Treesearch

With limited resources for habitat conservation, the accurate identification of high-value avian habitat is crucial. Habitat structure affects avian biodiversity but is difficult to quantify over broad extents. Our goal was to identify which measures of vertical and horizontal habitat structure are most strongly related to patterns of avian biodiversity across the conterminous United States and to determine whether new measures of vertical structure are complementary to existing, primarily horizontal, measures. For 2,546 North American Breeding Bird Survey routes across the conterminous...

In northeastern Sonora, isolated Sky Island mountain ranges with desertscrub, desert grassland, oak woodland, and pine-oak forest have high biodiversity. El Aribabi Conservation Ranch in the Sierra Azul (from 30°51’13”N, 110°41’9”W to 30°46’38”N, 110°32’3”W) was designated a Private Protected Natural Area by the Comisión Nacional de Áreas Naturales Protegidas in March 2011. The flora contains 447 taxa in 81 families and 301 genera. The most diverse families are Asteraceae (63 taxa, 14.1%), Poaceae (41 taxa, 9.2%), Fabaceae (36 taxa, 8.1%), Euphorbiaceae (18 taxa, 4.1%), Cactaceae (13 taxa,...

Yellow toadflax and Dalmatian toadflax are problematic invasive plant species in North America. Yellow toadflax was introduced multiple times to the United States from Europe, beginning in the late 1600s. Dalmatian toadflax has similarly been repeatedly introduced to the United States, starting in 1874. Both species are known to inhabit disturbed areas, competing for limiting resources with native plant species. Both are obligate outcrossed species, which allows them to maintain a high level of genetic diversity. Both species are known to inhabit a wide range of ecosystems.

Following what was then one of the most destructive fire years on record, President Bush signed into law the Healthy Forests Restoration Act of 2003. The law requires no less than fifty percent of all funds allocated for hazardous fuels reductions to occur in the wildland-urban interface (WUI), with the aim of enhancing the protection of homes and reducing the costs of fighting wildfire. Available resources, however, have not been able to keep up with the accumulation of fuels and a rapidly expanding WUI. In 2012, wildfires burned 9 million acres in 67,000 separate fires throughout the...

We created six new tree-ring chronologies in northern Utah, which were used with preexisting chronologies from Utah and western Wyoming to reconstruct mean annual flow for the Logan River, the largest tributary of the regionally important Bear River. Two reconstruction models were developed, a ''Local'' model that incorporated two Rocky Mountain juniper chronologies located within the basin, and a ''Regional'' model that also included limber pine and pinyon pine chronologies from a larger area. The Local model explained 48.2% of the variability in the instrumental record and the juniper...

Trends in streamflow timing and volume in the Pacific Northwest United States have been attributed to increased temperatures because trends in precipitation at lower elevation stations were negligible. We demonstrate that observed streamflow declines likely are associated with declines in mountain precipitation, revealing previously unexplored differential trends. Lower-troposphere winter (November-March) westerlies are strongly correlated to high elevation precipitation but weakly correlated with low elevation precipitation. Decreases in lower-tropospheric winter westerlies across the...

Armillaria species display diverse ecological roles ranging from beneficial saprobe to virulent pathogen. Armillaria solidipes (formerly A. ostoyae), a causal agent of Armillaria root disease, is a virulent primary pathogen with a broad host range of woody plants across the Northern Hemisphere. This white-rot pathogen grows between trees as rhizomorphs and attacks sapwood as mycelial fans under the bark. Armillaria root disease is responsible for reduced forest productivity due to direct tree mortality and non-lethal infections that impact growth. Here, we characterize a transcriptome of a...

Post-stratification is commonly used to improve the precision of survey estimates. In traditional poststratification methods, the stratification variable must be known at the population level. When suitable covariates are available at the population level, an alternative approach consists of fitting a model on the covariates, making predictions for the population and then stratifying on these predicted values. This method is called Endogenous Post-Stratification Estimation (EPSE) and it is well suited for applications using remote sensing data. In this article, we investigate the performanc...

Fall nutrient loading of deciduous forest nursery seedlings is of special interest because of foliage abscission and varied translocation patterns. For non-deciduous seedlings in the nursery, fall fertilization typically can reverse nutrient dilution and possibly increase nutrient reserves; however, this technique has received little attention with deciduous conifer trees that translocate nutrients before abscising foliage. We evaluated how fall nitrogen (N) fertilization affected N storage and translocation in the deciduous conifer Olga Bay larch (Larix olgensis Henry) seedlings during...

Few pine species develop a seedling grass stage; this growth phase, characterized by strong, carrot-like taproots and a stem-less nature, poses unique challenges during nursery production. Fertilization levels beyond optimum could result in excessive diameter growth that reduces seedling quality as measured by the root bound index (RBI). We grew longleaf pine (Pinus palustris), a grass stage species, in containers of four different volumes (60–336 ml) either coated with copper oxychloride or left untreated and fertilized at low, medium, or high levels of nitrogen (N). In general, N...