99 research outputs found
Western Juniper Field Guide: Asking the Right Questions to Select Appropriate Management Actions
Strong evidence indicates that western juniper has significantly expanded its range since the late 1800s by encroaching into landscapes once dominated by shrubs and herbaceous vegetation (fig. 1). Woodland expansion affects soil resources, plant community structure and composition, water, nutrient and fire cycles, forage production, wildlife habitat, and biodiversity. Goals of juniper management include an attempt to restore ecosystem function and a more balanced plant community that includes shrubs, grasses, and forbs, and to increase ecosystem resilience to disturbances. Developing a management strategy can be a difficult task due to uncertainty about how vegetation, soils, hydrologic function, and wildlife will respond to treatments.
When developing a management strategy, the first and possibly most important step towards success is asking the right questions. Identifying the attributes of the area to be treated and selecting the right treatments to be applied are of utmost importance. One must ask questions addressing the kind of site (that is, potential natural vegetation, soils, etc.), the current state of the site (that is, successional, hydrologic, etc.), what components need to be restored, how the management unit fits in with the overall landscape mosaic, and the long-term goals and objectives for the area or region. Keep in mind sagebrush-steppe vegetation is dynamic and management strategies must take into account multi-decade time frames.
This guide provides a set of tools that will help field biologists, land managers, and private landowners conduct rapid qualitative field assessments that address the kind of site and its current state. These tools include a list of questions to be addressed and a series of photographs, keys, tables, and figures to help evaluate a site. Conducting this assessment will help prioritize sites to be treated, select the best treatment, and predict outcomes.
Success of a juniper management program may be greatly enhanced if an interdisciplinary team of local managers and resource specialists, who are experienced with vegetation, fuels, soils, hydrology, wildlife, and economic and sociological aspects of the local resource, use this guide to aid their decision-making
Rhizosphere-mediated effects of the invasive grass Bromus tectorum L. and native Elymus elymoides on nitrogen cycling in Great Basin Desert soils
Background and aims: There is evidence that the invasive grass Bromus tectorum can affect soil nitrogen (N) cycling, possibly leading to a positive plant-soil feedback. Rhizosphere priming of N mineralization could provide a mechanistic explanation for such a feedback. Methods: We conducted a greenhouse study to isolate rhizosphere effects on N cycling by the invasive annual grass, Bromus tectorum L., and the native perennial grass, Elymus elymoides (Raf.) Swezey, in invaded and uninvaded soils. We compared the rhizosphere priming effect (RPE) on N mineralization by species and the distribution of N in various pools by planting treatment and soil type. Results: B. tectorum had a negative RPE (−23 and −22 % in invaded and uninvaded soils, respectively), while E. elymoides had no significant RPE. B. tectorum was more competitive over E. elymoides in invaded compared to uninvaded soil. Conclusions: B. tectorum had a negative effect on soil N availability via root-mediated processes, even though its growth and competitiveness increased in invaded soils. Positive plant-soil feedback effects of B. tectorum may be mediated by aboveground inputs rather than belowground and/or depend on site-specific conditions
Author Correction: Drivers of seedling establishment success in dryland restoration efforts
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Correción errata.In the version of this Article originally published, the surname of author Tina Parkhurst was incorrectly written as Schroeder. This has now been corrected.Peer reviewe
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Root length leaf area, and biomass of crested wheatgrass and cheatgrass seedlings
Cheatgrass (Bromus tectorum L.) dominates large tracts of rangeland in the western United States. Previous research has demonstrated the competitive nature of this species; however, the mechanisms contributing to its dominance have not been well elucidated. It is often suggested that cheatgrass outcompetes perennial seedlings because it germinates and grows at lower soil temperatures. However, even in studies where temperatures are not limiting, cheatgrass outcompetes perennial seedlings. Therefore, I conducted a study to compare accumulation of root length, leaf area, and biomass of cheatgrass and crested wheatgrass (Agropyron desertorum (Fisch. ex Link) Schult. cv. Nordan) seedlings under non-limiting conditions. Seedlings were grown in pots in the greenhouse for 60 days post-sowing. There were 4 seedlings per pot, and sampling was conducted weekly at 24-60 days after sowing. Maximum and minimum temperatures were 280 degrees C and 4 degrees C, respectively, and plants were watered twice a week. Cheatgrass had greater root length density and leaf area than created wheatgrass, especially during the later samplings. For the last 2 samplings, cheatgrass averaged about 12% more root mass and 56% more shoot mass, yet bad more than twice the root length and leaf area of crested wheatgrass. Cheatgrass was more efficient (per unit of biomass) in producing leaf area and root length, which helps explain its ability to quickly become established and exploit soil nutrient and moisture reserves.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
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Animal performance and diet quality as influenced by burning on tallgrass prairie
Burning on good to excellent condition tallgrass prairie in central Oklahoma yielded results which visually appeared much greater than would be expected from previous burning research. Therefore, a study was designed to quantify the effect of burning on plant and livestock responses. During 1984-1986, average daily gains of stocker cattle were monitored from late May to mid-October in replicated burned and unburned pastures. Stocking rates varied from 0.8 to 1.5 ha per animal depending on initial animal weights. Fistulated cattle were used to monitor diet quality on the pastures. Standing crops were measured at the end of the growing season (early October) in exclosures, and at the end of the grazing period (late October) in the pastures. Animal performance was improved by burning during the early part of the grazing season, and over the season animal production per ha averaged 11.2 kg higher on burned compared to unburned pastures. Dietary crude protein tended to be higher on unburned compared to burned pastures, but the opposite was true for in vitro organic matter digestibility. Standing crop remaining after the grazing period averaged 4,304 and 2,539 kg/ha for burned and unburned pastures, respectively. Standing crop was 57% higher in burned compared to unburned exclosures. Burning caused a shift in species composition to favor tallgrass species and lower production of weedy forbs in both exclosures and grazed pastures.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
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The Influence of Several Range Improvements on Estimated Carrying Capacity and Potential Beef Production
A simple calculation is proposed for estimating carrying capacity of range sites based on seasonal forage quality and standing crop. The model estimates animal unit days a pasture can support. Potential beef production of a particular site was estimated by multiplying animal unit days by average daily gain as indicated from forage quality. Improved and unimproved portions of 4 plant communities (grassland, mixed conifer, lodgepole pine, and moist meadow) were compared for carrying capacity and potential beef production. Improvement generally resulted in large increases in both carrying capacity and potential beef production; however, only in the case of the grassland did range improvement extend the period during which weight gains could be expected. Calculations indicate that energy generally became limiting before crude protein. Forage quality was insufficient to maintain weight gains of growing animals after mid-summer. Advantages and limitations of the calculations are discussed.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
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Effect of Hydroelutriation on Nonstructural Carbohydrates in Fibrous Roots
Hydroelutriation can reduce the time required to remove roots from soil cores relative to conventional washing methods. However, method of washing may affect subsequent chemical analysis. We compared a hydroelutriation method to dry, hand cleaning of roots for subsequent carbohydrate content of root tissue. Fibrous roots of winter wheat (Triticum aestivum L.), johnsongrass (Sorghum halepense (L.) Pers.), Caucasian bluestem (Bothriochloa caucasica (Trin.) C.E. Hubb.), and little bluestem (Schizachyrium scoparium (Michx.) Nash) were collected on 8 March and 25 May 1985. Roots were analyzed for both soluble carbohydrates and total nonstructural carbohydrates (TNC). Soluble carbohydrates were extracted using 2.5 mM H2 SO4; the TNC extraction included a 24-h incubation with amyloglucosidase at 50 degrees C in addition to weak acid hydrolysis. There were no significant differences (P>.05) between cleaning procedures for any of the species on the first sampling date, and only Caucasian bluestem roots were significantly affected (P<.05) by cleaning procedure the second date. Hydroelutriation washing resulted in a 15% reduction in both soluble carbohydrates and TNC in Caucasian bluestem roots relative to dry, hand cleaning. In general, loss of nonstructural carbohydrates from washed fibrous roots was not a major concern in the 4 species we tested. However, in specific instances it may be necessary to use a correction factor to account for loss of chemical constituents when using hydroelutriation methods.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
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The Influence of Grazing Pressure on Rooting Dynamics of Caucasian Bluestem
Caucasian bluestem (Bothriochloa caucasica (Trin.) C.E. Hubb.) is a warm-season grass introduced from Eurasia that is currently used for reseeding farmland and depleted range in the Southern Great Plains. Although this species is thought to be grazing tolerant, little specific information is available concerning its response to grazing. Variable (put-and-take) stocking was used to maintain heavy (3 to 8 steers/ha) and light (2.5 to 4.5 steers/ha) grazing treatments during mid May to late September from 1983 to 1985. Seasonal changes in root mass and root length to a depth of 60 cm were measured the first 2 years, and end-of-season root length was measured the third year. Leaf area index (LAI) was measured during the first 2 years. Peak root mass was 27 and 46% less in heavily relative to lightly grazed swards in 1983 and 1984, respectively. Total root length for heavily grazed swards was 33 and 45% less than lengths of lightly grazed swards in 1983 and 1984, respectively. Heavy grazing resulted in a relatively larger reduction in LAI than in either root mass or length, and thus the ratio of absorbing root surface to transpiring leaf surface was greater for heavily grazed than lightly grazed plants. This increased ratio may explain our previous observation that heavy grazing resulted in an improved water status of leaf tissue. End-of-season total root length over the 3-year period (15 to 18 and 24 to 28 km/m2 for heavily and lightly grazed swards, respectively) was remarkably consistent given the variable climatic conditions over the study period.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
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Grazing Effects on Water Relations of Caucasian Bluestem
Caucasian bluestem [Bothriochloa caucasica (Trin.) C.E. Hubb.] is a warm-season grass introduced from Eurasia that is currently used for reseeding rangelands in the southern Great Plains. Although this species is thought to be grazing tolerant, no specific information is available concerning its response to grazing. This study was conducted to evaluate the effect of 2 levels of grazing on xylem water potential and total leaf conductance (gT) of Caucasian bluestem. During the grazing period (mid May to mid September) diurnal xylem water potential and gT measurements were made on 3 days in 1983 and 1984, and afternoon measurements were taken at weekly intervals in 1984. Soil moisture at 15, 45, and 75 cm depths was monitored in 1984. Heavily grazed plants exhibited consistently higher (less negative) xylem water potential, and generally higher gT than lightly grazed plants. Averaged over the season, heavy grazing increased mean afternoon xylem water potential and gT by 28 and 76%, respectively, compared to light grazing. Soil moisture was conserved with heavy grazing; treatment differences were greatest during July, which is generally the driest summer month in central Oklahoma. Thus, for Caucasian bluestem, leaves from heavily grazed swards were under less water stress than leaves from lightly grazed swards.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
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