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Ecosystem structure and soil‐surface conditions drive the variability in the foliar δ 13 C and δ 15 N of Stipa tenacissima in semiarid Mediterranean steppes
Author(s) -
Maestre Fernando T.,
Cortina Jordi
Publication year - 2006
Publication title -
ecological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.628
H-Index - 68
eISSN - 1440-1703
pISSN - 0912-3814
DOI - 10.1007/s11284-005-0091-4
Subject(s) - steppe , perennial plant , stipa , environmental science , ecosystem , vegetation (pathology) , abiotic component , nitrogen , agronomy , mediterranean climate , spatial variability , atmospheric sciences , ecology , chemistry , biology , mathematics , medicine , statistics , organic chemistry , pathology , geology
We evaluated the effects of ecosystem composition and structure (species richness and diversity, cover and spatial attributes of vegetation), abiotic factors (climate and topographical features) and the condition of the bare‐ground areas (evaluated using soil‐surface indicators) on the performance of Stipa tenacissima [evaluated using foliar δ 13 C, δ 15 N, nitrogen concentration and the carbon‐to‐nitrogen (C:N) ratio] in 15 steppes of SE Spain. Foliar δ 13 C values of S. tenacissima showed a low degree of variation in the studied steppes, with average values ranging from −24.1 to −22.9‰. Higher variation was found in the δ 15 N values, which ranged from −5.5 to −2.4‰. The nitrogen concentration and the C:N ratio varied between 5.0 and 8.0 mg g −1 , and between 55.4 and 85.3, respectively. The δ 13 C values became less negative with increasing spatial aggregation of perennial vegetation, while the C:N values increased with increasing perennial vegetation cover. The δ 15 N values became more negative with increasing infiltration in the bare‐ground areas, but the nitrogen concentration was not related to any of the environmental variables measured. Our results suggest that the relative importance of ecosystem structure and soil‐surface conditions in the bare ground areas was higher than that of abiotic factors as determinants of the performance of S. tenacissima . The results also show that even subtle changes in these ecosystem features may lead to modifications in plant performance in semiarid S. tenacissima steppes, and thus to modifications in the associated ecosystem functions in the mid‐ to long‐term.