Treesearch

Climate and land-use change are predicted to lead to widespread changes in population dynamics, but quantitative predictions on the relative effects of these stressors have not yet been examined empirically. We analyzed historical abundance data of 110 terrestrial bird species sampled from 1983 to 2010 along 406 Breeding Bird Survey (BBS) across the western USA. Using boosted-regression trees, we modeled bird abundance at the beginning of this interval as a function of (1) climate variables, (2) Landsat-derived landcover data, (3) the additive and interactive effects of climate and...

Tree mortality is of considerable concern, but the magnitude and extent of forest canopy decline are relatively unknown in landscapes with high levels of topographic complexity, spatial heterogeneity, and species diversity. We assessed 30 years of canopy decline, including a 5-year period characterized by extreme drought, in one of North America’s most diverse landscapes in the Klamath Mountains of northern California, USA.

The relative importance of habitat fragmentation versus loss on species richness has been much debated. However, recent findings that fragmentation effects are relatively weak may be an artifact of using human-classified vegetation rather than adopting a species-eye view to measure landscape structure.

Climate and land‐use changes are expected to be the primary drivers of future global biodiversity loss. Although theory suggests that these factors impact species synergistically, past studies have either focused on only one in isolation or have substituted space for time, which often results in confounding between drivers. Tests of synergistic effects require congruent time series on animal populations, climate change and land‐use change replicated across landscapes that span the gradient of correlations between the drivers of change. Using a unique time series of high‐resolution climate...

Wildland fire scientists and land managers working in fire-prone areas require spatial estimates of wildfire potential. To fulfill this need, a simulation-modelling approach was developed whereby multiple individual wildfires are modelled in an iterative fashion across a landscape to obtain location-based measures of fire likelihood and fire behaviour (e.g. fire intensity, biomass consumption). This method, termed burn probability (BP) modelling, takes advantage of fire spread algorithms created for operational uses and the proliferation of available data representing wildfire patterns,...

Ips hauseri Reitter is themost important bark beetle on Picea schrenkiana in southeastKazakhstan, but its biology, ecology, and outbreak dynamics are poorly known. We dendrochronologically reconstructed a 200-year history of disturbances in the Kazakh Tien Shan P. schrenkiana forests. Only localized, low-severity bark beetle events occurred during the reconstructed period, indicating that extensive high-severity bark beetle outbreaks have not occurred historically in the Tien Shan spruce forest, unlike bark beetle outbreaks in spruce forests in North America, Europe, and Russia. Disturbance...

Multiple high-severity insect outbreaks and wildfires dramatically altered the character of the Pinaleño high-elevation forests with notable impacts on ecosystem services. The Pinaleños are a small mountain range positioned close to large population centers, but not so close that any large industry is dependent on their resources, so regional and local impacts of the insect outbreaks to provisional resources were minor. There were qualitative impacts to cultural services, particularly to recreation, but no documented economic impacts. Effects on carbon and fuels were significant, but...

The first Global Drylands Assessment is a thematic study complementing FAO’s Global Forest Resources Assessment (FRA) but differing from it in method and scope. Unlike FRA, which relies on official national statistics, the Global Drylands Assessment was prepared by a consortium of partner institutions and was carried out through visual interpretation of satellite images. The results are reported at the global and regional levels, not the country level.

Mating strategies contributing to a balance between inbreeding and outcrossing are understudied in all but a few model fungal pathogens. This study examined factors that influence the occurrence of the sexual state of Pyrenophora semeniperda. It was consistently found to have functional copies of the MAT1-1 and MAT1-2 idiomorphs essential for sexual reproduction, despite considerable polymorphism in both single nucleotide polymorphisms (SNPs) and number of 18- base minisatellite repeats. The two idiomorphs occurred at approximately equal frequencies across 25 populations on Bromus tectorum...

Radicinin (1), is a fungal dihydropyranopyran-4,5-dione isolated together with some analogues, namely 3-epi-radicinin, radicinol, 3-epi-radicinol, and cochliotoxin (2-5), from the culture filtrates of the fungus Cochliobolus australiensis, a foliar pathogen of buffelgrass (Cenchrus ciliaris), an invasive weed in North America. Among the different metabolites 1 showed target-specific activity against the host plant and no toxicity on zebrafish embryos, promoting its potential use to develop a natural bioherbicide formulation to manage buffelgrass. These data and the peculiar structural...