Biodiversity on rangelands: Definitions and values

Biodiversity is not just one phenomenon but is a concept cluster that involves many facets of biological variety. These facets include taxonomic richness; genetic differences within each taxon; the communities, ecosystems, and landscapes organisms occupy; and the knowledge of nature local people living on the land possess. Biodiversity is prized for a variety of intertwined moral, aesthetic, and practical reasons. The role of biodiversity in the globe\u27s life-support systems is poorly understood but probably pivotal. The world\u27s rangelands possess biodiversity out of proportion to their area or productivity. Livestock grazing may influence biodiversity either positively or negatively depending on what is being valued. It is impossible to maximize simultaneously all features of biodiversity. Therefore, management of rangelands to favor certain aspects of biodiversity will require compromise

Synecology and Disturbance Regimes of Sagebrush Steppe Ecosystems

The pre-Columbian mixed-growth form, composition, and structure of sagebrush steppes was mostly due to the highly variable semiarid climate and long fire-free intervals. The weak stability of this relatively complex vegetation was easily upset by excessive livestock grazing, especially in drought periods. After a few decades of uncontrolled livestock grazing, it was easy for introduced winter annuals, especially cheatgrass, to dominate the understory and alter the fire regime to larger, more frequent fires that occur earlier in the year. Accelerated soil erosion has caused many sites to lose the potential for management back toward native perennial dominance by controlling only livestock and fire. Major investments will probably be necessary to lengthen the current fire-free interval, as well as reduce the size of fires and their occurrence during late spring and early summer on large areas of cheatgrass dominance. Livestock could be used in some circumstances to help reverse the damage they did before grazing became regulated. Opportunities to apply genetic engineering to native plants and new herbicides to cheatgrass should also be explored before even more noxious biennials gain a major foothold

Think-tanking the challences in three regions: the Great Basin

The most unique characteristics of the Great Basin are the ecological fragility of the resources, scarcity of water, predominance of federal land, high degree of urbanization, independence of rural people. Factors most likely to impede EM are conflicting goals and missions of agencies, conflicting social values among stakeholders, slow recovery rates of biophysical systems, and difficulty of predicting responses to natural disturbances and management actions. Characteristics most likely to facilitate EM are new political climates promoting consensus, extensive federal lands, social diversity, and improving management technology. A critical need for successful EM is communication and promoting public understanding of the process

Intersection of ecosystem and biodiversity concerns in the management of rangelands

Maintenance of ecological functions and disturbance regimes within ecosystems is as important as preserving species populations or their genetic structure, biotic communities, and landscapes. There is considerable dispute as to how species diversity influences productivity and stability of various ecosystem structural and dynamic attributes. Some view each and every species as making an incremental contribution to these features. Others assume that some redundancy exists. Addition or loss of species can be anecdotally shown to influence ecosystems in proportion to the role such organisms. Subtle but essential interactions are easy to overlook, however. We should try to keep all the parts until more definitive research is available on this topic. Sustainable development will require balancing resource use with maintenance of our natural legacies. Ecosystem perspectives must contribute to decisions on where the balance exists

Methods in Historical Ecology: A Case Study of Tintic Valley, Utah

Through use of repeat photography, archival research, and field observation to reconstruct landscape vegetation patterns and changes across a 120 year period in the upper Tintic Valley of central Utah, researchers found significant changes in landscape vegetation pattern over time, including change in pinyon-juniper woodland area. Previously reported massive woodland harvest associated with early mining, domestic and agricultural activities elsewhere in the Intermountain West also took place in Utah. The impact on woodland area of the agricultural bull fence alone was significant. More recent study area woodland expansion also occurred. Because intensive industrial activity associated with development of the Tintic Mining District occurred prior to the taking of the study\u27s 1911 photographs, those photos failed to reflect presettlement, or even early settlement, vegetation conditions. Overall, results suggest that historical ecological studies must employ a range of overlapping methodologies to accurately interpret the nature and direction of landscape vegetation change. Such information is useful for managing regional ecosystems now and into the future

An analysis of montane forest vegetation on the east flank of the central Oregon Cascades

Montane forest vegetation as it occurs on the east flank of the central Oregon Cascades has provided excellent conditions for a "natural experiment" in the use of various methodologies in studying vegetational distribution. This "experiment" has reflected on some theory and practice for the discipline of plant synecology. Detailed descriptions, analysis, and interpretation of the data also document present conditions in relation to the past and allow prognostication of future changes, which in turn may be of silvicultural importance for a portion of this forest type found extensively on the east flank of the Sierra Nevada-Cascades cordillera. A major objective of this study was to determine the relative merits and deficiencies of attempting to transpose to this vegetation the methods of analyzing vegetation based on the individualistic or continuum philosophy of phytosociology that has developed and been practiced principally in the north-central United States. These attempts have been contrasted to strengths and short-comings of poly-climax theory, the most widely used basis of vegetational classification in the Pacific Northwest, in relation to the analysis of this and other vegetation types. The influences on and of these varying interpretations have been outlined and presented in tabular form. The study area is nearly ideal for posing these questions because edaphic and topographic factor complexes remain surprisingly uniform. The vegetation is superimposed in apparent primary response to the condensed gradient of total precipitation due to the orographic "rain shadow" effect from the Cascades intervening in this region of prevailing westerly winds. The stability of the vegetation concomitant with this nearly ideal set of "naturally controlled" physical conditions, minimized variations in successional status, except that due to fire exclusion. This latter variation, however, paralleled the complex gradient studied, a happenstance which allowed silviculturally important interpretations to be made. Stable vegetation occurring in general contiguity allowed stands to be sampled systematically, leaving little doubt concerning the validity of interpolation between stands and the areal representation of the samples. Another main objective of the study was to obtain and analyze data to substantiate the hypothesized influence of light periodic ground fires in initiating and maintaining the characteristic mosaic of size-age class distribution of ponderosa pine. The data also yielded a quantitative indication of the shift in species composition and dominance that is in largest measure due to the continued exclusion of fire by man for approximately the past 50 years. From these data the future appearance of the forest can be surmised, and silvicultural manipulations can be suggested that are best in harmony with the ecology of these forests. The circumstances that provided this "natural experiment" have allowed the author to demonstrate certain limitations to direct transposition of methods widely used in other areas of the United States, or even the Pacific Northwest, when description and analysis in closest feasible parallel to the nature of the patterns of vegetational distribution found in this area are attempted. This finding catalyzed the development of a method incorporating cluster analysis of matrices of relative parameter-weighted coefficients of association into a means of making very objective synecological delimitations. The dendrograms derived from this analysis allow a "sliding scale" of stratification to be made in this vegetation of most realistically intermediate, yet of more continuously variable than unit-association nature

Implement and Analysis on Current Ecosystem Classification in Western Utah of the United States & Yukon Territory of Canada

The study cases in western Utah of the United States and Yukon Territory of Canada have more natural land and conservative ecosystems in North America. The ecosystem classification of land (ECL) in these two ecoregions had been analyzed and validated through implementation. A full ECL case study was accomplished and examined with eight upper levels of ECOMAP plus ecological site and vegetation stand in Western Utah, the US. Theoretically, applying Köppen climate system classification, Bailey’s Domain and Division were applied to the United States, North America, and world continents. However, Canada’s continental upper level ecoregion framework defined the ecological Mozaic on a sub-continental scale, representing an area of the hierarchical ecological units characterized by interactive and adjusting abiotic and biotic factors. Using Bailey’s Domain as the top level of Canada’s territorial ecoregion was recommended. Eight levels of ELCs were established for Yukon Territory, Canada. Thus, the second study case recommends integrating the ecosystem approaches with Bailey’s upper level ECL, broad ecosystem classification, and objectively defined ecological site in different countries, or ecoregions. Our study cases had exemplified the implementations with a full ELCs in Bailey’s 300 Dry Domain and 100 Polar Domain

Predicting the Impact of Climate Change on Cheat Grass (Bromus tectorum) Invasibility for Northern Utah: A GIS and Remote Sensing Approach

Cheat grass (Bromus tectorum) invasibility represents a serious threat to natural ecosystems dominated by sagebrush (Artemisia tridentata). Ecosystem susceptibility to annual grass invasion seems to be driven by specific biophysical conditions. The study was conducted in Rich County, Utah, where cheat grass invasion is not yet an apparent problem, but an imminent invasion might be just a matter of time (temporal scale) to meet spatial variations in environmental conditions (spatial scale). Literature review and expert knowledge were used to define biophysical variables and their respective suitability ranges of where cheat grass takeover might occur. GIS, remote sensing and logistic regression-statistical analyses were employed to estimate probability of cheat grass invasion along environmental gradients. GIS procedures were used to spatially predict areas prone to be invaded by cheat grass under present climatic conditions (model prediction power was 47 percent). Afterwards, simulated climatic change projections (for 2099 year) from the Community Climatic System Model (CCSM-3) were used to model the invasibility risk of cheat grass. The 2099 cheat grass prediction map showed a favorable reduction of around 25 percent in the areas affected by cheat grass invasion, assuming that climate changes occurred as predicted by the CCSM model. The location of highly predisposed areas can be useful to alert managers and define where resources might be allocated to reduce a potential invasion and preserve native rangeland ecosystems