Treesearch

This primer provides resource inventory specialists with information on how to evaluate existing natural resource information and how to use it in preparing new resource inventortes. Subjects covered indude determining information needs, finding existing lnformation, determining its utility, evaluating Its suitability and quality, and incorporating It into new geographic information systems.

This guide details soil collection methods, sample analysis, and data translation. It outlines what field soil scientists need to make accurate interpretations of site information. Included are instructions for sampling typical Andisols found on National Forests of the Inland Northwest United States.

Fire exclusion in fire-dependent forest communities can alter stand structure and composition. The objective was to construct a fire history of two Pinus pungens Lamb. communities growing in southwestern Virgina. Treering analysis of fire-scarred P. pungens specimens and a tree survey were used to determine species composition and age distributions. From 1798-1944, fires burned approximately every 10 years. After acquisition by the United States Department of Agriculture Forest Service (ca. 1935) the study area burned only once (1944). Most of the population derives from two large cohorts...

The USDA Forest Service defined ecosystem management as "an ecological approach to achieve multiple-use management of national forests and grasslands by blending the needs of people and environmental values in such a way that national forests and grasslands represent diverse, healthy, productive, and sustainable ecosystems" (June 4, 1992, letter from Chief FS). This approach spans many different scales, both in time and space. It also implies that we need to carefully analyze and evaluate interactions between different parts of the ecosystem, including how humans interact and impact...

Human populations have increased dramatically along the Rio Grande since European settlement. Human use of water for irrigation and consumption, and human use of land for agriculture, urban centers, livestock grazing, and recreation have changed Rio Grande ecosystems by altering flood cycles, channel geomorphology, upslope processes, and water quality and quantity. Such abiotic changes have influenced the biological diversity and ecological functions of the Middle Rio Grande Basin, altering the distribution, structure, and composition of riparian plant and animal communities.

The Rio Grande was recently classified as one of the most endangered or imperiled rivers in North America (American Rivers 1993). Originating in southwestern Colorado, it passes through New Mexico and forms the international boundary between the United States (Texas) and Mexico. In its 2,000+ kilometer course to the Gulf of Mexico it passes through several major impoundments, is used in numerous irrigation diversion dams, and sustains massive groundwater pumping of its aquifer, especially in major metropolitan areas.

The Middle Rio Grande is part of the chain of structural basins, known as the Rio Grande depression, that extends from the San Luis Valley in Colorado to El Paso, Texas, and through which the Rio Grande flows (Chapin and Seager 1975). Bryan (1938) is credited with designating this reach as the Rio Grande "depression," because of his early research and the level of understanding he provided on the geology of the region. This area is also known as the Rio Grande "rift," a term coined by Kelly (1952), based on his belief in the possibility of significant longitudinal displacement in the...

The productivity, stability, and health of the Middle Rio Grande Basin, arid and semiarid grassland and shrub land ecosystems depend upon complex interactions. These relationships occur between factors such as climate, domestic livestock, and wildlife use, and human activities such as urban development, agriculture, and recreation. These grassland/ shrub land ecosystems are particularly sensitive to change because they depend highly upon water availability.

Pinyon-juniper woodlands are one of the largest ecosystems in the Southwest and in the Middle Rio Grande Basin (Fig. 1). The woodlands have been important to the region's inhabitants since prehistoric times for a variety of natural resources and amenities. The ecosystems have not been static; their distributions, stand characteristics, and site conditions have been altered by changes in climatic patterns and human use and, often, abuse. Management of these lands since European settlement has varied from light exploitation and benign neglect, to attempts to remove the trees in favor of...

The relationship of humans with Middle Rio Grande Basin ecosystems is complex. In historic times, humans had a critical role in the evolution of environmental landscapes and ecosystems throughout the Middle Rio Grande Basin. The relationship of humans with the land is based on and regulated by resource availability, environmental conditions, levels of technological knowledge, political and socioeconomic structures, and cultural values regarding the use of land and water. The general and specific impacts of historic human activities on Middle Rio Grande Basin ecosystems have only recently...