Sagebrush
This study compared trends of sagebrush-obligate songbirds from the Breeding Bird Survey and sage-grouse lek counts in 2 sage-grouse populations in Wyoming from 1996–2013. Our evaluation was focused on similarities among population performance of the umbrella species and the species under that umbrella. Sagebrush-obligate songbird and both sage-grouse populations occupied habitat within and outside of protected core areas. Trends of sagebrush-obligate songbirds were not parallel or consistently similar in trajectory to sage-grouse in either core or non-core areas. Our results indicated core areas were successful at maintaining higher sage-grouse trends compared to areas not protected under the core area policy. However, sagebrush-obligate songbird trends did not follow the same pattern. This suggests that protection of only the best sage-grouse habitat may not be a sufficient conservation strategy for other sagebrush-obligate birds.
Using data collected as part of the Sagebrush Steppe Treatment Evaluation Project (SageSTEP), this guide summarizes fuel loads, vegetation cover by functional group, and shrub and tree stem density 10 years after sagebrush and pinyon-juniper reduction treatments. The data was collected at 16 study sites in Washington, Oregon, California, Nevada, and Utah, and is summarized by treatment type, region, and roups or woodland development phases based on pre-treatment vegetation. These summarized data an be used by land managers and fire behavior specialists to quickly estimate fuel loads in older treatments or to predict fuel loads 10 years after a potential treatment. These fuel loading data can be used to create custom fuel beds to model fire behavior and effects.
In this issue:
- Fuels Guide for Sagebrush and Pinyon-Juniper Reduction Treatments: 10 years post-treatment
- Biological soil crusts as restoration targets in sagebrush steppe and woodland communities
Keys to greater sage-grouse management are maintenance of expansive stands of sagebrush, especially varieties of big sagebrush with abundant forbs in the understory, particularly during spring; undisturbed and somewhat open sites for leks; and healthy perennial grass and forb stands intermixed with sagebrush for brood rearing. Within suitable habitats, areas should have 15–25% canopy cover of sagebrush 30–80 cm tall for nesting and 10–25% canopy cover 40–80 cm tall for brood rearing. In winter habitats, shrubs should be exposed 25–35 cm above snow and have 10–30% canopy cover exposed above snow. In nesting and brood-rearing habitats, the understory should have at least 15 percent cover of grasses and at least 10 percent cover of forbs greater than or equal to 18 cm tall. Greater sage-grouse have been reported to use habitats with 5–110 cm average vegetation height, 5–160 cm visual obstruction reading, 3–51% grass cover, 3–20% forb cover, 3–69 percent shrub cover, 7–63% sagebrush cover, 14–51% bare ground, and 0–18% litter cover. Unless otherwise noted, this account refers to habitat requirements and environmental factors affecting greater sage-grouse but not Gunnison sage-grouse. Habitats used by Gunnison sage-grouse are generally similar to habitats used by Greater Sage-Grouse, but some differences have been reported. The greater sage-grouse is a game bird and is hunted throughout most of its current range. This account does not address harvest or its effects on populations; rather, this account focuses on the effects of habitat management.
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With remotely-sensed (Landsat) estimates of vegetation cover collected every 2–5 years from southwestern Wyoming, USA, over nearly three decades (1985–2015), we modeled changes in sagebrush cover on 375 former oil and gas well pads in response to weather and site-level conditions. We then used modeled relationships to predict recovery time across the landscape as an indicator of resilience for vegetation after well pad disturbances, where faster recovery indicates a greater capacity to recover when similarly disturbed. We found the rate of change in sagebrush cover generally increased with moisture and temperature, particularly at higher elevations. Rate of change in sagebrush cover also increased and decreased with greater percent sand and larger well pads, respectively. We predicted 21% of the landscape would recover to pre-disturbance conditions within 60 years, whereas other areas may require >100 years for recovery. These predictions and maps could inform future restoration efforts as they reflect resilience. This approach also is applicable to other disturbance types (e.g., fires and vegetation removal treatments) across landscapes, which can further improve conservation efforts by characterizing past conditions and monitoring trends in subsequent years.
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We used long‐term data from the Utah Division of Wildlife Resources Range Trend Project to assess short‐term (1–4 yr post‐treatment) and long‐term (6–10 yr post‐treatment) effects of fire on vegetation cover at 16 sites relative to sage‐grouse habitat vegetation guidelines. Sagebrush cover remained low post‐fire at sites considered historically unsuitable for sage‐grouse (<10% initial sagebrush cover). In contrast, at sites that had higher (>10%) pre‐fire sagebrush cover, sagebrush cover decreased to <10% in the short‐term post‐fire, but by 6–10 yr after fire, most of these sites exhibited a recovering trajectory and two sites had recovered to >10% cover. Post‐fire sagebrush cover was positively related to elevation. Across all sites, perennial grasses and forbs increased in cover to approximately meet the habitat vegetation guidelines for sage‐grouse. Cheatgrass cover did not change in response to fire, and increased perennial grass cover appears to have played an important role in suppressing cheatgrass. Our results indicate that, while fire poses a potential risk for sage‐grouse habitat loss and degradation, burned sites do not necessarily need to be considered permanently altered, especially if they are located at higher elevation, have high sagebrush cover pre‐fire, and are reseeded with perennial grasses and forbs post‐fire. However, our results confirm that fire at more degraded sites, for example, those with <10% sagebrush cover, can result in cheatgrass‐dominated landscapes and sagebrush loss at these sites should be avoided.
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Study objectives were (1) to quantify the magnitude and direction of change in the cover of native and exotic plant functional groups in relation to their exposure to fire; (2) to relate plant community changes to their historical composition, exposure to fire, and environmental conditions; and (3) to test for consistency of trends revealed by vegetation cover data derived from field plots and Landsat images. Results suggest that burned areas historically occupied by sagebrush‐dominated plant communities may have been invaded by exotic annuals prior to burning, possibly because of prior land uses, and after burning, have now transitioned to a persistent herbaceous‐dominated state. This type of state transition has important consequences for forage quality, wildlife habitat, soil nutrients, and future disturbances, such as drought and wildfire.
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Restoration targets for biological soil crusts are largely unknown. We surveyed seven 80‐year‐old grazing exclosures across northern Nevada for biocrusts to quantify reference conditions at relatively undisturbed sites. Exclosures were associated with the following plant communities: Wyoming big sagebrush, black sagebrush, and areas co‐dominated by winterfat and Wyoming big sagebrush. Cover of biocrusts and shrubs were generally higher than other plant groups at these sites, regardless of being inside or outside of the exclosures, suggesting these groups make up most of the native flora across the region. Important in forming soil structure, cyanobacteria of the order Oscillatoriales were less abundant and diverse in black sagebrush communities. Grazing had a negative effect on the abundance of Oscillatoriales but not the number of algal taxa, including cyanobacteria.
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Current methods for determining plant age of shrub species require destructive sampling and annual growth ring analysis on the primary stem. Although individual plant ages can frequently be determined in this manner, the method is time consuming and of limited value for plants that have lost stem wood from stem splitting and rot. This study evaluated traits including plant height, crown area, subcanopy litter depth, percent crown mortality, bark furrow depth, bark fiber length, circumference and diameter of plant basal stem, and circumference of secondary and tertiary branches.We measured and harvested basal cross-sections from 163 plants of varying sizes from five locations in central and south-central Utah. Results support previous findings that stem girth has value for estimating mountain big sagebrush plant age and that this trait is a better indicator of age than any other tested traits. Although the relationship between stem diameter and plant age was significant, substantial stem size variability associated with plants of the same approximate age indicates that the method is most appropriate when precise age estimates are not required. This technique was developed specifically for mountain big sagebrush, but it is expected that it can be adapted for other sagebrush taxa.
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Abstracts of Recent Papers on Range Management in the West. Prepared by Charlie Clements, Rangeland Scientist, USDA Agricultural Research Service, Reno, NV.