Dry-hot valleys represent underutilized marginal lands for industrial crop afforestation, where non-structural carbohydrates (NSCs) are critical for sustaining plant productivity and resilience to extreme aridity and nutrient limitation. However, how afforestation alters NSC dynamics to support industrial crop performance following savanna conversion remains poorly understood. We investigated this in China’s Yuanmou dry-hot valley using 70 sampling plots, evaluating the effect of six high-value industrial plantation species ( Leucaena leucocephala , Eucalyptus camaldulensis , Azadirachta indica, Dodonaea viscosa , Jatropha curcas , Dalbergia sissoo ) alongside native savanna reference vegetation (Albizia kalkora ) on NSC allocation in leaves and roots based on interactive effects of soil properties, microbial diversity, and leaf functional traits. Afforestation significantly enhanced leaf NSCs in all industrial species compared to Albizia kalkora , with Dodonaea viscosa exhibiting the highest levels. In contrast, effects on root NSC content varied considerably among species. Soil microbial diversity strongly influenced NSC allocation: leaf NSCs showed unimodal relationships with bacterial α-diversity (Chao1 index) and fungal β-diversity, and a U-shaped response to bacterial β-diversity. Acquisitive leaf traits correlated with these microbial-mediated leaf NSC patterns, while conservative traits drove root NSC variation. Soil fertility modulated microbial effects, enhancing benefits of bacterial β-diversity but reversing fungal diversity impacts. Structural equation modeling identified bacterial α-diversity and fungal β-diversity as primary drivers of leaf and root NSC variation, respectively, with bacterial β-diversity exerting a strong positive direct effect on leaf NSCs. Specific microbial phyla (e.g., Firmicutes, Chytridiomycota) and functional groups (e.g., nitrifying bacteria, plant saprotrophs) were key contributors to leaf NSC regulation, whereas sulfate-respiring bacteria and animal pathogens influenced root NSCs. Keystone bacterial taxa, but not fungal, differentially regulated leaf NSC content. Our findings reveal microbial-mediated mechanisms of NSC allocation and suggest that managing specific soil microbial communities can optimize carbon strategies in dryland afforestation.
Ma et al. (Tue,) studied this question.