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Studies on life patterns of evergreen broad-leaved trees growing in cool and nutrient-limited sites

凉爽和营养有限地区常绿阔叶树生活模式的研究

基本信息

批准号：
12640609
负责人：
YAMAMURA Yasuo
金额：
$ 1.98万
依托单位：
IBARAKI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

(1) Ecophysiology and matter economy were investigated for evergreen plants in montane and subalpine sites in Mt Fuji, a volcanic mountain in central Japan, to clarify the mechanism of dominance of evergreen plants under nutrient-limited conditions.(2) On a lava bed in the montane site, forest canopy is dominated by an evergreen conifer (Pinus densiflora) and under-canopy layer is dominated by evergreen broadleaf trees (Irex pedunculosa, Pieris japonica). Evergreen broadleaf trees were different from deciduous ones in several ecophysiological features; (1) Annual turnover rate of nitrogen of evergreens was lower, (2) Evergreen leaves served as storage organs and nitrogen was retranslocated from the leaves to growing shoots in spring, (3) Maximum photosynthetic rate of evergreens was lower, but there were no difference in daily matter production because midday depletion of photosynthetic activity did not occur in evergreens, (4) Annual productivity of evergreens was higher because of photosynthetic activity before and after growing season for deciduous trees. Consequently nitrogen use efficiency (NUE) of evergreens was higher.(3) The evergreen pine tree on the lava bed had much storage nitrogen in leaves, which was retranslocated to shoots growing under more favorable light condition, and had higher NUE than that on a deep soil. High NUE was also observed in an evergreen herb in the subalpine site. Evergreen leaves served to photosynthesize under a favorable light condition in early spring.(4) These results indicated that evergreenness caused a conservative nutrient economy and high NUE in cool and nutrient-limited sites.

(1)对日本中部火山山富士山山地和亚高山地区常绿植物的生态生理和物质经济进行了研究，以阐明常绿植物在营养限制条件下的优势机制。(2)在山地熔岩床上，林冠以常绿针叶树(Pinus Densiflora)为主，林下以常绿阔叶树(Irex edunculosa，Pieris Japan onica)为主。常绿阔叶树与落叶阔叶树在几个生理生态特征上存在差异：(1)常绿阔叶树氮素年周转率较低；(2)常绿树叶作为贮藏器官，氮素在春季从叶片转移到生长枝条；(3)常绿阔叶树最大光合作用速率较低，但由于常绿树种没有出现光合作用耗竭，日物质生产差异不大；(4)常绿树种由于生长季前后的光合作用活动，使常绿树种年生产力较高。熔岩床上的常绿松树具有较高的氮素利用效率(NUE)。(3)熔岩床上的常绿松树叶片中的氮素贮量较大，在光照条件较好的条件下转移到枝条上，且氮素利用效率高于深层土壤。在亚高山地区的一种常绿草本植物中也观察到了高NUE。在早春光照条件较好的情况下，常绿叶片有利于光合作用。(4)这些结果表明，常绿植物在阴凉和营养受限的地区具有保守的营养经济和较高的氮素利用效率。