Analysis of forage production for assessments and appraisals

Abstract

An understanding of the ecological factors affecting forage production is necessary if natural resource scientists are to develop models and other analytical tools that will more accurately and precisely estimate the forage response to management practices on specific ecosystems. Although the present knowledge on this subject is fairly comprehensive in several general areas, it is incomplete in others. Environmental factors related to processes that can be measured aboveground have been described to a much greater degree than those interacting with plants belowground. For example, scientists have described the ecological consequences of light intensity and CO2 concentration on photosynthesis more exactly than they have described belowground nutrient cycling pathways. Fortunately, increasing research in edaphology, nutrient cycling, and some aspects of ecophysiology is adding to knowledge of belowground ecological processes. Most techniques for estimating forage production on the ground have been known for some time; however, procedures for predicting forage production on the basis of climate, management, and other causal factors are more recently and less finely developed. Researchers have been able, however, to construct reasonably accurate models of the rate some species and species groups accumulate biomass. To date, such models have tended to be applicable only to specific plant communities, which narrows their usefulness in predicting responses to management at the regional or forest level. Models are being improved so that, within the coming decade, the use of ecological production models is likely to play an important part in resource management procedures. The most apparent obstacle in this modeling is a lack of an accepted general systems theory paradigm applicable to natural ecosystems. A general systems approach is based on the idea that system properties are not a function of characteristics of each ecosystem, but can be applied universally to many ecosystems (Halfon 1979). This report presents an overview of forage production as an ecological process. It describes production mechanisms for ecological modeling in a way that can be readily synthesized. In addition, it provides the reader who is familiar with basic concepts of ecology with a contemporary picture of what forage production is and, using current analysis tools, how it may be evaluated within the framework of natural resource assessments.

Assessment of the rangelands of southwestern Santiago del Estero, Argentina, for grazing management and research

“…The standing dry biomass of grass and broadleaf plants estimated in previous steps in each SU was used as an estimator of herbage biomass yield (Mitchell, 1983). This assumption implies that no specific period of time was considered for the estimation of yield.…”

Understory cover/biomass relationships in Alabama forest types

“…To be usable in multiresource inventories, understory measurement techniques must be relatively speedy and simple [14]. Clipping, a direct measure of herbaceous biomass, is time consuming [10]; because of its speed and simplicity, foliar cover has been a preferred measurement variable as an indirect estimator of biomass in multiresource inventories [13].…”

Seasonal Height-Weight Dynamics of Western Wheatgrass

“…Stubbendieck 1986), including the use of height-weight ratios. Plant height is easier to measure than biomass, which can approximate annual production at peak standing crop (Mitchell 1983). Because the 2 are strongly correlated, the height-weight method became an early management tool Jensen 1938, 1943).…”