Treesearch

Annual tree-ring patterns are a source of ecological and environmental information including the history of fires in forested areas. Tree-ring based fire histories include three fundamental phases: field collection, laboratory methods (preparation and dating), and data analysis. Here we provide step-by-step instructions and issues to consider, including the process for selecting the study area, sampling sites, plus how and which fire-scarred trees to sample. In addition, we describe fire-scar sample preparation and dating which are done in the laboratory. Finally, we describe basic...

Plastic wastes pose a serious threat to the environment and there has been strong interest in developing soy protein isolate (SPI)-based plastics to reduce the use of traditional petroleum-based ones. However, the use of SPI plastics has been hindered due to their inferior mechanical properties and poor water resistance compared with traditional plastics. In this work, SPI plastics with significantly improved mechanical properties and water resistance were developed using UV-curable SPI resin and UV-curable cellulose nanofibers. Three UV-curable materials, i.e., methacrylated SPI (MSPI),...

Forest age and species composition varies widely in the southern Appalachian Mountains, due to legacies of land use and disturbance such as repeat harvesting, fire exclusion, and invasive pests. In this highly productive region, leaf area recovers rapidly after harvesting (typically within five to ten years), while biomass accumulates more slowly (reaching peak basal area between 25 and 80 years). Although tree-level water use should generally increase with size, age-related differences in sap flow are unknown for many species. To address this knowledge gap, we measured sap flow, throughfal...

The Fourth National Climate Assessment (NCA4) provided the most up-to-date understanding of climate change and its effects on the Earth system and on consequences for the United States, including impacts and associated risks, along with approaches to coping with these effects. It is intended to provide guidance to decision-makers in governmental sectors while, in practice, providing guidance for nongovernmental actors. Its regional and topical chapters highlight current knowledge, uncertainties, gaps in knowledge, and emerging threats. The current knowledge and gaps can help set a research...

Strategies for deep soil water acquisition (WAdeep) are critical to a species’ adaptation to drought. However, it is unknown how WAdeep determines the abundance and resource economy strategies of understorey shrub species. With data from 13 understorey shrub species in subtropical coniferous plantations, we investigated associations between the magnitude of WAdeep, the seasonal plasticity of WAdeep, midday leaf water potential (Ψmd), species abundance and resource economic traits across organs. Higher capacity for WAdeep was associated with higher intrinsic water use efficiency, but was...

The ratio of leaf internal (ci) to ambient (ca) partial pressure of CO2, defined here as χ, is an index of adjustments in both leaf stomatal conductance and photosynthetic rate to environmental conditions. Measurements and proxies of this ratio can be used to constrain vegetation model uncertainties for predicting terrestrial carbon uptake and water use. We test a theory based on the least-cost optimality hypothesis for modelling historical changes in χ over the 1951–2014 period, across different tree species and environmental conditions, as reconstructed from stable carbon isotopic...

• The degree of plant iso/anisohydry is a popular framework for characterizing species-specific drought responses. However, we know little about associations between below-ground and above-ground hydraulic traits as well as the broader ecological implications of this framework.• For 24 understory shrub species in seasonally dry subtropical coniferous plantations, we investigated contributions of the degree of isohydry to species’ resource economy strategies, abundance, and importance value, and quantified the hydraulic conductance (Kh) of above-ground and below-ground organs, magnitude of...

Accurate and complete geospatial fire occurrence records are important in determining postfire effects, emissions, hazards, and fuel loading inventories. Currently, the Monitoring Trends in Burn Severity (MTBS) project maps the fire perimeter and burn severity of all large fires on public lands. Although the MTBS project maps a large proportion of the fire acreage, it maps a smaller proportion of the actual number of fires in the United States, thereby creating a data gap. To fill this data gap, fire scientists at the U.S. Geological Survey (USGS) Earth Resources Observation and Science...

Wildfire risk assessments rely on flame-length probabilities - the conditional probabilities that fire intensity will be within various flame-length classes. The factors affecting flame-length probability include the elements of the fire-behavior triangle - fuel, weather, and topography - plus the orientation of the flaming front relative to the heading direction. Current methods for determining flame-length probabilities include: (1) a single deterministic simulation of flame length at the head of the fire for one weather type (wind speed, wind direction, fuel moisture content); (2)...

Rehabilitation Capability Convergence for Ecosystem Recovery (RECOVER) postfire decision support system is a server-based application designed to rapidly provide land managers with the information needed to develop a comprehensive rehabilitation plan. This study evaluated the efficacy of RECOVER through structured interviews with land managers (n = 20) who used RECOVER and were responsible for postfire rehabilitation efforts on over 715,000 ha of fire-affected lands. Although the benefit of better-informed decisions is difficult to quantify, the results of this study illustrate that...