Browsing Journal of Range Management, Volume 42, Number 2 (March 1989) by Subjects
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Comparing the economic value of forage on public lands for wildlife and livestockDeciding how to allocate forage among animals is a fundamentally important process in range management. The wisdom of these decisions can be enhanced by estimating the marginal value of forage needed by competing species. We present a method for obtaining such estimates and apply this method to generate net economic values of forage for elk and deer in Challis, Idaho. Specifically, a demand curve derived using a regional travel cost model is used to statistically estimate the marginal value of wildlife and forage. Comparisons of the value of forage to livestock and wildlife indicate equivalent values in the Challis, Idaho, area for these 2 uses.
Silicon in C-3 grasses: effects on forage quality and sheep preferenceSilicon in forage reduces dry matter digestibility and may reduce grazing preference. Two studies were conducted with the following objectives: (1) to evaluate a method of determining grazing preference, and (2) to characterize the distribution and solubility of silicon in 31 accessions of C-3 grasses and relate these traits to grazing preference and estimated forage digestibility. Forage samples were clipped at the beginning of each 7 to 10-day grazing period corresponding to 6 phenological stages of the Agropyron sp. Samples were washed and analyzed for acid detergent fiber (ADF), neutral detergent fiber (NDF), and silicon in ADF and NDF residues. Leaf silicon concentrations increased from the vegetative to seed-ripe stage. Genera were aligned into 3 groups based on the increase in leaf silicon concentration with advancing phenological age. Silicon concentrations in leaves of Agropyron, Pseudoroegneria, and Thinopyrum increased at nearly twice the rate of those in Critesion, Hordeum, Leymus and Psathyrostachys. Elymus leaves contained higher concentrations of silicon at the vegetative stage than the other groups, but the accumulation rate was intermediate. About 32% of total leaf silicon remained in NDF and 76% in ADF residues at the vegetative stage. These insoluble portions of silicon increased with aging. Preference was positively related to estimated dry matter digestibility at boot and anthesis, but was not related to fiber or silicon measurements. Leaf harshness was negatively related to preference at seed-ripe stage. Further progress in characterizing the role of silicon in C-3 forage grasses should be possible by studying a representative species from each group.