Comparative Analysis of Soil Biological Activity and Macroinvertebrate Diversity in Amazonian Chakra Agroforestry and Tropical Rainforests in Ecuador

Soil biological activity and macroinvertebrate diversity are key indicators of ecosystem function in tropical landscapes. This study evaluates the effects of different land-use systems—Amazonian Chakra agroforestry (timber-based and fruit-based), cocoa monoculture, and tropical rainforest—on soil microbial respiration, enzymatic activity, and macroinvertebrate diversity in the Ecuadorian Amazon. Forest soils exhibited the highest edaphic respiration (240 ± 64.3 mg CO2 m2 ha−1, p = 0.034), while agroforestry systems maintained intermediate biological activity, surpassing monocultures in microbial diversity and enzymatic function. The soil organic matter (SOM) content at a 10 cm depth was significantly higher in monocultures (19.8 ± 3.88%) than in agroforestry and forest soils (p = 0.006); however, the enzymatic activity showed greater functional responses in agroforestry and forest systems. The relationship between recorded CO2 respiration (REC_CO2) and basal respiration (RBC_CO2) exhibited a non-linear trend, as revealed by LOWESS smoothing, suggesting that microbial respiration dynamics are influenced by substrate availability and enzymatic thresholds beyond simple linear predictions. These findings underscore the potential of agroforestry as a sustainable land-use strategy that enhances soil biodiversity, carbon sequestration and nutrient cycling. Implementing optimized agroforestry practices can contribute to long-term soil conservation and ecosystem resilience in tropical agroecosystems.