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Carrying capacity in arid rangelands during droughts: the role of temporal and spatial thresholds

  • F. Accatino (a1) (a2), D. Ward (a3) (a4), K. Wiegand (a1) and C. De Michele (a5)

Abstract

Assessing the carrying capacity is of primary importance in arid rangelands. This becomes even more important during droughts, when rangelands exhibit non-equilibrium dynamics, and the dynamics of livestock conditions and forage resource are decoupled. Carrying capacity is usually conceived as an equilibrium concept, that is, the consumer density that can co-exist in long-term equilibrium with the resource. As one of the first, here we address the concept of carrying capacity in systems, where there is no feedback between consumer and resource in a limited period of time. To this end, we developed an individual-based model describing the basic characteristics of a rangeland during a drought. The model represents a rangeland composed by a single water point and forage distributed all around, with livestock units moving from water to forage and vice versa, for eating and drinking. For each livestock unit we implemented an energy balance and we accounted for the gut-filling effect (i.e. only a limited amount of forage can be ingested per unit time). Our results showed that there is a temporal threshold above which livestock begin to experience energy deficit and burn fat reserves. We demonstrated that such a temporal threshold increases with the number of animals and decreases with the rangeland conditions (amount of forage). The temporal threshold corresponded to the time livestock take to consume all the forage within a certain distance from water, so that the livestock can return to water for drinking without spending more energy than they gain within a day. In this study, we highlight the importance of a time threshold in the assessment of carrying capacity in non-equilibrium conditions. Considering this time threshold could explain contrasting observations about the influence of livestock number on livestock conditions. In case of private rangelands, the herd size should be chosen so that the spatial threshold equals (or exceeds) the length of the drought.

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Adler, PB and Hall, SA 2005. The development of forage production and utilization gradients around livestock watering points. Landscape Ecology 20, 319333.
Ayantunde, AA, Fernández-Rivera, S, Hiernaux, PH, Van Keulen, H and Udo, HMJ 2002. Day and night grazing by cattle in the Sahel. Journal of Range Management 55, 144149.
Bahre, CJ and Shelton, ML 1996. Rangeland destruction: cattle and drought in southeastern Arizona at the turn of the century. Journal of the Southwest 38, 122.
Brosh, A, Henkin, Z, Ungar, ED, Dolev, A, Orlov, A, Tehuda, Y and Aharoni, Y 2006. Energy cost of cows’ grazing activity: use of the heart rate method and the Global Positioning System for direct field estimation. Journal of Animal Science 84, 19511967.
Chamaillé-Jammes, S, Valeix, M and Fritz, H 2007. Managing heterogeneity in elephant distribution: interactions between elephant population density and surface-water availability. Journal of Applied Ecology 44, 625633.
Demment, MW and van Soest, PJ 1985. A nutritional explanation for body-size patterns of ruminant and nonruminant herbivores. American Naturalist 125, 641672.
Desta, S and Coppock, L 2002. Cattle population dynamics in the southern Ethiopian rangelands, 1980-97. Journal of Range Management 55, 439451.
Ellis, JE and Swift, DM 1988. Stability of African pastoral ecosystems: alternate paradigms and implications for development. Journal of Range Management 41, 450459.
Fynn, RWS and O’Connor, TG 2000. The effect of stocking rate and rainfall on rangeland dynamics and cattle performance in a semi-arid savanna, South Africa. Journal of Applied Ecology 37, 491507.
Gillson, L and Hoffman, MT 2007. Rangeland ecology in a changing world. Science 315, 5354.
Grimm, V, Berger, U, Bastiansen, F, Eliassen, S, Ginot, V, Giske, J, Goss-Custard, J, Grand, T., Heinz, SK, Huse, G, Huth, A, Jepsen, JU, Jørgensen, C, Mooij, WM, Müller, B, Pe’er, G, Piou, C, Railsback, SF, Robbins, AM, Robbins, MM, Rossmanith, E, Rüger, N, Strand, E, Souissi, S, Stillman, RA, Vabø, R, Visser, U and DeAngelis, DL 2006. A standard protocol for describing individual-based and agent-based models. Ecological Modelling 198, 115126.
Grimm, V, Revilla, E, Berger, U, Jeltsch, F, Mooij, WM, Railsback, SF, Thulke, HH, Weiner, J, Wiegand, T and DeAngelis, DL 2005. Pattern-oriented modelling of agent-based complex systems: lessons from ecology. Science 310, 987991.
Heidtschmidt, RK, Klement, KD and Haferkamp, MR 2005. Interactive effects of drought and grazing on Northern Great Plains rangelands. Rangelend Ecology and Management 58, 1116.
Illius, AW and O’Connor, TG 1999. On the relevance of nonequilibrium concepts to arid and semiarid grazing systems. Ecological Applications 9, 798813.
Illius, AW and O’Connor, TG 2000. Resource heterogeneity and ungulate population dynamics. Oikos 89, 283294.
James, CD, Landsberg, J and Morton, SR 1999. Provision of watering points in the Australian arid zone: a review of effects on biota. Journal of Arid Environments 41, 87121.
Loza, HJ, Grant, WE, Stuth, JW and Forbes, TDA 1992. Physiologically based landscape use model for large herbivores. Ecological Modelling 61, 227252.
McLeod, SR 1997. Is the concept of carrying capacity useful in variable environments? Oikos 79, 529542.
Meissner, HH, Hofmeyr, HS, van Rensburg, WJJ and Pienaar, JP 1983. Classification of livestock for realistic prediction of substitution values in terms of a biologically defined large stock unit. Technical Communication No. 175. Government Printer, Pretoria, South Africa.
Oba, G 2001. The effect of multiple drought on cattle in Obbu, northern Kenya. Journal of Arid Environments 49, 375386.
Prins, HHT and Van Langevelde, F 2008. Assembling a diet from different places. In Resource ecology: spatial and temporal dynamics of foraging (ed. HHT Prins and F Van Langevelde), pp. 129155. Springer, Dordrecht, The Netherlands.
Scoones, I 1995. Exploring heterogeneity: habitat use by cattle in dryland Zimbabwe. Journal of Arid Environments 29, 221237.
Shackleton, CM 1993. Are the communal grazing lands in need of saving? Development Southern Africa 10, 6578.
Smit, IPJ, Grant, CC and Devereux, BJ 2007. Do artificial waterholes influence the way herbivores use the landscape? Herbivore distribution patterns around rivers and artificial water sources in a large African savanna park. Biological Conservation 136, 8599.
Sullivan, S and Rohde, RF 2002. On non-equilibrium in arid and semi-arid grazing systems. Journal of Biogeography 29, 126.
Thurow, SF and Taylor, CA 1999. Viewpoint: the role of drought in range management. Journal of Range Management 52, 413419.
Van Soest, PJ 1994. Nutritional ecology of the ruminant, 2nd edition. Comstock Publishing, Ithaca, NY, USA.
Vetter, S 2005. Rangelands at equilibrium and non-equilibrium: recent developments in the debate. Journal of Arid Environments 62, 321341.
Ward, D 2004. Ecological, historical and sociological perspectives of the effects of grazing on arid Namibian rangelands. In Rangelands at equilibrium and non-equilibrium: recent developments in the debate around rangeland ecology and management (ed. S Vetter), pp. 3740. Programme for Land and Agrarian Studies, Cape Town, South Africa.
Ward, D, Saltz, D and Ngairorue, BT 2004. Spatio-temporal rainfall variation and stock management in arid Namibia. Journal of Range Management 57, 130140.

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