林龄对思茅松人工林根系生物量的影响

目的]以云南省普洱市主要植被思茅松人工林为研究对象,探讨不同林龄思茅松人工林根系生物量的大小分布及变化特征。方法]分别在5、8、15、25、36年生思茅松人工林内,利用内径为8.5 cm的根钻分3层(0~10、10~20、20~30 cm)获取思茅松与其它物种的细根、粗根及死根生物量数据。结果]表明:随着思茅松人工林林龄的增长,思茅松细根生物量呈减少的趋势,而其它物种细根生物量呈增加趋势,细根生物量最大出现在36年生思茅松人工林。不同林龄思茅松人工林的思茅松粗根和死根生物量之间无显著差异,而其它物种及林分的粗根生物量和根系生物量则随林龄增长而增加。思茅松人工林的细根生物量主要分布在土壤深度0~10 cm内,其中,思茅松、其它物种、林分细根生物量以及根系生物量随土层深度的增加呈减少趋势。林龄和土壤深度对思茅松与其它物种的细根生物量有显著影响,林龄与土壤深度的交叉作用对思茅松细根生物量有显著影响,林龄对死根生物量有显著影响,林龄、土壤深度及林龄与土壤深度的交叉作用对粗根与根系的生物量有显著影响。结论]思茅松人工林随着林龄增长,群落结构与树种组成随之发生变化,从而对根系生物量产生较大影响。

Effect of Stand Age on Root Biomass in Pinus kesiya var. langbianensis Plantation

Objective] To analyze the size distribution and determine the effects of stand age on root biomass in Pinus kesiya var. langbianensis plantation based on the data of fine root, coarse root and dead root biomass among different species groups. Method] This study was conducted in 5-year-old, 8-year-old, 15-year-old, 25-year-old and 36-year-old P. kesiya" var. langbianensis plantations located in Pu''er city, Yunnan province, China. The soil cores with diameter of 8.5 cm were collected in October, 2014 at different stand age. Each soil core was separated into three sections at the depths of 010, 1020, and 2030 cm. Result] The fine root biomass of P. kesiya var. langbianensis decreased with the stand age, while the fine root biomass of other species groups increased with the stand age. The maximum of fine root biomass was found in the 36-year-old P. kesiya var. langbianensis plantation. There were no significant difference in the coarse root of P. kesiya var. langbianensis and dead root of different stand age in P. kesiya var. langbianensis plantations. On the contrary, the coarse root biomass of other species group and stand, and root biomass increased with the stand age. The fine root biomass mainly distributed in the soil with the depth of 010 cm. The fine root biomass of P. kesiya var. langbianensis, the other species group and all stand as well as root biomass decreased with the increase of soil depth. The stand age and soil depth had significant effect on the fine root biomass of P. kesiya var. langbianensis and other species group, respectively. The cross effect of stand age and soil depth had no significant influences on the fine root biomass of P. kesiya var. langbianensis. The stand age had a significant effect on the dead root biomass. The stand age, soil depth and the cross of stand age and soil depth had significant effect on the coarse root and all root biomass. Conclusion] With the growth of P. kesiya var. langbianensis plantations, the community structures and species composition will change and has a significant effect on the root biomass.