The distinct roles of water table depth and soil properties in controlling alternative woodland-grassland states in the Cerrado

Author(s)

Ribeiro, Jonathan W. F. ^{[1, 2]} ; Pilon, Natashi A. L. ^[3] ; Rossatto, Davi R. ^{[1, 4]} ; Durigan, Giselda ^[5] ; Kolb, Rosana M. ^{[1, 2]}

Affiliation

^[1] Univ Estadual Paulista UNESP, Inst Biociencias, BR-13506900 Rio Claro, SP - Brazil

^[2] UNESP, Fac Ciencias & Letras, BR-19806900 Assis, SP - Brazil

^[3] Univ Estadual Campinas, Inst Biol, Caixa Postal 6109, BR-13083865 Campinas, SP - Brazil

^[4] UNESP, Fac Ciencias Agr & Vet, BR-14884900 Jaboticabal, SP - Brazil

^[5] Inst Florestal, Floresta Estadual Assis, Caixa Postal 104, BR-19802970 Assis, SP - Brazil

• Document type: Journal article
• Source: Oecologia; v. 195, n. 3, p. 641-653, MAR 2021.
• Web of Science Citations: 0

Abstract

Open grassy vegetation and forests share riparian zones across the Neotropical savannas, characterizing alternative stable states. However, factors determining the occurrence and maintenance of each vegetation type are yet to be elucidated. To disentangle the role of environmental factors (soil properties and groundwater depth) constraining tree colonization of wet grasslands in the Cerrado, we assessed tree establishment during the early seedling and sapling stages and the influence of these factors on leaf gas exchange and leaf water potential of tree saplings. Three functionally distinct tree species were studied: (1) flood-tolerant species characteristic of gallery forests, (2) flood-intolerant species characteristic of seasonally dry savannas, and (3) generalist species found in both gallery forests and seasonally dry savannas. Savanna species was constrained by waterlogging, especially at the sapling stage, with restricted stomatal conductance and leaf water potential, resulting in low carbon assimilation, decreased plant size, and high mortality (above 80%). The gallery forest and the generalist species, however, were able to colonize the wet grasslands and survive, despite the low seedling emergence (below 30%) and sapling growth constrained by low gas exchange rates. Soil waterlogging is, therefore, an effective environmental filter that prevents savanna trees from expanding over wet grasslands. However, colonization by trees adapted to a shallow water table cannot be constrained by this or other soil properties, turning the wet grasslands dependent on natural disturbances to persist as an alternative state, sharing the waterlogged environments with the gallery forests in the Cerrado region. (AU)

• FAPESP's process: 15/24093-3 - Morphophysiology responses of tree species to edaphic conditions of wet grassland in Cerrado areas
• Grantee: Rosana Marta Kolb
• Support Opportunities: Regular Research Grants