Treesearch

Emissions of trace gases and particulate matter from burning of biomass are generally factored into global climate models. Models for improving the estimates of the global annual release of emissions from biomass fires are presented. Estimates of total biomass consumed on a global basis range from 2 to 10 Pg (1 petagram = 1015 g) per year. New data are now available for emission factors for a range of vegetation types and burning conditions for the tropical, mid-latitude, and boreal forest regions. We estimate the total emissions of CO, CO2, CH4, non-methane hydrocarbons (NMHC), and...

Fire affects nutrient cycling and the physical, chemical, and biological properties of soils occupied by western montane forests. Combustion of litter and soil organic matter (OM) increases the availability of some nutrients, although others are volatilized (for example, N, P, S). Soil OM loss also affects cation exchange capacity, organic chelation, aggregate stability, macro pore space, infiltration, and soil microorganisms. Nitrogen replenishment must be emphasized when prescribed burning programs are planned or during rehabilitation following wildfires.

Of 32 species of abundant breeding birds, populations of 10 species differed significantly between small cutting units and adjacent uncut forest. Foliage foragers and tree gleaners were less abundant in cutting units, while flycatching species and ground foragers were more common there. Of nesting guilds, conifer tree nesters were least abundant in cutting units, and ground nesters were more common there. Results suggest that bird management should consider diverse community-level habitat needs and that if maintenance of tree-dependent species is important, broadleaf trees and snags of all...

Includes color photos of 44 species of fishes, many published for the first time. Text describes aquatic systems in the mountains and deserts of the Southwest, the unique fishes they support, and habitats the fishes need.

Models were developed to describe genetic variation among 201 seedling populations of Pinus ponderosa var. ponderosa in the Inland Northwest of the United States. Common-garden studies provided three variables Jhat reflected growth and development in field environments and three principal components of six variables that reflected patterns of shoot elongation. Regression models were developed for describing genetic variation across the landscape. Using functions of latitude, longitude, and elevation as descriptors, these models produced values of R2 that were as large as 0.66, while...

Numbers of suckers produced following burning of aspen stands varied greatly between areas but followed similar trends over a 6-year period: a relative abundance the first year, followed by an abrupt decline by the third year and a gradual decline thereafter. First-year sucker numbers that ranged from 34,000 to 147,000/ha suffered mortality between 54 and 93 percent by the sixth year. Only 40 percent of the variability between sites in number of suckers the second postburn year, and only 44 percent of the variability the sixth year, could be accounted for by season of burn and preburn site...

Our objective was to model the radial growth response of individual ponderosa pines to prescribed burning in northern Arizona. We sampled 188 trees from two study areas, which were burned in 1976. Within each study area, control and burned trees were of similar age, vigor, height, and competition index. At Chimney Spring, trees were older, less vigorous, and taller and had a higher competition index than at Brannigan. For each tree, periodic basal area increment (PBA1) was calculated for the years 1974-1984. To determine which variable would best model growth, post-fire growth (1977-1984)...

I examined timing of reproduction and productivity in box-nesting House Wrens (Troglodytes aedon) inhabiting three riverbank woodlands subjected to different levels of flooding. In years when the North Platte River flooded its banks submerging ground foraging substrates, dates of nest initiation and egg laying in two wren populations were delayed and nonsynchronized. In contrast, timing of breeding was unrelated to annual variations in water levels or spring weather in wrens occupying a riparian area buffered from flooding. Rates of nest predation were unlikely to influence timing of...

Bird count data were used to characterize patterns of abundance and distribution among 20 bird species occupying streamside habitats of the central Rocky Mountains. Cluster analysis classified bird assemblages from 10 study plots into three elevational zones that varied in bird species diversity. Monotonic declines in total bird densities over the elevational gradient corresponded to spatial fluctuations in population levels of a few numerically dominant species. Of 190 correlations in counts of species pairs, 48 were significant, a much greater proportion than that expected by chance....

The regeneration period is a crucial time in the life of a stand because it determines species composition and tree density for the new stand. Silviculturists prescribe treatments to favor adequate and timely conifer regeneration of economically important species that grow well. This paper presents research results that will help silviculturists identify factors favoring natural regeneration of interior Douglas-fir. The data were obtained from retrospective examination of randomly chosen, conventionally harvested stands 3-20 years old in Idaho and Montana. The information covers the...