Practice Must Be Backed up by Theory! A Special Issue on Plant Community Ecology

Plant communities form the structural and functional basis for nearly all terrestrial ecosystems [1]. Plant community ecology, then, relies on the study of the organization and functioning of plant communities: it includes the study of the interactions between species, the evolutionary pathways of adaptation to the environment where plants live, and the dynamics and structure of the community. This discipline is based on common definitions and analytical methodologies that date back decades. This Special Issue (hereafter SI) presents a series of articles debating the modern concept of plant communities, both from a theoretical and an applied point of view, basing the selected papers on the concept that if practice is not backed up by theory, erroneous results can be produced. The issue brings together a collection of eight valuable articles that can be used as references for innovative ideas and as a starting point for the future development of the discipline. By a complete overview of the SI, it clearly emerges that there is, at the present time, a growing awareness among plant ecologists of the need to place their science on a more exact basis. The impetus given by the pioneers of ecology, which led to rapid advances in the past, is dying down, and the emphasis is changing from extensive work on vegetation to intensive work on selected aspects. On the one hand the need for improved techniques are made all the more urgent by the rapid depletion of natural vegetation, the only source of data on many of the more fundamental aspects of plant community ecology, and on the other hand by the realization that advances in many research branches depend upon answers to ecological questions. The analysis of the published articles in this SI also highlights that plant ecologists are fully aware of the value of the quantitative approach and of the valuable tools available in the techniques of statistical analysis and remote sensing approach. Nonetheless, faced with the rapidly expanding literature on new cutting-edge quantitative methods in ecology, there is a need for an assessment of the practical potentialities of these proposed techniques. This SI attempts to make such an assessment, although only partially, and it is hoped that any plant ecologist facing a particular problem will find guidance here on the most profitable means of obtaining and handling data, as well as a broad survey of the approaches available in plant community ecology. The SI collected articles focus on the whole communities, rather than a single species. Even if heterogeneous in terms of approaches and issues, the papers share cross-cutting issues dealing with the importance of the community approach and the variation that we can observe by changing the scale of observation. The SI is articulated around three main topics, following the intrinsic nature of the articles presented: one related to more theoretical approaches applied to plant community analyses (methods), and the others dedicated to the practical side of applied plant community studies, i.e., conservation, and present (and future) global threats and challenges.