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Type: Artigo de periódico
Title: Functional differences between woodland savannas and seasonally dry forests from south-eastern Brazil: Evidence from 15N natural abundance studies
Author: Viani, RAG
Rodrigues, RR
Dawson, TE
Oliveira, RS
Abstract: Nitrogen availability and N-cycling dynamics across ecosystems play a critical role in plant functioning and species distribution. Measurements of (15)N natural abundance provides a way to assess ecosystem N dynamics, and the range of nitrogen stable isotope values (delta(15)N) for plants in an ecosystem can indicate divergent strategies for N uptake. We tested the hypotheses that the N-rich seasonally dry forest would have higher soil and leaf delta(15)N and a smaller range of leaf delta(15)N values compared to the N-poor cerradao (savanna woodland). We measured N concentration and delta(15)N in two soil depths and leaves of 27 woody species in cerradao and 26 in seasonally dry forest. As expected, total soil N concentration decreased while soil delta(15)N value increased with soil depth. Regardless of soil depth, seasonally dry forest soils had higher delta(15)N and total N concentration compared to cerradao soils. Foliar delta(15)N values varied from -6.4 parts per thousand to 5.9 parts per thousand in cerradao and from -2.3 parts per thousand to 8.4 parts per thousand in seasonally dry forest plants. Phylogenetically independent contrasts analysis and comparisons of delta(15)N mean values of the most abundant species and species co-occurring in both sites confirmed the hypothesis of higher delta(15)N for seasonally dry forest in comparison to cerradao. These results corroborate the expectation of higher soil and leaf delta(15)N values in sites with higher soil N availability. However, except for the most abundant species, no across-site leafsoil (delta(15)N leaf delta(15)N soil) differences (delta(15)N) were found suggesting that differences in leaf delta(15)N between cerradao and seasonally dry forest are driven by differences in soil delta(15)N. Variation of leaf delta(15)N was large in both sites and only slightly higher in cerradao, suggesting high diversity of N use strategies for both cerradao and seasonally dry forest communities.
Subject: cerrado
comparative ecology
stable isotope
tropical forest
Country: EUA
Editor: Wiley-blackwell
Citation: Austral Ecology. Wiley-blackwell, v. 36, n. 8, n. 974, n. 982, 2011.
Rights: fechado
Identifier DOI: 10.1111/j.1442-9993.2010.02233.x
Date Issue: 2011
Appears in Collections:Unicamp - Artigos e Outros Documentos

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