Treesearch

The behavior of white pine blister rust at Mountain Home State Demonstration Forest and surrounding areas in the southern Sierra Nevada of California indicates that the epidemic has not yet stabilized and that the most likely prognosis is a pandemic on white pines in this region within the next few decades. The impact on sugar pines, from young regeneration to old growth, already has been severe in some areas, and silvicultural control measures have been largely ineffective. An operational genetic program, based on selection of seed parents carrying a major resistance gene, is described...

The wood of lodgepole pines and whitebark pines from a high elevation site in the east central Sierra Nevada of California was analyzed for chemical content to determine whether there were any temporal patterns of chemical distribution in tree rings. Cores were taken from 10 trees of each species and divided into 5-year increments for chemical analysis. Correlation analysis indicated that calcium and magnesium, both of which have divalent cations, were strongly correlated for both species. The elements copper, iron, cobalt, nickel, molybdenum, chromium, tin, and arsenic were all significant...

Forty-nine species of mammals regularly occur in California chaparral, but none lives only in chaparral. Among the 49 species, 7 are found primarily in mature chaparral, 9 in young chaparral or along ecotones between chaparral and other plant communities, and 19 in riparian areas. Five species occur in many habitats but prefer chaparral in California,and 9 have wide ranges that encompass many communities including chaparral. By altering the structure of the plant community, fire in chaparral is important in determining the distribution and abundance of mammalian populations. Fire is not...

Minerotrophic peatlands or fens in California's Sierra Nevada are small wet meadows surrounded by mixed conifer forest. The dynamics of vegetation change at the meadow edge and the ages and development of fens were investigated, in the Sagehen Creek Basin near Truckee, California, through the use of radiocarbon dating of peat, pollen studies, examination of processes of peat development and accumulation, stand age analysis of trees around peatlands, and evaluation of tree-ring variation. These approaches were used to evaluate both short- and long-term changes. Fens varied in age from more...

Studies stimulated by the International Biological Program showed total insect faunal biomass and diversity to be greatest in the spring of the year, which matches increased plant growth and flowering at this time. Ground-inhabiting beetle studies indicated the family Tenebrionidae to be overwhelmingly dominant in biomass, but the family Staphylinidae to be richest in species numbers. Ant studies showed the chaparral community to be rich in ant species; seed gatherers were particularly important. Flower-visiting insects are more abundant and more species-rich in chaparral than in any other...

Vegetation can reduce the cooling loads of buildings in hot arid climates by modifying air temperature, solar heat gain, longwave heat gain, and heat loss by convection. However, savings from reduced mechanical cooling may be offset by increased irrigation water costs. In this study, three similar model buildings were constructed and surrounded with different landscapes: turf, rock mulch with a foundation planting of shrubs, and rock mulch with no plants. Irrigation water use and electricity required to power the three room-sized air conditioners and interior lights were measured for two...

Our purpose is to use certain ecological measures, commonly adopted for understanding natural forest populations, to describe and compare street tree populations. Street trees compose only about 10-20 percent of the urban forest, hut there are sufficient data on these populations to apply certain measures of structure and to interpret the results. We used inventories from 22 U.S. cities to compare patterns in species and age composition, stocking levels, and growth forms. From this we infer trends toward greater species diversity and smaller tree size,· these trends are discussed in terms...

Fire managers across the nation are confronting the rapidly developing problem created by movement of people into wildland areas, increasing what has been termed the wildland-urban interface. The problem is very complex from the standpoint of fire planning and management. To plan and manage more effectively, fire managers should identify three types of interface areas, each with its own unique set of demographic factors, local land use, and fire protection problems. By examining and understanding how future trends will affect fire protection tactics and strategy in each of the interfaces,...

A relatively small number of forest fires are responsible for a very high proportion of the total damage. The proportion due to the fraction p of largest fires, when plotted against p, is a measure of variability of fire sizes that is especially sensitive to the important extreme events. We find the theoretical form of the plot for several commonly used distributions and show how the results can be used in the analysis of empirical plots from actual fire size distributions. Some simple graphical methods are suggested for the fitting of truncated Pareto and lognormal distributions to...