山西灵空山典型天然林空间结构特征及其对生产力的影响

Spatial Structure Characteristics and Their Influences on Productivity of Typical Natural Forests in the Lingkong Mountain,Shanxi Province

通过探究辽东栎林、油松林空间结构特征,揭示林分生产力变化的影响因素,为天然林保护和管理提供科学依据。以山西灵空山典型辽东栎林、油松林为例,选取角尺度(W)、混交度(M)、大小比数(U)、密集度(C)和林层指数(S)5个指标表征林分空间结构特征,通过年轮条估算林分生产力,采用冗余分析探讨天然林空间结构对林分生产力的影响。结果表明,2种天然林具有相似的空间结构特征,呈现出聚集分布的水平格局,整体林分呈弱中度混交状态。其中,辽东栎林处轻微劣势状态,油松林则呈中庸状态(U_(1)=0.502,U_(2)=0.471)。2种天然林密集度均持较高水平,辽东栎林略优于油松林(C_(1)=0.955,C_(2)=0.994)。2种天然林垂直结构均较为简单,油松林垂直结构略优于辽东栎林(S_(1)=0.408,S_(2)=0.419)。辽东栎林生产力(V_(1)=3.828 t·hm^(-2)·a^(-1))显著大于油松林(V_(2)=2.909 t·hm^(-2)·a^(-1))(P<0.05)。冗余分析表明,辽东栎林林分生产力与U呈极显著正相关(P<0.01),与W、C、M、S呈负相关,空间结构指标中U是其变化的主要驱动因子(解释度达50.7%);油松林林分生产力与U、C和M呈正相关,与S呈负相关,与W呈显著负相关(P<0.05),空间结构指标中W是其变化的主要驱动因子(解释度达57.1%)。林分空间结构能有效解释天然林生产力变化(75%以上),可依据空间结构参数对林分进行优化管理,从而更好地发挥天然林的生态价值。

The objectives of this study were to provide a scientific basis for the protection and management of natural forest by exploring the spatial structure characteristics of Quercus wutaishanica forest and Pinus tabuliformis forest,and to reveal the influencing factors of stand productivity change.Typical Q.wutaishanica forest and P.tabuliformis forest occurring in the Lingkong Mountain of Shanxi Province were taken as the research objects,5 factors were selected to characterize the stand spatial structure,including uniform angle index(W),mingling index(M),dominance index(U),crowding index(C),and storey index(S).The stand productivity was estimated through annual ring width,the impact of natural forest spatial structure on stand productivity was examined by using redundancy analysis method.The results showed that the two natural forests had similar spatial structure characteristics,presenting a horizontal pattern of aggregation,and the overall stands were in weak-moderate mixed state.Among them,Q.wutaishanica stand was in a slightly disadvantaged state,while P.tabuliformis was in a moderate state(U_(1)=0.502,U_(2)=0.471).The crowding index of the two natural forests was at a high level,but Q.wutaishanica forest was slightly better than P.tabuliformis forest(C_(1)=0.955,C_(2)=0.994).The vertical structure of the two natural forests was simple,while P.tabuliformis forest was slightly better than Q.wutaishanica forest(S_(1)=0.408,S_(2)=0.419).The productivity of Q.wutaishanica forest(V_(1)=3.828 t·hm^(-2)·a^(-1))was significantly higher than P.tabuliformis forest(V_(2)=2.909 t·hm^(-2)·a^(-1),P<0.05).Redundancy analysis showed that the stand productivity of Q.wutaishanica forest was positively correlated with U significantly(P<0.01),negatively correlated with W,C,M,and S,and U was the main driving factor in spatial structure index(the accountability reached 50.7%);the stand productivity of P.tabuliformis forest was positively correlated with U,C,and M,negatively correlated with S,and negatively correlated with W significantly(P<0.05),and W was the main driving factor in spatial structure index(the accountability reached 57.1%).Stand spatial structure can effectively explain the change of natural forest productivity(more than 75%),and can optimize the management of stand according to the spatial structure parameters,so as to better play the ecological value of the natural forest.