Abstract

Miombo woodlands stretch across eastern and southern Africa and occupy an area of around 2.7 million km2 . These forests provide a wide range of ecosystem services that are essential to the livelihoods of communities around them and play a crucial role in the carbon and hydrological cycles at regional and global scales. However, miombo woodlands are affected by deforestation and forest degradation, mainly due to agricultural expansion, charcoal production, timber and firewood harvesting, and livestock grazing. This thesis aims to assess the impacts of these land uses and tree cover on key soil properties, particularly soil organic carbon and soil hydrological properties such as infiltration capacity, which are important indicators of ecosystem health. The central hypothesis was that tree cover positively influences soil hydrological properties and soil organic carbon, while land uses that involve a decrease in tree cover or disturb the soil have a negative impact. I conducted the studies in two different sites in Tanzania; Kitulangalo forest reserve and the surrounding areas in Morogoro Rural district, and Ulaya mbuyuni village in Kilosa district. I measured infiltration capacity, preferential flow, tree basal area, livestock grazing intensity, and different soil properties, including soil organic carbon, bulk density, and texture. Results show that soil hydrological properties and soil organic carbon increased with increasing tree cover. Hence, croplands had relatively lower infiltration capacity and soil organic carbon than forest land. Both soil organic carbon and soil hydrological properties decreased with increasing livestock grazing intensity across land uses. Findings also indicate that the positive effect of trees on soil hydrological properties and soil organic carbon was significantly reduced when livestock grazing intensity was high. In addition, the combination of croplands and high livestock grazing intensity resulted in lower infiltration capacity and organic carbon than the combination of forest and high grazing intensity. When comparing small and large clearings for charcoal production, large clearings had lower values of infiltration capacity and soil organic carbon. I concluded that forest conversion to croplands reduces soil hydrological functioning and soil organic carbon. Trees could be an important tool to restore soils and their hydrological function in degraded landscapes, but the presence of high livestock grazing intensities reduces their effectiveness.

Keywords

Soil hydrological properties; land use; livestock grazing intensity; miombo woodlands; charcoal production; silvopastoralism, drylands

Published in

Acta Universitatis Agriculturae Sueciae
2022, number: 2022:69
ISBN: 978-91-8046-014-9, eISBN: 978-91-8046-015-6
Publisher: Swedish University of Agricultural Sciences

SLU Authors

• Lulandala, Lufunyo

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Forest Science
Soil Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/119376