Journal of Range Management, Volume 44, Number 4 (July 1991): Recent submissions
Now showing items 21-25 of 25
-
Effects of single season and rotation harvesting on cool- and warm-season grasses of a mountain grasslandA mountain bunchgrass community with cool-season Parry oatgrass (Danthonia parryi) and warm-season slimstem muhly (Muhlenbergia filiculmis) as major grasses was treated with early partial harvest of cool-season grasses and late partial harvest of warm-season grasses. Warm-season grasses in these communities were greatly reduced by repeated late harvest, slightly reduced by late harvest in alternate years, and slightly promoted by early harvest of cool-season grasses. The dominant cool-season grasses responded less to repeated early harvests than did the less abundant warm-season grasses to repeated late harvests. The hypothesis that different harvest schedules may lead to alternative equilibria is supported, and rest alone may not cause a shift from a cool-season dominated equilibrium toward a greater warm-season presence in the plant community.
-
Effects of established perennial grasses on yields of associated annual weedsPerennial grasses are needed for seeding annual grasslands in the Mediterranean/maritime climatic regime of southwest Oregon. Selection of plants for reseeding purposes would be facilitated by identification of perennial grasses that, once established, are able to suppress resident annual plant production. Perennial grasses were transplanted and allowed to establish in the absence of competition for the first growing season at 2 sites in the foothills of southwest Oregon. After the first growing season, resident annual plants were allowed to reinvade. Perennial grasses such as Berber orchardgrass (Dactylis glomerata L. var. Berber) and Idaho fescue (Festuca idahoensis Elmer) that begin growth early suppressed annuals more effectively than later growing perennial grasses such as intermediate and tall wheatgrasses (Agropyron intermedium (Host.) Beauv. and A. elongatum (Host.) Beauv., respectively). Of the perennial grasses adapted to these sites, those which initiated growth earliest, maintained some growth through winter months, and matured earliest were the best competitors.
-
Effect of water on morphological development in seedlings of three range grasses: Root branching patternsRoot morphology is important for successful seedling establishment and survival on semiarid rangelands. This study was conducted to determine the response of early seedling root morphological development of 'Hycrest' [Agropyron desertorum (Fisch. ex Link) Schult. X A. cristatum (L.) Gaert.], 'Whitmar' [Pseudoroegneria spicata (Pursh) Loeve], and cheatgrass (Bromus tectorum L.) to water. A greenhouse line-source sprinkler system provided a gradient of water application (77, 66, 37, and 5 ml/day). Root morphology was examined at 15, 30, and 45 days after seedling emergence. Order of branching of roots associated with the first foliar node was greater in cheatgrass than in Hycrest or Whitmar at all water applications and dates. Length of the primary root, length of the second group of seminal roots, and length of the first group of adventitious roots were similar in cheatgrass and Hycrest. Root branching for the 3 species decreased as less water was applied, except for cheatgrass irrigated with 5 ml/day. The ability of cheatgrass seedlings to grow with little water was related to their greater order of branching of seminal roots, branching density on the main axis, and length of lateral roots and external-external links. The greater root branching densities, lateral root lengths, and external-external link lengths enabled Hycrest seedlings to grow better than Whitmar seedlings with little water. These root morphological characteristics may prove useful in improving seedling establishment of perennial range grasses.
-
Cattle-deer interactions in the Sierra Nevada: A bioeconomic approachFour potential cattle grazing systems on summer range in the Sierra Nevada are compared in terms of deer harvest, number of hunters attracted, and the net economic value of hunting. Research on deer carrying capacity response to different 3-year rest rotation grazing patterns indicates continuous moderate grazing provides 82% of the potential deer carrying capacity. A 2-years-off, 1-year-on grazing system provides 94% of potential deer carrying capacity. The increase in carrying capacity associated with grazing 1 year in 3 could increase buck harvest by 200 animals in the Sierra Nevada's hunt zone D5. Change in deer harvest in the previous year is one of the key variables in a model that determines the attractiveness of hunt zones to California deer hunters. The model predicts that increasing buck harvest by 200 deer in hunt zone D5 results in 2,721 more hunters visiting this zone each year. This translates into nearly 11,835 more trips. The net economic value of these additional hunters is determined based on a simulated market approach. Using the value from the hunter survey, the annual increase in hunting value is 2.3 million. The present value of this change over each 3-year rest-rotation cycle is 6.5 million using a 4% discount rate. The incremental benefits of deer hunting gained under the 2-years-off, 1-year-on grazing system is greater than the lost net economic value of the forage to the rancher as computed by USDA Economic Research Service.
-
California oak-woodland overstory species affect herbage understory: Management implicationsConcerns for the future of California's oak-woodlands have intensified the need to better understand how different overstory species affect herbage standing crops and species frequencies. Data from over 8,000 plots harvested between 1961 and 1968 at the San Joaquin Experimental Range in the Sierra Nevada foothills of central California show that peak standing crops averaged 2,795 kg/ha in the open; 3,086 kg/ha under blue oak (Quercus douglasii); 1,840 kg/ha under interior live oak (Quercus wislizenii); 1,696 kg/ha under digger pine (Pinus sabiniana), and 1,917 kg/ha under buck brush (Ceanothus cuneatus). Overstory species affected standing crops differently on different range sites. On swales, standing crops were less under live oak and digger pine than in open areas. On open-rolling uplands, standing crops were less in the open and under live oak than under blue oak. On rocky-brush uplands, standing crops were less under all other overstory species than under blue oak. Data on species frequency suggest that herbage species of inter successional stages are more common under trees. The frequency of plant species varied with the species of overstory, and a diversity of overstory species may help to maintain adequate species diversity among understory species.
