Document Type : Research Paper

Authors

1 Professor, Gorgan University of Agricultural Sciences and Natural Resources, Iran

2 PhD Student in Rangeland Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Iran

3 Assistant Professor, Faculty of Natural Resources, Urmia University, Iran

Abstract

     Rangelands as dynamic ecosystems respond to the disturbances such as climatic fluctuations and grazing management patterns. Prediction of spatial trend of these changes could be contributed to management planning and rehabilitation of degraded landscape. In this study, changes in the function of ecosystem, affected by livestock grazing, were investigated along grazing gradient. To this end, in the winter rangelands of Gorgan, functional features of the rangeland ecosystem including: nutrient cycling, infiltration and stability were measured at the set of points along grazing gradient. Measured parameters were analyzed using statistical methods and regression models to determine changes in ecosystem function along grazing gradient. The results showed a significant trend in functional indices along the grazing gradient. Points close to the livestock camp had the minimum value of functional indices while those at the end of the grazing gradient were found to be maximized. Comparison of different regression models using Akaike Information Criterion revealed that, as per infiltration index four-parameter sigmoid model and also for stability and nutrient cycling indices, three-parameter sigmoid model had the lowest AIC value and were the best models to predict functional changes along grazing gradients. The results of this study may be promising as rangeland model input to identify critical areas and can be used to predict management effects on productivity and sustainability of rangeland ecosystems.

Keywords

-  Abedi, M., Arzani, H., Shahriari, A., Tongway, D. and Aminzadeh, M., 2006. Evaluation of the structure and function of plant patches in arid and semi-arid rangelands ecosystems. Journal of Environmental Studies, 40: 117-126.
-  Ahmadi, Z., Heshmati, Gh. A, Mohseni Saravi, M., Arzani, H. and Bihamta, M. R., 2008. Determination of critical threshold for rangeland ecosystems (case study: Rural habitat of three villages in Golestan province). Journal of Agricultural Sciences and Natural Resources of Gorgan, 15 (1): 102-110.
-  Arzani, H., Abedi, M., Shahriari, A. and Ghorbani, M., 2007. Investigation of changes in soil surface and functional characteristics of rangeland under grazing intensity and rangeland plowing (Case study: Orazan Taleghan). Iranian Journal of desert and rangeland researches, 14 (1): 68-79.
-  Bastin, G. N., Sparrow, A. D. and Pearce, G.,1993. Grazing gradients in central Australian Rangelands: ground verification of remote sensing-based approaches. Rangeland Journal, 15(2):217-233.
-  Bennett, A. and Radford, J., 2003. Know your ecological thresholds. Thinking Bush, 2: 1–3.
-  Birch, N. V. E., 2000. The vegetation potential of natural rangelands in the Mid-Fish river valley, Eastern Cape, South Africa: Towards a sustainable and acceptance management system. Ph.D. thesis, Rhodes University Grahams town, 149 p.
-  Friedel, M. H., 1991. Range condition assessment and the concept of thresholds: a viewpoint. Journal of Range Management, 44: 422–426.
-  Graetz, R. D. and Ludwig, J. A., 1978. A method for the analysis of biosphere data applicable to range assessment. Australian Rangeland Journal, 1: 126-136.
-  Heshmati, G. A., 1997. Plant and soil indicators for detecting zones around water point in arid perennial chenopod shrub lands of South Australia. Ph.D. Thesis, Department of Botany, University of Adelaide, Adelaide.
-  Klott, J. H., Smith, R. B. and Vullo, C., 1993. Sage grouse habitat use in the Brown s bench area of south central Idaho. USDI Bureau of Land Management, Technical Bulletin, 93(4): 14.
-  Ludwig, J. A., Tongway, D., Freudenberger, D., Noble, D. and Hodginson, K., 1997. Landscape Ecology, Function and Management: Principles from Australia’s Rangelands. CSIRO Publishing, Melbourne, Australia, 121-131.
-  Mesdaghi, M., 2011. Statistical and regression methods in agricultural studies and natural resources. Mashhad University Press, Mashhad, 420.
-  Mohseni Saravi, M., Chaei Chi, M. and Malekian, A., 2001. The effect of cattle trapping and grazing on soil physical properties of rangeland. Proceedings of the Second National Seminar on Rangeland and Rangeland management. Faculty of Natural Resources, University of Tehran. 577-590.
-  Noble, J. C., Habermehl, M. A., James, C. D. Landsberg, J.,  Langston, A.C. and Morton, S. R., 1998. Biodiversity implications of water management in the Great Artesian Basin. Rangeland Journal, 20(2): 275 – 300.
-  Noy-Meir, I., 1981. Spatial effects in modeling of arid ecosystem: 411-432. In: Goodall, D.W., Perry, R. A., (Eds,). Arid Land Ecosystem Structure, Function and Management. Vol. 2. Sydney: Cambridge University Press.
-  Sasaki, T., Okayasu, T., Jamsran, U. and Takeuchi, K., 2008. Threshold changes in vegetation along a grazing gradient in Mongolian rangelands. Journal of Ecology, 96: 145–154.
-  Sheidai Karkaj, A., Mofidi, M. and Jahanteb, A., 2013. Evaluation and Comparison of Different Distance Measurement Methods for Density in Inchebroun Area. Journal of Forest and Rangeland, 97: 46-50.
-  Toms, J. D. and Lesperance, M. L., 2003. Piecewise regression: a tool for identifying ecological thresholds. Ecology, 84: 2034-2041.
-  Tongway, D. and Ludwig, J., 2002. Reversing desertification: 343-345. In: Lalo, R., (Ed), Encyclopedia of soil science. New York: Marcel Dekker.
-  Tongway, D. and Hindley, N., 2004. Landscape Function Analysis: Methods for monitoring and assessing landscapes, with special reference to mine sites and rangelands. Canberra: CSIRO Sustainable Ecosystems. 
-  Walker, B. and Meyers, J. A., 2004. Thresholds in ecological and social-ecological systems: a developing database. Ecology Society, 9(2):3. [Online]URL: http://www.ecologyandsociety.org/vol9/iss2/art3.
-  Wiens, J. A., Van Horne, B. and Noon, B. R., 2002. Integrating landscape structure and scale into natural resource management: 23–67. In: Liu, J, Taylor W W. (Eds,). Integrating Landscape Ecology into Natural Resource Management, UK: Cambridge University Press.
-  Wilson, A. D., 1986. The monitoring of changes in range condition: a multivariate site potential approach. Proceedings of 2nd International Congress on Rangeland, Australia, Adelaide: 517-521.