Understanding the Influences of Spatial Patterns on N Availability Within the Brazilian Amazon Forest

详细信息    查看全文

• 作者：Gabriela Bielefeld Nardoto ; Jean Pierre Henry Balbaud Ometto ; James R. Ehleringer ; Niro Higuchi ; Mercedes Maria da Cunha Bustamante and Luiz Antonio Martinelli
• 关键词：nitrogen ; lowland tropical forest ; nitrogen stable isotopes ; Amazonia ; foliar phosphorus ; terra ; firme forest ; campinarana forest
• 刊名：Ecosystems
• 出版年：2008
• 出版时间：December, 2008
• 年：2008
• 卷：11
• 期：8
• 页码：1234-1246
• 全文大小：333.9 KB

文摘

Nitrogen variations at different spatial scales and integrated across functional groups were addressed for lowland tropical forests in the Brazilian Amazon as follows: (1) how does N availability vary across the region over different spatial scales (regional ¡Á landscape scale); (2) how are these variations in N availability integrated across plant functional groups (legume ¡Á non-legume trees). Leaf N, P, and Ca concentrations as well the leaf N isotope ratios (δ15N) from a large set of legume and non-legume tree species were measured. Legumes had higher foliar N/Ca ratios than non-legumes, consistent with the high energetic costs in plant growth associated with higher foliar P/Ca ratios found in legumes than in non-legumes. At the regional level, foliar δ15N decreased with increasing rainfall. At the landscape level, N availability was higher in the forests on clayey soils on the plateau than in forests on sandier soils. The isotope as well as the non-isotope data relationships here documented, explain to a large extent the variation in δ15N signatures across gradients of rainfall and soil. Although at the regional level, the precipitation regime is a major determinant of differences in N availability, at the landscape level, under the same precipitation regime, soil type seems to be a major factor influencing the availability of N in the Brazilian Amazon forest.