A Dual Role of Common Mammals as Dispersers of Plants and Micro-Invertebrates Across Isolated Wetlands

Aim

Dispersal strategies are vital for sessile or passively moving organisms, profoundly influencing the distribution and survival of plant and small-sized animal species. The role of large mammals in dispersal and habitat (re)colonisation is well recognised, yet their full contribution across propagule taxa, various dispersers and dispersal modes remains unclear. We assessed the role of common wild mammals in dispersing (semi-aquatic) plants and micro-invertebrates among isolated wetlands, identifying the most effective dispersal agent(s) within a natural assemblage.

Location

Northeast Germany.

Methods

In a system of small semi-natural wetlands within an intensive agricultural landscape, we combined non-invasive faecal sampling with opportunistic fur collection from managed and trapped mammals, cultivating plants and micro-invertebrates from these samples to explore dispersal-network structures, quantify taxon richness and propagule abundances, and comparedisperser effectiveness.

Results

We found distinct network topologies for (semi-aquatic) plants and micro-invertebrates, indicating differential contributions and complementary roles of disperser groups and dispersal modes. Roe deer (Capreolus capreolus), wild boar (Sus scrofa) and raccoons (Procyon lotor) were key dispersers, highlighting the broad role of generalist mammals in wetland propagule dispersal. In micro-invertebrates, endozoochorous communities were nested within more diverse epizoochorous communities, with both raccoons and wild boar transporting more diverse taxa through epizoochory. No quantitative differences in endozoochorous dispersal emerged among dispersers. Transported plant communities were dominated by taxa lacking predefined zoochorous syndromes, challenging assumptions about trait-based dispersal constraints.

Main Conclusions

The broad spectrum of wild mammals identified as dispersers, supported by quantitative means, offers significant potential for facilitating efficient dispersal of both plants and micro-invertebrates, consistent with the concept of ‘non-classical zoochory’. Dispersal by abundant and managed mammals is crucial for ecosystem connectivity and resilience. Altered disperser communities due to population control or habitat changes may affect (re)colonisation and local biodiversity, highlighting the need for strategies that preserve dispersal functions across landscapes.