The constant part of vegetation - Is that an assembly rule?

From the point of view redundancy in vegetation structure, the composition and diversity of plant functional groups can be the major filtering rule for community assembly. Studies of biogeography have shown that in relatively similar ecological conditions around the globe one can meet the repeating pattern of plant traits, without any constraint for overlap in taxonomical levels. Probably it is quite easy to accept the conclusion that there exists a common structural base rule for those communities: i.e. the constant part of the structure along the geographical gradient. The next step would be considering plant communities on a wide gradient of environmental conditions, and questioning that can one still detect any constant base of those communities? For instance, can we detect something common in the conditions of habitat disturbance and fragmentation? We assumed that analysing pooled data of very contrasting communities or landscapes should reveal a base structure for their assembly. Using a field layer data we intended to detect common patterns. Field layer has been sampled along the wide gradient range of light availability and disturbance intensity in European agricultural landscapes. In the analysis, we excluded the most evident pattern of functional groups correlated to environmental conditions to reveal the more fundamental structural trends in herb layer communities. This was done by analyzing composition of functional groups beyond the first two axes of ordination. The results show that beyond disturbance related traits the communities are structured by life-span, plant strategies and species performance in the landscape. The applicability of revealed structural rules in ecosystem evaluation and biodiversity indication will be discussed. Most of all, we would like to suggest to look beyond the most revealing patterns in community structure, which can hide the more essential rules for assembly of plant species, particularly in conditions of species loss due to anthropogenic disturbances