17 research outputs found
Context-dependent assembly rules and the role of dominating grasses in semi-natural abandoned sub-Mediterranean grasslands
We investigated fine-scale patterns of trait-based community assembly in calcareous grasslands of the
Central Apennines, Italy. We used the habitat template of environmentally contrasting north-facing and
south-facing slopes of a mountain valley to understand mechanisms that contribute to species coexistence
(i.e. the persistence of diversity) after cessation of previous land use practices. Firstly, we tested late
successional dominating grasses (Sesleria nitida, Brachypodium rupestre and Bromopsis erectus) for their
ability to serve as biotic filtering effects on the diversity of subordinate species in plant communities.
Secondly, we analyzed fine-scale trait-based (i.e. species-level traits related to competition, regeneration,
establishment, dispersal, and flowering) community assembly of subordinate species in absence of dominant
grass. We found that assembly rules for traits related to the same life-history process were mostly
consistent within habitats. Further we established that within habitats the traits related to different lifehistory
processes can show different assembly rules. For example, while generative regeneration traits
(seed mass) may show convergence pattern, divergence was inferred for the vegetative (clonal) regeneration
traits. Depending on traits, the assembly rules can be similar or contrasting in different habitats. We
conclude that our finding of non-random assembly in the majority of investigated traits emphasizes the
importance of hierarchical exclusion of strong biotic filters when searching for trait-based assembly rules
in abandoned grasslands. Thus, for nature conservation purposes, disturbance appears to be the process
that is most important in driving the survival of subordinate species by the exclusion of biotic filters.
Subsequently, a multitude of trait-based mechanisms allow for coexistence of the subordinate species.
These mechanisms depend on habitats and traits and thus may vary from community to community,
indicating that heterogeneous landscapes might support multiple processes of coexistence