Geology topics

Jeanne Chambers

Publications and source records attributed to Jeanne Chambers.

5 recordsLinked to original sources

USGS2016

Plant community resistance to invasion by Bromus species: The roles of community attributes, Bromus interactions with plant communities, and Bromus traits

The factors that determine plant community resistance to exotic annual Bromus species ( Bromus hereafter) are diverse and context specific. They are influenced by the environmental characteristics and attributes of the community, the traits of Bromus species, and the direct and indirect interactions of Bromus with the plant community. Environmental factors, in particular ambient and soil temperatures, have significant effects on the ability of Bromus to establish and spread. Seasonality of precipitation relative to temperature influences plant community resistance to Bromus through effects on soil water storage, timing of water and nutrient availability, and dominant plant life forms. Differences among plant communities in how well soil resource use by the plant community matches resource supply rates can influence the magnitude of resource fluctuations due to either climate or disturbance and thus the opportunities for invasion. The spatial and temporal patterns of resource availability and acquisition of growth resources by Bromus versus native species strongly influence resistance to invasion. Traits of Bromus that confer a “priority advantage” for resource use in many communities include early-season germination and high growth and reproductive rates. Resistance to Bromus can be overwhelmed by high propagule supply, low innate seed dormancy, and large, if short-lived, seed banks. Biological crusts can inhibit germination and establishment of invasive annual plants, including several annual Bromus species, but are effective only in the absence of disturbance. Herbivores can have negative direct effects on Bromus , but positive indirect effects through decreases in competitors. Management strategies can be improved through increased understanding of community resistance to exotic annual Bromus species.

Book chapter↗

USGS2014

A synopsis of short-term response to alternative restoration treatments in sagebrush-steppe: the SageSTEP project

The Sagebrush Steppe Treatment Evaluation Project (SageSTEP) is an integrated long-term study that evaluates ecological effects of alternative treatments designed to reduce woody fuels and to stimulate the herbaceous understory of sagebrush steppe communities of the Intermountain West. This synopsis summarizes results through 3 yr posttreatment. Woody vegetation reduction by prescribed fire, mechanical treatments, or herbicides initiated a cascade of effects, beginning with increased availability of nitrogen and soil water, followed by increased growth of herbaceous vegetation. Response of butterflies and magnitudes of runoff and erosion closely followed herbaceous vegetation recovery. Effects on shrubs, biological soil crust, tree cover, surface woody fuel loads, and sagebrush-obligate bird communities will take longer to be fully expressed. In the short term, cool wet sites were more resilient than warm dry sites, and resistance was mostly dependent on pretreatment herbaceous cover. At least 10 yr of posttreatment time will likely be necessary to determine outcomes for most sites. Mechanical treatments did not serve as surrogates for prescribed fire in how each influenced the fuel bed, the soil, erosion, and sage-obligate bird communities. Woody vegetation reduction by any means resulted in increased availability of soil water, higher herbaceous cover, and greater butterfly numbers. We identified several trade-offs (desirable outcomes for some variables, undesirable for others), involving most components of the study system. Trade-offs are inevitable when managing complex natural systems, and they underline the importance of asking questions about the whole system when developing management objectives. Substantial spatial and temporal heterogeneity in sagebrush steppe ecosystems emphasizes the point that there will rarely be a “recipe” for choosing management actions on any specific area. Use of a consistent evaluation process linked to monitoring may be the best chance managers have for arresting woodland expansion and cheatgrass invasion that may accelerate in a future warming climate.

Rangeland Ecology and Management↗

USGS2013

Fire history, effects and management in southern Nevada

Fire can be both an ecosystem stressor (Chapter 2) and a critical ecosystem process, depending on when, where, and under what conditions it occurs on the southern Nevada landscape. Fire can also pose hazards to human life and property, particularly in the wildland/urban interface (WUI). The challenge faced by land managers is to prevent fires from occurring where they are likely to threaten ecosystem integrity or human developments, while allowing fires to occur where they will provide ecosystem benefits. The Southern Nevada Agency Partnership (SNAP) Science and Research Strategy summarizes this desired outcome with Sub-goal 1.1, which is to manage wildland fire to sustain Southern Nevada’s ecosystems (table 1.3; Chapter 1). This chapter provides information that will help land managers develop strategies to achieve this goal. It begins with a background section on fire history, spatial and temporal patterns of fire, and fire effects for the major ecosystem types of southern Nevada, (table 1.1; Chapter 1). Potential fire management actions are then discussed, the overall implications of the information to fire management are summarized, and the major knowledge gaps are described.

Nevada↗

USGS2013

Wildfire and invasive species in the west: challenges that hinder current and future management and protection of the sagebrush-steppe ecosystem: a Gap Report

The Western Association of Fish and Wildlife Agencies (WAFWA) to satisfy the 45-day report requirement identified in Cooperative Agreement (F13AC00353) between WAFWA and the U. S. Fish and Wildlife Service (FWS) submit this “Gap Report”. This report summarizes the policy, fiscal and science challenges that land managers encounter related to the control and reduction of the invasive plant/fire complex, especially as it relates to the threaten or endangered species listing status of the Greater sage-grouse ( Centrocercus urophasianus ). While this Gap Report identifies 22 technical, policy, planning and funding gaps, it should be considered a “work in-progress”. To address this effort a Wildfire/Invasive Initiative Work Group (WG) was formed. The WG consist of nationally recognized experts in fire ecology, Sage-grouse ecology and management, range management and plant ecology. The WG developed this Gap Report and will be developing the final report for this Cooperative Agreement. Thus, as the WG evaluates the wildfire/invasive issue and makes recommendation to address scientific and management shortcomings, additional gaps will be identified and included in the final report. Within this report, the WG has suggested the top 5 gaps. However, the actual priority of what should be addressed first will depend on the significance and sequence of the limiting factor, available funding, current work, roles and responsibilities of the specific agencies, etc. The WG will continue to meet on a regular basis to further develop and expand this list of gaps. Additionally, the WG will offer specific options to address the identified gaps. However, the WG recommends that the FWS, possibly through the State/Federal (Western Governors Association) Sage Grouse Task Force or the National Sage-grouse Executive Oversight Committee, establish a Subcommittee to specifically review this Gap Report and develop a multi-agency approach on how to address each gap. The WG will continue to endeavor to establish a priority list and identify the “low hanging fruit” that can be addressed in the short-term to affect the listing decision. Additionally, the WG will propose a longer-term strategy. However, to successfully establish such a strategy it will take buy-in and commitment at the highest levels in federal and state governments. In an effort to provide managers an opportunity to address the most important issues this coming fiscal year, we offer the following top 5 gaps. Beyond these top 5, the WG has identified 17 additional gaps that should be evaluated by both federal and state agencies as a means to help better manage the wildfire/invasive threat in the west.

Report↗

USGS2013

Invasive species in southern Nevada

Southern Nevada contains a wide range of topographies, elevations, and climactic zones emblematic of its position at the ecotone between the Mojave Desert, Great Basin, and Colorado Plateau ecoregions. These varied environmental conditions support a high degree of biological diversity (Chapter 1), but they also provide opportunities for a wide range of invasive species. In addition, the population center of the Las Vegas valley, and the agricultural area scattered throughout Clark, Lincoln, and Nye counties, all connected by a network of roads and highways, plus ephemeral and perennial watercourses, provide abundant opportunities for new invaders to be transported into and within southern Nevada (Brooks 2009; Brookes and Lair 2009). Invasive species are a concern for land managers because they can compete directly with native species (Brooks 2000; Chambers and others 2007; DeFlaco and others 2003, 2007; Mazzola and others 2010), change habitat conditions (Brooks and Esque 2002; Esque and others 2010; Miller and others 2011), and alter ecosystems properties (Brooks and Matchett 2006; Brooks and Pyke 2001; Evans and others 2001). Many invasive species have already established and spread to the point that they are now considered to pose significant problems in southern Nevada. However, there are likely many more than have wither not been transported to or colonized the region, or have established by for various reasons not spread or increased in abundance to the point where they have a significant impact. Land managers must understand both current and potential future problems posed by invasive species to appropriately prioritize management actions. This chapter addressed Sub-goal 1.2 in the SNAP Science Research Strategy (table 1.3; Turner and others 2009), which is to protect southern Nevada's ecosystems from the adverse impacts of invasive species. It provides a brief overview of the key concepts associated with the ecology and management of invasive species, and includes information relevant to all five strategic goals identified by the National Invasive Species Council: prevention, early detection and rapid response, control and management, restoration, and organization collaboration (National Invasive Species Council 2001, 2008). Restoration also is discussed in a broader context in Chapter 5 and 7. This chapter does not present a comprehensive review of all invasive species associated land management issues in southern Nevada, but rather uses key species of concern to illustrate invasion ecology concepts and management strategies. It is focused on terrestrial and aquatic plants and animals, and does not address potential invasive taxa from the other Kingdoms. The information presented herein is intended to provide a foundation upon which land management plans can be developed and project-level decisions can be made relative to the management of invasive species in southern Nevada.

Nevada↗