秦岭锐齿栎林光合器官内营养元素的分布

The foliage nutrient contents of sharptooth oak stands with diameter classes, crown directions, crown layers, elevations and seasonal variation in Mt. Qinling were studied. The results show: there are not evident difference of the contents of foliage nutrient elements among diameter classes or crown directions. The contents of N、P、K and Mg in leaves gradually decrease with foliage age and from top to base of the crown, whereas content of Ca increases and reaches summit before falling of leaves. The contents of N、P、K and Ca in leaves were cut down by ascending elevation, but the content of Mg doesn't change much. There are marked positive relativity among N、P、K and Mg and negative relativity between Ca and N、P、K 、Mg in leaves. Ratio of N/P and N/K goes steadily up with foliage age, whereas ratio of K/Mg goes slow down. Ratio of K/Ca is higher at the beginning of spreading-leaves and than gradually decreases. The accumulation of foliage nutrient elements is influnced by foliage development and the accumulation contents of different nutrient elements are influnced by different essential factors. Meanwhile, the paper gives a sampling suggestion of location、period and number for analyzing foliage nutrient situation.