Treesearch

Understanding the successes and failures of nonnative species remains challenging. In recent decades, researchers have developed the enemy release hypothesis and other antagonist hypotheses, which posit that nonnative species either fail or succeed in a novel range because of the presence or absence of antagonists. The premise of classical biological control of invasive species is that top-down control works. We identify twelve existing hypotheses that address the roles that antagonists from many trophic levels play during plant and insect invasions in natural environments. We outline a...

Intercropping switchgrass (Panicum virgatum) with pine can increase bioenergy feedstock production without land opportunity costs but can potentially alter water budgets. Measuring evapotranspiration (ET) and its parameters (stomatal conductance (gs), leaf area index (LAI), canopy temperature (Tc), and soil moisture (SM)) across cropping systems is costly and time-consuming. However, interpretation of remotely-sensed data can facilitate the effective assessment of relative ET demands among competing forest landuses. This study develops and tests geospatial models informed by a normalized...

Real property passed to subsequent generations via intestate succession (i.e., without a will) is termed a tenancy-in-common, or more colloquially, “heirs’ property.” Property may also be classed as heirs’ property via an intentional simple will that divides real estate assets equally among descendants. With this kind of property ownership, co-heirs hold fractional interests in property that is not physically divided. As such, heirs’ property represents a form of collective ownership. Owners are private property holders but are limited in their ability to use such properties to build...

Lake Superior receives inputs from approximately 2,800 tributaries that provide nutrients and dissolved organic matter (DOM) to the nearshore zone of this oligotrophic lake. Here, we review the magnitude and timing of tributary export and plume formation in Lake Superior, how these patterns and interactions may shift with global change, and how emerging technologies can be used to better characterize tributary–lake linkages. Peak tributary export occurs during snowmelt-driven spring freshets, with additional pulses during raindriven storms. Instream processing and transformation of...

Molecular markers have shown a high level of genetic diversity in most extant populations of the federally endangered Lindera melissifolia in the southeastern United States. However, it is unknown if diversity in adaptive traits exists. We quantified adaptive trait variation in 17 L. melissifolia genotypes by growing genets from two disjunct populations in the Lower Mississippi Alluvial Valley in a common garden environment. We then examined genotype-environment interaction through introduction of a flooding treatment. Within a common garden environment, variation in adaptive traits was...

Increased drought intensity and frequency due to climate change may reduce the abundance and activity of nitrogen (N2)-fixing plants, which supply new N to terrestrial ecosystems. As a result, drought may indirectly reduce ecosystem productivity through its effect on the N cycle. Here, we manipulated growing season net rainfall across a series of plots in an early successional mesic deciduous forest to understand how drought affects the aboveground productivity of the N2-fixing tree Robinia pseudoacacia and three co-occurring nonfixing tree species. We found that lower soil moisture was...

This report highlights key findings from 2012 data collected by the Forest Inventory and Analysis program across all forested land on four islands in American Samoa, updating previously published findings from data collected in 2001 (Donnegan et al. 2004). We summarize and interpret basic resource information such as estimates of forest area, stem volume, biomass, numbers of trees, damages to trees, and tree size distribution as well as overstory and understory vegetation cover and information on invasive plant species presence and cover. Detailed tables and graphical highlights are...

Wetlands (called bofedales in the Andes of Peru) are abundant and important components of many mountain ecosystems across the globe. They provide many benefits including water storage, high quality habitat, pasture, nutrient sinks and transformations, and carbon storage. The remote and rugged setting of mountain wetlands creates challenges for mapping, typically leading to misclassification and underestimates ofwetland extent.We used multi-date, multi-sensor radar and optical imagery (Landsat TM/ PALSAR/RADARSAT-1/SRTM DEM-TPI) combined with ground truthing for mapping wetlands in Huascarán...