不同演替程度下马尾松人工林生物多样性对生物量的影响

  目的  为了解决长期纯林经营模式下马尾松Pinus massoniana林地力衰退、生物多样性降低、生物量下降等问题，探究马尾松人工林在自然演替程度下生物量与生物多样性变化规律以及相关关系。  方法  以湖北省荆门市京山县太子山3种不同自然演替程度下的马尾松人工林为研究对象，采用典型样地法探究其生物量与生物多样性、林分密度之间的关系。  结果  ① 40年生林分与50年生林分的生物量相对于30年生林分具有显著差异(P＜0.05)，其中40年生林分的平均生物量最高。②多样性指数随着演替的进行不断增加，但在不同演替阶段有所差异。其中Shannon-Wiener指数与Simpson指数在各个演替阶段之间都具有显著差异(P＜0.05)；Pielou指数在40年生林分与50年生林分之间差异不显著(P＞0.05)，但都与30年生林分差异显著(P＜0.05)；功能丰富度、功能多样性与Pielou指数变化一致；功能离散度在40年生林分与其他演替阶段的林分都差异不显著(P＞0.05)，30年生林分与50年生林分差异显著(P＜0.05)；功能均匀度在各个演替阶段林分之间都具有显著差异(P＜0.05)。③林分密度在40年生林分与其他演替阶段的林分都差异不显著(P＞0.05)，30年生林分与50年生林分之间差异显著(P＜0.05)，其变化趋势随着演替程度的进行有所增加。④最佳解释模型中，解释变量包含功能离散度、Shannon-Wiener指数、Simpson指数以及Pielou指数，其中功能离散度相较于其他物种多样性指数更能有效地解释生物量的变化。  结论  生物多样性因子对生物量的变化具有一定可解释性，其中功能参数中的功能离散度对于生物量的影响最大。图1表4参34

Effects of biodiversity on biomass of Pinus massoniana plantation under different succession degrees

Objective]The purpose of this study is to explore the change law of biomass and biodiversity of Pinus massoniana plantations under natural succession degree and the relationship between them,so as to solve the problems of fertility decline,biodiversity reduction,and biomass decline of P.massoniana forest under the long-term pure forest management mode.Method]Taking 3 P.massoniana plantations with different degrees of natural succession in Taizi Mountain,Jingshan County,Jingmen City of Hubei Province as the research object,the typical plot method was used to explore the relationship between biomass,biodiversity and stand density.Result](1)The biomass of 40-year-old and 50-year-old stands was significantly different from that of30-year-old stand(P<0.05),and the average biomass of 40-year-old stand was the highest.(2)The diversity index increased with the succession,but it was different in different succession stages.Among them,ShannonWiener index and Simpson index had significant differences among different succession stages(P<0.05).There was no significant difference in Pielou index between 40-year-old and 50-year-old stands(P>0.05),but both were different from 30-year-old stands.The changes of functional richness and diversity were consistent with Pielou index.There was no significant difference in functional dispersion between 40-year-old stands and stands of other succession stages(P>0.05),but significant difference between 30-year-old stands and 50-year-old stands(P<0.05).There was significant difference in functional evenness among different succession stages(P<0.05).(3)There was no significant difference in stand density between 40-year-old stand and the stands of other succession stages(P>0.05),but significant difference between 30-year-old stand and 50-year-old stand(P<0.05),and the change trend increased with the succession degree.(4)In the best explanation model,the explanatory variables included functional dispersion,Shannon-Wiener index,Simpson index and Pielou index,among which functional dispersion was more effective than other species diversity indexes in explaining biomass changes.Conclusion]Biodiversity factors can explain the changes of biomass to some degree,and the functional dispersion of functional parameters has the greatest impact on biomass.