College of Resources and Environment, University of Chinese Academy of Sciences 19-A Yuquan Road, Beijing 100049, China ; Ecology, Department of Biology, University of Konstanz, Universitätsstrasse 10 D-78457 Konstanz, Germany.
Ecology, Department of Biology, University of Konstanz, Universitätsstrasse 10 D-78457 Konstanz, Germany.
Ecol Evol. 2015 Mar;5(5):1068-75. doi: 10.1002/ece3.1401. Epub 2015 Feb 9.
Stable carbon isotope composition (δ (13)C) usually shows a negative relationship with precipitation at a large scale. We hypothesized that sampling method affects foliar δ (13)C and its response pattern to precipitation. We selected 11 sites along a precipitation gradient in Inner Mongolia and collected leaves of Leymus chinensis with five or six replications repeatedly in each site from 2009 to 2011. Additionally, we collected leaves of L. chinensis separately from two types of grassland (grazed and fenced) in 2011. Foliar δ (13)C values of all samples were measured. We compared the patterns that foliar δ (13)C to precipitation among different years or different sample sizes, the differences of foliar δ (13)C between grazed and fenced grassland. Whether actual annual precipitation (AAP) or mean annual precipitation (MAP), it was strongly correlated with foliar δ (13)C every year. Significant difference was found between the slopes of foliar δ (13)C to AAP and MAP every year, among the slopes of foliar δ (13)C to AAP from 2009 to 2011. The more samples used at each site the lower and convergent P-values of the linear regression test between foliar δ (13)C and precipitation. Furthermore, there was significant lower foliar δ (13)C value in presence of grazed type than fenced type grassland. These findings provide evidence that there is significant effect of sampling method to foliar δ (13)C and its response pattern to precipitation of L. chinensis. Our results have valuable implications in methodology for future field sampling studies.
稳定碳同位素组成（δ（13）C）通常在大尺度上与降水呈负相关。我们假设采样方法会影响叶片δ（13）C及其对降水的响应模式。我们在内蒙古的降水梯度上选择了 11 个地点，并于 2009 年至 2011 年在每个地点反复采集 5 到 6 个 Leymus chinensis 的叶片作为重复。此外，我们于 2011 年分别从两种草地（放牧和围栏）采集了 L. chinensis 的叶片。测量了所有样本的叶片δ（13）C 值。我们比较了不同年份或不同样本大小之间叶片δ（13）C与降水的模式，以及放牧和围栏草地之间叶片δ（13）C 的差异。无论是实际年降水量（AAP）还是年平均降水量（MAP），每年与叶片δ（13）C均呈强相关。每年，叶片δ（13）C 与 AAP 和 MAP 的斜率都存在显著差异，在 2009 年至 2011 年期间，叶片δ（13）C 与 AAP 的斜率也存在差异。每个地点使用的样本越多，叶片δ（13）C 与降水之间线性回归检验的 P 值越低且越收敛。此外，放牧草地的叶片δ（13）C 值明显低于围栏草地。这些发现提供了证据表明，采样方法对 L. chinensis 的叶片δ（13）C 及其对降水的响应模式有显著影响。我们的结果对未来野外采样研究的方法学具有重要意义。
