Regeneration Dynamics and Structural Changes in Miombo Woodland Stands at Kitulangalo Forest Reserve in Tanzania

Abstract

The sustainability of the seriously threatened African miombo woodlands depends on their capability to maintain sufficient natural regeneration. This study focused on the regeneration dynamics and the impacts of silvicultural treatments of fencing, site preparation, and thinning in the Kitulangalo forest reserve in Tanzania. Mixed models were applied to analyze the change in number of stems during the nine-years observation period on a set of permanent experimental plots. There was a significant decrease in the total number of stems (from 29 800 ha −1 to 19 100 ha −1 ) but a significant increase in the number of main stems (from 9 300 ha −1 to 11 100 ha −1 ) during observation period. The proportion of empty regeneration plots (zero seedlings and saplings on a regeneration plot of 4 m 2 ) was initially very low (7.3%) and decreased further during the study period to 5.3%. Greater stand density was associated with lower density of regeneration. Fencing implied a greater increase in the number of main stems but a sharper drop in the total number of stems by reducing animal disturbances. The findings indicate that the forests at Kitulangalo are recovering from past abuse and likely developing toward more sustainable stand structures and sustainability.

Excessive livestock grazing overrides the positive effects of trees on infiltration capacity and modifies preferential flow in dry miombo woodlands

“…KFR was first classified by the government as a 'productive reserve', meaning that wood harvesting is allowed by those who obtain a license. Later, in 1985, harvesting was forbidden, even though illegal encroachment for wood harvesting and livestock grazing still occurs (Hammarstrand & Särnberger, 2013; Njoghomi et al, 2020). Vegetation cover in the KFR and surrounding areas is typical open dry miombo woodland dominated by Julbernardia globiflora , Brachystegia boehmii , and Pterocarpus rotundifolius , with a canopy height of up to 20 m (Nduwamungu et al, 2009).…”

“…grazing still occurs (Hammarstrand & Särnberger, 2013;Njoghomi et al, 2020). Vegetation cover in the KFR and surrounding areas is typical open dry miombo woodland dominated by Julbernardia globiflora, Brachystegia boehmii, and Pterocarpus rotundifolius, with a canopy height of up to 20 m (Nduwamungu et al, 2009).…”

“…These exclosures were set out to test and quantify the effects of anthropogenic activities within the forest. At the time these plots were established, the two areas we compared (inside and outside) were both affected by grazing and had a similar disturbance level (Njoghomi et al, 2020).…”

Tree growth dynamics and ecological recovery in Kitulangalo miombo woodlands Morogoro, Tanzania

“…This type of regeneration occurs when the upper part of the stem is removed through cutting or other mechanical injuries (Luoga et al 2004). Disturbed miombo trees can produce massive numbers of coppices and suckers (Chidumayo 1988, Njoghomi et al 2020), but their recruitment is likely to be restricted by low survival due to harsh climatic conditions, annual fires, herbivory, and density-dependent tree mortality (Neelo et al 2013, Weiskittel et al 2011. The individual effect of the disturbance agents such as animal grazing, fire, and drought (Bognounou et al 2010) towards the reduction of the number of individual stems is, however, poorly known particularly for regeneration and tree growth of miombo woodlands of Tanzania.…”