Concepts of Carrying Capacity and Substitution Ratios: A Systems Viewpoint

Abstract

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 chamcteristic of range livestock systems. This paper develops simplified multi-objective concepts of carrying capacity and substitution ratios, and discusses their interpretation and application in agroecological 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.

Relation between NOAA-AVHRR Satellite Data and Stocking Rate of Rangelands

“…Stocking rate, an important variable in rangeland management (Scarnecchia 1990), is partially determined by both primary productivity, which sets an upper limit to the energy flow to herbivores, and forage quality, which determines the proportion of that energy that will be assimilated. Primary productivity and forage quality are difficult to measure, and have a complex pattern of spatial and temporal variation (both annual and seasonal) that by itself may also affect herbivore carrying capacity.…”

Pastoral systems and their interaction with spatiotemporal vegetation dynamics in the Atlas Mountains, Southern Morocco

“…In order to define sustainable rangeland use intensities, the concept of carrying capacity is widely used in rangeland resource management (Scarnecchia 1990). Carrying capacity is defined as the maximum livestock or wildlife population that an ecosystem can support on a sustainable basis (Dijkman 1999).…”

“…Carrying capacity is defined as the maximum livestock or wildlife population that an ecosystem can support on a sustainable basis (Dijkman 1999). This definition was revised by Scarnecchia (1990) as the optimum number of individuals or units to achieve specific objectives given Introduction specified management options. However, the assessment of carrying capacity, which is based on stocking rates and fodder production, remains a challenge in arid and semi-arid rangelands due to the high interannual and seasonal variability of plant growth (Cook and Stubbendieck 1986;De Leeuw and Tothill 1990;Gillson and Hoffman 2007;Jahantigh and Pessarakli 2009).…”

Animal exchange ratios: an alternative point of view

“…The development of the concept of exchange ratio and the related concept of carrying capacity has been concentrated on livestock and less so on multi‐species, including game animals (Scarnecchia, 1985; Scarnecchia, 1990).…”

“…Exchange ratio refers to the ratio of the number of individual animals or animal units of one species or class of livestock to the number of animals or animal units of another species or class to achieve a specific objective, given specific management objective(s), e.g. multi‐species forage harvesting objective (Scarnecchia, 1990). Heady & Child (1994) proposed approximate exchange ratios based on metabolic body weights that could be applied as a guide to herbivores with similar diets, but for animals with different habitat requirements, these exchange ratios should be modified according to dietary overlap among species.…”