日本中部10种树木叶片中氮和磷的季节变化及其转移

从叶完全展开到生长季结束，对常绿阔叶树种日本米储、具柄冬青、铁冬青、红楠和海桐及落叶阔叶树种袍栎、栓皮栎、日本朴、银杏和日本树五加的叶N和P含量进行了测定．结果表明，在整个生长季中，常绿阔叶树种中的日本米储和铁冬青的新叶和老叶的N和P含量呈现初期高、中期较低、后期上升的趋势；具柄冬青和海桐新叶的N和P含量的变化趋势与日本米储和铁冬青相似，而其老叶的N和P含量随季节推移而逐渐下降；红楠新叶和老叶的N含量呈现上升的趋势，其新叶和老叶的P含量则呈下降趋势；落叶阔叶树种的叶N和P含量随着时间的推移不断减少．各树种的N转移率为43％～75％，P为62％～84％．常绿阔叶树种的N平均转移率与落叶阔叶树种相似，而其P平均转移率大于落叶阔叶树种．所有树种的N平均转移率小于P平均转移率．

Seasonal changes of nitrogen and phosphorus and their translocation from leaves of ten tree species in central Japan

The leaves of evergreen broadleaved Quercus cuspidata, Ilex pedunculosa, Ilex rotunda, machilus thunbergii, Pittosporum tobira and deciduous broadleaved Quercus serrata, Quercus variabilis, Celtis sinensis, Ginkgo biloba, and Evodiopanax innovans were collected from the time of full leaf expansion to the end of growing season to describe the seasonal contents of N and P patterns in leaves of these species. The N and P contents in new and old leaves of evergreen Quercus cuspidata and Ilex rotunda had high levels in initial stage, low levels in medium stage, and increased in later stage. The seasonal changes of the N and P contents in new leaves of evergreen Ilex pedunculosa and Pittosporum tobira were similar to those of Quercus cuspidata and Ilex rotunda, whereas in old leaves of the two species, they tended to decline with time. The N content in new and old leaves of Machilus thunbergii tended to increase, whereas their P content tended to decrease. The N and P contents in leaves of deciduous species decreased during the growing season. The N translocation efficiency for all species ranged from 43-75%, whereas their P translocation efficiency ranged from 62-84%. The N translocation efficiency in evergreen broadleaved species was similar to that in deciduous broadleaved species, whereas the P translocation efficiency was higher than the latter. The mean N retranslocation efficiency for all species was higher than mean P retranslocation efficiency.