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Accueil du site → Master → Afrique du Sud → Relationship between veld condition, rainfall and animal stocking rate in the Mopani Veld.

University of Pretoria (1990)

Relationship between veld condition, rainfall and animal stocking rate in the Mopani Veld.

Snyman, Dutliff Daniel

Titre : Relationship between veld condition, rainfall and animal stocking rate in the Mopani Veld.

Auteur : Snyman, Dutliff Daniel

Université de soutenance : University of Pretoria

Grade : Master of Science (MS) 1990

Résumé
This study examines the relations between veld condition, rainfall and animal stocking rates in the semi-arid Mopani Veld. The aim was to test the following two hypotheses : H1 : Low stocking rates result in "good" veld. H2 : High rainfall results in "good" veld. In order to meet the objectives of the study, a relatively uniform area in terms of climate, topography and vegetation, was selected in the Mopani veld (Acocks, 1988), north of the Soutpansberg. Seven farms within the defined area, were Surveyed. Veld condition, rainfall and animal stocking rates were described and quantified. Data obtained, were statistically tested using Pearson correlation, multiple linear regression and factor analysis. It is important to note that interpretations of the relations between veld condition, rainfall and animal stocking rates, are influenced by the methods used in calculating sum variables. Any conclusions made, should be interpreted within the context of this study. The most important results are summarized in the subsequent paragraphs. 1. Woody canopy spread cover (1986/1987) was poorly correlated with veld condition for both the 1986/1987 (r = -0,275 ; P = 0,55) and 1987/1988 (r = -0,15 ; P = 0,75) season. 2. The amount of "C. mopane" seedlings per hectare (1987/1988) was poorly correlated with veld condition for both the 1986/1987 (r = -0,67 ; P = 0,11) and 1987/1988 (r = 0,01 ; P = 0,98) season. 3. Veld condition was not significantly (P ≤ 0,05) correlated with grazer stocking rates for the 1986/1987 (r = -0,24) and 1987/1988 (r = 0,53) season. The H1 hypothesis (low stocking rates result in "good" veld) is refuted. 4. Veld condition was not significantly (P ≤ 0,05) correlated with rainfall for the 1986/1987 (r = 0,58) and 1987/1988 (r = 0,57) season. This study refutes the H2 hypothesis (high rainfall results in "good" veld). 5. The correlation co-efficients between rainfall and veld condition are relatively higher than those between grazer stocking rate and veld condition. The relative higher correlation co-efficients between rainfall and veld condition as well as the co-linearity (factor analysis) between these two parameters indicate that rainfall has a greater effect on veld condition than grazer stocking rate has on veld condition. 6. Multiple linear regression models, which include nondependant variates such as rainfall, grazer stocking rates and their interaction term (rainfall x grazer stocking rate) were not able to account for a significant (R².. 0,8) percentage of the variance in veld condition. More than 35% of the variance in veld condition could not be accounted for by factors such as rainfall and grazer stocking rate. 7. This study uses the nearest plant survey method whereby species composition is determined. This, has certain shortcomings, for example, during a wet cycle, the increaser 2c species increase relatively faster than species belonging to the other ecological classes. This effect results in a lower veld condition score in wet cycles. Species composition should rather be determined on a dry mass basis. 8. The ecosystem of the Mopani Veld is inherently unstable, but shows a high degree of resilience. The system is event-orientated and is characterized by an abiotic component which dominates the biotic component. There are fluctuations in the condition of the system which are beyond the realm of managerial action. 9. Species respond from year to year to moisture stress. There are fundamental problems with the classification of Dyksterhuis. According to the Dyksterhuis classification, species are classified due to their response to grazing while the greater response is to rainfall. 10. Adaptive management is suggested as the underlying management philosophy whereby the wildlife in the Mopani Veld, north of the Soutpansberg should be managed. 11. Rainfall, production of the herbaceous layer, the presence or absence of a browseline and animal numbers need to be monitored in a monitoring program. 12. A decision analysis model is presented as an aid to qualitative decisions relating to the manipulation of grazer and browser numbers. Through a process of knowledge accumulation, by means of adaptive management, future management on a game farm may be refined.

Présentation (NRF)

Page publiée le 25 février 2015, mise à jour le 5 juillet 2017