Treesearch

In this study, we estimated the respective contributions of precipitation and reference evapotranspiration (ET0) to annual SPEI-3 (3-month Standardized Precipitation- Evapotranspiration Index) anomalies over southwest China (SWC) using numerical experiments. Results show that the dominant factor (i.e., precipitation or ET0) for the dryness/wetness anomalies during 1961–2012 existed due to inter-annual and interdecadal changes over SWC, which indicates the underlying mechanisms of dry/wet conditions have changed. On the other hand, we calculate the dryness/wetness sensitivity to precipitatio...

Aim: Much is known about the elevational diversity patterns of native species and about the mechanisms that drive these patterns. A similar level of understanding is needed for non-native species. Using published data, we examine elevational diversity patterns of non-native plants and compare the resulting patterns with those observed for native plants. Location: Global. Methods: We compiled data from 65 case studies on elevational diversity patterns of non-native plants around the world (including 32 cases in which both non-native and native plants were sampled). We compared the elevationa...

Weather is an important factor that determines smoke development, which is essential information for planning smoke field measurements. This study identifies the synoptic systems that would favor to produce the desired smoke plumes for the Fire and Smoke Model Evaluation Experiment (FASMEE). Daysmoke and PB-Piedmont (PB-P) models are used to simulate smoke plume evolution during the day time and smoke drainage and fog formation during the nighttime for hypothetical prescribed burns on February 5-8, 2011 at the Stewart Army Base in the southeastern United States. Daysmoke simulation is...

Improved understanding of the physiological mechanisms of tree mortality following fires is important with the predicted increase in wildfires under climate change, as well as continued use of prescribed fire for forest management. Disruption of water transport in the xylem from exposure to the heat plume of a fire has been hypothesized as a mechanism of delayed tree mortality. This heat plume rapidly increases vapor pressure deficit in the canopy, increasing transpiration and tension on the xylem causing cavitation, thus reducing water transport and leading to eventual tree death. We...

Shortleaf pine (Pinus echinata), Missouri’s only native pine species, experienced intense logging during the post-Civil War Ozark lumber boom. Although recent restoration efforts have occurred primarily on federal and state land, efforts are being made to incorporate shortleaf management strategies on private land through the distribution of 1 y old bare-root seedlings grown from seeds at the George O. White nursery in Licking, Mo. In this study we examined the genetic structure of Missouri’s historic shortleaf pines to determine if geographic compartmentalization of seed stock was...

The Mississippi Delta is an important agricultural area, producing 67% of the soybean, corn, and cotton grownin the state of Mississippi. Because irrigation can stabilize and increase crop yields and economic returns, approximately80% of the water withdrawn from the alluvial aquifer is used for irrigation. This region is experiencing severe declines ingroundwater level, which threaten the sustainability of irrigated agriculture. Therefore, better irrigation management practicesmust be developed, but there is lack of knowledge regarding crop water requirements, rain water deficits, and...

This study systematically evaluated the influence of masterbatch preparation techniques, solvent casting and spin-coating methods, on composite properties. Composites were manufactured by combining CNCs masterbatches and PLA resin using twin screw extruder followed by injection molding. Different microscopy techniques were used to investigate the dispersion of CNCs in masterbatches and composites. Thermal, thermomechanical, and mechanical properties of composites were evaluated. Scanning electron microscopy (SEM) images showed superior dispersion of CNCs in spin-coated masterbatches...

Longleaf pine forests are currently being restored in the southern U.S. To aid in the deployment of longleaf pine under current and future climate conditions, we tested the hypothesis that genetic variability in foliar carbon isotope composition (δ13C) exists in this species. Foliar δ13C, height and diameter were measured at ages of 5 and 6 years, and needle length, specific leaf weight (SLW) and foliar N concentration were measured at an age of 6 years in 16 longleaf pine families representing a large portion of the species’ range. Families were grown in common garden tests in North...

Applications of cellulose nanomaterials (CNMs) have attracted increasing attention in recent years. One conceivable path lies in their commercial applications for packaging, in which their barrier properties will play an important role in determining their competiveness with conventional materials. This review critically analyzes the performance of CNMs acting as a barrier against moisture and oxygen permeation in CNM films, CNM-coated polymers and papers, and CNM-reinforced polymer composites, gives some insights into remaining challenges, and brings an overall perspective of compositing...

The use of biological agents to control plant diseases is an attractive approach, especially at a time when managers and other stakeholders seek to limit the impact of synthetic pesticides. Further, chemical pesticides cannot be used in natural habitats because of their expense and potential negative effects on ecosystems.