Treesearch

Several spatial forest disturbance datasets exist for the conterminous USA. The major problem with forest disturbance mapping is that variability between map products leads to uncertainty regarding the actual rate of disturbance. In this article, harmonized maps were produced from multiple data sources (i.e., Global Forest Change, LANDFIRE Vegetation Disturbance, National Land Cover Database, Vegetation Change Tracker, and Web-Enabled Landsat Data). The harmonization process involved fitting common class ontologies and determining spatial congruency to produce forest disturbance maps for...

Due to the hotter droughts occurring with climate change, grasslands of southwestern deserts and southern plains in the United States are predicted to increasingly lose cover of native plant species, be invaded by nonnative species, and have accelerated soil erosion. We evaluated these predictions for desert grasslands in the Paint Gap Hills of Big Bend National Park, Texas. We used data from 10 monitoring transects established in 1981 and surveyed vegetation composition, canopy cover, and soil surface elevations in 1981, 1983, 1995, and 2014. Four longer and hotter droughts occurred...

Background and aims In northern regions, moss and lichen mats are the major carbon-cycling interface between soils and the atmosphere. We aimed to quantify sensitivity of ground layer nutrient stores to environmental predictors, to better understand interactions with vegetation, topography and climatic conditions. Methods With non-destructive forest inventory techniques, we estimated distributions of biomass, carbon and nitrogen among moss/lichen ground layers in a 1.1 million-ha watershed within Alaska’s boreal forest region. Using nonparametric multiplicative regression, we fit response...

Los inventarios forestales nacionales proporcionan datos básicos sobre la biodiversidad, la integridad de los ecosistemas, y la productividad de los recursos naturales en países de todo el mundo. Con mediciones repetidas, estos datos son una base de información muy poderosa para avanzar en nuestro conocimiento de los procesos ecológicos y su respuesta a la gestión forestal y las perturbaciones naturales. Aunque el análisis de datos dispares (“big data”) con nuevas técnicas (por ejemplo, aprendizaje automático) puede ser de utilidad, no hay sustituto para un diseño estadístico riguroso y...

Boreal forests play critical roles in global carbon, water and energy cycles. Recent studies suggest drought is causing a decline in boreal spruce growth, leading to predictions of widespread mortality and a shift in dominant vegetation type in interior Alaska. We took advantage of a large set of tree cores collected from random locations across a vast area of interior Alaska to examine long-term trends in carbon isotope discrimination and growth of black and white spruce. Our results confirm that growth of both species is sensitive to moisture availability, yet show limited evidence of...

Forest inventories require estimates and measures of uncertainty for subpopulations such as management units. These units often times hold a small sample size, so they should be regarded as small areas. When auxiliary information is available, different small area estimation methods have been proposed to obtain reliable estimates for small areas. Unit level empirical best linear unbiased predictors (EBLUP) based on plot or grid unit level models have been studied more thoroughly than area level EBLUPs, where the modelling occurs at the management unit scale. Area level EBLUPs do not...

The nine federally recognized tribes in Oregon represent the descendants of dozens of bands and communities that had knowledge about, and relationships with, every dimension of the state’s lands, waters, flora, and fauna. While some tribes and their reservations were formed by treaties ratified by the U.S. Senate, other tribes negotiated treaties with the U.S. that either were never ratified or were ignored. This legal and political complexity is characteristic of federal-tribal relations across what was once the Oregon Country (modern day Oregon, Washington, Idaho and parts of Montana and...

Owing to high rates of introgressive hybridization, the plastid genome is poorly suited to fine-scale DNA barcoding and phylogenetic studies of the oak genus (Quercus, Fagaceae). At the tips of the oak plastome phylogeny, recent gene migration and reticulation generally cause topology to reflect geographic structure, while deeper branches reflect lineage divergence. In this study, we quantify the simple and partial effects of geographic proximity and nucleome-inferred phylogenetic history on oak plastome phylogeny at different evolutionary scales. Our study compares pairwise phylogenetic...

Background: Perennial growth in plants is the product of interdependent cycles of daily and annual stimuli that induce cycles of growth and dormancy. In conifers, needles are the key perennial organ that integrates daily and seasonal signals from light, temperature, and water availability. To understand the relationship between seasonal cycles and seasonal gene expression responses in conifers, we examined diurnal and circannual needle mRNA accumulation in Douglas-fir (Pseudotsuga menziesii) needles at diurnal and circannual scales. Using mRNA sequencing, we sampled 6.1 × 109 reads from 19...

Sudden wind shifts caused by atmospheric gust fronts can lead to firefighter entrapments and fatalities. In this study, we describe the physical processes involved in the related phenomena of convective downdrafts, gust fronts and downbursts. We focus on the dominant process, evaporative cooling in a dry surface layer, as characterised by the measure known as downdraft maximum available potential energy (DMAPE). We present a climatological analysis of DMAPE for the coterminous United States, developed from the Climate Forecast System Reanalysis data for the period 1979–2008. Diurnal and...