Stoichiometric and isotopic flexibility: facultative epiphytes exploit rock and bark interchangeably
Stoichiometric and isotopic flexibility: facultative epiphytes exploit rock and bark interchangeably
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DOI：
10.1016/j.envexpbot.2020.104208
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发表时间：
2020-11
影响因子：
5.7
通讯作者：
Yi Wu;Wen-Yao Liu;Hua-Zheng Lu;Su Li;You-xin Shen;Weiguo Liu;L. Song
中科院分区：
文献类型：
--
作者：
Yi Wu;Wen-Yao Liu;Hua-Zheng Lu;Su Li;You-xin Shen;Weiguo Liu;L. Song
了解植物向基质转移的化学计量特征是利用化学计量框架预测生态系统对环境变化的响应的关键步骤。然而，化学计量学对兼性附生植物底物转移的反应和机制尚不清楚。测定了西双版纳喀斯特森林9种兼性附生植物叶片化学计量学（N、P、K、Ca、Mg、S、Mn、Na和Fe浓度）和同位素特征（δ13C和δ15N）。比较了兼性附生植物和岩生植物的化学计量学和同位素特征，探讨了元素浓度随底物变化的可能原因。与附生植物相比，岩生植物δ15N和Ca富集，Fe、K、Mn等元素富集。δ15N与P、N、S、K呈正相关，δ13C与δ15N、P、N、S、Fe呈负相关。根据主成分分析（PCA），第一个轴装载有机结合元素（P、N和S），而第二个轴装载非有机结合元素（Fe、Mn和K）。与有机结合元素相比，非有机结合元素的变化主要受基质相关因素的影响。这些结果表明，衬底因子对K、Ca、Fe、Mn和δ15N等元素有很强的分配作用。两种生态型间元素浓度和同位素的差异表明了化学计量学和同位素的灵活性，这使得兼性附生植物可以交替利用岩石和树皮。
Understanding the stoichiometric characteristics of plants to a substrate shift is a key step in the use of a stoichiometric framework to predict ecosystem responses to environmental change. However, the response and mechanism of stoichiometry to a substrate shift in facultative epiphytes remains unknown.The foliar stoichiometric (N, P, K, Ca, Mg, S, Mn, Na, and Fe concentrations) and isotopic characteristics (δ13C and δ15N) of nine facultative epiphyte species in Xishuangbanna karst forest in southwest China were determined. The stoichiometry and isotopy were compared between the epiphytic and lithophytic individuals in the facultative epiphytes, and the possible causes of changes in elemental concentrations to substrate shifts were studied.We found that the lithophytes were enriched in δ15N and Ca, but depleted in elements such as Fe, K, and Mn compared with the epiphytes. The δ15N was positively correlated with P, N, S, and K, while the δ13C was negatively correlated with δ15N, P, N, S, and Fe. Following a principal component analysis (PCA), the first axis loaded organically bound elements (P, N, and S), while the second axis loaded non-organically bound elements (Fe, Mn, and K). The variances of non-organically bound elements were mostly affected by the substrate-related factors than organically bound elements.These results revealed that the substrate factor has a strong partitioning effect on elements such as K, Ca, Fe, Mn, and δ15N. The differences of element concentration and isotopy between the two ecotypes suggested stoichiometric and isotopic flexibility, which enabled facultative epiphytes to exploit rock and bark interchangeably.