The development of the ecological index method for assessing veld condition in the Karoo

Abstract

The results of a previous study were used for the development of the Ecological Index Method (EIM) of veld condition assessment in the karoo areas. The EIM 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 EIM 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 EIM for extensive surveys is also proposed.

Uittreksel

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