Last update: March 30, 2012 03:27:32 PM E-mail Print

 

THE DEVELOPMENT OF THE ECOLOGICAL INDEX METHOD FOR ASSESSING VELD CONDITION IN THE KAROO

DIE ONTWIKKELING VAN DIE EKOLOGIESE INDEKSMETODE VIR EVALUASIE VAN VELDTOESTAND IN DIE KAROO

 

M.VORSTER

Agricultural Research Institute for the Karoo Region, Pte Bag X529, Middelburg C P, 5900

 

 

ABSTRACT

 

The results of a previous study were used for the development of the Ecological Index Method (ElM) of veld condition assessment in the karoo areas. The ElM makes use of a veld benchmark, which must be previously identified and characterised on each topographical unit in each Reasonably Homogenous Farming Area. As a result of the process of retrogression of the veld in the karoo areas, five different ecological groups of plants are identified, namely, Decreasers, Increasers II (a), Increasers II (b), Increasers II (c) and Invaders. A relative index value is allocated to each ecological group. The operation of the ElM is illustrated by the use of the data of four sites in different veld condition classes on the same topographical unit in the Grassridge Basin Area. A rapid method of veld condition assessment with the ElM for extensive surveys is also proposed.

 

UITTREKSEL

 

Die resultate van 'n vorige studie was gebruik om die Ekologiese Indeksmetode (ElM) van veldevaluasie vir die Karoogebiede te ontwikkel. Die ElM maak gebruik van ‘n veldverwysingspunt wat vooraf eers op elke topografiese eenheid binne elke Redelik Homogene Boerderygebied geïdentifiseer en gekarakteriseer moet word. Na aanleiding van die proses van veldagteruitgang in die Karoogebiede, is vyf verskillende ekologiese groepe van plante geïdentifiseer, naamlik, Afnemers. Toenemers II (a), Toenemers II (b), Toenemers II (c) en Indringers. ‘n Relatiewe indekswaarde is aan elke ekologiese groep toegeken. Die werking van die ElM is geïllustreer met behulp van die gebruik van data van vier persele in verskillende veldtoestandklasse op dieselfde topografiese-eenheid in die Grassridge Komgebied. Vinnige metode van veldevaluasie met die ElM vir ekstensiewe opnames is voorgestel.

 

Published

Proceedings Grassland Society Southern Africa 17