Edaphic factors controlling soil organic matter and C storage in miombo
woodlands, Zambia
Abstract
Soil organic matter (SOM) is a key component of forest productivity and
soil organic carbon stock. However, little is known about SOM and C
variability in miombo woodlands which is a significant ecosystem in
sub-Sahara African forests and vital for REDD+ strategies. In this
study, nine edaphic factors were measured and used to analyse the
variability of SOM in miombo woodland sites with different tree
structures in Luanshya, Zambia. The findings showed a large variability
of SOM stocks at different soil depths: 36.67 to 113.89 Mg ha-1 at 0–10
cm depth, 28.67 to 79.56 Mg ha-1 at 10–20 cm depth, and 31.89 to 98.56
Mg ha-1 at 20–30 cm depth. These SOM values at different depths also
varied between miombo woodland sites of different successional stages,
notably that areas affected by recent tree clearance had higher than
average SOM content per layer (0–10 cm: +5.57%; 10–20 cm: +4.20%;
20–30 cm: +4.30%). Canonical correspondence analysis (CCA) revealed
that the most significant environmental factors influencing SOM were
woodland thinning by clearance, and silt content within soils. This
study highlights that CCA can be used to show the relative importance of
different forest successional stages as a function of management
practices, as well as edaphic factors, in determining miombo soil SOM
content. The results of this study are particularly relevant for
addressing current REDD+ reforestation and management strategies that
are aimed at increasing carbon stocks in the tropical forests of
sub-Saharan Africa.