Differential effects of soil waterlogging on herbaceous and woody plant communities in a Neotropical savanna

Author(s)

Xavier, Rafael de Oliveira ^{[1, 2]} ; Leite, Marcelo Boccia ^[3] ; Dexter, Kyle ^{[1, 4]} ; da Silva Matos, Dalva Maria ^[3]

Affiliation

^[1] Univ Edinburgh, Sch GeoSci, Edinburgh EH9 3JN, Midlothian - Scotland

^[2] Univ Sao Paulo, Dept Ecol, Biosci Inst, Rua Matao 123, BR-05508090 Sao Paulo, SP - Brazil

^[3] Univ Fed Sao Carlos, Ecol & Conservat Lab, Dept Hydrobiol, Washington Luis Highway, Km 235, BR-13565905 Sao Carlos, SP - Brazil

^[4] Royal Bot Garden Edinburgh, 20A Inverleith Row, Edinburgh EH3 5LR, Midlothian - Scotland

• Document type: Journal article
• Source: Oecologia; v. 190, n. 2, p. 471-483, JUN 2019.
• Web of Science Citations: 0

Abstract

The impacts of soil properties and fire regime on Neotropical savannas are well-known, but the importance of hydrological regime for plant species assembly has received less attention. Here, we assessed changes in diversity patterns of herbaceous and woody communities along a water table gradient in a fire-excluded Neotropical savanna. We found that increased waterlogging of soils was associated with declines in both herbaceous and woody species richness. Woody species richness decreased once the water table depth is less than 4m and no woody species occurred once water table depth was less than 23cm. Herbaceous communities remained species rich until the shallowest water table depth, where there is flooding at some point in the year, and even there, over a dozen species occurred. Woody species that occurred in areas with shallower water tables were a nested subset of those in areas with deeper water tables. In contrast, herbaceous communities showed turnover over the hydrological gradient, with distinct species specialized for different water table levels. However, we found that those specialists are restricted to few evolutionary lineages, evidenced by increased phylogenetic clustering over the water table gradient in herbaceous communities. We suggest that evolutionarily conserved hydrological niches define the herbaceous layer over the hydrological gradient, whereas only generalist woody species persist under high water tables. Our findings show that the effect of soil waterlogging differs between the herbaceous and woody layer of savannas, indicating that these communities will respond differently to shifts in the hydrological regime under future environmental change. (AU)

• FAPESP's process: 11/21019-6 - Determinant factors to the dominance of African grasses in two tropical seasonally dry ecosystems
• Grantee: Rafael de Oliveira Xavier
• Support Opportunities: Scholarships in Brazil - Doctorate