Above- and below-ground biomass and carbon dynamics in Brazilian Cerrado wet grasslands

Author(s)

Fidelis, Alessandra ^[1] ; di Santi Lyra, Maria Fernanda ^[2] ; Pivello, Vania Regina ^[2]

Affiliation

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

^[2] Univ Sao Paulo, Dept Ecol, BR-05508900 Sao Paulo - Brazil

• Document type: Journal article
• Source: JOURNAL OF VEGETATION SCIENCE; v. 24, n. 2, p. 356-364, MAR 2013.
• Web of Science Citations: 16

Abstract

Questions Grasslands are usually neglected as potential carbon stocks, partially due to the lack of studies on biomass and carbon dynamics in tropical grasslands. What is the importance of Brazilian tropical wet grasslands as carbon sinks? Does fire frequency and season affect biomass and carbon allocation in Brazilian wet grasslands? Location Wet grasslands, tropical savanna, Jalapao, Tocantins, northern Brazil. Methods We determined biomass above- and below-ground, estimated carbon stocks in biennially burned plots (B2) and plots excluded from fire for 4 yr (B4). Moreover, we determined biomass in both rainy and dry seasons. Samples were 0.25 m x 0.25 m x 0.2 m (eight samples per treatment, applying a nested design, total of 48 samples). The biomass was classified in above-ground graminoids, forbs and dead matter, and below-ground roots and other below-ground organs. We used ANOVA to compare variables between treatments and seasons. Results More than 40% of the total biomass and carbon stocks were located below-ground, mostly in roots. A high proportion of dead biomass (B4) was found in the above-ground material, probably due to low decomposition rates and consequent accumulation over the years. Although these grasslands do not experience water stress, we found significant evidence of resource re-allocation from below-ground organs to the above-ground biomass in the rainy season. Conclusions We found more dead biomass in the rainy season, probably due to low decomposition rates, which can increase fire risk in these grasslands during the following dry season. These tropical wet grasslands stored high amounts of carbon (621 to 716 g C center dot m-2), mostly in the roots. Thus, policymakers should consider tropical grasslands as potential carbon stocks, since they are one of the most threatened and unprotected ecosystems in Brazil. (AU)

• FAPESP's process: 08/10049-9 - Effects of fire on herbaceous vegetation dynamics of Cerrado at the Parque Estadual do Jalapão: a functional approach
• Grantee: Alessandra Tomaselli Fidelis
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 09/14978-7 - Effects of fire on above- and belowground biomass in wet lands at Jalapão, Tocantins
• Grantee: Maria Fernanda Di Santi Lyra
• Support Opportunities: Scholarships in Brazil - Scientific Initiation