Determinants of herbaceous plant species composition on a number of ranches in the north‐western Transvaal

Abstract

Herbaceous plant species composition was measured on ranches in the Thabazimbi district, Transvaal, to obtain veld composition scores and to quantify the relations between such scores and certain determinants considered important in influencing species composition. Determinants investigated were mean annual rainfall and herbivory (stocking rate). The survey was undertaken on seven game and cattle ranches in Combretum apiculatum woodland of the Mixed Bushveld (Acocks 18) of the north‐western Transvaal. Rainfall for the season preceding the vegetation survey and bulk and selective grazer stocking rates had a significant effect on veld composition scores. The recommended agricultural grazer stocking rate for the survey area is 12.5 LSU 100 ha"¹ a"¹. Under the present conditions and in view of the findings of this survey, it is suggested that a grazer stocking rate of 6.25 LSU 100 ha⁻¹ a⁻¹ be implemented.

Kruidagtige plantspesiesamestelling is gemeet op plase in die Thabazimbi‐distrik om veldsamestellingtellings te verkry en om die verwantskappe tussen die tellings en sekere primere bepalende elemente te kwantifiseer. Bepalende faktore wat ondersoek is, is gemiddelde jaarlikse reenval en die effek van herbivore (belading). Die opname is op sewe wild en beesplase in die Combretum apiculatum veld van die Gemengde Bosveld (Acocks 18) van die noord‐wes Transvaal onderneem. Reënval vir die seisoen voor die plantegroeiopname en ru‐ en selektiewe grasvreterbelading het ‘n beteke‐nisvolle effek op die veldsamestellingtellings gehad. Die aanbevele landbou grasvreterbelading vir die opnamegebied is 12.5 GVE 100 ha⁻¹ j⁻¹. Onder die huidige toestande en gegrond op die bevindings van die opname, word dit voorge‐stel dat ‘n grasvreterbelading van 6.25 GVE 100 ha⁻¹ j⁻¹ geïmplementeer word.

Additional index words:

• Herbivory
• Mixed Bushveld
• rainfall