Modelling tree growth to determine the sustainability of current off-take from miombo woodland: a case study from rural villages in Malawi

Abstract

SUMMARYMiombo woodlands supply ecosystem services to support livelihoods in southern Africa, however, rapid deforestation has necessitated greater knowledge of tree growth and off-take rates to understand the sustainability of miombo exploitation. We established 48 tree inventory plots within four villages in southern Malawi, interviewed representatives in these same villages about tree management practices and investigated the impact of climate on vegetation dynamics in the region using the ecosystem modelling framework LPJ-GUESS. Combining our data with the forest yield model MYRLIN revealed considerable variation in growth rates across different land uses; forested lands showed the highest growth rates (1639 [95% confidence interval 1594–1684] kg ha–1 year–1), followed by settlement areas (1453 [95% confidence interval 1376–1530] kg ha–1 year–1). Based on the modelled MYRLIN results, we found that 50% of the villages had insufficient growth rates to meet estimated off-take. Furthermore, the results from LPJ-GUESS indicated that sustainable off-take approaches zero in drought years. Local people have recognized the unsustainable use of natural resources and have begun planting activities in order to ensure that ecosystem services derived from miombo woodlands are available for future generations. Future models should incorporate the impacts of human disturbance and climatic variation on vegetation dynamics; such models should be used to support the development and implementation of sustainable forest management.

Assessing the Welfare Impacts of Forest Ecosystem Service Management Policies and Their Distributional Rules

“…We calculated the biomass supplied by each block for each year by adding to the current estimated biomass the mean annual increment per ha estimated by Green et al (2016) for Malawi miombo woodlands. We calculated the total biomass demanded by each village cluster by estimating average consumption of a household based on data collected through household's survey data for six villages.…”

“…The ecologically sustainable amount is defined as the quantity of biomass that can be extracted without reducing the productive capacity of the forest (Luckert and Williamson, 2005). We assumed that the annual sustainable harvest rate for each forest co-management block is equal to 80% of the AGB growth (Otuoma et al, 2011) and we approximated the AGB growth using the mean annual increment per ha modelled by Green et al (2016). The average estimated quantity of biomass that Miombo woodlands in Malawi can provide in a year is 1.639 t/ha.…”

Why we fail: Stakeholders' perceptions of the social and ecological barriers to reforestation in southern Malawi

“…Malawi is among the 10 poorest countries on Earth, and has undergone marked land‐cover change as a result of population growth since political independence in 1964 (Figure 1) (Bone, Parks, Hudson, Tsirinzeni, & Willcock, 2017). Over 80% of the population still depends on agriculture for primary income (Tchereni & Sekhampu, 2013), and forest dependence is high (Green, Eigenbrod, Schreckenberg, & Willcock, 2017; Kamanga et al, 2008). Malawi's government has committed to restore 4.5 million hectares of forest under the Bonn Challenge—roughly 38% of the country's land area—yet the success of public planting projects on the ground has been poor (Moyo, Chikuni, & Chiotha, 2017).…”