Abstract
Although exposure to multiple cutting cycles reduces stored reserves, shoot diameter and shoot length, it, however, increases shoot production per resprouting stump and foliar nitrogen. In disturbance-prone environments with fluctuating seasonal rainfall such as savannas, the repeated cutting of the same trees eventually results in a possible decline in tree abundance. The effects of subjecting Terminalia sericea trees to one, two and multiple (eight) cutting events over a period of 2 years on coppice response were investigated in a savanna woodland in South Africa. Resprout shoot diameter, shoot length and the total cumulative diameter were lower in trees exposed to a high number of cutting events compared to trees exposed to one cutting event. Increasing the number of cutting events significantly reduced stem total non-structural carbohydrate levels in trees indicating a depletion of stored reserves. Foliar carbon content remained largely the same, while leaf nitrogen and phosphorus concentrations significantly increased with each cutting event, relative to uncut trees. Results indicate that trees cut once had not replenished depleted carbohydrate reserves even after a period of 18 months during which no cutting took place. Sustainable utilization of this tree species must allow for at least more than 18 months of undisturbed growth between harvests to allow for the replenishing of reserves.
Highlights
There is much concern about the sustainability of intensive cutting of trees for firewood in communal rangelands in Africa (Twine et al 2003; Kaschula et al 2005a; Neke et al 2006; Shackelton et al 2004)
The total number of shoots was significantly higher in cutting regime c (CRc) trees compared to cutting regime a (CRa) in October 2012, January and February 2013, while there were no significant differences in the total number of shoots due to treatment effects in December 2013 (Table 2)
Shoot production was significantly higher in repeatedly cut trees (CRc) through-out the monitoring period compared to the other treatments
Summary
There is much concern about the sustainability of intensive cutting of trees for firewood in communal rangelands in Africa (Twine et al 2003; Kaschula et al 2005a; Neke et al 2006; Shackelton et al 2004). Little is known about the factors that control the reserve content of a plant, how much of the reserve is utilized after a disturbance such as a harvest (Cruz et al 2003), and the changes in the recovery of nutrients such as nitrogen and carbon lost during a disturbance. These factors have significant implications for the sustainable use of rangelands subjected to intensive wood harvesting
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