Land-use Changes Impact Root-Fungal Network Connectivity in a Global Biodiversity Hotspot

Cross-kingdom associations play a fundamental role in ecological processes. Yet our understanding of plant-fungal co-occurrences in tropical rainforests and the potential impacts of land-use change shaping species connections remains limited. By using amplicon sequencing on DNA from roots and their associated fungal communities, we aim to understand the impact of rainforest transformation on the composition and structure of root-fungal ecological networks in human-modified landscapes in Sumatra, Indonesia. Each land-use type supports a distinctive set of indicator species, which are organisms that reflect specific environmental conditions and can signal changes in ecosystem health. We observed a decline in the richness of plant species indicators and plant-fungal associations with increasing land-use intensification. Additionally, there is a turnover in root communities, shifting from native and endemic species in rainforests to non-native, generalist herbaceous species in rubber and oil palm plantations. Plant-fungal connectivity significantly declined with increasing land-use intensification, suggesting that managed ecosystems may have weakened root-fungal interactions. Network analysis highlights the distinct responses of various fungal groups. For instance, arbuscular mycorrhizal fungi (AMF) showed fewer connections with modules linked to oil palm and rubber roots, indicating weakened root-fungal associations in monocultures. This aligns with the observed reduction in AMF diversity in converted land-use areas compared to forests, further reinforcing the negative impact of land-use practices in oil palm and rubber monocultures on AMF diversity. Synthesis. Dimensioning the impacts of rainforest transformations belowground is constrained by our understanding of fungal functional guilds. Highly modified systems exhibited fewer connections, suggesting a dynamic restructuring of root-fungal relationships in response to land-use changes. Understanding the intricate interplay between plants and fungi in the face of land-use change can provide valuable information for conservation efforts, agricultural practices, and ecosystem management strategies aimed at promoting biodiversity, soil health, and ecosystem resilience in the context of changing environmental conditions. Moreover, it underscores the importance of communities' networks in land-use planning and management decisions to support plant and fungal diversity in terrestrial ecosystems. ### Competing Interest Statement The authors have declared no competing interest.