Treesearch

Short-term studies show that American chestnut (Castanea dentata) grows faster on mesic compared to xeric sites. Long-term impacts of site quality and corresponding moisture and nutrient availability on backcross chestnut establishment success and resistance to the chestnut blight fungus, Cryphonectria parasitica, however, have not been evaluated. We report here the first year results from a study designed to evaluate the effects of three site quality treatments—mesic, xeric, and intermediate—on the establishment success and blight resistance of chestnut seedlings planted on the Allegheny...

RATIONALE: Carbon dioxide isotope (Δ13C value) measurements enable quantification of the sources of soil microbial respiration, thus informing ecosystem C dynamics. Tunable diode lasers (TDLs) can precisely measure CO2 isotopes at low cost and high throughput, but are seldom used for small samples (≤5 mL). We developed a TDL method for CO2 mole fraction ([CO2]) and Δ13C analysis of soil microcosms.METHODS: Peaks in infrared absorbance following constant volume sample injection to a carrier were used to independently measure [12CO2] and [13CO2] for subsequent calculation of Δ13C values....

Species and populations of forest trees stressed by a rapidly changing climate must adjust or they will not survive. Loss of species and populations could occur if they lack the genetic variability to adapt, the capacity to migrate to suitable habitats, or the ability to adjust to new environments through phenotypic plasticity. Fortunately, many forest tree provenance studies were established in the 20th century across the United States. Most of the studies were initiated or funded by the United States Department of Agriculture (USDA). Many of these plantations are now over a half-century...

Valley oak (Quercus lobata) is a majestic, endemic California native oak, found throughout California's foothills, valleys and flood plains. It is threatened because: Contracted range due to housing and agriculture. Low recruitment in existing stands as a function of land use and increased stress on existing trees and recruitment due to recent and projected climate change. Valley oak substantially shapes ecosystem functions and biodiversity where it occurs through above ground (e.g., provides shelter with cavities, and food with acorns) and below ground (e.g., soil stability and productivit...

The emerald ash borer (EAB, Agrilus planipennis) is a non-native forest pest that has been sweeping across North America causing widespread mortality of trees in the genus Fraxinus, which includes the economically valuable white ash (F. americana). The rapid spread and lethality of EAB, paired with low levels of natural resistance in ash trees, has left forest managers with few management options to slow EAB or to conserve ash trees. Here we present the initial findings of a collaborative project to pursue regional genetic conservation of white ash trees across the Allegheny National...

Provincial tree improvement programs in Alberta began in 1976. Early gene conservation focused on ex situ measures such as seed and clone banking, and research trials of commercial species with tree improvement programs. The gene conservation program now encompasses representative and unique populations of all native tree species in situ. The ex situ program aims to capture representative samples of each species by natural subregion combination in the provincial seed archive. Species whose seeds do not store well may be represented in clone banks, but resources limit those archives to...

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...