Can ruderal components of biocrust (mosses and cyanobacteria) be maintained under increasing threats of drought, grazing and feral horses?
Biological soil crusts (biocrusts) are a community of living organisms, like moss, lichen, and algae, covering soils in arid and semi-arid ecosystems, providing important ecological functions like carbon cycling and soil stabilization. Analyses show that biocrusts are negatively associated with the abundance of invasive annual grasses that are responsible for increasing fire across the Great Basin. Although biocrusts thrive under soil and climate conditions that are stressful for most plants, components of biocrusts vary in tolerance of climate (snow, wetting and drying cycles), and disturbance, such that plant communities demonstrate consistent compositions of biocrusts. For example, we know that mosses will succumb to frequent wetting and drying events at short intervals. Although some biocrusts that are tolerant of disturbances can be maintained under certain conditions, feral horses can reduce biocrusts. We are examining the effects of these stressors on different groups of biocrusts, using both existing data and newly collected data, to help inform resource management agencies, like the Bureau of Land Management, as they prioritize management efforts.
Research Objectives
Our research objectives are to identify conditions under which some components of biocrusts can be maintained given three common stressors across the state of Nevada: (1) climate change, specifically modeled changes in wetting and drying cycles at the soil surface, (2) trampling by livestock and (3) trampling by feral horses. This work is important in Nevada, which is the driest state in the US and has the highest number of wild horses.
Methods
Several data layers were used to conduct a random, stratified sampling of potential field sites that were surveyed for composition of biocrusts. We used data from the Rangeland Administration System (RAS) to categorize allotments by season of grazing. Allotments were overlaid with data from the Gridded Soil Survey Geographic Database (gSSURGO) to obtain soil texture. We also accounted for the abundance of feral horses using boundaries of horse and burro herd areas and herd management areas. Potential sampling plots were then overlaid with fire perimeter data from the Monitoring Trends in Burn Severity program to avoid burned sites and focus sampling on impacts related to grazing and feral horses.
Approximately 175 plots were surveyed across northern Nevada during 2023. We are compiling these data before calculating site-specific data related to modeled wetting and drying cycles.
Funders
United States Bureau of Land Management Wildlife Program
Biological soil crusts (biocrusts) are a community of living organisms, like moss, lichen, and algae, covering soils in arid and semi-arid ecosystems, providing important ecological functions like carbon cycling and soil stabilization. Analyses show that biocrusts are negatively associated with the abundance of invasive annual grasses that are responsible for increasing fire across the Great Basin. Although biocrusts thrive under soil and climate conditions that are stressful for most plants, components of biocrusts vary in tolerance of climate (snow, wetting and drying cycles), and disturbance, such that plant communities demonstrate consistent compositions of biocrusts. For example, we know that mosses will succumb to frequent wetting and drying events at short intervals. Although some biocrusts that are tolerant of disturbances can be maintained under certain conditions, feral horses can reduce biocrusts. We are examining the effects of these stressors on different groups of biocrusts, using both existing data and newly collected data, to help inform resource management agencies, like the Bureau of Land Management, as they prioritize management efforts.
Research Objectives
Our research objectives are to identify conditions under which some components of biocrusts can be maintained given three common stressors across the state of Nevada: (1) climate change, specifically modeled changes in wetting and drying cycles at the soil surface, (2) trampling by livestock and (3) trampling by feral horses. This work is important in Nevada, which is the driest state in the US and has the highest number of wild horses.
Methods
Several data layers were used to conduct a random, stratified sampling of potential field sites that were surveyed for composition of biocrusts. We used data from the Rangeland Administration System (RAS) to categorize allotments by season of grazing. Allotments were overlaid with data from the Gridded Soil Survey Geographic Database (gSSURGO) to obtain soil texture. We also accounted for the abundance of feral horses using boundaries of horse and burro herd areas and herd management areas. Potential sampling plots were then overlaid with fire perimeter data from the Monitoring Trends in Burn Severity program to avoid burned sites and focus sampling on impacts related to grazing and feral horses.
Approximately 175 plots were surveyed across northern Nevada during 2023. We are compiling these data before calculating site-specific data related to modeled wetting and drying cycles.
Funders
United States Bureau of Land Management Wildlife Program