Rangeland Ecology & Management, Volume 66, Number 4 (July 2013)
http://hdl.handle.net/10150/635378
2024-03-29T06:47:18ZMarmot Disturbance Drives Trait Variations Among Five Dominant Grasses in a Mongolian Grassland
http://hdl.handle.net/10150/642736
Marmot Disturbance Drives Trait Variations Among Five Dominant Grasses in a Mongolian Grassland
Sasaki, Takehiro; Kakinuma, Kaoru; Yoshihara, Yu
We examined how disturbances by Siberian marmots (Marmota sibirica) and associated spatial heterogeneity of foraging patterns and soil properties affect trait variations in five dominant perennial grasses (including sedges) in a Mongolian grassland. Using four continuous traits (leaf height, leaf area, leaf mass per area, and root length) of each grass species, we compared species and plot mean trait values and species’ niche breadth (calculated on the basis of species’ traits) between sites with and without marmots. At sites with marmots, investment in leaves was not favored, probably because of the prevalence of foraging, with the result that plot mean values of leaf height and area were smaller than at control sites. Niche breadth values for leaf area and leaf mass per area were greater at marmot sites, probably due to the spatially heterogeneous patterns of foraging. We observed greater values of species and plot mean root length values at marmot sites. We suggest that the modification of soil physicochemical properties by marmot burrowing, defecation, and urination might enhance root growth for ensuring physical stability of plant bodies and increasing the rate of nutrient acquisition. Niche breadth value for root length was greater at marmot sites, probably due to the spatial heterogeneity of soil properties. Quantification of trait distributions among plant species may help to explain the different plant adaptive mechanisms in relation to external drivers, such as disturbance.
2013-07-01T00:00:00ZOptimal Placement of Off-Stream Water Sources for Ephemeral Stream Recovery
http://hdl.handle.net/10150/642735
Optimal Placement of Off-Stream Water Sources for Ephemeral Stream Recovery
Rigge, Matthew; Smart, Alexander; Wylie, Bruce
Uneven and/or inefficient livestock distribution is often a product of an inadequate number and distribution of watering points. Placement of off-stream water practices (OSWP) in pastures is a key consideration in rangeland management plans and is critical to achieving riparian recovery by improving grazing evenness, while improving livestock performance. Effective OSWP placement also minimizes the impacts of livestock use radiating from OSWP, known as the ‘‘piosphere.’’ The objective of this study was to provide land managers with recommendations for the optimum placement of OSWP. Specifically, we aimed to provide minimum offset distances of OSWP to streams and assess the effective range of OSWP using Normalized Difference Vegetation Index (NDVI) values, an indicator of live standing crop. NDVI values were determined from a time-series of Satellite Pour l’Observation de la Terre (SPOT) 20-m images of western South Dakota mixed-grass prairie. The NDVI values in ephemeral stream channels (in-channel) and uplands were extracted from pre- and post-OSWP images taken in 1989 and 2010, respectively. NDVI values were normalized to a reference imagine and subsequently by ecological site to produce nNDVI. Our results demonstrate a significant (P<0.05) increase in the nNDVI values of in-channel vegetation within 1 250 m of OSWP following their implementation. The area of piospheres (n=9) increased with pasture size (R2=0.49, P=0.05) and increased with average distance to OSWP in a pasture (R2=0.43, P=0.07). Piospheric reduction in nNDVI was observed within 200 m of OSWP, occasionally overlapping in-channel areas. The findings of this study suggest placement of OSWP 200 to 1 250 m from streams to achieve optimal results. These results can be used to increase grazing efficiency by effectively placing OSWP and insure that piospheres do not overlap ecologically important in-channel areas.
2013-07-01T00:00:00ZRestoring the Sagebrush Component in Crested Wheatgrass-Dominated Communities
http://hdl.handle.net/10150/642734
Restoring the Sagebrush Component in Crested Wheatgrass-Dominated Communities
Davies, Kirk W.; Boyd, Chad S.; Nafus, Aleta M.
Monotypic stands of crested wheatgrass (Agropyron cristatum [L] Gaertm. and Agropyron desertorum [Fisch.] Schult.), an introduced grass, occupy vast expanses of the sagebrush steppe. Efforts to improve habitat for sagebrush-associated wildlife by establishing a diverse community of native vegetation in crested wheatgrass stands have largely failed. Instead of concentrating on a diversity of species, we evaluated the potential to restore the foundation species, Wyoming big sagebrush (Artemisia tridentata spp. wyomingensis [Beetle A. Young] S. L. Welsh), to these communities. We investigated the establishment of Wyoming big sagebrush into six crested wheatgrass stands (sites) by broadcast seeding and planting seedling sagebrush across varying levels of crested wheatgrass control with glyphosate. Planted sagebrush seedlings survived at high rates (~70% planted sagebrush survival 3 yr postplanting), even without crested wheatgrass control. However, most attempts to establish sagebrush by broadcast seeding failed. Only at high levels of crested wheatgrass control did a few sagebrush plants establish from broadcasted seed. Sagebrush density and cover were greater with planting seedlings than broadcast seeding. Sagebrush cover, height, and canopy area were greater at higher levels of crested wheatgrass control. High levels of crested wheatgrass control also created an opportunity for exotic annuals to increase. Crested wheatgrass rapidly recovered after glyphosate control treatments, which suggests multiple treatments may be needed to effectively control crested wheatgrass. Our results suggest that planting sagebrush seedlings can structurally diversify monotypic crested wheatgrass stands to provide habitat for sagebrushassociated wildlife. Though this is not the full diversity of native functional groups representative of the sagebrush steppe, it is a substantial improvement over other efforts that have largely failed to alter these plant communities. We also hypothesize that planting sagebrush seedlings in patches or strips may provide a relatively inexpensive method to facilitate sagebrush recovery across vast landscapes where sagebrush has been lost.
2013-07-01T00:00:00ZManaging High-Elevation Sagebrush Steppe: Do Conifer Encroachment and Prescribed Fire Affect Habitat for Pygmy Rabbits?
http://hdl.handle.net/10150/642733
Managing High-Elevation Sagebrush Steppe: Do Conifer Encroachment and Prescribed Fire Affect Habitat for Pygmy Rabbits?
Woods, Bonnie A.; Rachlow, Janet L.; Bunting, Stephen C.; Johnson, Timothy R.; Bocking, Kelly
Both fire and conifer encroachment can markedly alter big sagebrush communities and thus habitat quality and quantity for wildlife. We investigated how conifer encroachment and spring prescribed burning affected forage and cover resources for a sagebrush specialist, the pygmy rabbit. We studied these dynamics at spring prescribed burns in southwestern Montana and eastern Idaho during the summer of 2011. Within each spring prescribed burn, we established plots that described the habitat conditions for pygmy rabbits (forage plant biomass and habitat components that influence predation risk) in areas that were burned, adjacent areas of conifer encroachment, and areas that were neither burned nor encroached. We analyzed the data for significant differences in habitat conditions between the paired reference and encroachment plots and modeled when the burned areas would approximate the conditions on the paired reference plots. Biomass of forage plants and habitat components that reduce predation risk differed between undisturbed reference plots and areas that were either burned or encroached with >30% conifer canopy. Our models estimated that 13-27 yr were required for a spring prescribed burn to provide levels of cover and forage resources similar to sagebrush steppe reference plots. We documented that vegetation composition was associated with the plot designations (burn, reference, or conifer encroachment), but not with other abiotic factors, such as soil texture, aspect, or study site; this suggested that the documented differences in habitat were related to the treatments, rather than being site-specific characteristics. The information from this study can contribute to habitat management plans for high-elevation mountain big sagebrush sites where conifer encroachment is altering habitat for sagebrush-dependent wildlife species.
2013-07-01T00:00:00Z