Changes in the structure and composition of miombo woodlands mediated by elephants (Loxodonta africana) and fire over a 26‐year period in north‐western Zimbabwe

Abstract

Changes in structure and composition of miombo woodlands mediated by elephants and fire were studied in 26-year-old permanent transects established in 1972 in north-western Zimbabwe. Elephants caused 48% decline in proportions of large trees (>11 cm diameter), significant reductions (30.9-90.9%) in tree heights, reductions in stem areas (43.5%) and densities (2.5%) of all trees. There were increases in proportions of small trees (64.8%), shrub canopy volumes (271%) and shrub densities (172%). These increases are attributed to natural recruitment because of longer fire-free periods and reduction of tree suppression effects on lower strata as a result of elephantinduced tree declines. Frequencies of occurrence of most species dropped by 28-89.6%. Brachystegia boehmii was replaced by Pseudolachnostylis maprouneifolia as the most dominant tree, largely because of high elephant preference for Brachystegia boehmii. A new suite of species, dominated by Combretaceae, increased in dominance resulting in local floristic changes. Reductions in old elephant (33.4%), old unknown (89.9%) and new elephant (13.7%) damage suggest that elephant occupancy of miombo woodlands has declined, possibly because of limited availability of preferred browse species. This study clearly shows that elephants and fire have contributed significantly to the changes in miombo woodlands in the area.Key words: elephant damage, fire, miombo, Sengwa, Zimbabwe (9,9%) et « nouveaux dus aux éléphants » (13,7%) suggère que l'occupation des forêts de miombo par les éléphants a diminué, peut-être à cause de la disponibilité limitée des espèces fourragères qu'ils préfèrent. Cette étude montre clairement que les éléphants et les feux ont contribué significativement aux changements survenus dans les forêts de miombo de la région.

Miombo Woodlands Research Towards the Sustainable Use of Ecosystem Services in Southern Africa

“…and D. condylocarpon. Similar results were obtained by [33] in the Miombo Woodlands of northwestern Zimbabwe, where elephants and fires reduced the proportions of large trees, tree heights, stem basal area and densities of all trees. Besides that, tree species frequencies dropped 28-89.6% and the most visible floristic alteration was the replacement of the typical Brachystegia boehmii Taub.…”

Diversity, Population Structure, and Above Ground Biomass in Woody Species on Ngomakurira Mountain, Domboshawa, Zimbabwe

“…References [41,42] made similar observations in studies of fire and elephant affected miombo regions in Zimbabwe and Mozambique, respectively. Figure 2 are typical miombo woodlands dominated by the Caesalpinoid species B. glaucescens and J. globiflora and their associated species.…”

Decline and Die-Back of Woody Plants in a Physiognomic and Floristically Complex Sebungwe Region and the Factors Modifying Mosaic Patch Landscapes at Sengwa Wildlife Area, Zimbabwe

“…Elephants alone at a density of 0.27 km -2 will convert the woodland into coppice in 120 years due to resulting massive declines of large trees [16,17]. The same result is achieved in only 10 years if elephant density is at 2 km -2 [1].…”