national parks – Page 5 – Center for Invasive Species Prevention

Hawaii’s unique forests now threatened by insects and pathogens – APHIS & State should act

We have known since Darwin that oceanic islands can be cradles of speciation & endemism. Hawai`i exemplifies the phenomenon. Ninety-eight percent of native flowering plants are endemic (Cox). The density of native insect species in Hawai`i is higher than on mainland North America (Yamanaka).

We have known since Elton or earlier that oceanic islands are highly vulnerable to bioinvasion because their unique species did not evolve defenses against predation, herbivory, competition, or diseases; or the ability to adapt to changed soil chemistry or increased fire frequency.

Chapter 8 of the Office of Technology Assessment study of harmful invasive species states:

“Hawaii has a unique indigenous biota, the result of its remote location, topography, and climate. Many of its species, however, are already lost, and at least one-half of the wild species in Hawaii today are non-indigenous. New species have played a significant role in the extinction of indigenous species in the past and continue to do so. Hawaii, the Nation, and the world would lose something valuable as the indigenous fauna and flora decline.”

I apologize for not addressing the disasters wreaked on Hawai’i’s fauna and non-arboreal flora by invasive mammals and birds, plants, and such animal diseases as avian malaria and avian pox. For more on these topics, see the other sources listed below and the websites maintained by the Hawai`i Invasive Species Council and Coordinating Group on Alien Pest Species. Cox notes that alien species span all trophic groups and threaten the complete replacement of the native terrestrial biota.

Outside of land clearing for ranches and other uses, much of the damage to Hawaii’s native forest trees has been caused by introduced mammals – especially pigs and goats; and invasive plants. Few of the enormous number of non-native insects that have established in Hawai`i appear to have attacked native trees. More than 2,600 non-native insects have been introduced; their number equals three-quarters of the NIS insects established in North America, yet Hawai`i constitutes less than 0.01% of the area of North America. The ratio of non-native to native insect species is higher for Hawai`i than for the other geographic areas studied by Yamanaka and colleagues (mainland North America, “mainland” Japan, and two offshore Japanese islands) (Yamanaka).

More than 13% of the non-native insects (=~350) in Hawai`i were introduced intentionally for biological control of agricultural pests and non-native plants (Yamanaka). Cox, Elton, and the Office of Technology Assessment discuss briefly the sometimes damaging effects of these deliberate introductions.

I am aware of only one NIS insect that has seriously threatened a native tree species: the Erythrina gall wasp, which killed many native wiliwili trees as well as lots of introduced coral trees planted in towns and as windbreaks. Biocontrol agents have helped prevent continuing damage from the gall wasp.

Disease pathogens have so far proved greater threats to Hawaiian native trees than introduced insects. Koa wilt is killing koa, especially at lower elevations. It is not certain whether the pathogenic Fusarium fungus is introduced or native; it has been found on all four major islands. Koa is second only to `ohi`a (see below) in abundance in mid to upper elevation Hawaiian forests. It is extremely important ecologically and culturally (koa was the tree from which large, ocean-going canoes were made). Koa also has a wood valued for a range of uses.

`Ohi`a lehua is the most widespread tree on the Islands, dominating approximately 80% of Hawai`i’s remaining native forest (about 965,000 acres, 1500 square miles). These forests are home to Hawai`i’s one native mammal (Hawaiian hoary bat) and 30 species of forest birds (Loope and LaRosa). One threat to `ohi`a comes from `ohi`a or eucalyptus rust. Detected in April 2005, it had spread to all the major islands by August. Fortunately, the strain of `ohi`a rust established in Hawai`i is not very virulent on `ohi`a, but it has killed many plants of an endangered native shrub, Eugenia koolauensis and in Australia it has killed many plants in the Myrtaceae family. Hawaiian conservationists worry that a different, more virulent, strain might be introduced on plants or cut foliage shipped to the Islands from either foreign sources or the U.S. mainland.

A new, apparently more damaging, pathogen was detected in 2010. This new disease is caused by two newly discovered species of the fungal genus Ceratocystis — Ceratocystis lukuohia and C. huliohia. By October 2015 the disease has killed 50% of the `ohi`a trees in several scattered locations totaling 6,000 acres on the southeast lowlands of Hawai`i (the “Big Island”). Tree mortality was nearing the boundary of Hawaii Volcanoes National Park. Hawaii Volcanoes pioneered methods for controlling invasive pigs and plants that threatened to destroy the Park’s forests. Through 40 years of sustained effort, Hawaii Volcanoes has brought those threats under control. Now the Park faces loss of its invaluable `ohi`a forest to this pathogen – which will be infinitely harder to keep out of the Park. (For updates on “rapid ohia death” visit the write-up here.)

The Hawai`i Department of Agriculture has adopted an emergency regulation aimed at preventing transport of infected wood or tree parts from the Big Island to other islands.

Although tree-killing insects and pathogens have so far not been as damaging in Hawai`i as might be expected, the Islands are highly vulnerable due to the large volumes of cargo and people from around the globe which land on the Islands and the few tree species native there. The Erythrina gall wasp has island-hopped from the east coast of Africa to Hawai`i and many islands in between. `Ohi`a rust is native to tropical America and probably reached the islands on cut stems used in floral decorations. It is unknown where the Ceratocytis fimbriata strain evolved or how it reached Hawai`i.

USDA APHIS is responsible for preventing introduction of new plant pests to Hawai`i from non-U.S. jurisdictions (as well as from Guam). APHIS has traditionally paid little attention to plant pests that are thought likely to threaten “only” Hawai`i but not plant (agricultural) resources on the mainland.

Hawaiian authorities are responsible for preventing introductions from the Mainland – but they struggle with inadequate resources to address the huge volumes of incoming freight and they sometimes hesitate to act. (Hawai`i Department of Agriculture considered restricting shipments of foliage in the Myrtacea to minimize the risk of introduction of a new strain of `ohi`a rust, but in the end did not adopt such a measure.)

Hawai`i’s unique biota is an irreplaceable treasure. All Americans should act to prevent introduction additional introductions to the Islands.

SOURCES:
Cox, George W. Alien Species in North America and Hawaii Impacts on Natural Ecosystems 1999
Elton, Charles S. The Ecology of Invasions by Animals and Plants 1958; see especially Chapter 4: The Fate of Remote Islands
Loope, L. and LaRosa, A.M. `Ohi`a Rust (Eucalyptus Rust) (Puccinia psidii Winter) Risk Assessment for Hawai`i
U.S. Congress Office of Technology Assessment. 1993. Harmful Non-Indigenous Species In the United States. OTA-F-565; available at http://govinfo.library.unt.edu/ota/Ota_1/DATA/1993/9325.PDF

Yamanaka, T., N. Morimoto, G.M. Nishida, K. Kiritani, S. Moriya, A.M. Liebhold. 2015. Comparison of insect invasions in North America, Japan and their Islands. Biol Invasions DOI 10.1007/s10530-015-0935-y

Posted by Faith Campbell

National Parks Failing to Protect Forests

Americans love their National parks and expect the National Park Service to ensure the parks’ natural resources are protected “unimpaired for future generations” – as is required by the Service’ founding law.
Despite these expectations, the National Park Service does not take obvious actions to protect trees in the parks from non-native tree-killing insects and plant diseases.

Horton House plantation ruins, Jekyll Island, GA. (Photo by F.T. Campbell) The two large redbay trees shading the house are now gone, killed by laurel wilt. Use your favorite web browser to see how stark the house is now, denuded of its trees.

At historic sites ranging from Horton House plantation on Jekyll Island, Georgia to the Presidio in San Francisco, trees that create atmosphere & maintain visible links to the past have died.

Even more important is the damage occurring to forests in the “crown jewel” wilderness parks:
• Whitebark pines at high elevations of Yellowstone, Glacier, and Crater Lake National parks have been killed by white pine blister rust (see photo below, of dead whitebark pine at Crater Lake). Photo by F.T. Campbell

• The forests of Great Smoky Mountains and Shenandoah National parks, already damaged by chestnut blight, hemlock woolly adelgid, beech bark disease, and gypsy moth, are now losing their ash trees to the emerald ash borer and their walnut trees to thousand cankers disease.
• Everglades National Park and Big Cypress National Preserve are losing their swamp bay trees to laurel wilt
• Tanoak trees in Muir Woods, Redwood National Park, and Pt. Reyes National Seashore have been killed by sudden oak death
• Ash trees in Sleeping Bear Dunes National Lakeshore in Michigan have been killed by the emerald ash borer.

Forests in other “crown jewel” parks are not yet under attack, but are threatened by nearby pests:
• The black oak trees of Yosemite National Park’s signature Valley are at risk to goldspotted oak borer, which has killed more than 100,000 trees in San Diego county.
The threat is obvious … yet the National Park Service dropped efforts to develop a strategy for addressing it. And the NPS has not adopted a national policy requiring campers to obtain their firewood either in the Park or from nearby vendors.

As explained on the Don’t Move Firewood website, firewood is a highly dangerous commodity, since it can transport tree-killing pests to new, vulnerable areas [see also the report Fading Forests III. Some National parks – including Great Smoky Mountains and Shenandoah – have adopted regulations prohibiting visitors from bringing firewood from long distances. However, other parks – including Yosemite – only ask visitors to avoid bringing firewood. In all cases, the firewood regulation or appeal is buried deep within the park’s website. On a more positive note, campers who reserve a campground on such federal websites as www.reserve.gov receive warnings about firewood when they finalize their reservation.

The National Park Service has developed a Manual providing guidance to park managers that describes the threat from firewood and laws and regulations that relate to natural resource protection. However, the Service has left the decision whether to take action to the individual parks’ superintendents.

I think that such a passive stance betrays the Service’ statutory obligation, as laid out in the Organic Act of 1916: the purpose of the National Park Service is
“to conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations.” [emphasis added]

Next year, the National Park Service celebrates its Centenary. I think it should celebrate this anniversary by adopting regulations requiring visitors to obtain firewood locally and finalizing a strategy for combating tree-killing pests.

California Government Ignores Threats to State’s Hardwood Trees

CDFA Fails to Regulate Movement of Firewood

Many of California’s hardwood trees are threatened by two introduced insects – the goldspotted oak borer (or here) and the polyphagous shot hole borer or here. Both are established in southern California, but threaten trees throughout the state.

One of the most likely pathways by which these insects can be moved to vulnerable areas is by the transport of firewood. Yet the California Department of Food & Agriculture (CDFA) has not regulated firewood movement.

goldspotted oak borer

Two Tree-Killers

California’s oaks – including California black oak, canyon live oak, coast live oak, Engelmann oak, Shreve’s oak, and valley oak – are threatened by one of both of these insects. The goldspotted oak borer (GSOB) is established in San Diego County with additional outbreaks in Riverside and Orange counties. In less than 20 years, GSOB has killed nearly 100,000 black oaks in these counties. GSOB also kills coast live and canyon oaks. These oaks growing throughout the state are at risk to GSOB.

areas of California at risk to goldspotted oak borer

The polyphagous shot hole borer (PSHB) carries a fungus. The beetle-disease complex has been found in areas of Los Angeles, Orange, San Bernardino, Riverside, and San Diego counties. The insect attacks more than 300 species of trees, shrubs, and vines; the fungus survives in more than 100 of these.

Trees attacked by PSHB include: 11 species native to southern California; 13 agriculturally important trees, such as avocado; and 53 species that, cumulatively, constitute more than half of all trees planted in urban areas of southern California. While PSHB might not be able to reproduce in all these hosts, it is known to reproduce in five types of maples, five types of oaks, a couple of willows, as well as a poplar, a sycamore, and an alder.

areas of southern California where polyphagous shot hole borer is established

Many of the vulnerable tree species are important components of riparian communities in southern California. PSHB apparently attacks only trees that receive enough water to support the fungus – hence the threat to riparian areas. Since PSHB comes from tropical Southeast Asia, its spread to the north and upslope would probably be limited by winter cold. Nevertheless, a wide variety of trees in large parts of the state appear to be at risk.

Among the natural areas at risk to one or both of these pests is Yosemite National Park. The oak trees growing in Yosemite Valley are black oaks, vulnerable to GSOB.

Both State & National Park Service have Failed to Act

Despite the threat to natural and even agricultural resources throughout the state, CDFA has not adopted regulations governing the movement of firewood – the pathway most likely to spread these pests. CDFA has funded outreach efforts, including flyers, posters at campgrounds, and highway billboards. Broad coalitions – made up of academics; county agriculture and parks officials; federal forestry and public lands staff; and others –are educating the public and firewood vendors about the risk and asking them not to move firewood. But when people ask whether there is a law against moving firewood, these volunteers must answer, “no”. This undermines their message!

Yosemite and the other National parks in the region also have not adopted regulations prohibiting visitors from bringing in firewood obtained outside the park. While the National Park Service discourages people from bringing firewood into the Park from farther than 50 miles away, this request is buried in the detailed description of camping regulations or here.

The other National parks in California also do not regulate visitors’ movement of firewood.

It is past time for state and federal agencies to accept their responsibility to protect priceless natural and agricultural resources by adopting regulations to control the movement of firewood.