Environmental and species-specific controls on δ13C and δ15N in dominant woody plants from central-western Argentinian drylands
Environmental and species-specific controls on δ13C and δ15N in dominant woody plants from central-western Argentinian drylands
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DOI：
10.1111/aec.12473
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发表时间：
2017-08-01
期刊：
影响因子：
1.5
通讯作者：
Pucheta, Eduardo
中科院分区：
文献类型：
--
作者：
Gatica, Mario Gabriel;Aranibar, Julieta N.;Pucheta, Eduardo
年平均降水量的空间变化是旱地植物水氮状况的主要驱动因素。C3植物光合组织中碳稳定同位素（δ C-13）的天然丰度是气孔导度的时间综合行为的指标;而氮稳定同位素（δ N-15）的天然丰度是植物氮的主要来源（土壤N与大气N-2）的指标。以前在旱地的研究已经证明，植物C-13和N-15的增量值随着平均年降水量的减少而增加，这分别是由于气孔导度的减少和土壤富含N-15。然而，这方面的证据来自于研究集中在稳定同位素测量集成在植物群落水平或在网站上的优势植物水平，但很少有人努力研究C和N同位素的变化在一个物种生长沿着降雨梯度。我们分析了植物三角洲C-13，三角洲N-15和C/N值的三种木本植物具有不同的物候叶性状（落叶，多年生和无叶）沿着区域平均年降水量梯度从阿根廷中西部旱地。值得注意的是，植物Δ C-13和Δ N-15值在三个木本物种没有增加对网站的降水量低，或在生长季节开始（干燥期），正如我们所预期的。这些结果表明，环境因素，而不是平均年降水量可能会影响植物三角洲C-13和三角洲N-15。短期环境条件可能与特定物种的植物性状有关的水和氮的使用策略和推翻的预测影响的平均年降水量对植物的三角洲C-13和三角洲N-15广泛报告在旱地。
Spatial variation in mean annual precipitation is the principal driver of plant water and nitrogen status in drylands. The natural abundance of carbon stable isotopes (delta C-13) in photosynthetic tissues of C3 plants is an indicator of time-integrated behaviour of stomatal conductance; while that of nitrogen stable isotopes (delta N-15) is an indicator of the main source of plant N (soil N vs. atmospheric N-2). Previous studies in drylands have documented that plant delta C-13 and delta N-15 values increase with decreasing mean annual precipitation due to reductions in stomatal conductance, and soil enriched in N-15, respectively. However, evidence for this comes from studies focused on stable isotopes measurements integrated at the plant community level or on dominant plants at the site level, but little effort has been made to study C and N isotope variations within a species growing along rainfall gradients. We analysed plant delta C-13, delta N-15 and C/N values of three woody species having different phenological leaf traits (deciduous, perennial and aphyllous) along a regional mean annual precipitation gradient from the central-western Argentinian drylands. Noticeably, plant delta C-13 and delta N-15 values in the three woody species did not increase towards sites with low precipitation or at the start of the growing season (drier period), as we expected. These results suggest that environmental factors other than mean annual precipitation may be affecting plant delta C-13 and delta N-15. The short-term environmental conditions may interact with species-specific plant traits related to water and nitrogen use strategies and override the predictive influence of the mean annual precipitation on plant delta C-13 and delta N-15 widely reported in drylands.