Reabilitação da biodiversidade e funções ecológicas dos solos em agroecossistemas alto-andinos do Equador sobre Cangahua

Abstract

The sustainable management of high-Andean agroecosystems relies heavily on the dynamics of soil organic carbon (SOC), microbial activity, and the maintenance of ecosystem services, particularly in soils with cangahua, a hardened volcanic material highly prone to degradation. This study synthesized the effects of diverse soil management practices—agroecological, traditional, fallow, and degraded ecosystem as control—on organic matter decomposition, carbon content, soil respiration, microbial diversity, and biogeochemical functionality across two Ecuadorian highland sites, Cacha (Chimborazo) and La Merced (Pichincha), which differ in their historical rehabilitation periods (5 versus 15 years, respectively). The methodology integrated tea bag indices (green and rooibos) to evaluate decomposition rates of labile and recalcitrant organic materials, loss-on-ignition for SOC quantification, Solvita® assays for soil respiration, and microbial community assessments through taxonomic and functional diversity metrics. Statistical analyses employed a fully factorial design with 24 experimental units, enabling detection of management, site, and interaction effects. Results consistently demonstrated that agroecological management enhanced green and rooibos tea decomposition, SOC accumulation, and soil respiration relative to traditional, fallow, and degraded systems, with La Merced exhibiting generally higher rates than Cacha, reflecting both climatic and historical management influences. Traditional and fallow practices provided intermediate benefits, insufficient to counteract long-term degradation, whereas degraded ecosystems exhibited severely reduced microbial activity, low SOC content, and diminished biogeochemical functionality, confirming functional collapse under cangahua exposure. Microbial analyses revealed that agroecological soils harbored greater taxonomic richness and functional redundancy, supporting higher nutrient cycling efficiency and resilience to perturbations. Moreover, the study found strong positive correlations between SOC content, microbial biomass, and respiration rates, indicating that sustained organic inputs, permanent ground cover, and crop diversification directly enhance soil functional capacity and carbon stabilization. Integrating these findings, the research demonstrates that systematic agroecological interventions not only rehabilitate degraded soils but also contribute to carbon sequestration and climate change mitigation in fragile mountainous landscapes. Importantly, the comparative analysis across sites and historical contexts highlights the temporal dimension of soil restoration, emphasizing that long-term implementation is critical to realizing full ecosystem benefits. In conclusion, this integrative assessment provides robust scientific evidence supporting agroecological transitions as a key strategy to restore high-Andean cangahua soils, improve soil fertility and structure, enhance microbial diversity and activity, maintain ecosystem services, and strengthen the capacity of rural communities to sustain agricultural production while contributing to global climate mitigation goals. The findings inform policy formulation, extension services, and participatory management approaches, underscoring the value of combining ecological principles with traditional practices to achieve both environmental restoration and socio-economic resilience in highly vulnerable highland territories.