Treesearch

The diurnal flight response of the walnut twig beetle, Pityophthorus juglandis Blackman (Coleoptera: Scolytidae), was assessed during two seasonal periods at two sites in northern California. Males and females flew primarily at dusk in response to aggregation pheromone-baited traps during late June/early July, and the percentage of beetles that flew between sunrise and late afternoon was positively correlated with the temperature at 6 AM of that day. Between late August and early November, the diurnal flight pattern was more varied and generally bimodal, though approx. 42 to 55% of the...

Forest ecosystems experience various disturbances that can affect belowground carbon cycling to different degrees. Here, we investigate if successive annual foliar scorching events will result in a large and rapid decline in soil CO2 efflux, similar to that observed in girdling studies. Using the fire-adapted longleaf pine (Pinus palustris Mill.) tree species, we experimentally manipulated foliar leaf area and thus, canopy photosynthesis, via foliar scorching over two consecutive growing seasons. We monitored the effect of scorching on soil CO2 efflux and fine root production, mortality,...

The macroarthropods are those large enough to be sampled as individuals, in contrast to the microarthropods that are sampled by extraction from a fragment of habitat (Section 25.3; Dindal, 1990; Borror et al., 1992; Arnett, 1993). Although smaller macroarthropods overlap in size with the larger microarthropods (Figure 25.2), the distinction between them is a practical one, based on method of sampling. A functional difference lies in their impact on soils. Macroarthropods are capable of restructuring soil profiles or relocating large amounts of soil, whereas microarthropods typically...

Afforestation has been proposed as a climate change mitigation strategy by sequestrating atmospheric carbon dioxide. With the goal of increasing carbon sequestration, a Congressional project has been planned to afforest about 18 million acres by 2020 in the Southeast United States (SEUS), the Great Lake states, and the Corn Belt states. However, biophysical feedbacks of afforestation have the potential to counter the beneficial climatic consequences of carbon sequestration. To assess the potential biophysical effects of afforestation over the SEUS, the authors designed a set of initial...

Improved fire management of savannas and open woodlands requires better understanding of the fundamental connection between fuel heterogeneity, variation in fire behaviour and the influence of fire variation on vegetation feedbacks. In this study, we introduce a novel approach to predicting fire behaviour at the submetre scale, including measurements of forest understorey fuels using ground-based LIDAR (light detection and ranging) coupled with infrared thermography for recording precise fire temperatures. We used ensemble classification and regression trees to examine the relationships...

Watershed export of phosphorus (P) from anthropogenic sources has contributed to eutrophication in freshwater and coastal ecosystems. We explore impacts of watershed urbanization on the magnitude and export flow distribution of P along an urban-rural gradient in eight watersheds monitored as part of the Baltimore Ecosystem Study Long-Term Ecological Research site. Exports of soluble reactive phosphorus (SRP) and total P (TP) were lowest in small watersheds with forest and low-density residential land use (2.8–3.1 kg-1 km-2 yr-1). In contrast, SRP and TP exports increased with watershed...

The lesser cornstalk borer (Elasmopalpus lignosellus) affects seedlings of Arizona cypress, bald cypress, black locust, dogwood, black tupelo, loblolly pine, redcedar, sand pine, slash pine, and sycamore. Agricultural host plants (more than 60 species) include beans, corn, millet, peas, sorghums, and soybeans.

A cellular automata fire model represents ‘elements’ of fire by autonomous agents. A few simple algebraic expressions substituted for complex physical and meteorological processes and solved iteratively yield simulations for ‘super-diffusive’ fire spread and coupled surface-layer (2-m) fire–atmosphere processes. Pressure anomalies, which are integrals of the thermal properties of the overlying heated plume, drive the surface winds around and through the fire. Five simulations with differing fuel and wind conditions were compared with fire and meteorological data from an experimental...

This document is a summary of a mixed methods dissertation that examined the communicative construction of safety in wildland firefighting. For the dissertation, I used a two-study mixed methods approach, examining the communicative accomplishment of safety from two perspectives: high reliability organizing (Weick, Sutcliffe, & Obstfeld, 1999), and safety climate (Zohar, 1980).