Treesearch

Female gypsy moths (Lymantria dispar) of Asian heritage studied in central Siberia and Germany exhibit a highly synchronous flight at dusk, after light intensity falls to about 2 lux. This critical light intensity sets the timing of flight behaviors independent of ambient temperature. Flight follows several minutes of preflight wing fanning during which females in Germany and those from a laboratory colony (derived from Siberian stock) raised their thoracic temperatures to 32-33?C at ambient temperatures of 19-22?C. Thoracic temperature of females in free flight exceeded the air temperature...

We are using a deterministic regression tree analysis model (DISTRIB) and a stochastic migration model (SHIFT) to examine potential distributions of ~66 individual species of eastern US trees under a 2 x CO2 climate change scenario. This process is demonstrated for Virginia pine (Pinus virginiana).

Differential responses of species to environmental stress may interfere with restoration of prairie ecosystems or change community structure. The impact of increasing atmospheric ozone (O3) concentrations and/or low water on the growth of Andropogon gerardii Vitm. (big bluestem) and Sorghastrum nutans (L.) Nash (Indian grass), two common warm-season native grasses, and Setaria faberi Herrm. (giant foxtail), a vigorous annual weed species, were studied in replacement series.

Lumber grade effect on hardwood-part processing time was investigated with a digitally described lumber database in conjunction with a crosscut-first rough mill yield optimization simulator. In this study, the digital lumber sample was subdivided into five hardwood lumber grades. Three cutting bills with varying degrees of difficulty were Cut." The three cutting bills and the five grade sorts were input into the rough mill simulator. Ten randomized replications were run for each of the lumber grade/cutting bill combinations. These 10 were used in the statistical analysis. The dependent...

Including character marks in dimension parts of the furniture, cabinet, and dimension industries offers an opportunity to increase lumber yield substantially. However, little quantitative knowledge exists as to how the incorporation of character marks in parts influences yield when processing lumber in a crosscut-first rough mill. Using computer simulation, this study researched the theoretical attainable yield increases in a crosscut first rough mill due to the incorporation of character marks in furniture parts. Also, the performance of the crosscut-first system was compared to the...

Low rates of natural regeneration of big-leaf mahogany were found in gaps due to felling and natural treefalls in the Yucatan. This finding is consistent with low post-logging abundances of reproductive-sized trees as well as relatively low growth rates of planted mahogany seedlings in small felling gaps. High growth rates of seedlings in large felling gaps and landings provides optimism that the extensive plantings done in the region will provide timber in the future. The long-term effects of shoot borers, which predominantly attach the fastest growing seedlings, are uncertain.

This study quantified relationships of understory vascular plant species composition and richness along environmental gradients over a broad spatial scale in second-growth oak forests in eastern North America. Species frequencies were recorded in 108 25 x 25 m plots in four study sites extending over 70 km in southern Ohio, U.S.A. The plots were stratified into three long-term soil moisture classes with a GIS-derived integrated moisture index (IMI). In addition to the IMI, the environmental data matrix included eight soil and three overstory variables. Canonical correspondence analysis...

The white-rot wood decay fungus Resinicium bicolor (Abertini & Schwein.: Fr.) Parmasto was studied for its ability to solubilize and translocate ions from the naturally occurring mineral strontianite. Resinicium bicolor colonized a soil mixture culture medium containing strontianite sand, solubilized strontium ions from this mineral phase, translocated the ions vertically, and reprecipitated the strontium into strontium-containing calcium oxalate crystals. Storage of the Sr in crystals was highest in mycelial cords and was dynamic in character. These results suggest that non-mycorrhizal...

Cambial electrical resistance (CER) was used as an objective measure of vitality of silver fir (Abies alba) in the forests of Slovenia. Trees were rated during the growing season by CER and a subjective crown status index (CSI). Both CER and CSI were inversely correlated to annual ring width increment. Using both CER and CSI, fir were assigned to vitality and vigour categories.