Underdispersion of anti-herbivore defence traits and phylogenetic structure of cerrado tree species at fine spatial scale

Question Do species phylogeny and herbivory-related defence traits influence species co-occurrence in the cerrado? Are anti-herbivory defence traits under- or overdispersed in the quadrats? Do soil features mediate these patterns? Location A cerrado site in SE Brazil (21 degrees 58'05.3?S, 47 degrees 52'10.1?W). Methods We analysed 100 quadrats of 5mx5m each, and sampled all woody individuals. For each species, we measured nine defence traits against herbivory and tested against null models whether (1) phylogenetic dissimilarities were under- or overdispersed, (2) trait species dissimilarities were under- or overdispersed, and (3) these spatial patterns were associated with soil nutrient content, considering the variation of sum of bases, organic matter, and aluminium. Results We found phylogenetic signals in two traits, and conservatism of traits as a whole was significant. Phylogenetic structure of communities was in general clustered. We found trait underdispersion for specific leaf area, water content, leaf toughness, and leaf nutritional quality. Specific leaf area was also overdispersed in quadrats. We did not find either under- or overdispersion related to soil features. Conclusions As phylogenetic and trait underdispersion were not associated with soil features, and fire and drought are not expected to change at study scale, some biotic interaction may be responsible for underdispersion. We postulated that insect herbivory, when representing a large constraint to trees in this environment, could lead to functional and phylogenetic underdispersion.