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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.

我们研究了生长在蒙古草原湿度梯度中的物种的氮素利用效率(NUE)和水分利用效率(WUE)，以检验这两种效率之间是否存在权衡。共采集7个采样点131种。用ィイD113ィエD1C(δィイD113ィエD1C)的组成偏差来评价WUE。氮素利用效率是叶片氮素浓度(LNC)的倒数。干旱生境中的物种往往具有较高的WUE，而NUE则没有这种趋势。在不同气候分布的树种间，水分利用效率和氮素利用效率之间不存在权衡。然而，当WUE和NUE的值相对于其平均值进行标准化时，发现3个以上的物种，WUE随干旱程度的增加而增加，而NUE则随着干旱程度的增加而减少，这表明了物种内NUE和WUE之间的权衡。在131种植物中，只有2种具有C4代谢，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育区：Partizan(中生草原)、Tumentsogt(典型草原)和Bayan-Unjuul(干燥草原)。第一年的植被调查表明，游击队有45种(含7种草)，图门索格特有46种(8种)，巴彦翁珠有18种(4种)。地上生物量在帕里赞为122g dw mィイD2-2ィエD2，在图门索格特为122，在巴彦翁珠尔为53。围栏和放牧地之间的差异很小，可能是因为围栏建立以来时间很短，而且1999年夏季异常干燥。