Plant diversity and microbial interaction on soil carbon stock in the tropical homegardens: a nature-based solution to climate change

Understanding relationship between plant diversity, microbial activity and carbon sequestration is crucial for mitigating climate change and promoting sustainable land management, particularly in agroforestry systems such as homegardens. This study evaluated five Land Management Type (LMT) which consist of three homegarden classes: Small Homegardens (SHG) (less than 0.2 ha), Medium Homegardens (MHG) (0.2–0.4 ha), and Large Homegardens (LHG) (more than 0.4 ha), forest area (Fo) a natural land use, and a treeless open area (TrO) in the North central laterite Agro-Ecological Unit of Kerala, India for assessing their impact on soil carbon, nutrient cycling, tree diversity, and microbial activity. Plant diversity was found to be highest in the forest (22.85 ± 0.06) and was on par with small homegardens (SHG) (2.71 ± 0.0), which exceeded the diversity observed in medium (MHG) and large homegardens (LHG). Soil organic carbon (SOC) stock up to a depth of 1 m was highest in forest (202.21 Mg C ha⁻¹), which was on par with SHG (157.62 Mg C ha⁻¹), and significantly different from MHG (135.79 Mg C ha⁻¹), followed by LHG (119.60 Mg C ha⁻¹) and TrO (24.29 Mg C ha⁻¹). Microbial activity also followed the same trend for the bacterial and fungal population. A Hierarchical cluster analysis based on euclidean distance grouped the five LMT into four clusters, among that the MHG and LHG falls into single cluster due to its similarities. From the PCA and the inter cluster distances, the SHG exhibited characteristics that closely resemble natural forests, as compared to other three LMT.