Treesearch

The future of ponderosa pine (Pinus ponderosa var. scopulorum) forests in the southwestern United States is uncertain because climate-change-induced stresses are expected to increase tree mortality and place greater constraints on regeneration. Silvicultural treatments, which include thinning, are increasingly being used to address forest health concerns by restoring ponderosa pine forests to more open conditions representative of historical forest structure. In light of the greater use of thinning and mounting concerns about the future of the species at the southern edge of its range,...

Soil changes associated with forest harvesting, differing utilization levels, and post-harvest prescribed burning were determined using an empirical study to investigate the long-term impacts on soil physical and chemical properties at Coram Experimental Forest in northwestern Montana. In 1974, two replications of three regeneration cuttings (shelterwood, group selection, and clearcut) were installed. In addition, four residue management regimes (high utilization with no burning, medium with no burning, medium with broadcast burning, and low with broadcast burning) were implemented (~74,...

Sonic anemometry is fundamental to all eddy-covariance studies of surface energy and ecosystem carbon and water balance. Recent studies have shown that some nonorthogonal anemometers underestimate vertical wind. Here it is hypothesized that this is due to a lack of transducer and structural shadowing correction. This is tested with a replicated intercomparison experiment between orthogonal (K-probe, Applied Technologies, Inc.) and nonorthogonal (A-probe, Applied Technologies, Inc.; and CSAT3 and CSAT3V, Campbell Scientific, Inc.) anemometer designs. For each of the 12 weeks, five randomly...

The San Dimas Experimental Forest (SDEF) is located in the San Gabriel Mountains, about 45 km northeastof Los Angeles, California. The SDEF was originally established in 1934 to document and quantify the hydrologic cycle in semiarid uplands with intermittent headwater streams. New and innovative equipment was necessary to measure rainfall and streamflow in this mountainous terrain. Long-term monitoring has revealed a number of hydrologic patterns following land use change and wildfire. Water quality monitoring shows that the SDEF has had very high levels of nitrate due to its proximity to...

We investigated the long-term impact of biomass utilization on shrub recovery, species composition, and biodiversity 38 years after harvesting at Coram Experimental Forest in northwestern Montana. Three levels of biomass removal intensity (high, medium, and low) treatments combined with prescribed burning treatment were nested within three regeneration harvest treatments (shelterwood, group selection, and clearcut). Four shrub biomass surveys (pre-treatment, 2, 10, and 38 years after treatment) were conducted. Shrub biomass for all treatment units 38 years after treatment exceeded the...

Long-term forest inventories provide a unique opportunity to quantify changes in forest structure and evaluate how changes compare with current stand development models. An examination of a 70 year record at the Bartlett Experimental Forest, New Hampshire, indicated that although species abundances have primarily changed as expected under natural succession, some unexpected results were also detected. This included a significant decline in sugar maple (Acer saccharum Marsh.) abundance driven by reduced regeneration and increases in red spruce (Picea rubens Sarg.) at the expense of sympatric...

Monitoring solutes in precipitation inputs and stream water exports at small watersheds has greatly advanced our understanding of biogeochemical cycling. Surprisingly, although inputs to and outputs from ecosystems are instrumental to understanding sources and sinks of nutrients and other elements, uncertainty in these fluxes is rarely reported in ecosystem budgets. We illustrate error propagation in input-output budgets by comparing the net hydrologic flux of Ca in a harvested and reference watershed at the Hubbard Brook Experimental Forest, New Hampshire. We identify sources of uncertaint...

Armillaria spp. occur widely in Missouri mixed-oak ecosystems. In order to better understand the ecology and management of this pathogen and its effects on oak coppice, we observed a transect of 150 stumps after clearcutting in southeastern Missouri, noting Armillaria infection and oak sprout demography one year and seven years after harvest. Additionally, we visited a 50-year-old clearcut in the same area to sample oak root systems of stump-sprout origin for comparison with the seven-year-old clearcut. One year after harvest, 55% of stumps supported Armillaria infections, while 62% of...

Many recent wildfires in ponderosa pine (Pinus ponderosa Lawson & C. Lawson) - dominated forests of the western United States have burned more severely than historical ones, generating concern about forest resilience. This concern stems from uncertainty about the ability of ponderosa pine and other co-occurring conifers to regenerate in areas where no surviving trees remain. We collected post-fire conifer regeneration and other data within and surrounding five 11-18 year-old Colorado Front Range wildfires to examine whether high severity burn areas (i.e., areas without surviving trees) are...

This publication chronicles the understanding, controlling, and impacts of mountain pine beetles (MPB) central to the Black Hills of South Dakota and Wyoming from the time they were described by Hopkins in 1902, through the presentation of data from work started by Schmid and Mata in 1985. The plots established by these two men from 1985 through 1994 were subjected to the most intense MPB stress to occur since 1900 in the Black Hills. The differentiation of western bark beetle species is discussed and how the final species designations of MPBs and western pine beetles (WPB) came about. The...