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Analysis of Canopy Structure of Plant Communities in Mongolian Grasslands

蒙古草原植物群落冠层结构分析

基本信息

批准号：
09041142
负责人：
HIROSE Tadaki
金额：
$ 4.1万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

We studied the nitrogen use efficiency (NUE) and water use efficiency (WUE) of species growing in a humidity gradient in Mongolian grasslands to examine if there is a trade-off between the two efficiencies. Total 131 species were collected from 7 sites. WUE was evaluated by the compositional deviation of ィイD113ィエD1C(δィイD113ィエD1C). NUE was evaluated as a reciprocal of leaf nitrogen concentration (LNC). Species in drier habitats tended to have higher WUE, but there was no such trend in NUE. No trade-off was found between WUE and NUE across species distributed in different climates. However, when the values for WUE and NUE were standardized against their means for species found more than three sites, WUE increased and NUE decreased with increasing aridity, indicating the trade-off between NUE and WUE within species. Only two (Cleistogenes squarrosa and Salsola passerina) out of 131 species were found to have the C4 metabolism.Effects of climate and grazing intensities on the structure of grassland vegetation were studied. We have established three exclosures in different climates : Partizan (mesic steppe), Tumentsogt (typical steppe) and Bayan-Unjuul (dry steppe). First year vegetation survey gave 45 species (including 7 grasses) in Partizan, 46 species (8 grasses) in Tumentsogt and 18 species (4 grasses) in Bayan-Unjuul. Aboveground biomass was 122 g dw mィイD2-2ィエD2 at Parizan, 122 at Tumentsogt, and 53 at Bayan-Unjuul. Difference between exclosure and grazing plots was small, probably because of the short time since establishment of the exclosure and an unusually dry summer in 1999.

本文研究了蒙古草原不同湿度梯度下物种的氮素利用效率（NUE）和水分利用效率（WUE），探讨两者之间是否存在权衡关系。在7个地点共采集到131种。WUE采用γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ。利用叶片氮浓度（LNC）的倒数来评价氮素利用效率。干燥生境的物种WUE倾向于较高，而NUE则没有这种趋势。不同气候条件下不同物种间水分利用效率与氮肥利用效率之间不存在权衡关系。然而，当对超过3个立地的物种的WUE和NUE进行标准化时，随着干旱程度的增加，WUE增加，NUE减少，表明物种内部的NUE和WUE之间存在权衡关系。131种植物中仅发现2种植物具有C4代谢，分别为：squarrosa Cleistogenes和Salsola passerina。研究了气候和放牧强度对草地植被结构的影响。我们在不同的气候条件下建立了三个封闭区：Partizan（中度草原）、Tumentsogt（典型草原）和Bayan-Unjuul（干燥草原）。第一年的植被调查结果显示，Partizan地区有45种（包括7种禾本科），Tumentsogt地区有46种（8种禾本科），Bayan-Unjuul地区有18种（4种禾本科）。Parizan、Tumentsogt和Bayan-Unjuul的地上生物量分别为122 g / dw / m2、122 g / dw / m2和53 g / dw / m2。圈闭与放牧区差异较小，可能与圈闭建立时间较短，且1999年夏季异常干燥有关。