Treesearch

Following a resource pulse, animals may finance reproduction by consuming concurrently available resources (income breeding) or by storing resources for future reproduction (capital breeding). Understanding how these reproductive strategies are used is important for determining the ecological mechanisms that structure timing of reproduction and that drive interannual population fluctuations in animals. We gathered a reproductive dataset for five small mammal species over a 12-year period in Northeastern USA during which six masting events of American beech (Fagus grandifolia) and eastern...

Context: Land use history of urban forests impacts present-day soil structure, vegetation, and ecosystem function, yet is rarely documented in a way accessible to planners and land managers. Objectives: To (1) summarize historical land cover of present-day forest patches in Baltimore, MD, USA across land ownership categories and (2) determine whether social-ecological characteristics vary by historical land cover trajectory. Methods: Using land cover classification derived from 1927 and 1953 aerial imagery, we summarized present-day forest cover by three land cover sequence classes: (1)...

Songbirds incidentally ingest soil contaminated with lead and several species in the Southeast Missouri Lead Mining District have a negative relationship between soil lead concentration and reproduction. We used an individual-based model (IBM) to simulate nesting processes throughout the breeding season to estimate annual productivity for 5 songbirds in relation to soil-lead concentration. We modeled daily nest survival and number fledged in relation to soil lead and incorporated these relationships into the IBM using a Bayesian approach that fully captured parameter uncertainty and...

Forest inventory data are useful for determining forest stand structure, growth, and change. Among the information collected on forest inventory plots by the USDA Forest Service Forest Inventory and Analysis Program, attributes characterizing various types of disturbance provide researchers a means of selecting plots specifically affected by disturbances, such as fire. We determine the performance of three of these attributes as indicators of recent fires on forest inventory plots of the United States by comparing them to independent records of wildland fire occurrence. The indicators are...

Forests play a critical role in mitigating climate change by sequestering carbon dioxide (CO2) from the atmosphere. A new study led by Yude Pan, research scientist with the U.S. Department of Agriculture, Forest Service, Northern Research Station, provides a unique perspective and a long-term, ground-based benchmark on the recent magnitude, trends, drivers, and locations of Earth’s critical forest carbon sinks. The study compiles and analyzes data from extensive ground-based forest inventories and ecological studies as well as commonly used forest area estimates based on remote sensings in...

The uptake of carbon dioxide (CO2) by terrestrial ecosystems is critical for moderating climate change. To provide a ground-based long-term assessment of the contribution of forests to terrestrial CO2 uptake, we synthesized in situ forest data from boreal, temperate and tropical biomes spanning three decades. We found that the carbon sink in global forests was steady, at 3.6 ± 0.4 Pg C yr−1 in the 1990s and 2000s, and 3.5 ± 0.4 Pg C yr−1 in the 2010s. Despite this global stability, our analysis revealed some major biome-level changes. Carbon sinks have increased in temperate (+30 ± 5%) and...

Interactions among wood-decay fungi can have a profound effect on fungal community composition, decay rates and ultimately the chemical composition of the material remaining after the decay process. Interspecific interactions among fungi as they decay wood have been well-studied but almost nothing is known about the effect of intraspecific interactions between individual genets on the decay process. In this study we examine the effect of both intra- and interspecific competition on wood mass-loss for five species of wood-decay fungi: Cerrena unicolor, Fuscoporia gilva, Irpex lacteus,...

Although climate change is expected to drive tree species toward colder and wetter regions of their distribution, broadscale empirical evidence is lacking. One possibility is that past and present human activities in forests obscure or alter the effects of climate. Here, using data from more than two million monitored trees from 73 widely distributed species, we quantify changes in tree species density within their climatic niches across Northern Hemisphere forests. We observe a reduction in mean density across species, coupled with a tendency toward increasing tree size. However, the...

Spatially continuous patterns of genetic differentiation, which are common in nature, are often poorly described by existing population genetic theory or methods that assume either panmixia or discrete, clearly definable populations. There is therefore a need for statistical approaches in population genetics that can accommodate continuous geographic structure, and that ideally use georeferenced individuals as the unit of analysis, rather than populations or subpopulations. In addition, researchers are often interested in describing the diversity of a population distributed continuously in...

Broadly speaking, prediction of the negative impacts of prescribed fire on air quality is limited by gaps in our understanding of the underlying fire, fuels, and atmospheric processes. These knowledge gaps hinder our ability to accurately predict smoke concentration distributions, leading to unintended smoke intrusions into nearby communities and subsequent threats to public health and safety. In this study, numerical simulations are performed using the Flexible Particle Weather Research and Forecasting (FLEXPART-WRF) Model, a Lagrangian particle dispersion model, with particle motion...