European Union – 46 member states compared to 27. Members of the Council of Europe which are not in the EU include the United Kingdom, Norway, Switzerland, Bosnia-Hercegovina, Serbia, Kosovo, Albania; several mini-states, e.g., Monaco and San Remo; and countries in arguably neighboring regions, e.g., Armenia, Azerbaijan, Georgia, and Turkey.

While I rejoice that invasive species are included in the new Directive, I confess that I am uncertain about the extent to which this inclusion will advance efforts to prevent spread. The species under consideration would apparently have to be identified by some European body as “invasive” and its importation restricted. As we know, many of the most damaging species are not recognized as invasive before their introduction to a naïve environment. On the other side, the requirement that companies recognize new information and halt damaging actions – even when complying with a permit! – provides for needed flexibility.

Posted by Faith Campbell

www.fadingforests.org

Read both: a short call to action (41 pp) based on a long report (952 pp!) Then Act!!!

U.S. Department of Agriculture headquarters; lets lobby these people! photo by Wikimedia

Twenty-three scientists based around the world published a Letter to the Editor titled “Overwhelming evidence galvanizes a global consensus on the need for action against Invasive Alien Species” It appears in the most recent edition of Biological Invasions (2024) 26:621–626.

The authors’ purpose is to draw attention to the release of a new assessment by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services’ (IPBES).

The report was issued in September 2023. It is described as the most comprehensive global synthesis of the current knowledge on the bioinvasion process and the impacts of invasive alien species (952 pages!). Its preparation took nearly a decade. Most important, it represents the first consensus among governments and scientists worldwide on the magnitude and extent of the threats that bioinvasions pose to nature, people, and the economy.

The proposed solutions are astoundingly broad and ambitious: transformation of how governments and societies perform. I don’t disagree! However, we need interim steps – “bites of the elephant.” In my view, the report falls short on providing these.

Our challenge: join others in bringing this analysis to decision-makers’ attention. Can we pull out information that will help persuade U.S. decision-makers – governmental and non-governmental – that the threat is both urgent and solvable? How do we more effectively advocate for the aggressive, science-based action that we all know is needed?

(I hope that the fact that the report was prepared under the auspices of the Convention on Biodiversity, to which the U.S. is not a party, does not intensify the challenge for us.)

Why we need to restructure the behavior of governments and societies

Bioinvasions are facilitated by policies, decision-making structures, institutions, and technologies that are almost always focused on achieving other goals. Species transport and introduction are driven by policies aimed at promoting economic growth – especially trade. Later stages of invasions, i.e., establishment and some spread, are accelerated by certain uses of land and sea plus climate change. For example, activities that fragment habitats or cause widespread habitat disturbance provide ready places for bioinvasions. Rarely are those who gain by such policies held accountable for the harms they produce via bioinvasions.

To address these unintended consequences, the IPBES report calls for “integrated governance.” Its authors want coordination of all policies and agencies that touch on the indirect drivers, e.g., conservation; trade; economic development; transport; and human, animal, and plant health. Policy instruments need to reinforce – rather than conflict with — strategic invasive species management across sectors and scales. This involves international agreements, national regulations, all governmental sectors, as well as industry, the scientific community, and ordinary people – including local communities and Indigenous Peoples.

The report also calls for establishment of open and inter-operable information systems. This improved access to information is critical for setting priorities; evaluating and improving regulations’ effectiveness; and reducing costs by avoiding duplication of efforts.

Critically important information that is often unspoken:

Indirect causes underlying the usual list of human activities that directly promote bioinvasions are the rapid rise of human population and even more rapid rise in consumption and global trade.
Biosecurity measures at international borders have not kept pace with the growing volume, diversity, and geographic origins of goods in trade.

Continuation of current patterns is expected to result in one-third more invasive species globally by 2050. However, this is an underestimate because today’s harms reflect the consequences of past actions – often from decades ago. Drivers of invasions are expected to grow in both volume and impact.
We can prevent and control invasive alien species – but that success depends on the availability of adequate, sustained resources, plus capacity building; scientific cooperation and transfer of technology; appropriate biosecurity legislation and enforcement; and engaging the full range of stakeholders. These require political will.
A major impact of bioinvasion is increased biotic homogenization (loss of biological communities’ uniqueness). This concerns us because we are losing the biotic heterogeneity that provides insurance for the maintenance of ecosystem functioning in the face of ongoing global change.
The IPBES study asserts that successfully addressing bioinvasions can also strengthen the effectiveness of policies designed to respond to other drivers, especially programs addressing conservation of biological diversity, ensuring food security, sustaining economic growth, and slowing climate change. All these challenges interact. The authors affirm that evidence-based policy planning can reflect the interconnectedness of the drivers so that efforts to solve one problem do not exacerbate the magnitude of others and might even have multiple benefits.

More Key Findings

Overall, 9% (3,500) of an estimated 37,000 alien species established in novel environments are invasive (those for which scientists have evidence of negative impacts). Proportions of invasives is high among many taxonomic groups: 22% of all 1,852 alien invertebrates; 14% of all 461 alien vertebrates; 11% of all 141 alien microbes; and 6% of all 1,061 alien plants. (The discussion of probable undercounts relates to aquatic systems and certain geographic regions. However, I believe these data are all undermined by gaps in studies.)
Invasive alien species – solely or in combination with other drivers – have contributed to 60% of recorded global extinctions. Invasive species are the only driver in 16% of global animal and plant extinctions. Some invasive species have broader impacts, affecting not just individual species but also communities or whole ecosystems. Sometimes these create complexoutcomes that push the system across a threshold beyond which ecosystem restoration is not possible. (No tree pests are listed among the examples.)

dead whitebark pine in Glacier National Park; photo by National Park Service

The benefits that some non-native – even invasive – species provide to some groups of people do not mitigate or undo their negative impacts broadly, including to the global commons. The report authors note that beneficiaries usually differ from those people or sectors that bear the costs. The authors cite many resulting inequities.
There are insufficient studies of, or data from, aquatic systems, and from Africa; Latin America and the Caribbean; and parts of Asia.
The number of alien species is rising globally at unprecedented and increasing rates. There are insufficient data specifically on invasive species, but they, too, are thought to be rising at similar rates.
Horticulure is a major pathway for introducing 46% of invasive alien plant species worldwide.
Regarding invasive species’ greater impact on islands,the IPBES report mentions brown tree snakes on Guam and black rats on the Galapagos Islands. It also notes that on more than a quarter of the world’s islands, the number of alien plants exceeds the total number of native ones. See my blogs on non-native plants on Hawai`i and Puerto Rico. In addition, I have posted several blogs regarding disease threats to rare bird species in Hawai`. The IPBES report does not mention these.

Where the Report Is Weak: Interim Steps

The report endorses adoption of regulated species (“black”) lists.
The report emphasizes risk analysis of species. Unfortunately IPBES’ analysis was completed before publication of the critique of risk analysis methods by Raffa et al. ( (2023) (see references). However, we must take the latter into consideration when deciding what to advocate as U.S. policy.
The report authors call for more countries to adopt national legislation or regulations specifically on preventing and controlling invasive species. (They note that 83% of countries lack such policies). They also list the many international agreements that touch on invasive species-relevant issues. However, Raffa et al. found that the number of such agreements to which a country is a party bears no relationship to the numbers of alien species detected at its border or established on its territory.
The challenge to risk assessment posed by multiple sources of uncertainty can be managed by recognizing, quantifying, and documenting the extent of that uncertainty.

Beech leaf disease – one of many non-native pests that were unknown before introduction to a naive ecosystem. Photo by Jennifer Koch, USDA Forest Service

I appreciate the report’s emphasis on the importance of public awareness and engagement, but I thought the discussion of effective campaigns lacked original ideas.

The report did not fulfill its own goal of fully exploring unappreciated impacts of policies in its discussion of habitat fragmentation. For example, the report notes that grazing by feral alien ungulates facilitates the spread of invasive alien plant species. However, it does not mention the similar impact by livestock grazing (Molvar, et al. 2024).

SOURCES

Molvar, E.M., R. Rosentreter, D. Mansfield, and G.M. Anderson. 2024. Cheat invasions: History, causes, consequences, and solutions. Hailey, Idaho: Western Watersheds Project, 128 pp.

Raffa, K.F., E.G. Brockerhoff, J-C. GRÉGOIRE, R.C. Hamelin, A.M. Liebhold, A. Santini, R.C. Venette, and M.J. Wingfield. 2023. Approaches to forecasting damage by invasive forest insects and pathogens: a cross-assessment. BioScience 85 Vol. 73 No. 2 (February 2023) https://academic.oup.com/bioscience

Posted by Faith Campbell

www.fadingforests.org

Birds v. mosquitoes: hope in Hawai`i

‘i‘iwi (Drepanis coccinea) – formerly very common from low to high elevations; photo by James Petruzzii_U

The endangered honeycreepers (birds) of Hawaiian forests are receiving the attention they deserve – and desperately need. There is good news! Promising and significant efforts are under way, matched to a recent strategic plan. However, it is too early to know their results.

Nearly two and a half years ago, I blogged about efforts by a multi-agency consortium (“Birds, Not Mosquitoes” ). It was working to suppress populations of non-native mosquitoes, which vector two lethal diseases: avian malaria (Plasmodium relictum) and avian pox virus (Avipoxvirus). A single bite from an infected mosquito is enough to weaken and kill birds of some species, e.g., the ‘i‘iwi.

The threats from these diseases – and their spread to higher elevations as mosquitoes respond to climate change – pile on top of – other forms of habitat loss and inroads by other invasive species. All of the 17 species of honeycreeper that have persisted until now are listed as endangered or threatened under the federal Endangered Species Act. Four are in danger of extinction within as little as 1 – 2 years. These are ‘Akeke`e (Loxops caeruleirostris), ‘Akikiki (Oreomsytis bairdi)), Kiwikiu (Maui parrotbill, (Pseudonestor xanthophrys), and `Akohekohe (Palmeria dolei).

All these bird species are endemic to the Hawaiian archipelago — found nowhere else on Earth. They are already remnants. Nearly 80 bird species have gone extinct since people first colonized the Hawaiian Islands 1,500 years ago. Eight of these extinctions were recognized in October 2021. Extinction of the final cohort would compromise the integrity of unique ecosystems as well as the Islands’ natural and cultural heritage.

I rejoice to report that the federal government has responded to the crisis. In late 2022 several Interior Department agencies adopted a multiagency Strategy for Preventing the Extinction of Hawaiian Forest Birds. The strategy specifies responsibilities for the key components of the program. These include: a) planning and implementing landscape-level mosquito control using Incompatible Insect Technique (IIT); b) translocating birds to higher elevation sites on other Hawaiian islands; c) establishing captive populations of at-risk birds; and d) developing next-generation tools that increase the scope or efficacy of these actions. All these activities are being developed and conducted through intensive consultation with Native Hawaiians.

On August 8, 2023, the Secretary of Interior announced the allocation of $15,511,066 for conservation and recovery efforts for Hawaiian forest birds. About $14 million of the total was from the Bipartisan Infrastructure Law (Public Law 117-58). The funds are being channelled primarily through the U.S. Fish and Wildlife Service (FWS) ($7.5 million) and the National Park Service (NPS) ($6 million). Other sources of funding are the “State of the Birds” Program (FWS – $963,786); the national-level competitive Natural Resource grants program (NPS – $450,000); and the Biological Threats Program of the U.S. Geological Survey (USGS – $100,000).

What Is Under Way

I do worry continuing these efforts will be harder once their funding is subject to annual appropriations. However, they are a good start!

Steps have been taken on each of the four key component of the Strategy for Preventing the Extinction of Hawaiian Forest Birds:

a) Planning and implementing landscape-level mosquito control using Incompatible Insect Technique (IIT – see below) to reduce the mosquito vector of avian malaria.

The Consortium has obtained all necessary state permits, regulatory approval of the approach by the U.S. Environmental Protection Agency, and done required consultations under the Endangered Species Act.
The Department of the Interior has funded a public-private partnership between the National parks and The Nature Conservancy (TNC) to develop, test, and carry out the first deployments of IIT. These occurred in May 2023 at high-elevation sites on the island of Maui. The next releases are planned for Kaua`i.
Consortium participants are carrying out the consultations and scientific preparations need to support the next deployment on the Big Island.

b) Translocating birds to higher elevation sites on the one island where they exist – Hawai`i.

Initial planning has begun to guide translocation of the endangered Kiwikiu (Maui parrotbill) and Akohekohe to higher-elevation, mosquito-free, habitats on the Big Island.

c) Establishing captive populations of the most at-risk species

To facilitate captive breeding of the four most endangered species, the two existing aviaries in Hawai`i need to be expanded. Space must be provided for at least 80 more birds. A contract has been signed for construction of this new aviary space.

d) Developing next-generation tools that increase the scope or efficacy of these actions.

Lab capacity has been expanded to monitor the effectiveness of IIT, as well as for developing next-generation mosquito control tools.

those who decide funding work here … & they work for us!!!!

The Incompatible Insect Technique (IIT) explained

The incompatible insect technique has been used successfully elsewhere to combat mosquitoes that transmit human diseases. Many insect taxa – including mosquitoes – harbor a naturally-occurring bacteria (Wolbachia). This bacterium has more than one strain or type. When a male mosquito with one type of Wolbachia mates with a female mosquito bearing a different, incompatible type, resulting eggs do not hatch. The IIT project releases male mosquitoes that have an incompatible strain of the bacterium than do local females. (Male mosquitoes do not bite animals seeking a blood meal, so releasing them does not increase the threat to either birds or people.) Implementation requires repeat treatment of sites at a cost of more than $1 million per site per year. It is hoped that this cost will fall with more experience.

Funding for the Strategy’s Four Components

As I noted above, much of the funding for these efforts has come from the Bipartisan Infrastructure Law (Public Law 117-58). Grants under this one-time statute are intended to cover project costs for perhaps five years. Other sources of funds are Congressional appropriations to Interior Department agencies under programs which presumably will continue to be funded in future years. These include the “State of the Birds” program; Endangered Species Act (ESA) implementation, especially its §6 Cooperative Endangered Species Conservation Fund; and State Wildlife Grants administered by the U.S. Fish and wildlife Service. However, funding under these programs is never guaranteed and competition is fierce. I hope participants – and the rest of us! – can be effective in lobbying for future funds required to save Hawaii’s birds from extinction.

a) Deploying IIT

Over Fiscal Years 2017 – 2021 (ending September 2021), Interior Department agencies supported the IIT program by:

Providing $948,000 to the State of Hawai`i from “State of the Birds”, State Wildlife Grants, and Endangered Species Act (ESA) §6;
The U.S. Fish and Wildlife Service provided $545,000 plus staff time’
National Park Service provided $1.2 million for IIT preparations at Haleakala National Park and surrounding state and Nature Conservancy lands
U.S. Geological Survey provided about $7.05 million in research on Hawaiian forest birds, invasive mosquitoes, and avian malaria.

The State of Hawai’i allocated $503,000 and employee staff time.

In addition,

the National Fish and Wildlife Fund provided a total of $627,000 in grants to TNC and American Bird Conservancy for Wolbachia IIT.
TNC committed to supporting some of the initial costs to deploy Wolbachia IIT for the first site in Hawai`i through a contractor (see below)
American Bird Conservancy provided funding for coordination and public outreach.

In FY2022 (which ended in September 2022),

NPS provided $6 million for on-the-ground work on Maui, also development and initial production of Wolbachia IIT.
Interior Department Office of Native Hawaiian Relations provided in-kind services to engage with Native communities’ members

b) Moving endangered birds to mosquito-free areas at high elevations on the Big Island

This is planned to begin by 2030. Interior committed unspecified funds to planning and consultation with Native Hawaiians.

c) Rearing captive birds

FWS supports operation of the two existing aviaries through two funding channels: $700,000 annually provided directly to the aviaries, plus another $500,000 per year through ESA §6through the State of Hawai`i. The San Diego Zoo – which operates the aviaries — provides $600,000 – $800,000 per year in the form of in-kind services, staffing, veterinarians, and administrative support. Interior’s Office of Native Hawaiian Relations provided in-kind services to support to engagement with Native Hawaiian community members

d) Regarding exploration of “next-generation” mosquito control tools

The FWS provided $60,000 to a scientific laboratory to study precision-guided Sterile Insect Technique (pgSIT) tools to protect bird species threatened by avian malaria.

Funding for the portions of these programs dependent upon annual appropriations is uncertain. Current signs are promising: House and Senate bills to fund for the current year (Fiscal Year 2024) – which began in October 2023! – both support at least some aspects of the program. According to American Bird Conservancy, the Senate appropriations bill has allocated $2.5 million to parts of the program. According to the Committee report, the House appropriations bill allots $4.7 million to the State of the Birds program to respond to urgent needs of critically endangered birds. The report goes on to direct the FWS to “incorporate adaptation actions into new and revised recovery plans and recovery implementation strategies, such as with the mosquito vector of avian pox & malaria in the revised Hawaiian Forest Birds recovery plan. …” Per the report, the Appropriations Committee “continues to encourage the [NPS] to respond to the urgent landscape-scale needs of critically endangered forest birds with habitats in national parks.” The report then specifies species threatened by non-native mosquitoes carrying avian malaria and other pathogens. Finally, the report allocates $500,000 to the U.S. Geological Survey for research on the Hawaiian forest birds.

Meanwhile, the American Bird Conservancy is preparing to advocate for $20 million for FY25 through “State of the Birds” Activities and associated NPS and USGS programs. The details of this amount have not yet been laid out.

CISP will support this request and urges you to do so also. We will suggests ways to help when we know more.

Posted by Faith Campbell