Soil carbon, nutrient, and vegetation dynamics of an old Anogeissus grove in Mole National Park, Ghana

Abstract

Formation of forest islands in West Africa has been linked to anthropogenic soil improvement resulting in luxuriant tree growth in otherwise open savanna landscapes. However, there is limited understanding of how such unique ecosystems modulate soil carbon (C) dynamics and nutrient cycling. In this study, we report soil nutrient characteristics and two distinct soil organic carbon pools of Anogeissus grove (forest island) associated with abandoned village sites of the Mole National Park in the Guinea savanna or tropical continental climatic zone of Ghana, taking opportunity of a previously published study in Biotropica in 1978. We compared present‐day differences in soil characteristics between the previously studied forest grove and adjoining open savanna in the Park and evaluated vegetation dynamics since first measurement in 1974. Overall, we see changes related to self‐thinning and expansion of the grove on a decadal timescale. Soil organic matter and available phosphorus contents were greater in the grove and increased by 19.6% and 18.7%, respectively over time, showing persistence after four decades. Mineral‐associated organic carbon (MAOC) differed significantly (p < .05) between the vegetation types, being 3.44% in the grove and 2.34% in the savanna. The grove was ca. 25% greater in particulate organic carbon (POC) content than the savanna. In both vegetation types, >55% of carbon was stabilized in the mineral fraction. Our study demonstrates long‐term human impacts on soil and vegetation and offers a clear nature‐based solution for climate change mitigation through sustainable land management by indigenous people toward achievement of the “4p1000” initiative.

Exploring the West African forest island phenomenon: scientific insights gained, successes achieved and capacities strengthened

“…By virtue of its persistence in soil [38], global efforts are directed towards increasing carbon sequestration through the MAOC pool. Overall, our study clearly indicates that sustainable land management through indigenous effort in West Africa aligns with the recent global initiative of 're-carbonizing global soils' [39], serving unarguably as a right step towards achievement of the '4p1000' initiative towards ecosystem services and sustainability [32,40].…”

“…[36,37]). Thus, 'our results suggest that the greater portion of soil carbon sequestered in the anthropogenic grove is persistent' [32]. By virtue of its persistence in soil [38], global efforts are directed towards increasing carbon sequestration through the MAOC pool.…”

“…Data accessibility. Table 1 was sourced from publication of the authors' paper in Plant and Soil and Figures 3-5 were also from the authors own publications (see [5,11,32]).…”

“…We revisited the site 42 years after the previous survey was carried out and 58 years after the original human activities stopped to understand persistence of soil traits after abandonment and to quantify the soil carbon sequestration potential of the abandoned grove. We hypothesized that 'human-induced soil improvement can persist in savanna landscape over decadal timescale and modulate soil carbon sequestration in the long term' (see Logah et al [32]). Here, we present key results on the mineral-associated organic carbon (MAOC) and particulate organic carbon (POC) pools in comparison with adjacent natural savanna vegetation.…”

One-time conventional tillage, crop diversification and mulching enhanced hydro-physical properties of a tropical sandy loam soil

“…In this era of climate change, climate-smart agriculture is becoming increasingly important globally with keen concerns for low crop yields in the tropics confronted with erratic rainfall patterns (Logah et al, 2024). Thus, soil management measures aimed at enhancing soil moisture retention and other hydro-physical properties are needed.…”