Dynamics and sustainable utilization of rangeland ecosystems in arid and semi-arid climates of southern Africa

Journal of Arid Environments

Volumn 39, Issue 4, 1998, Pages 645-666

  Snyman, H A ^a  

^a UNIVERSITY OF THE FREE STATE   (South Africa)

Author keywords

Degradation; Drought; Organic matter; Productivity; Range condition; Soil loss; Soil water balance; Water use efficiency

Indexed keywords

LAND MANAGEMENT; MANAGEMENT PRACTICE; RANGELAND; SUSTAINABLE AGRICULTURE;

(SOUTHERN); AFRICA;

EID: 0032143486     PISSN: 01401963     EISSN: None     Source Type: Journal    
DOI: 10.1006/jare.1998.0387     Document Type: Review

References (156)

1. Acocks, J.P.H. (1953). Veld types of South Africa. Memoirs of Botanical Survey of Southern Africa. 28. 146 pp.
2. Armijo, J.D. (1972). Development of a large undisturbed weighing lysimeter for evapotranspiration studies on grassland. Technical Report 165. Grassland Biome, Clorado State University. 35 pp.
3. Badenhorst, N.C. & Erasmus, J.F. (1994). NOAA/AVHRR derived vegetation indices as a monitoring tool for drought and rangeland condition in southern Africa. Proceedings of the 7th Australasian Remote Sensing Conference, Melbourne, Australia, pp. 1087-1094.
4. Barnes, D.L., Swart, M., Smith, M.F. & Wiltshire, G.H. (1991). Relations between soil factors and herbage yield of natural grassland on sandy soils in the south-eastern Transvaal. Journal of the Grassland Society of southern Africa, 8: 92-98.
5. Bennie, A.T.P. (1991). Volhoubare landbou in die halfdroë gebiede van Suid-Afrika Die bydrae van Grondkunde. Inaugural address, University of the Free State, Bloemfontein. 26 pp.
6. Berg, W.A., Bradford, J.A. & Sims, P.L. (1997). Long-term soil nitrogen and vegetation change on sandhill rangeland. Journal of Range Management, 50: 182-486.
7. Booysen, J. (1983). Twee metodes vir die kwantitatiewe simulering van groeitoestande van klimaksgras. M. Sc. (Agric.)-thesis, University of the Free State, Bloemfontein. 89 pp.
8. Bosch, O.J.H. (1989). Degradation of the semi-arid grassland of southern Africa. Journal of Arid Environments, 16: 143-147.
9. Bosch, O.J.H. & Kellner, K. (1991). The use of degradation gradients for the ecological interpretation of range condition assessment. Journal of Arid Environments, 21: 21-29.
10. Bozzo, J.A., Beason, S.L. & Fullright, T.E. (1992). Vegetation responses to 2 brush management practices in south Texas. Journal of Range Management, 45: 170-175.
11. Burger, S.J., Grunow, J.O. & Rabie, J.W. (1975). Die reaksie van Anthephora pubes cens op verskillende intensiteite en frekwensies van ontblaring. Proceedings of the Grassland Society of southern Africa, 10: 29-34.
12. Christie, E.K. (1978). Ecosystem processes in semi-arid grassland. Australian Journal of Agricultural Research, 29: 773-787.
13. Coe, K.H. (1991). Effects of thinning on Colophospermum mopane in an indigenous woodland setting. Journal of the Forestry Association of Botswana, 263: 47-57.
14. Coetzee, J.A. & Page, M.J. (1946). Root studies in Highveld Grassland Communities. South African Journal of Science, 62(6): 105-118.
15. Crider, F.J. (1955). Rootgrowth stoppage resulting from defoliation of grass. USDA Technical Bulletin, 1102: 3-22.
16. Danckwerts, J.E. (1982). The grazing capacity of sweetveld: 2. A model to estimate grazing capacity in the False Thornveld of the Eastern Cape. Proceeding of the Grassland Society of southern Africa, 17: 94-98.
17. Danckwerts, J.E. & Barnard, H.J. (1981). Short-term influence of defoliation on the production of three veld conditions in the False Thornveld of the Eastern Province. Proceedings of the Grassland Society of southern Africa, 16: 79-84.
18. Danckwerts, J.E. & King, P.G. (1984). Conservative stocking or maximum profit: A grazing management dilemma. Journal of the Grassland Society of southern Africa, 1: 25-28.
19. Danckwerts, J.E. & Nel, L.O. (1989). The effect of frequency of defoliation on Themeda triandra in the False Thornveld of the eastern Cape. Journal of the Grassland Society of southern Africa, 6: 32-36.
20. Danckwerts, J.E. & Stuart-Hill, G.C. (1987). Adaptation of an increaser and a decreaser grass species to defliation in semi-arid grassveld. Journal of the Grassland Society of southern Africa, 4: 68-73.
21. Danckwerts, J.E. & Stuart-Hill, G.C. (1988). The effect of severe drought and management after drought on the motality and recovery of semi-arid grassveld. Journal of the Grassland Society of southern Africa, 5: 218-222.
22. Danckwerts, J.E. & Tainton, N.M. (1996). Range management: Optimization forage production and quality. Bulletin Grassland Society of southern Africa, 7: 36-42.
23. De Jager, J.M., Howard, M.D. & Fouché, H.J. (1997). Computing drought severity and forcasting its future impact on grazing in a GIS. In: Wilhite, D. (Ed.), Hazards and Disaster: A series of definitive works, pp. 103-141. Lincoln: Routledge Publishers. 163 pp.
24. Domaar, J.F., Smoliak, S. & Willms, W.D. (1990). Distribution of nitrogen fractions in grazed and ungrazed fescue grassland Ah-horizons. Journal of Range Management, 43: 6-9.
25. Dunin, F.X. & Reyenga, W. (1978). Evaporation from a Themeda - grassland. Journal of Applied Ecology, 15: 317-325.
26. Du Pisani, L.G. (1991). Simulasiestudies met Cenchrus ciliaris. Ph.D. thesis, University of the Free State, Bloemfontein. 129 pp.
27. Du Plessis, M.C.F. & Mostert, J.W.C. (1965). Afloop-en grondverliese by die land-bounavorsingsinstituut Glen. South African Journal of Agricultural Research, 8: 1051-1060.
28. Du Preez, C.C. & Snyman, H.A. (1993). Organic matter content of a soil in a semi-arid climate with three longstanding veld conditions. African Journal of Rangeland and Forage Science, 10: 108-110.
29. Du Toit, G.V.N. (1986). Die fisiese uitwerking van beweiding deur skape op Karooveld. M. Sc. (Agric.) thesis, University of the Free State, Bloemfontein. 132 pp.
30. Du Toit, P.C.V. (1995). The grazing index method of range condition assessment. African Journal of Range and Forage Science, 12(2): 61-67.
31. Du Toit, M.E., Du Preez, C.C., Hensley, M. & Bennie, A.T.P. (1994). Effek van bewerking op die organiese materiaalinhoud van geselekteerde droëlandgronde in Suid-Afrika. South African Journal of Plant Soil, 11: 71-79.
32. Dye, P.J. & Spear, P.T. (1982). The effects of bush clearing and rainfall variability on grass yield and composition in south-west Zimbabwe. Zimbabwe Journal of Agricultural Research, 20: 103-118.
33. Edwards, P.J. (1961). Studies on veld burning and mowing the tall grassveld of Natal. M.Sc. thesis, University of Natal, Pietermaritzburg. 90 pp.
34. Elkins, N.Z., Sabol, G.V., Ward, T.J. & Whitford, W.G. (1986). The influence of subterranean termites on the hydrological characteristics of a Chihuahuan Desert ecosystem. Oecologia, 68: 521-528.
35. Erasmus, J.F. (1991). Methodologies for drought monitoring using meteorological data. Ph.D thesis, University of the Free State, Bloemfontein. 184 pp.
36. Fischer, R.A. & Turner, N.C. (1978). Plant productivity in the arid and semi-arid zones. Annual Review of Plant Physiology, 29: 277-317.
37. Fouché, H.J. (1984). Ondersoek na die gebruik van die Putu II simulasiemodel en Panmerindeks vir die karakterisering van droogtetoestande. M.Sc. (Agric) thesis, University of the Free State, Bloemfontein. 133 pp.
38. Fouché, H.J. (1992). Simulering van die produksiepotensiaal van veld en die kwantifisering van droogte in die sentrale Oranje-Vrystaat. Ph.D. thesis, University of the Free State, Bloemfontein. 96 pp.
39. Fouché, H.J., De Jager, J.M. & Opperman, D.P.J. (1985). A mathematical model for assessing the influence of stocking rate on the incident of droughts and for estimating the optimal stocking rate. Journal of the Grassland Society of southern Africa, 2: 4-6.
40. Fourie, J.H. (1985). Die invloed van veebelading op veeproduksie en veldtoestand. Glen Agric, 14: 8-12.
41. Fourie, J.H., Engels, E.A.N. & Roberts, B.R. (1986). Herbage intake by cattle on Tarchonanthus veld in the northern Cape as affected by stocking rate and grazing system. Journal of the Grassland Society of southern Africa, 3: 85-89.
42. Friedel, M.M. (1991). Range condition assessment and the concept of thresholds: A viewpoint. Journal of Range Management, 44: 422-426.
43. Friedel, M.H., Foran, B.D. & Stafford, Smith D. M. (1990). Where creeks run dry or ten feed high: pastoral management in arid Australia. Proceedings of the Ecological Society of Australia, 16: 185-194.
44. Harrington, G.N. & Johns, G.G. (1990). Herbaceous biomass in a Eucalyptus savanna woodland after removing trees and/or shrubs. Journal of Applied Ecology, 27: 775-787.
45. Hatch, G.P., Tainton, N.M. & Ortmann, G.F. (1986). Towards the development of a bio-economic stocking model for the semi-arid and savanna of KwaZulu-Natal. African Journal of Range Forage Science, 13: 67-71.
46. Haworth, K. & McPherson, G.R. (1994). Effects of Quercus emoryi on herbaceous vegetation in a semi-arid savanna. Vegetatio, 112: 153-159.
47. Haylett, D.G. (1960). Run-off and soil erosion studies at Pretoria. South African Journal of Agricultural Science, 3: 379-392.
48. Heitschmidt, R.K. & Walker, J.W. (1996). Grazing management: Technology for sustaining rangeland ecosystems. Rangeland Journal, 2: 194-215.
49. Howard, M.D. (1997). Development and application of a simulation model to determine production potential of Themeda veld in a semi-arid climate. Ph.D. thesis, University of the Free State, Bloemfontein. 112 pp.
50. Jones, R.J. & Sandland, R.L. (1974). The relation between animal gain and stocking rate. Cambridge Journal of Agricultural Science, 83: 333-342.
51. Jordaan, F.P., Biel, L.C. & Du Plessis, P.I.M. (1997). A comparison of five range condition assessment techniques used in the semi-arid western grassland biome of southern Africa. Journal of Arid Environments, 35: 665-671.
52. Kopec, D.M., Shearman, R.C. & Riordan, T.P. (1988). Evapotranspiration of tall fescue turf. Horticultural Science, 23: 300-301.
53. Laker, M.C. (1993). Human-induced Soil Degradation in Africa. Pretoria: National Veld Trust Conference. 99 pp.
54. Lavado, R.S., Sierra, J.O. & Hashimoto, P.N. (1996). Impact of grazing on soil nutrients in a Pampean grassland. Journal of Range Management, 49: 452-457.
55. Le Houérou, H.N. (1984). Rain use efficiency: A unifying concept in arid-land ecology. Journal of Arid Environments, 7: 213-247.
56. Le Houérou, H.N. (1989). The Grazing Land Ecosystems of the African Sahel. Berlin: Spring-Verslag. 121 pp.
57. Le Houérou, H.N. (1994). Drought-tolerant and water-efficient fodder shrubs, their role as a "drought insurance" in the agricultural development of arid and semi-arid zones of southern Africa. Water research commission report 65/94, South Africa. 139 pp.
58. Le Houérou, H.N. & Hoste, C.F. (1977). Rangeland production and annual rainfall relations in the Mediterranean Bason and the African Sahelian and Sudanian zones. Journal of Range Management, 30: 181-189.
59. Le Houérou, H.N., Bingham, L.R. & Skerbek, W. (1988). Relationship between the variability of primary production and the variability of annual precipitation in world arid lands. Journal of Arid Environments, 15: 1-18.
60. Le Houérou, H.N., Popov, G.F. & See, L. (1993). Agro-bioclimatic classification of Africa. Agrometeorology Series Working Paper. No. 6. Rome, Italy: FAO. 228 pp.
61. Le Roux, C.J.G. (1989). Die invloed van brand en maai on onbeweide langgrasveld in Natal. Journal of the Grassland Society of southern Africa, 6: 69-64.
62. MacLeod, N.D. & Taylor, J.A. (1994). Perceptions of beef cattle producers and scientists relating to sustainable land use issues and their implications for technology transfer. Rangeland Journal, 16: 238-253.
63. MacRae, R.J., Henning, J. & Hill, S.B. (1993). Strategies to overcome barriers to the development of sustainable agriculture in Canada: the role of agribusiness. Journal of Agricultural Environment Ethics, 6(1): 21.
64. Manley, J.F., Schuman, G.E., Reeder, J.D. & Hart, R.H. (1995). Rangeland soil carbon and nitrogen responses to grazing. Journal of Soil and Water Conservation, 50: 294-298.
65. Martinez-Meza, E. & Whitford, W.G. (1996). Stemflow, throughfall and channelization of stemflow by roots in three Chihuahuan Desert shrubs. Journal of Arid Environments, 32: 271-287.
66. McNaughton, S.J., Ruess, R.W. & Seagle, S.W. (1988). Large mammals and process dynamics in African ecosystems. Bioscience, 38: 794-800.
67. McPhee, P.J. (1983). Report on study tour to USA to attend ASAE summer meeting and investigate rainfall simulation technology. Agricultural Engineering, Silverton. 21 pp.
68. Mentis, M.T. & Tainton, N.M. (1981). Stability, resilience and animal production in continuously grazed sour grassveld. Proceedings of the Grassland Society of southern Africa, 16: 37-43.
69. Midgley, G.F. & Moll, E.J. (1993). Gas exchange in arid-adapted shrubs: when is efficient water use a disadvantage? South African Journal of Botany, 59: 491-495.
70. Milton, S.J. & Dean, W.R.J. (1997). Rates of wood and dung disintegration in arid South African rangelands. African Journal of Range & Forage Science, 13: 89-93.
71. Milton, S.J. & Hoffman, M.T. (1994). The application of state-and-transition models to rangeland research and management in arid succulent and semi-arid grassy Karoo, South Africa. African Journal for Range and Forage Science, 11(1): 18-26.
72. Moore, A.C. (1990). Sekere fenologiese en fisiologiese reaksies van Themeda triandra op verskillende ontblaringskedules. M.Sc thesis, University for CHE, Potchefstroom. 77 pp.
73. Mworia, J.K., Nnene, W.N., Musembi, D.K. & Reid, R.S. (1997). Resilience of soils and vegetation subjected to different grazing intensities in a semi-arid rangeland of Kenya. African Journal of Range and Forage Science, 14(1): 26-31.
74. Noble, I.R. (1986). The dynamics of range ecosystems. Proceedings of the Second International Rangeland Congress. 63 pp.
75. O'Connor, T.G. & Bredenkamp, G.J. (1997). Grassland. In: Cowling, R.M., Richardson, D.M. & Pierce, S.M. (Eds), Vegetation of Southern Africa, pp. 215-257. Cambridge: Cambridge University Press. 615 pp.
76. O'Connor, T.G. & Roux, P.W. (1995). Vegetation changes (1949-71) in a semi-arid, grassy dwarf shrubland in the Karoo, south African: influence of rainfall variability and grazing by sheep. Journal of Applied Ecology, 32: 612-626.
77. Oppermnan, D.P.J. & Roberts, B.R. (1975). Evapotranspiration studies on Themeda triandra. Proceedings of the Grassland Society of southern Africa, 10: 103-109.
78. Opperman, D.P.J., Roberts, B.R. & Van Rensburg, W.L.J. (1969). The influence of defoliation on dry matter production and nutritive value of perennial veld grasses. Agroplantae, 1: 133-138.
79. Opperman, D.P.J., Roberts, B.R. & Van Rensburg, W.L.J. (1970). Die invloed van ontblaring op die wortelgewigte, stoppelgewigte en reserwestatus van die meerjarige veldgrasse. Agroplantae, 2: 51-60.
80. Opperman, D.P.J., Human, J.J. & Roberts, B.R. (1976). Die invloed van ontblaring en vogstremming op die groeikragtigheid van Themeda triandra. Proceedings of the Grassland Society of southern Africa, 12: 65-69.
81. Pressland, A.J. (1973). Rainfall partitioning by an arid woodland Acacia aneura F. Muell. in southwestern Queensland. Australian Journal of Botany, 21: 235-265.
82. Roux, P.W. (1981). Interaction between climate, vegetation and runoff in the Karoo. Karoo Agric, 2(1): 4-8.
83. Roux, P.W. & Opperman, D.P. J. (1986). Soil erosion. In: Cowling, R.M., Roux, P.W. & Pieterse, A.J. H. (Eds), The Karoo Biome, A preliminary Synthesis. Part I. Physical environment, pp. 92-111. Programme Report 124. Pretoria: Council for Scientific and Industrial Research. 113 pp.
84. Roux, P.W. & Vorster, M. (1983). Vegetation change in the Karoo. Proceedings of the Grassland Society of southern Africa, 18: 25-29.
85. Rutherford, M.C. & Westfall (1994). Biomes of southern Africa - an objective categorization. Memoirs of Botanical survey of southern Africa. 63 pp.
86. Scanlan, J.C. & Burrows, W.H. (1990). Woody overstorey impact on herbaceous understorey in Eucalyptus spp. communities in central Queensland. Australian Journal of Ecology, 15: 191-197.
87. Scheepers, J.C. & Kellner, K. (1995). Biological issues. In: Arluthmot, F.D. (Ed.), Report of the ESA Working Group on Land Degradation, pp. 51-63. Directorate of Resource Conservation, Department of Agriculture. 74 pp.
88. Schofield, C.J. & Bucher, E.H. (1986). Industrial contributions to desertification in South America. Trends in Ecology Evolution, 1: 78-80.
89. Scholes, R.J. (1987). Response of three semi-arid savannas on contrasting soils to the removal of the woody component. Ph.D. thesis, University of the Witwatersrand, Johannesburg.
90. Scholes, R.J. & Walker, B.H. (1993). An African Savanna: synthesis of the Nylsvlei study, p. 306. Cambridge University Press. 306 pp.
91. Schulze, B.R. (1979). Climate of South Africa. Part 8. General Survey. Pretoria: Weather Bureau. 96 pp.
92. Schulze, R.E. (1979). Soil loss in the key areas of the Drakensberg. Agricultural Engineering, 13: 22-23.
93. Schulze, R.E. (1984). Hydrological simulation as a tool for agricultural drought assessment. Water South Africa, 10(1): 55-65.
94. Schulze, R.E. (1997a). False African atlas of agrohidrology and climatology. Water Research Commission Report. Pretoria. 273 pp.
95. Schulze, R.E. (1997b). Hydrology and agrohidrology. Water Research Commission Report. Pretoria. 532 pp.
96. Scifres, C.J., Mutz, J.L., Whitson, R.E. & Drawe, D.L. (1982). Interrelationships of usage canopy cover with range forage on the coastal prairie. Journal of Range Management, 35: 558-562.
97. Scotney, D.M. & McPhee, P.J. (1991). Soil erosion and concentration. In: van Oudtshoorn, F. (Ed.), Guide to Grasses of South Africa, pp. 11-44. Arcadia: Briza Publications. 301 pp.
98. Scott, J.D. & Rabie, J.W. (1956). Preliminary studies on growth and development of Eragrostis curvula and Themeda triandra. Southern African Journal of Science, 52(9): 207-210.
99. Seghieri, J., Floret, C.H. & Pontarier, R. (1994). Development of an herbaceous cover in a Sudano-Sahelian savanna in north Cameroon in relation to available water. Vegetatio, 114: 175-184.
100. Seitlhelo, E.M., Allen, B.L. & Webster, D.B. (1993). Effect of three grazing intensities on selected soil properties in semi-arid west Texas. African Journal of Range and Forage Science, 10: 82-85.
101. Shackleton, C.M., McKenzie, B. & Granger, J.E. (1988). Seasonal changes in root biomass, root/shoot ratios and turnover in two coastal grassland communities in Transkei. South African Journal of Botany, 54: 465-471.
102. Shackleton, C.M., McKenzie, B. & Granger, J.E. (1989). Breakdown and decomposition in three coastal grassland communities in Transkei. South African Journal of Botany, 5: 551-559.
103. Shih, S.F. & Snyder, G.H. (1985). Water-table effects on pasture yield and evapotranspiration. Transaction of the American Society of Agricultural Engineering, 28: 1573-1577.
104. Smit, G.N. (1994). The influence of intensity of tree thinning on Mopani veld. Ph.D. thesis, University of Pretoria. 169 pp.
105. Smit, G.N. & Swart, J.S. (1994). The influence of leguminous and non-leguminous woody plants on the herbaceous layer and soil under varing competition regimes in Mixed Bushveld. African Journal of Range and Forage Science, 11: 27-33.
106. Smit, G.N., Rethman, N.F. G. & Moore, A. (1996). Review article: Vegetative growth, reproduction, browse production and response to tree clearing of woody plants in African savanna. African Journal of Range & Forage Science, 13(2): 78-88.
107. Smith, E.L. (1989). Range condition and secondary succession: A critique. In: Lauenroth, W.K. & Laycock, W.A. (Eds), Secondary Succession and the Evolution of Range Condition, pp. 103-141. Boulder, CO: Westview Press. 163 pp.
108. Smyth, A.J. & Dumanski, J. (1993). FESLM: An International Framework for evaluating Sustainable Land Management. Working Paper 1659. Rome: Food and Agricultural Organization of the United Nations. 74 pp.
109. Snyman, H.A. (1985). Waterbalansstudies op natuurlike veld in die sentrale Orange-Vrystaat. Ph.D. thesis, University of the Free State, Bloemfontein. 312 pp.
110. Snyman, H.A. (1988). Bepaling van waterverbruiksdoeltreffendheid van veld in die Sentrale Orangje-Vrystaat vanaf evapotranspirasiemetings. Water South Africa, 14: 153-158.
111. Snyman, H.A. (1989). Evapotranspirasie en waterverbruiksdoeltreffendheid van verskillende grasspesies in die sentrale Orange-Vrystaat. Proceedings of the Grassland Society of southern Africa, 6: 146-151.
112. Snyman, H.A. (1993a). Streef na optimale veldtoestand en weidingkapasiteit. SA Koöp, 9(5): 25-28.
113. Snyman, H.A. (1993b). The effect of defoliation during wilting on the production of Themeda triandra and Eragrostis lehmanniana in semi-arid grassland. African Journal of Range and Forage Science, 10: 113-117.
114. Snyman, H.A. (1994a). Evapotranspiration, water-use efficiency and quality of six dryland planted pasture species and natural vegetation, in a semi-arid rangeland. African Journal of Range and Forage Science, 11(3): 82-88.
115. Snyman, H.A. (1994b). Die invloed van ontblaring en wortelontwikkeling by grasse. SA Koöp, 10(4): 21-24.
116. Snyman, H.A. (1995). Knowledge and the Grassland Scientist in a rapidly changing southern Africa. Bulletin of the Grassland Society of southern Africa, 6: 41-47.
117. Snyman, H.A. (1997a). The influence of range condition on the hydrological characteristics in semi-arid rangeland. Proceedings XVIII International Grassland Congress, Canada, 2(23): 1-2.
118. Snyman, H.A. (1997b). Sustainable utilization of the grassland ecosystem. Inaugural address, University of the Free State, Bloemfontein. 30 pp.
119. Snyman, H.A. & Fouché, H.J. (1991). Production and water-use efficiency of semi-arid grasslands of South Africa as affected by veld condition and rainfall. Water South Africa, 17(4): 263-268.
120. Snyman, H.A. & Fouché, H.J. (1993). Estimating seasonal herbage production of a semi-arid grassland based on veld condition, rainfall and evapotranspiration. African Journal of Rangeland and Forage Science, 10: 21-24.
121. Snyman, H.A. & Opperman, D.P.J. (1983). Die invloed van vog-en ontblaringsbehandelings in hidrologiese eenhedf op natuurlike veld van die sentrale Oranje-Vrystaat. Proceedings of the Grassland Society of southern Africa, 18: 124-130.
122. Snyman, H.A. & Opperman, D.P.J. (1984). Afloopstudies vanaf natuurlike veld in verskillende suksessestadia van die Sentrale Oranje-Vrystaat. Journal of the Grassland Society of southern Africa, 1: 11-15.
123. Snyman, H.A. & Van Rensburg, W.L.J. (1986). Effect of slope and cover on runoff, soil loss and water use efficiency of natural veld. Journal of the Grassland Society of southern Africa, 3: 153-158.
124. Snyman, H.A. & Van Rensburg, W.L.J. (1990). Korttermyn invloed van strawwe droogte op veldtoestand en waterverbruiksdoeltreffendheid van grasveld in die sentrale Oranje-Vrystaat. Journal of the Grassland Society of southern Africa, 7: 249-256.
125. Snyman, H.A., Opperman, D.P.J. & Van den Berg, J.A. (1980). Hidrologiese siklus en waterverbruiksdoeltreffendheid van veld in verskillende suksessiestadia. Proceedings of the Grassland Society of southern Africa, 15: 69-71.
126. Snyman, H.A., Van Rensburg, W.L.J. & Opperman, D.P.J. (1985). Grond-en afloop-verliesbepalings vanaf natuurlike veld, met behulp van 'n reënvalnabootser. Proceedings of the Grassland Society of southern Africa, 2: 35-40.
127. Snyman, H.A., Van Rensburg, W.L.J. & Opperman, D.P.J. (1986). Toepassing van 'n gronderosievergelyking op natuurlike veld van die Sentrale Oranje-Vrystaat. Proceedings of the Grassland Society of southern Africa, 3: 4-9.
128. Snyman, H.A., Venter, W.D. & Van Rensburg, W.L.J. (1997). Transpiration and water use efficiency in response to water stress in Themeda triandra and Eragrostis lehmanniana. South African Journal of Botany, 63(1): 55-59.
129. Snyman, H.A., Venter, W.D., Van Rensburg, W.L.J. & Opperman, D.P.J. (1987). Ranking of grass species according to visible wilting order and rate of recovery in the Central Orange Free State. Journal of the Grassland Society of southern Africa, 4: 78-81.
130. Tainton, N.M. (1981). Growth and defoliation of veld and pasture plants and swards. In: Tainton, N.M. (Ed.), Veld and Pasture Management in South Africa, pp. 215-239. Pietermaritzburg: Shuter & Shooter. 481 pp.
131. Tainton, N.M. (1988). A consideration of veld condition assessment technique for commercial livestock production in South Africa. Journal of the Grassland Society of southern Africa, 5: 76-79.
132. Tyson, P.D. (1986). Climatic Change and Variability in Southern Africa. Cape Town: Oxford University Press. 196 pp.
133. Van den Berg, J.A., Roberts, B.R. & Vorster, L.F. (1975). The effect of seasonal grazing on the cover and composition of Cymbopogon-Themeda veld. Proceedings of the Grassland Society of southern Africa, 10: 111-117.
134. Van den Berg, J.A., Roberts, B.R. & Vorster, L.F. (1976). Die uitweking van seisoenbeweiding op die infiltrasievermoë van gronde in 'n Cymbopogon-Themeda veld. Proceedings of the Grassland Society of southern Africa, 11: 91-95.
135. Van der Westhuizen, H.C. (1994). Die kwantifisering van veldtoestand in die sentrale Vrystaat. M.Sc. (Agric.) thesis, Department Grassland Science, University of the Free State, Bloemfontein. 83 pp.
136. Venter, W.D. (1988). Die invloed van cogstremmin gop die groei van Themeda triandra en Eragrostis lehmanniana. M.Sc. (Agric.) thesis, University of the Free State, Bloemfontein. 84 pp.
137. Venter, W.D., Snyman, H.A. & Van Rensburg, W.L.J. (1997). Photosynthetic response to water stress in Themeda triandra and Eragrostis lehmanniana. South African Journal of Botany, 63(1): 37-41.
138. Walker, B.H. (1980). Stable production versus resilience: a grazing management conflict. Proceedings of the Grassland Society of southern Africa, 15: 79-83.
139. Walker, B.H. (1988). Outecology, synecology, climate and livestock as agent of rangeland dynamics. Australian Rangeland Journal, 10: 69-75.
140. Walker, J., Robertson, J.A., Penridge, L.K. & Sharpe, P.J.H. (1986). Herbage response to tree thinning in a Eucalyptus creba woodland. Australian Journal of Ecology, 11: 135-140.
141. Walker, A.B., Frizell, J.A. & Morris, S.D. (1994). The New Zealand policy framework for sustainable agriculture and some implications for animal production research. Proceedings of the New Zealand Society of Animal Production, 54: 367-372.
142. Weinmann, H. (1940). Seasonal chemical changes in the roots of some South African Highveld grasses. Journal of South African Botany, 6: 131-139.
143. Weismann, H. (1943). Effects of defoliation intensity and treatment on Transvaal Highveld. Empirical Journal of Experimental Agriculture, 11: 113-123.
144. Weinmann, H. (1948). Underground development and reserves of grasses. A review. Journal British Grassland Society, 3: 115-140.
145. Westoby, M. (1979). Elements of a theory of vegetation dynamics in arid rangelands. Journal of Botany, 28: 169-194.
146. Westoby, M., Walker, B.H. & Noi-Meir, I. (1989). Opportunistic management for rangelands not at equilibrium. Journal of Range Management, 42: 266-274.
147. Whitford, W.G. (1996). The importance of the biodiversity of soil biota in arid ecosystems. Biodiversity and Conservation, 5: 185-195.
148. Whitford, W.G., Steinberger, Y., MacKay, W., Parker, L.W., Freckman, D., Wallwork, J.A. & Weems, D. (1986). Rainfall and decomposition in the chichuahuan desert. Oecologia, 68: 512-515.
149. Whitford, W.G., Anderson, J. & Rice, P.M. (1997). Stemflow contribution to the 'fertile island' effect in creasotebush, Larrea tridentata. Journal of Arid Environments, 35: 451-457.
150. Wight, J.R. & Hanson, C.L. (1990). Crop coefficients for rangeland. Journal of Range Management, 43: 482-485.
151. Wilmott, C.J. (1982). Some comments on the evaluation of model performance. Bulletin American Meterology Society, 63: 1309-1313.
152. Wiltshire, G.H. (1990). Nitrogen mineralization, nitrification and nitrogen balance in laboratory incubation of soil from natural grassland in the central Orange Free State. South African Journal of Plant and Soil, 7: 45-49.
153. Winter, W.H., Mott, J.J. & McLean, R.W. (1989). Evaluation of management options for increasing the productivity of tropical savanna pastures. Australian Journal of Experimental Agriculture, 29: 631-634.
154. Wischmeier, W.H. (1975). Estimating the soil loss equations cover and management factor for undisturbed areas. In: Proceedings Sediment-yield workshop, Oxford, pp. 118-124. Mississippi: United States Department of Agriculture, ARS-S-40. 130 pp.
155. Wischmeier, W.H. & Smith, D.D. (1978). Predicting Rainfall Erosion Losses, a guide to conservation planning. USDA Handbook No. 537. 210 pp.
156. Yunlong, C. & Smit, B. (1994). Sustainability in agriculture: A general review. Agriculture, Ecosystems and Environment, 49: 299-307.