Plant–plant interactions: from competition to facilitation

[Extract] The way plant species influence the composition of their surrounding plant community has been a subject of interest since Alexander von Humboldt developed the foundations of biogeography in the 19th century. In the same century, Adolphe Dureau de la Malle introduced a preliminary idea of succession (1825), formally developed by the end of the century by Henry Chandler Cowles (1899) and founded on the importance of environmental constraints and plant–plant competitive interactions. The view of plant–plant interactions as primarily competitive was nearly exclusive until the end of the 20th century, when Bertness and Callaway formally established the concept of facilitation, as opposed to competition, to stress the importance of mutualism among plant species in shaping plant communities (Bertness andCallaway, 1994; Callaway, 1995). Those foundational papers started an important movement devoted to the study of positive interactions among plants, and Web Ecology, first published in the year 2000, has played a significant role in propagating those ideas in its pages since then; this includes abroad range of studies and authors, including several works by R. M. Callaway and many of his collaborators