Treesearch

National and international efforts to manage forest biosecurity create tension between opposing sources of ecological and economic irreversibility. Phytosanitary policies designed to protect national borders from biological invasions incur sunk costs deriving from economic and political irreversibilities that incentivizes wait-and-see decision-making. However, the potential for irreversible ecological and economic damages resulting from failed phytosanitary policies argues for precautionary measures, creating sunk benefits while increasing the risk of over-investment in phytosanitary...

Headwater fishes in the southeastern United States make up much of the fish biodiversity of the region yet many are imperiled. Despite this, the specific habitat requirements of imperiled headwater fishes in lowland Coastal Plain streams have rarely been quantified. Using data collected over three years of seasonal sampling we provide estimates of the microhabitat requirementsof the imperiled Yazoo darter (Etheostoma raneyi Suttkus and Bart), a small benthic insectivore. Our results indicate that the species is a microhabitat specialist and that optimum microhabitat within degraded...

Land surface evapotranspiration (ET) is a central component of the Earth's global energy balance and water cycle. Understanding ET is important in quantifying the impacts of human influences on the hydrological cycle and thus helps improving water use efficiency and strengthening water use planning and watershed management. China has experienced tremendous land use and land cover changes (LUCC) as a result of urbanization and ecological restoration under a broad background of climate change. This study used MODIS data products to analyze how LUCC and climate change affected ET in China in...

Biotic resistance, the ability of communities to resist exotic invasions, has long attracted interest in the research and management communities. However, inconsistencies exist in various biotic resistance studies and less is known about the current status and knowledge gaps of biotic resistance in forest ecosystems. In this paper, we provide a brief review of the history and mechanisms of the biotic resistance hypothesis, and summarize the central topics and knowledge gaps related to biotic resistance with a special emphasis on forest ecosystems. Overall, although the amount of research...

Key message TRACC is an open-source software for standardizing the cleaning, conversion, and calibration of sap flux density data from thermal dissipation probes, which addresses issues of nighttime transpiration and water storage. Abstract Thermal dissipation probes (TDPs) have become a widely used method of monitoring plant water use in recent years. The use of TDPs requires calibration to a theoretical zero-flow value (DT0); usually based upon the assumption that at least some nighttime measurements represent zero-flow conditions. Fully automating the processing of data from TDPs is...

Laurel wilt is an extraordinarily destructive exotic tree disease in the southeastern United States that involves new-encounter hosts in the Lauraceae, an introduced vector (Xyleborus glabratus) and pathogen symbiont (Raffaelea lauricola). USDA Forest Service Forest Inventory and Analysis data were used to estimate that over 300 million trees of redbay (Persea borbonia sensu lato) have succumbed to the disease since the early 2000s (ca 1/3 of the pre-invasion population). In addition, numerous native shrub and tree species in the family are susceptible and threatened in the Western...

Hemlock woolly adelgid (Adelges tsugae Annand) (HWA) is an invasive forest insect sweeping across the native range of eastern (Tsuga canadensis [L.] Carr.) and Carolina (Tsuga caroliniana Engelm.) hemlocks, threatening to severely reduce eastern hemlock extent and to push Carolina hemlock to extirpation. HWA poses a significant threat to these eastern US natives, now infesting hemlocks across 19 states and more than 400 counties. For the long-term preservation of the species, ex situ genetic resource conservation efforts such as seed collection, storage, and adelgid-resistant hemlock...

The mechanisms governing the ability of water-soluble polymers (WSP) to alter the rheological properties of lignocellulosic biomass to achieve processing advantages are investigated. Lignocellulosic fiber surface chemistry is found to be an important factor in the efficacy of WSPs as rheological modifiers, and a strong correlation between the amount of adsorbed polymer at fiber surfaces and the yield stress of the fiber suspension indicate that adsorption of polymer is important for rheological modification. Three fiber suspensions of varying physical chemistry were produced from Aspen...

Hydraulic geometry offers robust scaling of channels across many orders of magnitude in natural rivers, irrigation canals, and laboratory channels (Ferguson 1986). Although the authors’ analysis focuses on fluvial deposits, it is worth noting that hydraulic geometry relations can be developed for a variety of fluids, which may have relevance for some Martian channels given that differences in gravity and atmospheric conditions (pressure, temperature, and, thus, viscosity) may cause channel hydraulics and flow rheology (Froude and Reynolds numbers) to differ from those on Earth. Data from...