Effects of environmental conditions and space on species turnover for three plant functional groups in Brazilian savannas

Abstract

Aims Different plant functional groups display diverging responses to the same environmental gradients. Here, we assess the effects of environmental and spatial predictors on species turnover of three functional groups of Brazilian savannas (Cerrado) plants—trees, palms and lianas—across the transition zone between the Cerrado and Amazon biomes in central Brazil. Methods We used edaphic, climatic and plant composition data from nine one-hectare plots to assess the effects of the environment and space on species turnover using a Redundancy Analysis and Generalized Dissimilarity Modeling (GDM), associated with variance partitioning. Important Findings We recorded 167 tree species, 5 palms and 4 liana species. Environmental variation was most important in explaining species turnover, relative to geographic distance, but the best predictors differed between functional groups: geographic distance and silt for lianas; silt for palms; geographic distance, temperature and elevation for trees. Geographic distances alone exerted little influence over species turnover for the three functional groups. The pure environmental variation explained most of the liana and palm turnover, while tree turnover was largely explained by the shared spatial and environmental contribution. The effects of geographic distance upon species turnover leveled off at about 300 km for trees, and 200 km for lianas, whereas they were unimportant for palm species turnover. Our results indicate that environmental factors that determine floristic composition and species turnover differ substantially between plant functional groups in savannas. Therefore, we recommend that studies that aim to investigate the role of environmental conditions in determining plant species turnover should examine plant functional groups separately.

Environmental filtering and spatial processes shape the beta diversity of liana communities in a valley savanna in southwest China

“…In addition to the effect of habitat filtering, our study showed that spatial processes were also important in liana community assembly in this dry-hot savanna (Figure 3; Appendix S8), as is also true in other liana communities (Macía et al, 2007;López-Martínez et al, 2013;Murphy et al, 2016;Menegat et al, 2019). Moreover, we found that spatial processes explained a higher proportion of varia- The shared fraction explained by spatially structured environmental variables was 15.9%, 14.6% and 13.7% in taxonomic, functional and phylogenetic beta diversity, respectively, which is higher than that only explained by environment or space, consistent with another study (Chain-Guadarrama et al, 2012).…”

“…and environmental variables when selecting protected areas to conserve liana diversity in terms of the three beta diversity dimensions. Menegat et al (2019) compared the relative importance of environment and space on the taxonomic beta diversity of three plant functional groups in Brazilian savanna, concluding that environments play a different role in determining the taxonomic beta diversity of different plant groups. In the light of their study, we suggest testing whether the role of environment differs in determining functional and phylogenetic beta diversity between lianas and other plant groups in savanna ecosystems.…”

“…In those few studies on liana beta diversity (López-Martínez et al, 2013;Menegat et al, 2019), the focus has been on taxonomic beta diversity, as in many studies on forest tree diversity (Legendre et al, 2009;Baldeck et al, 2013;Myers et al, 2013). Taxonomyfocused beta diversity may sometimes be insufficient because all species are treated as evolutionarily independent and ecologically equivalent and species-environment relationships could be misrepresented (Swenson, 2011;Swenson et al, 2011).…”

“…The only study comparing tree, palm and liana community assembly is from a savanna in Brazil (Menegat et al, 2019). It reports that both environmental and spatial distances play important roles in structuring liana beta diversity, but the number of liana species included in maintenance in savanna, which is necessary to inform conservation management in this vulnerable ecosystem.…”

“…In those few studies on liana beta diversity (López‐Martínez et al , 2013; Menegat et al. , 2019), the focus has been on taxonomic beta diversity, as in many studies on forest tree diversity (Legendre et al. , 2009; Baldeck et al.…”