Treesearch

Pyrodiversity or variation in spatio-temporal fire patterns is increasingly recognized as an important determinant of ecological pattern and process, yet no consensus surrounds how best to quantify the phenomenon and its drivers remain largely untested. We present a generalizable functional diversity approach for measuring pyrodiversity, which incorporates multiple fire regime traits and can be applied across scales. Further, we tested the socioecological drivers of pyrodiversity among forests of the western United States. Largely mediated by burn activity, pyrodiversity was positively...

Sierra Nevada mixed-conifer forests have undergone significant changes in structure and composition and are increasingly vulnerable to altered disturbance regimes and climate-related extreme events. Fuel reduction treatments, including thinning and follow-up surface fuel treatments, can reduce this vulnerability by creating forest structural and woody fuel conditions that not only allow forest stands to mitigate wildfire, but also alleviate individual tree stress. However, direct observations that quantify these longer-term effects are lacking. This study compares observed changes in...

Aggregated states of celluloses remain poorly understood, and therefore, the topic requires careful investigation. In this study, Raman, IR, and Xray diffraction (XRDs) were used to study cotton microcrystalline cellulose (MCC) and MCC that has been ball-milled to various degrees. Raman and IR spectroscopy methods indicated that when these ball-milled samples were wet with water, most underwent conformational changes at the molecular level. Although formation of cellulose II was observed in longer duration ball-milled samples, the changes primarily gave rise to increased contributions in...

Two scalable coating techniques, slot die and spray coating (SC), are used to apply cellulose nanocrystals (CNCs) to the surface of glass fibers with the goal of enhancing interfacial interactions between glass fibers and epoxy and, consequently, the strength of fiber-reinforced composites. The quality of the cellulose coatings and the interfacial shear strength, assessed via the single fiber fragmentation test, are determined as a function of the method and conditions used to coat the fibers. In addition, a comparison with glass fibers coated with identical CNC formulations using a...

We use optimization of a structural dynamic model to evaluate the cost of carbon sequestration when afforestation subsidies are used to encourage private landowners to switch from cropland to forestry. Our model allows for the planting of either softwood or hardwood forest types with flexible rotation lengths, in addition to irrigated crops. We apply the model to a portion of the Lower Mississippi River Basin in Arkansas where groundwater overdraft lowers the profitability of irrigated crops. In our baseline model with a 5% discount rate, a subsidy for afforestation from $1000 to $4500 per...

Increases in burned area and large fire occurrence are widely documented over the western United States over the past half century. Here, we focus on the elevational distribution of forest fires in mountainous ecoregions of the western United States and show the largest increase rates in burned area above 2,500 m during 1984 to 2017. Furthermore, we show that high-elevation fires advanced upslope with a median cumulative change of 252 m (-107 to 656 m; 95% CI) in 34 y across studied ecoregions. We also document a strong interannual relationship between high-elevation fires and warm season...

Rhododendron maximum, a native ericaceous evergreen shrub, is expanding in forests of the southern Appalachian region following eastern hemlock (Tsuga canadensis) mortality due to hemlock woolly adelgid (Adelges tsugae) infestations. The goal of our study was to examine soil microbial community responses to experimental R. maximum removal treatments. The experiment was implemented as a 2 × 2 factorial design, including two R. maximum canopy removal levels (cut vs. not cut) combined with two forest floor removal levels (burned vs. not burned). These treatments were designed as potential...

Ranaviruses are emerging pathogens of poikilothermic vertebrates. In 2015 the Global Ranavirus Reporting System (GRRS) was established as a centralized, open access, online database for reports of the presence (and absence) of ranavirus around the globe. The GRRS has multiple data layers (e.g., location, date, host(s) species, and methods of detection) of use to those studying the epidemiology, ecology, and evolution of this group of viruses. Here we summarize the temporal, spatial, diagnostic, and host-taxonomic patterns of ranavirus reports in the GRRS. The number, distribution, and host...

Terrestrial ecosystems are experiencing increasing frequency and intensity of droughts as a result of climate change. Despite a wealth of previous studies investigating soil responses to drought, the importance of historical land use in mediating drought effects remains poorly understood. To identify interactions between drought and historical land use, we sampled soils from two adjacent forested watersheds at the USFS Coweeta Hydrologic Laboratory: a ‘reference’ forest that has remained undisturbed for approximately a century and a ‘disturbed’ forest with a history of conversion to...

Oaks (Quercus) are economically important, and their seed (acorns) are a valuable food for many animals. Thus, forest managers must consider potential tradeoffs between oak growth and acorn production. I used 13 years of dbh growth and 17 years of acorn trapping data on 195 trees of five common eastern oak species to compare stand-level growth and acorn production between closed canopy mature forest (M) and recent shelterwood with reserves regeneration harvests (SW) (BA 27.3 ± 1.7 m2/ha in M; 5.1 + 0.8 m2/ha in SW at study establishment). I also examined treatment differences in dbh...