...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >PROFILES OF PHOTOSYNTHETICALLY ACTIVE RADIATION, NITROGEN AND PHOTOSYNTHETIC CAPACITY IN THE BOREAL FOREST - IMPLICATIONS FOR SCALING FROM LEAF TO CANOPY
【24h】

PROFILES OF PHOTOSYNTHETICALLY ACTIVE RADIATION, NITROGEN AND PHOTOSYNTHETIC CAPACITY IN THE BOREAL FOREST - IMPLICATIONS FOR SCALING FROM LEAF TO CANOPY

机译：北方森林中光合有效辐射，氮和光合能力的分布特征-从叶片到冠层尺度的涵义

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Profiles of photosynthetically active radiation (PAR), leaf nitrogen per unit leaf area (N-area), and photosynthetic capacity (A(max)) were measured in an aspen, two jack pine, and two black spruce stands in the BOREAS northern study area. N-area decreased with decreasing %PAR in each stand, in all conifer stands combined (r = 0.52) and in all stands combined (r = 0.46). Understory alder had higher N-area for similar %PAR than did aspen early in the growing season. A(max) decreased with decreasing N-area except for the negative correlation between N-area and A(max) during shoot flush for jack pine. For the middle and late growing season data, N-area and A(max) had r values of 0.51 for all stands combined and 0.60 for all conifer stands combined. For similar N-area the aspen stand had higher A(max) than did the conifer stands. Photosynthetic capacity expressed as a percentage of A(max) at the top of the canopy (%A(max0)) decreased with %PAR similarly in all stands, but %A(max0) decreased at a much slower rate than did %PAR. To demonstrate the implications of the vertical distribution of A(max), three different assumptions were used to scale leaf A(max) to the canopy (A(can-max)): (1) constant A(max) with canopy depth, (2) A(max) scaled proportionally to %PAR, and (3) a linear relationship between A(max) and cumulative leaf area index derived from our data. The first and third methods resulted in similar A(can-max); the second was much lower. All methods resulted in linear correlations between normalized difference vegetation indices measured from a helicopter and A(can-max) (r = 0.97, 0.93, and 0.97, respectively), but the slope was strongly influenced by the scaling method. [References: 60]
机译：在BOREAS北部研究中，在白杨，两个千斤顶松木和两个黑色云杉林中测量了光合有效辐射（PAR），单位叶面积的叶氮（N-面积）和光合能力（A（max））的分布。区。在所有针叶树组合（r = 0.52）和所有树组合（r = 0.46）中，每个林分的N面积均随着％PAR的降低而降低。相对于％PAR，林下al木的N面积要比生长期初期的白杨高。 A（max）随N区域的减少而降低，除了杰克松的枝条冲洗期间N区域与A（max）之间的负相关性。对于生长中期和后期的数据，N面积和A（max）的r值对于所有林分组合均为0.51，对于所有针叶林分组合均为0.60。对于类似的N区，白杨林的针叶林比针叶林的A（max）高。在所有林分中，光合能力以冠层顶部的A（max）百分比（％A（max0））的百分比表示，与％PAR相似，但％A（max0）的降低速率远低于％PAR。为了证明A（max）的垂直分布的含义，我们使用了三种不同的假设将叶子A（max）缩放到冠层（A（can-max））：（1）具有冠层深度的常数A（max）， （2）A（max）与％PAR成正比，（3）A（max）与根据我们的数据得出的累积叶面积指数之间存在线性关系。第一种和第三种方法得出的A（can-max）相似;第二个要低得多。所有方法都导致直升机测量的归一化差异植被指数与A（can-max）之间的线性相关性（分别为r = 0.97、0.93和0.97），但是坡度受缩放方法的强烈影响。 [参考：60]

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号