Soil Seed Bank Characteristics in Relation to Distance from Watering-Points in Arid Ecosystems (Case Study: Kahnuj, Kerman Province)

Authors
1 Associate Professor, Department of Rangeland Management, Faculty of Natural Resources, Tarbiat Modares University, Mazanderan Province, Noor, Iran
2 Former M.Sc. Student, Department of Rangeland Management, Faculty of Natural Resources, Tarbiat Modares University, Mazanderan Province, Noor, Iran
Abstract
Epizoochory and endozoochory are well-known mechanisms by which seeds are dispersed by animals. Since, livestock gather around the watering-points to rest and drink, we expected to find that seeds would be frequently moved to the areas surrounding watering-points, resulting a higher soil seed density (and diversity) closest to the water. We investigated this issue by assessing soil seed bank density and composition along a distance gradient from the water and compared them with an ungrazed-control area in 2010. Therefore, three watering-points were selected in a dry rangeland of Kahnuj, Kerman Province, Iran. Soil seed bank characteristics were measured at eight distances with different intervals from the watering-points (totally 80 sampling points) and in an ungrazed area (30 sampling points) after seed dispersion in autumn. The results showed that in spite of the assumption, soil seed density and similarity between the soil seed bank and above ground vegetation increased with distance from the watering-points. A clear trend was not detected for the diversity of soil seed bank with distance from water source. Our findings suggested that the restoration of degraded sites could not rely on soil seed bank. Areas surrounding watering-points, where soil seed losses are potentially higher than those at greater distances from water source, should be given more attention for conservation by the rangeland managers.
Keywords

Allington, G.R.H. and Valone, T.J. Reversal of desertification: the role of physical and chemical soil properties. J. Arid Environ., 2010; 74: 973-977.
Beheshti Rad, M. and Beheshti Rad, M. Investigation on the efficiency of different methods for spatial variation of intensity of drought in Kerman Province. Iran. J. Local Plan., 2013; 3: 89-101. 
Bertiller, M.B. and Ares, J.O. Does sheep selectivity along grazing paths negatively affect biological crusts and soil seed banks in arid shrublands? A case study in the Patagonian Monte, Argentina. J. Arid Environ., 2011; 92: 2091-2096.
Bertiller, M.B. Grazing effects on sustainable semi-arid rangelands in Patagonia: the state and dynamics of the soil seed bank. Environ. Manage., 1996; 20: 123-132.
Call, C.A. and Roundy, B.A. Perspectives and processes in revegetation of arid and semiarid rangelands. Range. Ecol. Manage., 1991; 44: 543-549.
de las Heras, M.M., Turnbull, L. and Wainwright, J. Soil seed-bank structure and seed-germination dynamics contribute to pulsed shrub encroachment in a grassland-shrubland Chihuahuan ecotone. Geophys. Res. Abst., 2015; 17: 1-2.
Dreber, N. and Esler, K.J. Spatio-temporal variation in soil seed banks under contrasting grazing regimes following low and high seasonal rainfall in arid Namibia. J. Arid Environ., 2011; 75: 174-184.
Dreber, N., Oldeland, J. and van Rooyen, G.M.W. Species, functional groups and community structure in seed banks of the arid Nama Karoo: Grazing impacts and implications for rangeland restoration. Agr. Ecosys. Environ., 2011; 141: 399-409.
Du Toit, G., van, N., Snyman, H.A. and Malan, P.j. Physical impact of grazing by sheep on soil parameters in the Nama Karoo subshrub/grass rangeland of South Africa. J. Arid Environ., 2009; 73: 804-810.
Erfanzadeh, R., Garbutt, A., Pétillon, J., Maelfait, J.P. and Hoffmann, M. Factors affecting the success of early salt-marsh colonizers: Seed availability rather than site suitability and dispersal traits. Plant Ecol., 2010a; 206: 335-347.
Erfanzadeh, R., Hendrickx, F., Maelfait, J.P. and Hoffmann, M. The effect of successional stage and salinity on the vertical distribution of seeds in salt marsh soils. Flora. 2010b; 205: 442-448.
Erfanzadeh, R., Hosseini Kahnuj, S.H. and Azarnivand, H. Comparison of soil seed banks of habitats distributed along an altitudinal gradient in northern Iran. Flora. 2013; 208: 312-320.
Heady, H.F. and Child, R.D. Rangeland ecology and management. Westview Press, USA. 1999; 519 P.
Hempy-Mayer, K. and Pyke, D.A. Defoliation effects on Bromus tectorum seed production- Implications for grazing. Range. Ecol. Manage., 2008; 61: 116-123.
Hopfensperger, K.N. A review of similarity between seed bank and standing vegetation across ecosystems. Oikos, 2007; 116: 1438-1448.
Howes, A.L. and McAlpine, C.A. The impact of artificial watering points on rangeland biodiversity: A review. Desert Knowledge CRC Working Paper 15: The WaterSmart™ Literature Reviews. The University of Queensland, Australia, 2008; 41 P.
Kassahun, A., Snyman, H.A. and Smit, G.N. Soil seed bank evaluation along a degradation gradient in arid rangelands of the Somali region, eastern Ethiopia. Agr. Ecosys. Environ., 2009; 129: 428-436.
Kemp, P.R. Seed banks and vegetation processes in deserts. In: Leck, M.A., Parker, V.T., Simpson, R.L. (Eds.), Ecology of soil seed banks. Academic Press, San Diego, 1989; 257-281.
Kent, M. and Coker, P. Vegetation description and analysis. A practical approach. Wiley, Chichester. UK. 1994; 265 P.
Kinloch, J.E. and Friedel M.H. Soil seed reserves in arid grazing lands of central Australia. Part 1. Seed bank and vegetation dynamics. J. Arid Environ., 2005; 60: 133-161.
Li, Y.J., Bao, W.K. and Wu, N. Spatial patterns of the soil seed bank and extent vegetation across the dry Minjiang River vally in southwest China. J. Arid Environ., 2011; 75: 1083-1089.
Nsinamwa, M. Seed-bank analysis for herbaceous species along grazing gradients in the Sandveld and Hardveld grazing areas of Botswana. Bots. J. Agr. Appl. Sci., 2007; 3: 55-66.
Omar, S.A.S., Razzaque, M.A. and Alsdirawi, A.F. Range management in arid zones. Routledge Press, New York, US. 2013; 330 P.
Osem, Y., Perevolotsky, A. and Kigel, J. Size traits and site conditions determine changes in seed bank structure caused by grazing exclusion in semiarid annual plant communities. Ecography, 2006; 29: 11-20.
Paruelo, J.M., Pütz, S., Weber, G., Bertiller, M.B., Golluscio, R.A., Aguiar, M.R. and Wiegand, T. Long-term dynamics of a semiarid grass steppe under stochatic climate and different grazing regimes: a simulation analysis. J. Arid Environ., 2008; 72: 2211-2231.
Poschlod, P., Tackenberg, O. and Bonn, S. Plant dispersal potential and its relation to species frequency and coexistence. In: van der Maarel, E. (Eds.), Vegetation Ecology. John Wiley and Sons, Hoboken, 2005; 147-171.
Salemi, H., Shahnooshi, N. and Thomsom, K. The economic impacts of drought on the economy of Iran: An integration of linear programming and macroeconometric modeling approaches. Ecol. Econ., 2009; 68: 1032-1039.
Snyman, H.A. Soil seed bank evaluation and seedling establishment along degradation gradient in a semi-arid rangeland. Afr. J. Range and Forage Sci., 2004; 21: 37-47.
Solomon, T.B., Snyman, H.A. and Smit, G.N. Soil seed bank characteristics in relation to land use systems and distance from water in a semi-arid rangeland of southern Ethiopia. S. Afr. J. Bot., 2006; 72: 263-271.
Sternberg, M., Gutman, M., Perevolotsky, A. and Kigel, J. Effects of grazing on soil seed bank dynamics: an approach with functional groups. J. Veg. Sci., 2003; 14: 375-386.
Tessema, Z.K., de Boer1, W.F., Baars, R.M.T. and Prins, H.H.T. Influence of Grazing on Soil Seed Banks Determines the Restoration Potential of Above ground Vegetation in a Semi-arid Savanna of Ethiopia. Biotropica, 2012; 4: 211-219.
Van Rooyen, N., Bredenkamp, G.J., Theron, G.K., Bothma, J. du P. and Le Riche, E.A.N. Vegetation gradients around artificial watering points in the Kalahari Gemsbok National Park. J. Arid Environ., 1994; 26: 349-361.
Visser, N., Botha, J.C. and Hardy M.B. Re-establishing vegetation on bare patches in the Nama Karoo, South Africa. J. Arid Environ., 2004; 57: 155-177.
Wu, G.L., Shang, Z.H., Zhu, Y.J., Ding, L.M., and Wang, D. Species-abundance–seed-size patterns within a plant community affected by grazing disturbance. Ecol. Ogical. Appl., 2015; 25: 848-855.