Treesearch

At a “clean air” trade winds site in northeastern Puerto Rico, we found an apparent paradox: atmospheric total mercury (THg) deposition was highest of any site in the USA Mercury Deposition Network, but assimilation into the local food web was quite low. Avian blood THg concentrations (n = 31, from eight species in five foraging guilds) ranged widely from 0.2 to 32 ng g−1 (median of 4.3 ng g−1 ). Within this population, THg was significantly greater at a low-elevation site near a wetland compared to an upland montane site, even when the comparison was limited to a single species. Overall,...

El huracán Otto, registrado históricamente como el huracán que tocó tierra firme más al sur en Centroamérica, fue un fenómeno de categoría 3 que impacto el sureste de Nicaragua el 24 de noviembre del 2016. Para describir los efectos del huracán en la avifauna, se realizaron en la Estación Biológica La Lupe conteos de aves antes y después del paso del fenómeno. En los sitios que se realizaron las observaciones, se catalogaron los hábitats como bosque maduro y joven de acuerdo a la diversidad florística y DAP, y se anotó el estrato vertical en el que se observaban. Se determinaron los grupos...

The world´s urbanization forecast shows that 60% of the human population will be living in cities by 2050 (United Nations et al. 2017). This growth will negatively impact natural forests surrounding urban areas and will contribute to losses of biodiversity, ecosystem functions, and ecosystem services. Urban green infrastructure is often associated with improvements to city aesthetics and even with improvements in resident (Kabisch and van den Bosch 2017).

Loblolly pine (Pinus taeda L.) is one of the most widely planted tree species globally. As the reliability of estimatingforest characteristics such as volume, biomass and carbon becomes more important, the necessary resourcesavailable for assessment are often insufficient to meet desired confidence levels. Small area estimation (SAE)methods were investigated for their potential to improve the precision of volume estimates in loblolly pineplantations aged 9–43. Area-level SAE models that included lidar height percentiles and stand thinning status asauxiliary informationwere developed to...

Monitoring is a system for detecting trends over a period of time in areas such as habitat, water, and more. Herein we focus on animal populations and evaluate common quantitative methods for monitoring wildlife species. Animal distribution, abundance, survival, and productivity are examples of important biological parameters that can show trends based on ecosystem condition. Although there are different monitoring types (Morrison and Marcot 1995), monitoring is at its best with targeted (or focused) monitoring (Nichols and Williams 2006), when specific goals and objectives are identified...

When alien plant species arrive in a new environment, they develop novel interactions with native biota that can range from negative to positive. Determining the nature and strength of these interactions is integral to understanding why some aliens are suppressed and others become highly invasive pests. For introduced terrestrial plants, seed and seedling interactions with native biota are crucial, because most nascent populations start from seed. Herein, we explored interactions between native generalist rodent and bird consumers and seeds of the invasive wild cucumber Echinocystis lobata...

Urbanization results in the systemic conversion of land-use, driving habitat and biodiversity loss. The "urban convergence hypothesis" posits that urbanization represents a merging of habitat characteristics, in turn driving physiological and functional responses within the biotic community. To test this hypothesis, we sampled five cities (Baltimore, MD, United States; Helsinki and Lahti, Finland; Budapest, Hungary; Potchefstroom, South Africa) across four different biomes. Within each city, we sampled four land-use categories that represented a gradient of increasing disturbance and...

This paper numerically models the behavior of double-shear, single-bolted joints in wood-steel structures when subjected to very large deformations and compares results with test information. A three-dimensional finite-element model is developed of the main Douglas-fir wood member, steel side plates, bolt, washers, and nut. The model accounts for friction, bolt clearance, progressive damage in the wood, nonlinear and inelastic behavior in the steel bolts and side plates, and complete (linear and nonlinear) compressive constitutive response parallel to the grain in the wood. Hashin’s 3-D...

This study aimed to identify and quantify phytosterols of six black walnut (Juglans nigra L.) varieties, and compare the levels of these phytosterols between black walnuts and English walnut (Juglans regia L.). Totally, 13 phytosterols were identified in the black walnut kernels, with β-sitosterol predominating over the other sterols. The analysis also revealed the presence of 3 phytosterols, Δ5,23-stigmastadienol, cycloeucalenol and 28-methylobtusifoliol, which have never been reported in black walnuts. The average levels of total sterols ranged from 1236.0 mg/kg to 1542.3 mg/kg. No...

For most bird species, little is known about their ecology and survival between fledging and independence despite the potential for post-fledging survival to be a factor limiting population dynamics. Cerulean Warblers (Setophaga cerulea) are a declining migratory species, and full-life-cycle conservation efforts that include the post-fledging period are warranted to attempt to reverse their decline. To understand movement, habitat selection, and survival, we radio-tracked 20 fledglings throughout the dependent post-fledging period. Broods were split by their parents, typically (88%) left...