Regeneration by coppicing (resprouting) of miombo (African savanna) trees in relation to land use

Abstract

This study compared and contrasted natural regeneration by coppicing of tree species in a forest reserve and more disturbed adjacent public lands in eastern Tanzanian miombo woodlands. Data were collected between August and October 1997 using sixty-four 20 m×50 m plots. Eighty-three percent of the 30 harvested woody species in the forest reserve resprouted after harvesting compared with 90% of the 39 species in the public lands. Coppicing effectiveness (mean number of shoots per stump) varied among species and depended on plant size at the time of cutting, stump height and percentage of the stand removed. Comparing the 16 species effectively sampled in both sites, coppicing effectiveness was 4.9±1.6 (S.E.) shoots per stump in public lands, which is greater than the 3.1±1.4 shoots per stump in the reserve (paired t 15=2.433, P=0.014). However, the percentage of resprouting stumps did not differ (paired t 15=1.440, P=0.085), but tended to be higher in public lands. The percentages of stumps sprouting per species varied from 0 to 100%, with means of 59 (reserve) and 74% (public lands). Coppicing effectiveness for the most utilised species, Combretum molle (fuelwood; 4.0 shoots per stump in the reserve, 6.1 shoots per stump in public lands), Julbernardia globiflora (fuelwood; 5.6 vs. 5.3 shoots per stump), Pterocarpus angolensis (carpentry; absent vs. 7.3 shoots per stump) and Spirostachys africana (building poles; 1.0 vs. 0.4 shoots per stump) showed typical variation. The greater levels of resprouting in public lands is interpreted as release from self-thinning dynamics, as the reserve has a much higher tree biomass. Despite high levels of harvesting in public lands, tree densities are virtually identical between land uses as a result of the high levels of resprouting. Due to the prolific coppicing of trees in public lands, it is recommended that the woodland should be managed using coppice rotation as a silvicultural system.