Data from: Seedling resistance, tolerance and escape from herbivores: insights from co-dominant canopy tree species in a resource-poor African rain forest

Although plants can reduce the impacts of herbivory in multiple ways,
these defensive traits are often studied in isolation and an understanding
of the resulting strategies is incomplete. In the study reported here,
empirical evidence was simultaneously evaluated for the three main sets of
traits available to plants: (1) resistance through constitutive leaf
traits, (2) tolerance to defoliation, and (3) escape in space, for three
caesalpiniaceous tree species Microberlinia bisulcata, Tetraberlinia
bifoliolata and T. korupensis, which co-dominate groves within the lowland
primary rain forest of Korup National Park (Cameroon). Mesh cages were
placed around individual wild seedlings to exclude insect herbivores at 41
paired canopy-gap and understorey locations. After following growth and
survival for c. 2 yr, caged and control treatments were removed, leaves
harvested to determine nutrient and phenolic concentrations, leaf mass per
area estimated, and seedling performance in gaps followed for a further c.
2 yr to quantify tolerance to the leaf harvesting. The more nutrient-rich
leaves of the weakly shade-tolerant M. bisulcata were damaged much more in
gaps than the two strongly shade-tolerant Tetraberlinia species, which had
higher leaf mass per area and concentrations of total phenols. Conversely,
the faster-growing M. bisulcata was better able to tolerate defoliation in
terms of height growth (re-flushing capacity), but not at maintaining
overall leaf numbers, than the other two species. Across gaps,
insect-mediated Janzen-Connell effects were most pronounced for M.
bisulcata, less so for T. korupensis, and not detectable for T.
bifoliolata. The three species differed distinctly in their secondary
metabolic profiles. Taken together, the results suggested a conceptual
framework linking the three sets of traits, one in which the three
co-dominant species adopt different strategies towards herbivore pressure
depending on their different responses to light availability. This study
is one of the first in a natural forest ecosystem to examine resistance
to, tolerance of, and escape from herbivory among a group of co-occurring
tropical tree species.