湘中丘陵区两类林分生产力与土壤肥力的比较研究

Comparative Studies of Productivity and Soil Fertility of Two Forest Stands in Central Hunan's Hilly Country

以湘中丘陵区石栎马尾松混交林和马尾松纯林为研究对象,对两类林分进行了生物量和封理化性质的测定分析,结果表明:混交林林分生物量远高于马尾松纯林,是纯林的2.99倍;混交林乔木层生物量也高于纯林;混交林林分平均净生产力高于纯林,是纯林的3.62倍;混交林和纯林的根系总质量分别占林分生物量的9.76%和11.08%.在各级根中,两类林分均以粗根所占比例最大,细根所占比例最小,根系质量均随深度的增加而递减;混交林枝叶比略小于纯林,而枝叶指数、冠根比及光合部分与非光合部分比值则相反;混交林土壤营养元素含量显著高于马尾松纯林,但混交林土壤容重比纯林低,总孔隙度与毛管孔隙度、非毛管孔隙度比纯林林地高,本研究结果,为湘中丘陵区石栎马尾松混交林及马尾松纯林的培育提供了重要参考依据。

Studied objects are the mixed forest of Pinus massoniana with Lithocarpus glaber, and the pure forest of P. massoniana in Central Hunan's hilly country. The biomass and soil physical chemistry properties of the two stands have been determined and analysed. The results are as follows. The biomass of the mixed is far higher than that of the pure,and is 2. 99 times of that of the pure. The tree stratum biomass of the mixed is also higher than that of the pure. The average net productivity of the mixed is higher than that of the pure by 2. 62 times. The mass of root system of the mixed and the pure is respectively 9. 76% and 11. 08% of the total biomass of the two stands. About the grades of the tree roots of both stands,the ratio of thick roots to total roots is the highest,and that of thin roots to total roots is the lowest. The mass of root system decreases progressively with the increase of root depth. The ratio of branches to leaves of the mixed is slightly lower than that of the pure,while the pure has a lower index of branches and leaves, a lower ratio of crown to roots,and lower ratio values of photosynthesis parts than the mixed. The content of soil nutritional elements of the mixed is obviously higher than that of the pure.The mixed also has a lower ratio of water conservancy unit weight than the pure and its ratio of total soil void to capillary void and ratio of total soil void to non-capillary void are higher than those of the pure.