Improved carrying capacity of grasslands has been attributed to the effect of time-controlled grazing with high animal density, which can be achieved by increased stocking rates as well as by fencing. Therefore, a study was conducted to test the hypothesis that time-controlled grazing with high animal densities and high stocking rates will improve grassland condition. The study was made over a 6-year period on 3 sites with time-controlled grazing imposed. One site was on native grassland in the Fescue Prairie and 2 sites, 1 on seeded and the other on native grassland, were in the Mixed Prairie. On each site, stocking densities averaged 3, 6, and 15 cow-calf pairs/ha, respectively, and stocking rates averaged 1.65, 4.45, and 2.72 animal unit months/ha, respectively. Species composition and root mass and distribution were compared on grazed and protected areas within each site. Utilization averaged about 80% of available forage over the study period. Range condition was less on grazed areas than on protected areas in the Fescue Prairie (38 vs 53% of climax) and in the Mixed Prairie (49 vs 53%). Average ash-free root mass, throughout the sampling profile, tended to be greater on the ungrazed vs the grazed area of the native Mixed Prairie site but not on the seeded Mixed Prairie or Fescue Prairie sites. The grazed areas of the Mixed Prarie sites tended to have more available phosphorus, possibly due to the application of manure, but less nitrogen and organic matter. The results led to a rejection of the hypothesis and a conclusion that high animal density and high stocking rates with time-controlled grazing would result in range deterioration.

The possibility of attenuating the negative effects of high stocking rate (SR) on animal production by using inexpensive low energy supplements (mainly poultry litter) was examined in a herd of small, crossbred cows graxing year;ong on Mediterranean grassland. Herds of 15 to 25 cows were stocked at 0.50, 0.67, and 0.83 cows/ha in replicated blocks. Weaning weights and ADG of calves were higher (P<.001) at the low SR, but there were no differences between the moderate and heavy stocking treatments. Weaned weight per hectare as well as supplementary feed consumption were highest at the high SR, but differences between the low and moderate stocking treatments were not significant. Conception rates fluctuated between years and declined at the heavy SR, only to recover dramatically in the inst year of the experiment. Weaning rates were variable both within and between SR’s from year to year, but overall 5-year SR means were not significantly different. It is concluded that on the seasonal Mediterranean grassland typical of eastern Galilee where quality of dry summer pasture is low, supplementation based mainly on poultry litter and straw can buffer some of the effects of high stocking rates on animal production but cannot ensure consistently high productive performance even at low SR.

Competitive relations between a half-shrub and 2 wheatgrasses were determined on 2 disturbed sites in northwestern Colorado. Leaf conductance and transpiration of winterfat [Eurotia lanata (Pursh) Moq., also known as Ceratoides lanata] were measured in association with a neighboring plant of either winterfat, beardless bluebunch wheatgrass [Pseudoroegneria spicata subsp. inermis (Scribn. and Smith A. Löve], or western wheatgrass [Pascopyrum smithii Rydb.) A. Löve] and as affected by a shallow disturbance of soil to a depth of 30 cm or a deep disturbance of soil to a depth of 1 m. Reduced leaf conductance was associated with advancing phenology and plant water stress as soil water was depleted during the growing season. Leaf conductance and transpiration of winterfat was often lower when it was associated with the 2 grasses than when growing adjacent to another winterfat plant. Lowest transpiration rates of winterfat were found when it was growing adjacent to beardless bluebunch wheatgrass. Thus, the intensity of competition for soil water may be greater for winterfat when associated with wheatgrasses than when growing adjacent to another winterfat plant.

Heavy communal grazing pressure and rapid phytomass decomposition reduce shrub interspace cover in Somalia from 100% at the end of the growing season to 5% at the end of the dormant season. Intense monsoonal rain, characteristic of Somalia and other areas of subsaharan Africa, combined with sparse vegetative cover at the beginning of the rainy season, may result in overland flow and excessive erosion, even where sand content of the soil exceeds 9%. Little watershed research has been conducted in this region other than to document that the problem is extreme. The objectives of this study were to assess the seasonal hydrologic responses as influenced by 2 soils (sand vs. clay), grazing intensity (exclusion vs. heavy communal grazing), and cover types (shrub understory vs. interspace) in Somalia. Infiltration rate and interrill erosion on the sand site were significantly greater than on the clay site regardless of cover type or season. The clay site was dominated by annual forbs which rapidly decomposed. The sand site had greater annual and perennial grass cover which decomposed slower than forbs, providing longer and perhaps better protection from raindrop impact energy. Three growing seasons of livestock exclusion did not significantly increase soil cover on shrub interspaces; consequently, infiltration rates and interrill erosion remained similar to the communally grazed sites. Interspace cover left by livestock was instead removed by termites and other microorganisms. Restricted ability of livestock to graze beneath thorny shrubs and increased phytomass from shrub leaf-fall resulted in a greater accumulation of cover and litter beneath shrubs, which aided infiltration on clay sites, regardless of season.

Establishment of forage kochia (Kochia prostrata subsp. virestens) stands from planting utricles has been erratic in the northern Great Basin. This study evaluated the effect of different seedbed environments varied by planting date on germination of utricles and seedling establishment. Utricles harvested in 1986 were planted on tilled seedbeds in late fall, winter, early and late spring 1986-87, and late fall, winter, and early spring 1987-88. Soils are fine-loamy, mixed, mesic, Xerollic Haplargids underlain by coarse gravel at a depth of 1.5 m. Utricles were broadcast at 400 pure live utricles/m2 in 2 by 2-m plots replicated 5 times. Additionally, nylon bags containing utricles were placed on the soil surface during planting, and on each subsequent planting date, bags of utricles were retrieved for germination trials. Seedling establishment was improved 85% (p<0.05) when utricles were planted in late fall and winter compared to spring of both 1987 and 1988. Utricles imbibed moisture when incubated in the field from late fall to winter and late fall to early spring 1986-87. When collected in winter 1987, imbibed utricles germinated 7 to 12 days faster (p<0.05) than dry controls, and those collected in early spring germinated 4 to 7 days faster (P<0.05) than controls. Total germination of utricles declined 9 to 2% with an additional year of storage in the laboratory. Utricles incubated in the field from late fall to winter and late fall to early spring 1987-88 germinated about 1.5 days faster (P<0.05) than controls when collected in winter and early spring 1988. These findings show why better seedling establishment can be expected from planting freshly harvested forage kochia utricles in late fall and winter before the soil surface begins to dry than in early and late spring in the northern sagebrush (Artemisia) steppe.

Response of key warm-season grasses to time, frequency, and duration of defoliation is needed to develop grazing systems for the Nebraska Sandhills. A 3-year (1986 to 1988) study was conducted on a Valentine fine sand (mixed, mesic Typic Ustipsamments) at the Gudmundsen Sandhills Laboratory near Whitman, Nebraska, to determine the effect of defoliation on little bluestem [Schisachyrium scoparium (Michx.) Nash]. Treatments were: 1 defoliation (to 7 cm) on 10 June, 10 July, or 10 Aug.; 2 defoliations on 10 June and 10 Aug.; and 3 defoliations on 10 June, 10 July, and 10 Aug. Control plants were harvested only at the end of the growing season (October). All plots receiving summer defoliation were harvested in October to obtain aftermath yield. Treatments were initiated in 1986, 1987, and 1988 and the effects of 1, 2, and 3 years of defoliation on dry matter (DM) yield, bud and tiller numbers, and tiller weight were measured. Experimental design was a split block with 4 plants as replications. In the flrst year of treatment annual DM yield from control plants was 2 times greater than that from all defoliated plants, but bud and tiller numbers were similar. In the second year of treatment, all treatments reduced annual DM yield and morphological development below that of the control if precipitation was subnormal, but not if precipitation was above normal. In the third year of defoliation, with above-normal precipitation, single June or July defoliations produced DM yields and morphological development similar to that of the control, but single August or multiple defollations generally reduced yield and development. Little bluestem may not persist if exposed to multiple, close defoliatlons during the growing season.

Usefulness of the concepts of carrying capacity and species substitution ratios in natural resource management has been limited by single objectives and single management options implicit in their definitions. When applied to livestock, they have been further limited by poor conceptualisation of the animal-unit concept often used to quantify them. A systematic approach to the animal-unit concept logically leads to concepts of livestock carrying capacity and livestock substitution ratios compatible with the multiple objectives and multiple management options characteristic of range livestock systems. This paper develops simplified multi-objective concepts of carrying capacity and substitution ratios, and discusses their interpretation and application in agro-ecological systems. Also discussed is the applicability of these concepts to describe components other than livestock in managed and unmanaged systems. Some thoughts are presented on abstraction and simplification of concepts.

A sample adequacy equation is recommended to calculate the number of point frame samples required for measuring cover on reclaimed land and to assure sample size is adequate to meet Federal rules and regulations. When applied to field data, mining companies and regulatory agencies often find the sample number requirements estimated by the equation are so large that the equation is impractical to use. This equation was studied by sampling with 20, 40, 60, and 100 sets of 10-point frames on 12 X 67-m areas of grazed and ungrazed mixed prairie at Mandan, N.D., and by examining cover data collected with 60 sets of frames from 1.86-ha pastures on reclaimed mined land and native range near Center, N.D. Increasing the number of frames used did not produce more consistent mean values nor did variance decrease. Both total ground cover and bare soil ground cover measure the amount of cover protecting the soil from soil loss; yet, the formula estimated that 1 frame was required to measure total cover whereas 10,086 frames were required to measure bare soil within 10% of the mean with 90% statistical confidence. Histograms suggest cover components that comprise a small percentage of the total ground area are distributed in a Poisson rather than normal fashion; therefore, the equation does not provide a good guide for determining how many samples are required. Another equation, appropriate for binomial and Poisson variates is suggested as a solution to the problem.