Treesearch

The La Sal Daisy, Erigeron mancus Rydb., is endemic to timberline and alpine habitats of the La Sal Mountains in Utah, an insular, laccolithic mountain range on the Colorado Plateau in southeastern Utah. It occurs in alpine herbaceous communities from timberline to the crestline of the La Sals. Our primary goal in this study was to measure basic population biology parameters for the E. mancus population on the ridge from Mt. Laurel in the Middle Group of the La Sals west to treeline. We measured both E. mancus density and vascular plant species composition within 1-m x 1-m square frames...

Herbivores and pathogens come quickly to mind when one thinks of the biotic challenges faced by plants. Important but less appreciated enemies are parasitic plants, which can have important consequences for the fitness and survival of their hosts. Our knowledge of plant perception, signaling and response to herbivores and pathogens has expanded rapidly in recent years, but information is generally lacking for parasitic species. In a recent paper we reported that some of the same defense responses induced by herbivores and pathogens - notably increases in jasmonic acid (JA), salicylic acid...

Vegetation commonly managed by prescribed burning was collected from five southeastern and southwestern US military bases and burned under controlled conditions at the US Forest Service Fire Sciences Laboratory in Missoula, Montana. The smoke emissions were measured with a large suite of state-of-the-art instrumentation including an open-path Fourier transform infrared (OP-FTIR) spectrometer for measurement of gas-phase species. Keywords: trace gas emissions, biomass burning, smoke emissions, open-path Fourier transform infrared (OP-FTIR)

Southwestern USA ponderosa pine (Pinus ponderosa C. Lawson var. scopulorum Engelm.) forests evolved with frequent surface fires and have changed dramatically over the last century. Overstory tree density has sharply increased while abundance of understory vegetation has declined primarily due to the near cessation of fires. We examined effects of varying prescribed fire-return intervals (1, 2, 4, 6, 8, and 10 years, plus unburned) on the abundance and composition of understory vegetation in 2007 and 2008 after 30+ years of fall prescribed burning at two ponderosa pine sites. We found...

The extent and severity of overstory lodgepole pine (Pinus contorta var. latifolia Engelm. ex Wats.) mortality from mountain pine beetle (Dendroctonus ponderosae Hopkins) has created management concerns associated with forest regeneration, wildfire risk, human safety, and scenic, wildlife, and watershed resources in western North America. Owing to the unprecedented nature of the outbreak and associated management in the southern Rocky Mountains, it is unknown if the forests that regenerate after this current period of extensive change will differ from those that regenerated in the past....

Ecosystem energy is now recognized as a primary correlate and potential driver of global patterns of species richness. The increasingly well-tested species-energy relationship is now ripe for application to conservation, and recent advances in satellite technology make this more feasible. While the correlates for the species-energy relationship have been addressed many times previously, this study is among the first to apply species-energy theory to conservation. Our objectives were to: (1) determine the strongest model of bird richness across North America; (2) determine whether the slope...

Increasing surface temperatures and climatic variability associated with global climate change are expected to produce more frequent and intense heat waves and droughts in many parts of the world. Our goal was to elucidate the fundamental, but poorly understood, effects of these extreme weather events on avian communities across the conterminous United States. Specifically, we explored: (1) the effects of timing and duration of heat and drought events, (2) the effects of jointly occurring drought and heat waves relative to these events occurring in isolation, and (3) how effects vary among...

In Michigan, the most important white grub pests of nursery seedlings are European chafer beetle (Rhizotrogus majalis) and June beetles (Phyllophaga spp.). If damage is observed and white grubs found, beds can be protected from future damage with imidacloprid applied as Discus or Marathon once per year in June or July.

The importance of seed moisture in maintaining high seed viability is well known. The seed storage chapters in the Tropical Tree Seed Manual (Hong and Ellis 2003) and the Woody Plant Seed Manual (Bonner 2008a) give a detailed discussion and many references on this point. Working with seeds in an operational setting requires a test of seed moisture status. It is necessary to know if the seeds are high in moisture or if they are dry enough to store without losing germination. Seed moisture testing was originally done by drying seeds for about 16 hours in a hot oven to drive off the water in...

We transplanted one-year old Douglas-fir (Pseudotsuga menziesii var. menziesii) seedlings into compost-amended soil that had either been spring-fumigated with a methyl bromide/chloropicrin combination or left unfumigated. Seedling nutrient, pathology, morphology, and packout measurements were significantly better for those transplanted into fumigated rather than non-fumigated soil, regardless of compost treatment. Among seedlings transplanted into non-fumigated soil, those grown in the biosolid and bark-based composts had the highest average number of packable seedlings.