Treesearch

The species abundance distribution (SAD) is a fundamental pattern in macroecology. Understanding how SADs vary spatially, and identifying the variables that drive any change, is important from a theoretical perspective because it enables greater understanding of the factors that underpin the relative abundance of species. However, precise knowledge on how the form of SADs varies across large (continental) scales is limited. Here, we use the shape parameter of the gambin distribution to assess how meta‐community‐scale SAD shape varies spatially as a function of various climatic variables...

The Normalized Difference Vegetation Index (NDVI) is one of the most commonly used vegetation indices for monitoring ecosystem dynamics and modeling biosphere processes. However, global NDVI products are usually provided with relatively coarse spatial resolutions that lack important spatial details. Producing NDVI timeseries data with high spatiotemporal resolution is indispensable for monitoring land surfaces and ecosystem changes, especially in spatiotemporally heterogeneous areas. The Improved Flexible Spatiotemporal DAta Fusion (IFSDAF) method was developed in this study to fill this...

Meta-analyses are powerful tools for synthesizing wildlife-habitat relationships, but small sample sizes and complex species-habitat relationships often preclude correlative metaanalyses on endangered species. In this study, we demonstrate qualitative comparative analysis (QCA) as a tool that can reliably synthesize habitat-fitness relationships from small sample sizes for species with narrow habitat requirements.We apply QCA to results from a habitat threshold regression tree model and identify habitat thresholds with consistent positive effects on fitness of the federally endangered...

Forest harvesting and management techniques were hypothesized to result in significant differences in stream water N (NO3–N), P (total P [TP]), and total suspended sediment (TSS) responses among regions of United States. The objectives were (i) to determine the mean response periods after harvesting for each water quality variable, (ii) to compare the regional response yields, and (iii) to determine relationships among water quality, rainfall, and flow. Watershed-scale studies where best management practices were implemented provided a basis for water quality analyses. A mixed model was...

Southern pine beetle, Dendroctonus frontalis Zimmermann, is a major native pest of pine trees in the southeastern United States, Mexico, and Central America. The species' range has recently expanded north for the first time in recorded history. Accordingly, information about the timing of population divergence and past geographic range occupancy may provide an important yardstick for understanding rapid range expansions. Using 16 new and eight existing microsatellite loci, together with mitochondrial (COI) and nuclear (EF-1α and 28S) DNA sequence data, we characterized broad-scale patterns...

Anthropogenic disturbances fragmenting wildlife habitat greatly contribute to extinction risk for many species. In western Canada, four decades of oil and gas exploration have created a network of seismic lines, which are linear disturbances where seismic equipment operates. Seismic lines cause habitat fragmentation and increase predator access to intact forest, leading to declines of some wildlife populations, particularly the threatened woodland caribou, Rangifer tarandus caribou. Restoration of forests within seismic lines is an important activity to reduce habitat fragmentation and...

In addition to their unusually long life cycle, periodical cicadas, Magicicada spp., provide an exceptional example of spatially synchronized life stage phenology in nature.Within regions ("broods") spanning 50,000–500,000 km2, adults emerge synchronously every 13 or 17 years. While satiation of avian predators is believed to be a key component of the ability of these populations to reach high densities, it is not clear why populations at a single location remain entirely synchronized. We develop nonlinear Leslie matrix-type models of periodical cicadas that include predation-driven Allee...

Statistically downscaled climate change scenarios from four General Circulation Models for two Representative Concentration Pathways (RCP)were applied as inputs to a biogeochemical model, PnET-BGC, to examine potential future dynamics of water, carbon, and nitrogen in an old-growth Douglas-fir forest in the western Cascade Range. Projections show 56% to 77% increases in stomatal conductance throughout the year from 1986–2010 to 2076–2100, and 65% to 104% increases in leaf carbon assimilation between October and June over the same period. However, future dynamics of water and carbon under...

Forest ecosystem nutrient cycling is controlled to a large extent by environmental conditions, including soil and air temperature and patterns and forms of precipitation (i.e., rain, snow, and fog). Climate changes around the globe have led to increases in mean land surface temperatures (Hansen et al., 2010; Lawrimore et al., 2011; Jones et al., 2012; Rohde et al., 2013), altered patterns of precipitation (Smith et al., 2012), and an increased occurrence of extreme temperature and precipitation events (Hartmann et al., 2013) over the last several decades. Temperatures are expected to...

In Elko County, Nevada, grazing practices on federal and private lands began to change in the early 1990s to restore proper functioning condition to degraded riparian areas that provide habitat for Lahontan cutthroat trout (Oncorhynchus clarkii henshawi), which is listed as threatened under the Endangered Species Act. Changes in grazing management focused on changing the frequency and duration of hot-season grazing in riparian areas. These changes led to the recovery of riparian vegetation accompanied by the natural colonization of streams by beavers. Beavers and their dams, in turn, have...