Treesearch

Climate is a critical factor shaping the structure and function of forest ecosystems in the Southern United States. Human induced changes in climate systems have resulted in an increase in the global average air temperature of about 0.8°C since the 1900s (Pachuri and Reisinger 2007). Data from long-term weather stations show that overall, the continental United States has warmed during the past century, but that the magnitude and direction of change vary by geographic area (Backlund et al. 2008). The primary driving force behind this overall warming is an increase in carbon dioxide (C02)...

The rapid pace of climate change and its direct and indirect effects on forest ecosystems present a pressing need for better scientific understanding and the development of new science-management partnerships. Understanding the effects of stressors and disturbances (including climatic variability), and developing and testing science-based management options to deal with them, have been core research tasks for researchers in the southern United States for decades. Climate change adds a new dimension to this task because it can directly impact forest ecosystems over large spatial scales and...

In the present study, 3D FT-IR spectroscopic imaging measurements were applied to study the phase separation of a poly(3-hydroxybutyrate) (PHB)/poly(L-lactic acid) (PLA) (50:50 wt.%) polymer blend film. While in 2D projection imaging the z-dependent information is overlapped, thereby complicating the analysis, FT-IR spectro-micro-tomography, obtained from computed tomographic back projection calculations, results in distinct 3D chemical images that provide detailed information of phase separation of the two polymer components that are well separated.

Xylans, including methylglucuronoxylans (MeGXn) and methylglucuronoarabinoxylans (MeGAXn), are the predominant polysaccharides in hemicellulose fractions of dicots and monocots available for conversion to biofuels and chemicals. Paenibacillus sp. strain JDR-2 (Pjdr2) efficiently depolymerizes MeGXn and MeGAXn and assimilates the generated oligosaccharides, resulting in efficient saccharification and subsequent metabolism of these polysaccharides. A xylan utilization regulon encoding a cell associated GH10 (glycoside hydrolase family 10) endoxylanase, transcriptional regulators, ABC (ATP...

American chestnut trees were an important source of timber in Connecticut until chestnut blight disease reduced them to understory shrubs. Breeding begun in 1930 has now produced trees with enough resistance to initiate field trials in the forest. Biological control by hypovirulence viruses is being used in the plots in an effort to keep native trees alive. If native trees cross with the planted trees with resistance, future generations should have increased resistance to chestnut blight disease and the genetic diversity of the population will be increased.

The thought of genetically engineered (GE) trees might conjure images of mutant trees with unnatural and invasive tendencies, but there is much more to the story. GE trees are a new reality that, like it or not, will probably be part of the future of forestry. The basic inclination of most Forest Guild stewards is to reject GE trees as violating our principle to imitate nature, but are there cases where GE trees should be used? The American chestnut (Castanea dentate) may be the most compelling case thus far for the use of genetic engineering.

Endoxylanases classified into glycoside hydrolase family 30 subfamily 8 (GH30-8) are known to hydrolyze the hemicellulosic polysaccharide glucuronoxylan (GX) but not arabinoxylan or neutral xylooligosaccharides. This is owing to the specificity of these enzymes for the -1,2-linked glucuronate (GA) appendage of GX. Limit hydrolysis of this substrate produces a series of aldouronates each containing a single GA substituted on the xylose penultimate to the reducing terminus. In this work, the structural and biochemical characterization of xylanase 30A from Clostridium papyrosolvens (CpXyn30A)...

Dispersal is a key process influencing population dynamics and gene flow in species. Despite this, little is known about breeding dispersal in threatened Mexican Spotted Owls (Strix occidentalis lucida), here defined as movement of a non-juvenile owl between territories where it had the opportunity to breed. We observed 28 cases of breeding dispersal during a study of color-banded Mexican Spotted Owls in the Sacramento Mountains, New Mexico, 2003-2011. This represented 4.9% of total opportunities to disperse (n = 575 observed occasions, range = 0-9.0% of owls dispersing per yr). Breeding...

In sagebrush ecosystems invasion of annual exotics and expansion of pinon (Pinus monophylla Torr. and Frem.) and juniper (Juniperus occidentalis Hook., J. osteosperma [Torr.] Little) are altering fire regimes and resulting in large-scale ecosystem transformations. Management treatments aim to increase resilience to disturbance and enhance resistance to invasive species by reducing woody fuels and increasing native perennial herbaceous species. We used Sagebrush Steppe Treatment Evaluation Project data to test predictions on effects of fire vs. mechanical treatments on resilience and...

In response to the recent expansion of pinon and juniper woodlands into sagebrush-steppe communities in the northern Great Basin region, numerous conifer-removal projects have been implemented, primarily to release understory vegetation at sites having a wide range of environmental conditions. Responses to these treatments have varied from successful restoration of native plant communities to complete conversion to nonnative invasive species. To evaluate the general response of understory vegetation to tree canopy removal in conifer-encroached shrublands, we set up a region-wide study that...