This dataset hosts the main data and R codes of the analyses carried out to study the role of canopy cover dynamics over a decade of changes in the understory of an Atlantic Beech-Oak forest. We measured changes in understory taxonomical and functional composition, richness and diversity between 2006 and 2016, and relate those changes to changes in canopy coverage between both years.

The data show changes between 2006 and 2016 in the species abundance, richness and diversity of 102 understory communities, and in the functional composition, richness and diversity for five functional traits (Leaf dry matter content, Specific leaf area, Leaf size, Plant height and Seed mass). Changes in canopy coverage between 2006 and 2016 were studied as an explanatory variable.

The R codes show the main analyses carried out in the study: 1) The calculation of the functional composition, richness and diversity of the five traits studied (Leaf dry matter content, Specific leaf area, Leaf size, Plant height and Seed mass), 2) a Dunnett’s modified Tukey-Kramer test used to test for significant relationships between four plot categories defined according to the presence or absence of canopy gaps (no gaps, gap closure, gap opening and gap persistence) and changes in the taxonomical and functional composition and diversity of the understory from 2006 to 2016. 3) An Indicator Species Analysis used to study the species that were indicators of gap opening or closure in the Atlantic Beech-Oak forest studied. 4) The calculation of the Standardized Effect Size for the functional traits of the indicator species, used to see if the species selected as gap indicators shared similar values of functional traits and had values significantly different from non-indicator species.