Functional analysis of canopy structure of grasslands

草原冠层结构功能分析

基本信息

批准号：
04044027
负责人：
HIROSE Tadaki
金额：
$ 6.72万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04044027/
关键词：
Grassland vegetation Canopy structure Photon flux density Leaf area Nitrogen Biomass Species coexistence Cost-benefit analysis 葉面積指数(LAI)葉面積比(LAR)

项目摘要

1. Canopy structure was studied in the following grasslands : flood plain vegetation of River Rhein (Amerongen), pasture (Molenpolder), chalk grassland (Limburg), floating fen (Westbroek) and Miscanthus sinensis grassland (Kawatabi). In each vegetation, distribution and partitioning of photon flux density (PPFD), leaf area, biomass, and nitrogen among species were determined.2. Tall dominant species in a canopy received higher PPFD averaged over leaf area (PHI_<area>). However, the PPFD absorbed per unit aboveground biomass (PHI_<mass>) of the tall species was not higher than that of the subordinate species. Aboveground biomass was regarded as an investment cost to capture PPFD (benefit). PHImass, as a ratio of benefit to cost, indicates an efficiency of biomass investment to capture photon flux. Tall species have an advantage over subordinate species in receiving a large fraction of incident PPFD, while subordinate species have an advantage in efficiently using their biomass to capture PPFD.3. Photon absorption per unit leaf nitrogen (PHI_N) was determined for each species to indicate in situ PNUE (photosynthetic nitrogen use efficiency). Both tall dominant species and short subordinate species could have high PHI_N, but through different processes : high PHI_N of dominants resulted from high PHI_<area>, while high PHI_N of subordinates resulted from low n_L (nitrogen concentration per unit leaf area).4. Light-saturated CO_2 exchange rates per unit leaf area (CER) and per unit leaf nitrogen (potential PNUE) was determined. Species with high CER and high n_L had low potential PNUE, while species with low CER and low n_L showed high potential PNUE. Nitrogen use efficiency (NUE) was also evaluated as a reciprocal of plant nitrogen concentration. Three measures of NUE showed strong conformity. It was concluded that NUE of subordinate species was as high as or even higher than that of dominant species.

1。在以下草原中研究了树冠结构：莱茵河（Amerongen），牧场（Molenpolter），粉笔草原（Limburg），浮动芬（Westbroek）和Sinensis sinensis Grassland（Kawatabi）。在每种植被中，都确定了物种之间光子通量密度（PPFD），叶面积，生物量和氮的分布和分配。2。在树冠中的高位主要物种在叶片区域（PHI_ <区域>）平均获得较高的PPFD。但是，高个子物种的PPFD吸收的PPFD不高于下属物种的PPFD。地上生物质被认为是捕获PPFD（福利）的投资成本。作为收益与成本的比率，凤凰表明生物质投资捕获光子通量的效率。高个子物种比下属物种具有优势，在接收大量的入射PPFD方面，而下属物种在有效使用其生物量捕获PPFD.3方面具有优势。确定每个物种的每单位叶氮（PHI_N）的光子吸收，以表明原位（光合氮的使用效率）。高占主导地位的物种和短下属物种都可能具有很高的phi_n，但是通过不同的过程：高phi_n的高phi_n是由高phi_ <区域>产生的，而下属的高phi_n是由低N_L（每单位叶子面积的氮浓度）引起的。4。确定每单位叶面积（CER）（CER）和每单位叶氮（电势PNU）的光饱和CO_2汇率。高Cer和高N_L的物种具有低潜在的PNUE，而较低的CER和低N_L的物种显示出高电位的PNUE。还将氮的利用效率（NUE）评估为植物氮浓度的倒数。 NUE的三种措施表现出很强的符合性。得出的结论是，下属物种的nue高达甚至高于主要物种。