The effect of fire, with and without subsequent defoliation, on the herbaceous layer of Burkea Africana savanna¹

Part of a thesis submitted by the senior author for an M.Sc. degree at the University of Pretoria.

Abstract

A back‐fire applied to the herbaceous layer during September 1978 resulted in significantly less dry matter production over the following year, compared to an unburnt area. This was largely due to the significant reduction in dry matter and basal cover of the non‐forage species group which had, prior to the fire, exhibited a notable accumulation of dead material. In contrast, basal cover and dry matter production of the leafier forage species group were not significantly affected by the back‐fire. On plots where the burn was followed by an 8‐weekly clipping treatment, a slower biomass accumulation rate of the sward as a whole was recorded than on burnt plots allowed unchecked post‐fire regrowth. The lowest rate was recorded on unburnt plots allowed unchecked growth. The burn plus 8‐weekly clipping reduced the biomass accumulation rate of the non‐forage species compared with the same group on unburnt undipped plots. In a similar comparison, the rate of accumulation of forage species biomass was, however, stimulated by the burn plus 8‐weekly clipping.

Uittreksel

‘n Windopbrand van die kruidlaag gedurende September 1978 het ‘n betekenisvolle laer produksie van droë materiaal in die daaropvolgende jaar as gevolg gehad in vergelyking met ‘n ongebrande area. Dit was hoofsaaklik te wyte aan ‘n betekenisvolle verlaging in droe materiaal en basale bedekking van die nie‐voerspesiesgroep wat voor die brand ‘n groot hoeveelheid dooie materiaal ge‐akkumuleer het. In teenstelling daarmee is die basale bedekking en seisoenale droë materiaal produksie van die blaarryker voerspesiesgroep nie betekenisvol deur die windopbrand beïnvloed nie. Op persele waar die brand gevolg is deur ‘n 8‐weeklikse snybehandeling is ‘n stadiger biomassa‐akkumuleringstempo van die grasveld as geheel aangeteken as op gebrande persele waar ongestremde navuurse hergroei toegelaat is. Die stadigste tempo is aangeteken op ongebrande persele wat ongestremd toegelaat is om te groei. Die brand plus 8‐weeklikse sny het die biomassa‐akkumuleringstempo van die nie‐voerspesies verlaag in vergelyking met die van dieselfde groep op ongebrande nie‐gesnyde persele. In ‘n soortgelyke vergelyking is die akkumuleringstempo van voerspesiesbiomassa egter gestimuleer deur die brand plus 8‐weeklikse snybehandeling.

Notes

Part of a thesis submitted by the senior author for an M.Sc. degree at the University of Pretoria.