Influence of macchia eradication techniques on botanical composition of grasses in the döhne sourveld of the amatole mountains

Abstract

Grass communities identified through association‐analysis were used for determining the effects of several methods for eradicating and controlling macchia. Follow‐up burns at three frequencies applied over a ten‐year period to control macchia were found to have masked most differences in species composition of the grass sward which may have arisen as a result of eradication treatments of burning, spraying and cutting. However, Ely onurus argenteus Nees and Harpechloa falx (L.) Kuntze were absent only from stumped plots. Themeda triandra Forsk. and Apochaetae hispida (L.f.) Phipps survived in a vegetative state in unburned, control plots for about 20 years in spite of competition from a dense, bushy growth of macchia (Cliffortia paucistaminea H. Weim., C. linearifolia Eckl. & Zeyh. and Erica brownleeae Bolus). Themeda triandra was best adapted to withstand frequent burning while Heteropogon contortus (L.) Beauv. ex Roem. & Schult. was suppressed by this treatment. Certain other grasses may have survived entirely below the soil, and without evidence of aerial portions, in moribund veld. Basal cover was used for recommendations on veld burning management, whether for purposes of water production or for grazing.

Uittreksel

Grasgemeenskappe wat deur verwantskapanaliese geidentifiseer is, is gebruik om die uitwerking van verskeie uit‐wissingsmetodes, wat gedurende drie proewe toegepas is, vas te stel. Enige veranderinge in die grassamestelling wat moontlik kon voortspruit uit die toepassing van brand, bespuiting of kap uitwissingsmetodes wat tien jaar tevore toegedien is, is versteek deur daaropvolgende brand behandelings, behalwe uitgekapte persele wat geen Elyonurus argenteus of Harpechloa falx bevat het nie. Themeda triandra en Apochaetae hispida het, ten spyte van sterk mededinging deur ‘n digte bosagtige fynbos aanwas (Cliffortia paucistaminea, C. linearifolia en Erica brownleeae in ‘n vegetatiewe toestand vir 20 jaar in die kontrole persele bly voortbestaan. Themeda triandra was die beste aangepas om her‐haaldelike brand te weerstaan terwyl die groei van Heteropogon contortus deur hierdie behandeling in bedwang gehou is. ‘n Driejarige veldbrand het die mees wenslike grasveld tot gevolg gehad. In uitgestorwe veld het sekere ander grasse moontlik onder grondvlak en sonder enige tekens van bogrondsegroei oorleef. Basalebedekking is gebruik om veld‐brandbeheer voor te skryf beide vir die doel om water opvangs te verbeter of om die weiding te bevorder.