Data from: Tree recruitment failure in old-growth forest patches across human-modified rainforests

1. Land-use change threatens biodiversity in tropical landscapes, but its
impact on forest regeneration remains poorly known. In fact, the
landscape-scale patterns driving the diversity of regenerating plants
within forest fragments have been rarely explored, and we are uncertain
whether such drivers vary across regions with different land-use change
patterns.  2. We assessed the effect of landscape composition
(forest cover and matrix openness) and configuration (forest patch
density) on species diversity of sapling assemblages (trees ≥30 cm height
and <1 cm diameter) in old-growth forest fragments from three
Mexican rainforest regions with different disturbance levels (n = 20
landscapes per region). We separately assessed old-growth forest
specialists (OGS) and forest generalist (FG) species to test the
hypothesis that: (i) OGS species shows recruitment limitation (‘loser
species’), and can therefore be negatively impacted by landscape changes,
especially by forest loss and matrix openness in more deforested regions;
and (ii) FG species can regenerate and even proliferate in more disturbed
landscapes (‘winner’ species).  3. We recorded ~24,000 plants
from 415 species. Landscape composition showed stronger effects than
landscape configuration. The diversity of OGS species generally decreased
in more deforested landscapes dominated by open matrices, and FG species
followed the opposite response, especially in regions with
high-to-intermediate degree of disturbance. Overall, forest fragmentation
(patch density) showed weak or no effects on species diversity, especially
after controlling for forest cover effects (i.e., fragmentation per se).
In contrast to the fragmentation threshold hypothesis, the effect of
fragmentation was independent of the regional context. Moreover, OGS
species were affected by landscape attributes operating at larger scales
than FG species.  4. Synthesis. Our findings support our
hypotheses, and indicate that forest loss and matrix openness, not
fragmentation per se, can cause the recruitment failure of tree
assemblages in highly deforested rainforests. This can be related to
source and dispersal limitation in more deforested landscapes with
treeless matrices. Therefore, to promote the regenerative potential
(resilience) of forest patches in human-modified tropical landscapes,
conservation programs should focus on preventing forest loss (even the
smallest forest patches) and improving matrix quality with treed elements,
particularly in highly deforested tropical regions.