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

(1)研究了日本中部富士山山地和亚高山常绿植物的生态生理和物质经济特征，阐明了常绿植物在营养受限条件下的优势机制。(2)在山地样地熔岩床上，林冠层以常绿针叶树松（Pinus densiflora）为主，林下层以常绿阔叶树（Irex peduncullosa, Pieris japonica）为主。常绿阔叶树在几个生理生态特征上与落叶阔叶树不同；(1)常绿植物的年氮素周转率较低；(2)常绿叶片作为贮藏器官，氮素在春季从叶片重新转运到生长期；(3)常绿植物的最大光合速率较低，但日产量没有差异，因为常绿植物的光合活性没有发生正午耗散。(4)由于落叶乔木生长季前后的光合作用，常绿乔木的年生产力较高。因此，常绿植物的氮素利用效率较高。(3)熔岩床常绿松树在叶片中储存了大量的氮，在光照条件较好的情况下，这些氮被重新分配给生长在较深土壤中的笋，其氮素利用效率高于深层土壤。亚高山样地常绿草本植物的氮肥利用效率也较高。在早春有利的光照条件下，常绿叶片有利于光合作用。(4)这些结果表明，在低温和养分受限的条件下，常绿植被造成了保守的养分经济性和较高的氮肥利用效率。

(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.