Desert Ecology Commons^™

Exploring The Seed Bank Dynamics Of Red Brome: Longevity, Density, And Relationship To Fire, Benjamin S. Jurand

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research explores several untested aspects of the seed bank characteristics of red brome (Bromus rubens), an invasive annual grass in southwestern United States arid lands. Red brome is a formidable competitor to native plant species, both annual and perennial alike, and produces many seeds that germinate easily. The stalks of red brome contribute continuous-cover fuel loads that facilitate wildfires destructive to mature native Mojave Desert plant communities. This makes it a priority species for land managers, particularly when dealing with recovery after fire.

This project addressed questions related to the longevity of red brome seeds in soil seed banks …

Can Resource-Use Traits Predict Native Vs. Exotic Plant Success In Carbon Amended Soils?, Robert J. Steers, Jennifer L. Funk, Edith B. Allen

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Productivity in desert ecosystems is primarily limited by water followed by nitrogen availability. In the deserts of southern California, nitrogen additions have increased invasive annual plant abundance. Similar findings from other ecosystems have led to a general acceptance that invasive plants, especially annual grasses, are nitrophilous. Consequently, reductions of soil nitrogen via carbon amendments have been conducted by many researchers in a variety of ecosystems in order to disproportionately lower invasive species abundance, but with mixed success. Recent studies suggest that resource-use traits may predict the efficacy of such resource manipulations; however, this theory remains largely untested. We report findings …

Assessing Invasive Plant Species As Threats In Mojave Desert Parks, Sara L. Mcpherson, Donovan J. Craig, Scott R. Abella

Graduate Research Symposium (GCUA) (2010 - 2017)

The invasion and persistence of exotic plant species threatens the natural features that national parks are designed to protect. For example, park managers have witnessed an increase in the frequency, extent and intensity of fires along with a reduction in native species richness and diversity. Many park managers are familiar with a suite of highly invasive plants, but lack a comprehensive and systematic way of prioritizing invasive plant species based on potential threats to the parks’ resources. We have entered into a collaborative project with the National Park Service’s Inventory and Monitoring program to develop an invasive plant early detection …

Trying To Beat The Brome: Understanding Establishment Thresholds And Choosing Competitive Native Species At Parashant National Monument, Scott R. Abella, E. Cayenne Engel

Public Policy and Leadership Faculty Publications

Desert fires fueled by exotic grasses like the omnipresent red brome (Bromus rubens) can be intense and cause widespread mortality of native vegetation. Native desert scrub communities such as those dominated by blackbrush (Coleogyne ramosissima) do not readily reestablish after fire (Abella 2009) and may even become more abundant in the post-burn landscape initiating a fire cycle that occurs at a greater frequency than the recovery time of the long-lived desert perennial community.

Native Species Interactions With Red Brome: Suggestions For Burn-Area Revegetation, Scott R. Abella

Public Policy and Leadership Faculty Publications

In deserts, native perennial plants often actually facilitate the establishment of exotic annual grasses. One of our focal areas of research is to identify native species for use in revegetation projects that reduce the establishment of exotic annual grasses, or at least do not strongly facilitate exotic species establishment. An initial research effort involving a competition experiment of red brome with native species and a correlational field study of brome distribution among native perennial plants is in press with the journal Invasive Plant Science and Management.

Heat And Smoke Effects On Red Brome Soil Seed Banks, Scott R. Abella, E. Cayenne Engel

Public Policy and Leadership Faculty Publications

Management of exotic plants that are annuals entails understanding and managing their soil seed banks. We completed a study of the influences of heat and liquid smoke on red brome (Bromus rubens) soil seed banks collected from Red Rock Canyon in southern Nevada as part of a collaborative fire effects monitoring effort with Bureau of Land Management - Las Vegas. We collected the samples from the 2005 Loop Fire, where we observed in a monitoring field study that exotic grasses such as red brome were relatively sparse in the first 2-3 years (which were during a dry period) following the …

Early Post-Fire Plant Establishment On A Mojave Desert Burn, Scott R. Abella, E. Cayenne Engel, Christina L. Lund, Jessica E. Spencer

Public Policy and Leadership Faculty Publications

Fire has become more extensive in recent decades in southwestern United States arid lands. Burned areas pose management challenges and opportunities, and increasing our understanding of post-fire plant colonization may assist management decision-making. We examined plant communities, soils, and soil seed banks two years after the 2005 Loop Fire, located in a creosote-blackbrush community in Red Rock Canyon National Conservation Area in southern Nevada’s Mojave Desert. Based on a spring sampling of 20, 0.01-ha plots, live + dead cover of the exotic annual Bromus rubens averaged nine times lower on the burn than on a paired unburned area. Perennial species …

Plant Community Response To Fire: A Chronosequence Study, Scott R. Abella, E. Cayenne Engel

Public Policy and Leadership Faculty Publications

Fires are becoming more prevalent events across the landscape in the southwestern US. Over the next several decades the already arid southwest is predicted to become warmer and drier, with longer summers, and an increase of “extreme” weather events such as lightening inducing thunderstorms. While the “hotter and drier” forecast may indicate less abundant plant life, and thus less available biomass for fuel, exotic invasive plant species are becoming more dominant across the landscape with increases in human travel and commerce. Exotic species (particularly many of the invasive grasses) are adding fuel for the fires to burn when the annuals …

Exotic Annual Plant Invasions And Their Relationships To Roads And Native Perennial Species In The Mojave Desert, Southwestern Usa, Donovan J. Craig, Jill Pacovsky Craig, Scott R. Abella

Vegetation Monitoring Presentations

For the last five years, roadside monitoring for exotic invasive species has been a common practice for documenting distributions in Clark County, Nevada (Abella et al., in press). Yet, studies have shown that weed relationships to road corridors differ depending upon the natural system (Hansen and Clevenger, 2005). In the Mojave Desert, it is unknown whether exotic species are limited to or even predominant along roadsides.

Compounding this uncertainty, fertile islands under shrubs are known to enhance conditions for many annuals (Thompson et al., 2005). Thus, a site’s shrub composition could influence exotic invasive plant distributions.

Implications For Management Prioritization Of Exotic Annual Weed Monitoring Near Roadsides In The Eastern Mojave Desert, Usa, Donovan J. Craig, Jill E. Craig, Scott R. Abella, Public Lands Institute,

Vegetation Monitoring Presentations

Invasive exotic plants provide an unnatural conduit for fires in the Mojave Desert. For the last five years, roadside monitoring for exotic invasive species has been a common practice for documenting distributions in Clark County, Nevada (Abella et al., in press). Yet, studies have shown that weed relationships to road corridors differ depending upon the natural system (Hansen and Clevenger, 2005). In the Mojave Desert, it is unknown whether exotic species are limited to or even predominant along roadsides.

Compounding this uncertainty, fertile islands under shrubs are known to enhance conditions for many annuals (Thompson et al., 2005). Thus, a …

Management Techniques For The Control Of Sahara Mustard (Brassica Tournefortii) In The Mojave Desert, Dianne N. Bangle, Scott R. Abella, Public Lands Institute,

Vegetation Monitoring Presentations

In the southwestern United States, Brassica tournefortii(Sahara mustard) is a highly invasive plant that colonizes roadsides, beaches, sand dunes, and open desert threatening native annuals. Sahara mustard is believed to contribute to fuel loads in the Mojave Desert in areas where Schismussp. and Bromussp. occur. Sahara mustard may act as ladder fuel, thereby facilitating the spread of fire throughout the landscape. Manpower limitations and insufficient funding limits the abilities of managers to effectively control Sahara mustard. We tested seed germinability in Sahara mustard after fruiting plants were treated with either 2%, 5%, or 12% triclopyr. Sahara mustard seed pods were …

Response Of Sahara Mustard (Brassica Tournefortii) To Water Addition And Soil Disturbance, Alexis Suazo, Jessica E. Spencer, Scott R. Abella

Vegetation Monitoring Presentations

Invasive exotic species can have a significant impact on the structure, function, and diversity of ecological communities. Sahara mustard (Brassica tournefortii) is one of the top exotic invasive species spreading through the southwestern deserts of North America. In arid environments, it is well documented that species abundance is sensitive to rainfall (Beatly 1974, Ernest et al. 2000). In the Mojave Desert, winter precipitation can trigger massive germination events (Beatly 1974). As a winter annual, Sahara mustard may have a positive response to winter precipitation by germinating, growing, and reproducing before native annuals, monopolizing soil moisture and nutrients, and potentially changing …