Journal d'écosystème et d'écographie

Abstrait

Invasive Woody Plants, Diminishing Ecosystems in Potentially Productive African Rangelands

Clifford Tafangenyasha, Stanley Musungwa and Blessing Kavu

Lantana camara L. (Verbenaceae) has been known in literature to impact adversely on biodiversity, resulting in the decline or elimination of native species through competition, destruction, and the disruption of local ecosystems and ecosystem functions. Invasive alien species, introduced and/or spread outside their natural habitats, have affected native biodiversity in almost every ecosystem type. This research addresses capacity of L.camara to invade and displace sites inside protected areas which would otherwise have intact natural vegetation. This study aimed at assessing the distribution of the invasive Lantana camara L. hereafter L. camara and its influence on undegraded and degraded soils and herbaceous species diversity in the SWRA.

To assess the impacts of L. camara in SWRA 18 belt transects were randomly placed in the dominant woodland types occurring in the study area. The weed-free native vegetation and weed-infested sites with similar soils were examined in a vegetation condition assessment. The 18 belt transects were randomly located by pairing nine plots that were considered degraded and undegraded. A mosaic of patchy disturbance by elephant feeding habits occur in SWRA in which L. camara colonise. Random stratified sampling method was used in two categories; stream banks, and grazing lands. L. camara was heavily distributed in stream banks and grazing lands. Estimates of L. camara were derived by visual assessment of their relative cover in 20x20 m plots. The Braun Blanquet scales were adopted for scoring L. camara cover. Density (individuals/ha) was established by enumerating woody species in a plot. Density of woody species was significantly higher (P<0.05) on undegraded plots than degraded plots and Shannon- Weaver diversity indices (H’) was significantly higher (P<0.05) on undegraded plots than on degraded plots. The study formed part of a vegetation condition assessment of the SWRA.