The grassland dynamics of Mkambati game reserve.

[摘要] This work describes the coastal grasslands of Mkambati Game Reserveand their suitability for the present large herbivore complement.The initial description makes use of both field survey andquantitative sampling and multivariate analysis which facilitatedthe production of soil and vegetation maps at tre scale of 1:10 000. Suitability of these grasslands for herbivores is assessedin terms of both quantity and quality of food available and thepresent herbivore impact.Local variation in soil type was considerable. Eight standard soilforms were distinguished as well as severaI others previouslyundescribed. Most of the soils were dystrophic although nutrient'hot-spots' were common. This determined floristic composition ofthe various communities to some extent.Three grassland communities and four subcommunities were recognizedwhich contributed 81, 5% to the total area of the reserve. Theremaining area comprised forest. wetlands. exposed rock andaccommodation camps. Each grassland community was associated withparticular ranges of the measured environmental variables.The standing crop of the three communities was high relative toother areas of Southern Africa. Absolute amounts varied seasonallybeing highest in summer and lowest in winter Partitioning betweenthe phytomass, necromass and litter components also variedseasonally. Total standing crop increased with increasing intervalsince the last fire. Litter breakdown rates differed betweencommunities and species.Forage quality was poor being lowest in autumn and winter anddeclining with age. This was probably a result of the dystrophicsoils. Crude protein and phosphorus were limiting for severalmonths of the year. Total forage quantity was in excess of thepresent herbivore needs although availability declined with age andduring the non-growing season. However, the poor quality reducedthe amount available such that present herbivore impact was low, atall times being less than 9%.. Removal by herbivores was highestseveral months after a fire when absolute amounts of variousnutrients were at a maxinum per unit area. Thereafter it declinedto less than 1% with aging of the sward.The implications of the results for management are discussed andfuture research needs identified.

[发布机构] University of the Witwatersrand