Irrigation and fertilization effects on foliar and soil carbon and nitrogen isotope ratios in a loblolly pine stand
Irrigation and fertilization effects on foliar and soil carbon and nitrogen isotope ratios in a loblolly pine stand
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DOI：
10.1016/j.foreco.2005.03.016
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发表时间：
2005-07-18
影响因子：
3.7
通讯作者：
Ro, HM
中科院分区：
文献类型：
--
作者：
Choi, WJ;Chang, SX;Ro, HM
我们在灌溉和施肥实验中检查了针叶（当前和 1 年生）和两次（1999 年 7 月和 9 月）从 15 年生火炬松 (Pinus taeda L.) 林中收集的土壤样品中的 δ(13) C 和 δ(15) N，以调查这些处理是否在样品中留下特定的同位素信号，从而推断处理对 C 和 N 循环的影响。 h无论是叶龄还是采样日期，碳同位素辨别力（，）因灌溉而增加，因施肥而减少。碳同位素辨别模型表明，灌溉导致的 A 增加是由于气孔和/或叶肉导度增加导致水利用效率 (WUE) 降低。施肥导致的 A 值降低以及同一地点公布的气体交换测量结果表明，施肥地块需水量增加导致的水分胁迫通过加强气孔控制水分流失而改善了 WUE。叶面δ(15) N值不受灌溉影响，但因施肥而增加。土壤NH4+的Delta N-15值高于NO3-，且与叶面Delta N-15呈正相关，表明树木对NH4+的吸收是影响叶面Delta N-15的因素之一。我们得出结论，灌溉和施肥影响植物和土壤样品中的 613 C 和 615 N 值，反映了所研究的火炬松林中 C 和 N 循环模式以及水分利用效率的变化。 (c) 2005 Elsevier B.V. 保留所有权利。
We examined delta(13) C and delta(15) N in needle (current and 1-year-old) and soil samples collected on two occasions (July and September 1999) from a 15-year-old loblolly pine (Pinus taeda L.) stand in an irrigation and fertilization experiment to investigate whether these treatments leave specific isotope signals in the samples and thus to infer the effects of treatments on C and N cycling. hTespective of foliar age or sampling date, carbon isotope discrimination (,) was increased by irrigation, and decreased by fertilization. The carbon isotope discrimination model suggested that increased A by irrigation was due to decreased water use efficiency (WUE) through increased stomatal and/or mesophyll conductance. The decreased A by fertilization and published gas exchange measurements at the same site suggest that water stress resulting from increased water demand in the fertilized plots improved WUE through increased stomatal control of water loss. Foliar delta(15) N values were not affected by irrigation, but were increased by fertilization. The delta N-15 value of soil NH4+ were higher than those of NO3- and were positively correlated with foliar delta N-15, suggesting that tree uptake of NH4+ was one of the factors affecting foliar delta N-15. We conclude that irrigation and fertilization affected 613 C and 615 N values in plant and soil samples, reflecting changed C and N cycling patterns and water use efficiency in the studied loblolly pine stand. (c) 2005 Elsevier B.V. All rights reserved.