4种阔叶树种叶中氮和磷的季节动态及其转移

从叶完全展开到生长季结束 ,对常绿阔叶树种日本米槠 (Castanopsis cuspidata(Thunb.) Schottky)和具柄冬青 (Ilexpedunculosa Miq)及落叶阔叶树种栎 (Quercus serrata Murr.)和栓皮栎 (Quercus variabilis Blume)叶片的 N和 P浓度、含量和养分转移进行了测定 .在生长期中日本米槠新叶的 N浓度在 5月为 36 .6 g/ kg,然后降到 15 .5和 17.5 g/ kg之间 ,其老叶的N浓度波动于 10 .4和 13.1g/ kg的范围内 ,而具柄冬青新叶的 N浓度从 2 7.3下降到 16 .0 g/ kg,接着上升到 18.3g/ kg,其老叶的 N浓度在 12 .0到 15 .5 g/ kg的范围内。栎和栓皮栎的叶 N浓度分别从 2 8.8下降到 18.1g/ kg和从 2 8.5下降到17.5 g/ kg。日本米槠新叶的 N含量从 1.5 4下降到 1.35 g/ m2 ,接着上升到 1.5 0 g/ m2 ,其老叶 N含量从 1.36下降到1.0 0 g/ m2 ,接着上升到 1.2 1g/ m2 ,而具柄冬青新叶的 N含量从 2 .2 5下降到 1.6 0 g/ m2 ,接着上升到 2 .2 0 g/ m2 ,其老叶的 N含量从 2 .13下降到 1.6 5 g/ m2。栎和栓皮栎的叶 N含量分别从 2 .10下降到 1.2 8g/ m2和从 2 .95下降到 2 .13g/ m2。日本米槠新叶的 P浓度由 3.39g/ kg降到 1.12和 1.15 g/ kg之间 ,其老叶的 P浓度变化于 0 .6 6和 0 .88g/ kg的范围内 ,而具柄冬青新叶的

Seasonal patterns in nitrogen and phosphorus and resorption in leaves of four tree species

The leaves of evergreen Castanopsis cuspidata (Thunb.) Schottky and Ilex pedunculosa Miq and deciduous Quercus serrata Murr., Quercus variabilis Blume were collected from the time of full leaf expansion to the end of growing season to describe the seasonal patterns of concentrations and contents of N and P in leaves of these species. N and P resorption rates from the leaves of the four species were also measured. The concentrations of N and P in leaves of deciduous Q. serrata and Q. variabilis and P concentration in new leaves of evergreen C. cuspidata were the highest at the first sampling data, and then tended to decrease with time, whereas N concentration in new leaves of evergreen C. cuspidata and concentrations of N and P in new leaves of evergreen I. pedunculosa decreased from maximum and then increased during the growing season. The changes of N and P concentrations in old leaves of C. cuspidata and I. pedunculosa were small. Both leaf type and sampling time significantly affected leaf nutrient concentrations. The maximums of N and P concentrations for new leaves of the evergreen species agree with their litter peak. The seasonal patterns of N and P concentrations on percentage of dry weight basis were generally similar to N and P contents on leaf area basis. Mean N resorption in the deciduous species was higher than in the evergreen species, whereas their P resorption was similar. There is lower resorption for N than for P, suggesting compared with N, all species translocated greater percentage P out of senescing leaves.