Niche differentiation, competition or habitat filtering? Mechanisms explaining co-occurrence of plant species on wet meadows of high conservation value

Questions Due to the diverse abiotic conditions and the extensive, early-autumn, manual mowing practiced once per few years, Molinia semi-natural wet meadows are known for their high plant species diversity. However, recent socio-economic transformations and land-use changes (i.e. cessation of use) have been contributing to significant biodiversity loss in Molinia meadows. Thus, understanding the mechanisms of species co-occurrence patterns operating on well-developed Molinia meadows may be a precondition for the restoration or regeneration success of this type of vegetation. We aimed to identify community-level co-existence patterns of the whole set of plant species typical of Molinia meadows, and to assess the role of co-occurring vegetation in shaping the performance of individual species. Location Natura 2000 Special Area of Conservation Laki Dabrowskie (S Poland). Methods Using generalised multiple regression techniques on a set of vegetation traits and components of functional diversity, we assessed the role of different ecological mechanisms in shaping co-occurrence patterns of the entire group of species typical of Molinia meadows, as well as individual species belonging to this group. Results When the entire group of Molinia meadow species was taken into account, niche differentiation emerged as the main mechanism influencing the co-occurrence of plant species. When considering individual species, we revealed that their co-existence patterns were mostly species-specific, pointing out the predominant role of either niche differentiation, competition, habitat filtering, or a combination of these three drivers in shaping assembly processes. Conclusions Our results showed that the variability of niches realised by target species typical of Molinia meadows was high. Therefore, conservation of well-developed Molinia meadows should focus on both the community, and on a single species level, aiming to maintain a complex of specific microhabitat conditions. Considering small-size patches of these meadows scattered in a transformed, agricultural landscape, conservation of individual target species should be of the highest priority.

Automated summary

This study aimed to investigate the co-occurrence patterns of plant species in Molinia meadows. The results indicate that niche differentiation is the primary mechanism influencing plant co-occurrence, and individual species show species-specific coexistence patterns driven by niche differentiation, competition, habitat filtering, or a combination of these factors.