Data from: Functional diversity and composition of Caatinga woody flora are negatively impacted by chronic anthropogenic disturbance

Tropical plant assemblages can be taxonomically and phylogenetically
impoverished by chronic anthropogenic disturbance (CAD), such as firewood
collection and extensive grazing. However, to what extent the functional
dimension responds to CAD is still unclear. Such knowledge is urgently
required for predicting, preventing or even reversing the impacts of CAD.
Chronic anthropogenic disturbance may operate as an ecological filter by
selecting functional trait values (e.g. low wood density), thereby
altering the functional composition and diversity of plant assemblages. We
tested this hypothesis using 29 woody plant assemblages across three
ontogenetic stages (seedlings, saplings and adults) in a 220‐km2 landscape
of the Caatinga, northeast Brazil. We adopted a CAD index consisting of
four indicators (proximity to urban centre and houses and the density of
both people and livestock) and tested how well it explained the functional
diversity and effect sizes (richness, evenness and dispersion) and
composition (community‐weighted mean). Chronic anthropogenic disturbance
affected several functional metrics across the three ontogenetic stages.
However, CAD effects were stronger in adult communities by negatively
affecting functional richness, dispersion and their effect sizes. CAD also
altered the functional composition of leaf mass per area, woody density
and leaf area of adult assemblages. Sapling communities were affected in
terms of functional composition (leaf area, leaf dry matter and wood
density), with positive and negative effects, while seedling assemblages
responded positively to CAD only in terms of functional evenness and its
effect size. Some changes in functional metrics were influenced by
dominant Euphorbiaceae species across ontogenetic stages, especially in
terms of leaf area and woody density. Synthesis. Chronic anthropogenic
disturbance is an important driver of plant‐community functional
organization across ontogenetic stages in the Caatinga. Adult assemblages
are particularly sensitive and tend to lose functional niche space and
support more acquisitive rather than conservative strategies as chronic
anthropogenic disturbance increases. The proliferation of Euphorbiaceae
disturbance‐adapted species can explain part of the community responses to
chronic anthropogenic disturbance. Our findings highlight the ecological
effects of chronic anthropogenic disturbance and show that it is a key
influence on tropical biotas. Changes in plant functional traits
associated with plant resource use are likely to affect ecosystem
functioning and services provided by Caatinga.