Treesearch

Mangroves in many parts of the world are subjected to frequent, large-scale disturbances. A possible exception is Kosrae, Federated States of Micronesia (FSM), a small volcanic island in the west-central Pacific Ocean. Relative sea level has been stable for most of the last 1000 years and the last tropical cyclone to affect the island was in 1905. Many trees on Kosrae, especially individuals of the species Sonneratia alba, therefore appear to die only after reaching advanced ages and exceptional sizes. The most widespread anthropogenic disturbance is harvesting of trees for fuelwood and...

Wildfire usually promotes flooding and accelerated erosion in upland watersheds. In the summer of 1999, a high-severity wildfire burned a series of mixed pine/oak headwater catchments in the San Jacinto Mountains of southern California. Log erosion barriers (LEBs) were constructed across much of the burned area as an erosion control measure. We built debris basins in two watersheds, each about 1 ha in area, one with LEBs, the other without, to measure post-fire hydrologic response and sediment yield and to evaluate the effectiveness of the LEBs. The watersheds are underlain by granitic...

In the southern Sierra Nevada, California, relatively thin soils overlie granitic bedrock that is weathered to depths of several metres. The weathered granitic bedrock is porous and has a plant-available water capacity of 0.124 m3•m–3, compared with 0.196 m3•m–3 for the overlying soil. Roots confined within bedrock joint fractures access this rock-held water, especially during late summer when overlying soils are dry. We sought to determine seasonal soil and bedrock water changes in a Jeffrey pine (Pinus jeffreyi Grev & Balf.) plantation and to examine concurrent effects on the water...

The Scripps Experimental Climate Prediction Center (ECPC) has been making experimental, near-real-time seasonal global forecasts since 26 September 1997 with the NCEP global spectral model used for the reanalysis. Images of these forecasts, at daily to seasonal timescales, are provided on the World Wide Web and digital forecast products are provided on the ECPC anonymous FTP site to interested researchers. These forecasts are increasingly being used to drive regional models at the ECPC and elsewhere as well as various application models. The purpose of this paper is to describe the...

A height increment equation was used to determine the effects of site quality and competing herbaceous vegetation on the development of ponderosa pine seedlings (Pinus ponderosa var. scopulorum Engelm.). Study areas were established in 36 plantations across northwest and west-central Montana on Champion International Corporation's timberland (currently owned by Plum Creek Timber Company). Site quality indices used in the equation were available water index (available water capacity multiplied by the natural logarithm of annual precipitation) and site index (SI) of the previous stand....

Forestry, conservation, wildfire risk reduction, and agricultural uses of planned or prescribed fires as a tool for meeting the needs of wildland managers are increasingly in collision at the air pollution control and climate change cross-roads. The inevitable conflict resulting from the disparate goals of users has long been the subject of a combination of both systems and ecologically integrated analysis attempting to minimize the environmental impact and maximize the economic and societal benefits of this land management technique. We offer here experimental evidence for the viability...

Accurate knowledge of the number of newly-fledged juveniles offshore is critical to estimates of productivity of the threatened Marbled Murrelet (Brachyramphus marmoratus). We describe a method for collecting productivity data which allows researchers to objectively evaluate age determinations and their effect on juvenile percentages. This has the potential to reduce the effect of observer variability and the number of misidentified birds, especially late in the breeding season when adults in late pre-basic molt are very similar to juveniles. We analyzed the timing of this molt in adults,...

This report contains the detailed formulation of an individual-based model (IBM) of cutthroat trout developed for three study sites on Little Jones Creek, Del Norte County, in northwestern California. The model was designed to support research on relations between habitat and fish population dynamics, the importance of small tributaries to trout populations, and the usefulness of individual-based models for forest management. The model simulates the full trout life cycle at a daily time step; habitat is modeled at a resolution of several square meters. The major trout activities simulated...

We assessed the direct and indirect effect of the herbicide glyphosate on soil microbial communities from soil bioassays at glyphosate concentrations up to 100-fold greater than expected following a single field application. Indirect effects on microbial biomass, respiration, and metabolic diversity (Biolog and catabolic response profile) were compared seasonally after 9-13 years of vegetation control using repeated glyphosate applications in a replicated field study. Three pine plantations were selected to provide a range of soil characteristics associated with glyphosate binding (clay,...

Findings from 30 outdoor recreation visitor contact studies that wereconducted in California between 1989 and 1998 are summarized. Analyses focuson recreationist profiles, patterns of participation, beliefs and opinions,communication patterns, and depreciative behaviors. Although the “typical”respondent to the survey sites was white, there were many sites where significantnumbers of racial and ethnic minorities were recreating. Visitors chose the areasbecause the mountains and deserts are important to them. Some sites hadmoderately sized visitor groups; others had large groups, though the...