Shrubland Ecosystem Genetics And Biodiversity

The 53 papers in this proceedings include a section celebrating the 25-year anniversary of the Shrub Sciences Laboratory (4 papers), three sections devoted to themes, genetics, and biodiversity (12 papers), disturbance ecology and biodiversity (14 papers), ecophysiology (13 papers), community ecology (9 papers), and field trip section (1 paper). The anniversary session papers emphasized the productivity and history of the Shrub Sciences Laboratory, 100 years of genetics, plant materials development for wildland shrub ecosystems, and current challenges in management and research in wildland shrub ecosystems. The papers in each of the thematic science sessions were centered on wildland shrub ecosystems. The field trip featured the genetics and ecology of chenopod shrublands of east-central Utah. The papers were presented at the 11th Wildland Shrub Symposium: Shrubland Ecosystem Genetics and Biodiversity held at the Brigham Young University Conference Center, Provo, UT, June 13-15, 2000.

The 26 papers in these proceedings are divided into five sections. The first two sections are an introduction and a plenary session that introduce the principles and role the shrub life-form in the High Plains, including the changing dynamics of shrublands and grasslands during the last four plus centuries. The remaining three sections are devoted to: fire, both prescribed fire and wildfire, in shrublands and grassland-shrubland interfaces; water and ecophysiology shrubland ecosystems; and the ecology and population biology of several shrub species.

Invasions by exotic grasses, particularly annuals, rank among the most extensive and intensive ways that humans are contributing to the transformation of the earth’s surface. The problem is particularly notable with a suite of exotic grasses in the Bromus genus in the arid and semiarid regions that dominate the western United States, which extend from the dry basins near the Sierra and Cascade Ranges across the Intermountain Region and Rockies to about 105° longitude. This genus includes approximately 150 species that have a wide range of invasive and non-invasive tendencies in their home ranges and in North America. Bromus species that became invasive upon introduction to North America in the late 1800’s, such as Bromus tectorum and B. rubens, have since became the dominant cover on millions of hectares. Here, millenia of ecosystem development led to landscapes that would otherwise be dominated by perennial shrubs, herbs, and biotic soil crusts that were able to persist in spite of variable and scarce precipitation. This native ecosystem resilience is increasingly coveted by land owners and managers as more hectares lose their resistance to Bromus grasses and similar exotics and as climate, land use, and disturbance-regime changes are also superimposed. Managers are increasingly challenged to glean basic services from these ecosystems as they become invaded. Exotic annual grasses reduce wildlife and livestock carrying capacity and increase the frequency and extent of wildfi res and associated soil erosion. This book uses a unique ecoregional and multidisciplinary approach to evaluate the invasiveness, impacts, and management of the large Bromus genus. Students, researchers, and practitioners interested in Bromus specifically and invasive exotics in general will benefit from the depth of knowledge summarized in the book.

The 51 papers in this proceedings include an introductory keynote paper on ecotones and hybrid zones and a final paper describing the mid-symposium field trip as well as collections of papers on ecotones and hybrid zones (15), population biology (6), community ecology (19), and community rehabilitation and restoration (9). All of the papers focus on wildland shrub ecosystems; 14 of the papers deal with one aspect or another of sagebrush (subgenus Tridentatae of Artemisia) ecosystems. The field trip consisted of descriptions of biology, ecology, and geology of a big sagebrush (Artemisia tridentata) hybrid zone between two subspecies (A. tridentata ssp. tridentata and A. t. ssp. vaseyana) in Salt Creek Canyon, Wasatch Mountains, Uinta National Forest, Utah, and the ecotonal or clinal vegetation gradient of the Great Basin Experimental Range, Manti-La Sal National Forest, Utah, together with its historical significance. The papers were presented at the 10th Wildland Shrub Symposium: Shrubland Ecotones, at Snow College, Ephraim, UT, August 12-14, 1998.