Seasonal variation of growth and nutrient contents for photosynthetic organ of the sharptooth oak stands
锐齿栎林个体光合器官生长与营养季节动态

The individual growth and nutrient contents for photosynthetic organ of the sharptooth oak stands in Mt Qinling with seasonal variation have been studied in this paper The individual leaf area and dry matter content of the sharptooth oak stands with seasonal variation followed different S curves, the ratio between leaf area and dry matter followed imperfect S curve The period from budding to fallen leaves of sharptooth oak stands lasted about 160 days, the absolute increment of foliage dry matter in the first week of budding was higher than that of leaf area, and then the other way round The absolute increment of leaf area went faster up and rapider down and sustained shorter period than one of foliage dry matter The percentage contents of N, P, K and Mg in the leaves gradually decreased with foliage age, whereas contents of Ca increased till fallen leaves There are marked positive relations among N, P, K and Mg in leaves, but negative relations between Ca and N, P, K, Mg in the leaves The N/P and N/K went steadily up with foliage age, whereas K/Mg played gradually down, K/Ca was higher at beginning of spreading leaves, and then decreased gradually The nutrient accumulation contents to photosynthetic organ of sharptooth oak stands with seasonal variation followed a partial Normal Function, the accumulation contents of N, P, K and Mg in a leaf went up with foliage age and reached summit at 11 59, 0 56, 5 80 and 0 78mg, then went steadily down, whereas accumulation contents of Ca in a leaf increased gradually and arrived at 6 89mg before fallen leaves The nutrient accumulation contents were influenced by foliage development among the different seasons