Treesearch

Reconstructing the geographic origins of non-native species is important for studying the factors that influence invasion success, however; these analyses can be constrained by the amount of diversity present in the native and invaded regions, and by changes in the genetic background of the invading population following bottlenecks and/or hybridization events. Here we explore the geographical origins of the invasive winter moth (Operopthera brumata L.) that has caused widespread defoliation to forests, orchards, and crops in Nova Scotia, British Columbia, Oregon, and the northeastern...

Proper understanding of the diversity and natural structure of woody species and the impacts of human interventions are prerequisites for maintaining the remaining forests as well as restoration of deforested and degraded areas. This research was conducted to document the impact of human interventions on the population structure and the species diversity in the Arasbaran biosphere reserve in Iran due to the limited research and insufficient knowledge. The study area was divided into three adjacent sampling areas of low, medium, and high destruction intensity. Thirty fixed area 0.1-hectare...

Chestnut blight, a disease that has spread rampantly among American (Castanea dentata (Marsh.) Borkh.) and European chestnut (C. sativa Mill.) trees, results from infection by the fungal pathogen Cryphonectria parasitica (Murrill) M.E. Barr (C. parasitica). This fungus was introduced in the early 1900s and has almost functionally eliminated chestnut trees from the North American landscape. In 2017, we collected chestnut blight samples from two sites (Site B, (Fulton Co., IN) and Site C (Marshall Co., IN)). At the Fulton County planting, Site B, cankers had formed, healed over, and the...

Pistachio (Pistacia vera) is a dioecious tree species in the cashew family originating from Central Asia and the Middle East. The sex of pistachio genotypes cannot be established until inflorescence growth during the reproductive stage. The ability to determine sex before flowering would be extremely beneficial for pistachio growers and breeders. In this study, different methods of soft computing, using classifiers (i.e. KNN, SVM, SOM, ANFIS and RBF) were employed to determine pistachio sex based on geometric features of mature leaves. Data were collected from more than 900 leaves represent...

Conservation of old-growth forests has become an increasingly important objective of Forest Service managers over the last three decades. The US Forest Service recently made changes to policies that prohibit cutting of live trees >53 cm (the “21-inch rule”). We review the disturbance ecology of dry and mesic old-growth forests of Oregon and contrast conservation policies for these two forest types. We describe the development of age-based alternatives to the 21-inch rule on the Klamath Reservation and in the Malheur National Forest in eastern Oregon. We conclude by outlining an adaptive...

Tree pollen with allergenic potential in cities triggers nasal, skin, eye, and asthmatic allergic reactions in humans. Pollen is one of the most common allergy-causing inhaled substances. Tree species composition, cultivar selection and the proximity of certain trees to humans can influence allergic responses. Data from 53 cities or states from various parts of the world were used to assess the magnitude and differences in an allergy index (AI) among the sampled locations and among land uses within cities. Index values for species ranged from one (most allergyfree species) to 10 (highest...

The water balance is an essential tool for hydrologic studies and quantifying water-balance components is the focus of many research catchments. A fundamental question remains regarding the appropriateness of water-balance closure assumptions when not all components are available. In this study, we leverage in-situ measurements of water fluxes and storage from the Southern Sierra Critical Zone Observatory (SSCZO) and the Kings River Experimental Watersheds (KREW) to investigate annual water-balance closure errors across large (1016–5389 km2) river basins and small (0.5–5 km2) headwater-catc...

Photograph 1 [22423A]: When the USDA Forest Service’s Southern Forest Experiment Station began operating on July 1, 1921, the Station had its inaugural silvicultural research project already in the woods. In 1915, Samuel Trask Dana, C.R. Tillotson, and some others from the agency’s Washington office collaborated with Henry Hardtner and Urania Lumber Company to establish a series of plots on the Company’s lands in LaSalle and Winn parishes in central Louisiana (Wakeley and Barnett 2011). The plots were in young (10 to 20 years old), even-aged, oldfield stands of loblolly (Pinus taeda) and...

Fire suppression and other factors have drastically reduced wet prairie and pine savanna ecosystems on the Coastal Plain of the southeastern United States. Restoration of these open‐canopy environments often targets one or several charismatic species, and semi‐aquatic species such as burrowing crayfishes are often overlooked in these essentially terrestrial environments. We examined the relationship between primary burrowing crayfishes and three vegetation treatments implemented over at least the past two decades in the Mississippi Sandhill Crane National Wildlife Refuge. Vegetation in the...

We examined tradeoffs between managing for fire resilience versus economic objectives for a large scale (240,000 ha) federal collaborative forest restoration project in the southwestern United States - the Four Forest Restoration Initiative - created to improve fire resilience in fire-adapted ponderosa pine forests that have experienced a century of fire exclusion. However, scaling up forest restoration to substantially change fuels and future fire behavior over large areas is constrained by marginal economic returns from harvested materials. We simulated a range of forest management...