Treesearch

Facing a Challenge Non-native diseases and insects as well as a changing climate pose serious threats to native trees in North America. Genetic variation in a species is key to its enduring persistence in the face of these abiotic and biotic threats. Efforts to conserve genetic diversity of North American tree at-risk species will ensure the genetic resources of a species are available to help foster management activities to preserve tree species in native and urban forests, retain their invaluable roles in providing ecosystem services, and commercial and cultural uses. One species facing...

Challenge Port-Orford-cedar (POC) (Chamaecyparis lawsoniana) is a long-lived conifer native to southwest Oregon and northwest California, occurring from sea level to above 1500 m (5085 ft). It is a foundational species in its native ecosystems and is used world-wide horticulturally. A non-native pathogen, Phytophthora lateralis, cause of Port-Orford-cedar root disease, has caused high mortality in native forest ecosystems and ornamental plantings (Betlejewski et al. 2011). The presence of P. lateralis has limited the use of POC in managed plantations and urban forests. There is concern...

Kentucky coffeetree, Gymnocladus dioicus, is a picturesque shade tree adaptable to urban conditions and drought, with no serious insect or disease problems. These traits make G. dioicus a promising candidate among diverse tree genera to replace ash (Fraxinus) trees affected by the emerald ash borer (Agrilus planipennis) or oaks (Quercus) being affected by oak wilt (caused by the fungus Ceratocystis fagacearum) within our cities. In nature, Kentucky coffeetree comprises only a small percentage of forested systems across the Midwest, warranting the assembly of an ex situ germplasm collection....

Quercus oglethorpensis (Oglethorpe oak) is an endangered species native to the southeastern United States. It is threatened by land use changes, competition, and chestnut blight disease caused by Cryphonectria parasitica. The species is distributed sparsely over a linear distance of ca. 950 km. Its range includes several disjunct populations potentially harboring unique genetic diversity or adaptive variation. Protected populations in the Bienville National Forest (Mississippi), Oconee National Forest (Georgia), and Sumter National Forest (South Carolina) are regularly monitored and...

Changing climate and declining forest populations imperil the future of certain forest tree species. To complement forest management and genetic conservation plans, we propose a new paradigm for seedling seed orchards: foster genetic mixing among a variety of seed sources to increase genetic diversity and adaptive potential of seed supplies used for forest restoration. This new type of seed orchard, a restoration seed reserve (RSR) targeting imperiled species, would incorporate into seed production the seed transfer concepts of assisted gene flow and composite provenancing (Aitken and...

Butternut (Juglans cinerea), a native riparian forest tree, has suffered significant decline throughout most of its range due to a fatal fungal disease, butternut canker (caused by Sirococcus clavigignenti-juglandacearum). It has also been subject to natural hybridization pressures from Japanese walnut (J. ailantifolia), first introduced to North America ~1850. Butternut is now listed as a “species of concern” in Canada and similarly classified in several states of the United States. Previous experience indicates site-related shifts in fitness for Japanese walnut × butternut hybrids...

American chestnut (Castanea dentata) was once a foundational species in much of its native range, especially in the Appalachian Mountains of the eastern United States. Unfortunately, the species was driven to functional extinction by the accidental importation of an exotic fungal pathogen (Cryphonectria parasitica), the causal agent of chestnut blight disease. Efforts to restore the American chestnut have been ongoing since the early 20th century and include three primary techniques: classical plant breeding, genetic modification, and reduction of fungal virulence. While restoration of the...

Long term storage of seeds at freezing temperatures is one strategy for genetic conservation of tree species. It can be used to preserve species that produce seeds that remain viable after drying to a low seed moisture content. The U.S. Department of Agriculture Forest Service (USDA FS) National Seed Laboratory (NSL) began long term seed storage for genetic conservation in 2005. The program is mostly focused on five-needle pines (Pinus) and ash (Fraxinus) species. The genetic resources of both groups of species are eroding rapidly in the wild because of attack from invasive exotic pests...

Mexico is both an oak (Quercus) biodiversity hotspot (over 160 described species) and the western hemisphere's leader in magnolia (Magnolia) diversity (36 described species). In the face of myriad threats to these groups, including climate change, habitat loss/fragmentation, overharvesting, and plant pests/pathogens, the imperative to preserve the genetic diversity of these trees has become a high priority of the Vallarta Botanical Garden (VBG). In collaboration with researchers from the University of Guadalajara, the VBG has several new initiatives underway to acquire diverse and well-docu...

Resource managers in Hawaii face unique forest conservation challenges. Invasive species continue to inundate the remote island archipelago, directly threatening its forest resources. Hawaii has the largest number (> 400) of endangered plants in the United States, and managers use genetic approaches to preserve these small populations which are often island endemics. Many of the common forest tree species that grow throughout the islands face threats from pests and disease, but in most cases, little is known about their genetics and whether breeding resistance is a viable option. This...