毛竹林扩展过程中主要群落结构指标的变化特征

Changing characteristics of main structural indexes of community during the expansion of moso bamboo forests

以竹-阔、竹-杉、竹-荒界面为研究对象,采用样带调查的方法对毛竹(Phyllostachys edulis)扩展过程中主要群落结构指标进行了研究,结果表明:随着毛竹向阔叶林扩展,毛竹胸径、生物量、叶面积指数、凋落叶现存量、C、N、P含量及C∶P、N∶P降低;毛竹向杉木林扩展,扩展前沿的毛竹胸径和生物量较低,扩展中段毛竹的胸径和生物量较高,叶面积指数、凋落叶现存量和C、N含量随着毛竹比例的增加而降低,凋落物P含量和凋落物C∶P和N∶P随着毛竹比例的增加而增加;毛竹向撂荒地扩展,胸径、生物量、叶面积指数和凋落物量随着毛竹立竹度的增加而增加,凋落物C、N、P含量降低,C∶P、N∶P增加。综上所述,毛竹在向阔叶林、杉木林和荒地扩展时,胸径和生物量、叶面积指数和凋落物数量和质量都发生了适应性改变。其中,毛竹向阔叶林扩展时,通过增大个体胸径和叶面积指数来适应竞争环境,扩展前沿较多的凋落物量和较高的C、N、P含量,增加了养分归还潜力,会进一步促进毛竹的生长;毛竹向杉木林扩展时,通过增加叶面积指数来适应竞争环境,随着毛竹林的扩展毛竹胸径增加、凋落物C∶P、N∶P增加,毛竹生长受到P的制约减弱;毛竹向撂荒地扩展,通过减小个体大小、降低叶面积指数来适应撂荒地相对极端的环境条件,随着毛竹的扩展个体胸径增加,凋落物量增多,P含量和N∶P增加。

To clarify the changes of main structural indexes of community during the expansion of moso bamboo forests （Phyllostachys edulis）, the interfaces of bamboo-broadleaved forest, ham, boo-Chinese fir forest and bamboo-abandoned land were selected by setting transects. The results indicated that with the expansion of bamboo forests to broadleaved forests, diameter at breast height （DBH）, biomass, leaf area index （LAI）, litterfall amount, carbon （C）, nitrogen （N） and phosphorus （P） contents, C ： P and N ： P showed a decreasing trend. With the expansion of bamboo forests to Chinese fir forests, the DBH and biomass of forefront bamboos were low while they were high for bamboo in the middle of interface. LAI, litterfall amount and C and N contents decreased with the increasing indensity of bamboo to Chinese fir, while litterfall P con- tent, litterfall C ： P and N ： P increased with the increasing proportion of bamboo to Chinese fir. With the expansion of bamboo forests to abandoned land, DBH, biomass, LAI, litterfall bio- mass, C ： P and N ： P increased with the increasing proportion of bamboo while the contents of C, N and P declined. Overall, with the expansion of bamboo forests to broadleaved forests, Chi- nese fir forests and abandoned land, DBH, LAI and the quantity and quality of litterfall were changed adaptively. Specifically, when bamboo expanded to broadleaved forests, the growth of bamboo was promoted by increasing the DBH, LAI and litterfall quantity in forefront interface, as well as higher contents of C, N and P. With the expansion of bamboo forests to Chinese fir for-ests, the limitation of P for bamboo growth was reduced by increasing the LAI, DBH and litterfall C ： P and N ： P. With the expansion to abandoned land, the body size and LAI of bamboo were reduced to accommodate a relatively extreme environmental condition; Litterfall amount, P con- tent and N ： P increased with the increase of DBH.