松林“低改阔”林分干扰和植被空间格局分析

Pattern association of stand things in transforming pure pine forest into mixed coniferous and broad-leaved forest

我国南方各省均在加快松树纯林提质改造提高森林质量,为减少以马尾松(Pinus masonniana)、湿地松(P.elliottii)等为主的松树纯林比重,降低因松材线虫病造成松林大面积死亡的风险,优化林分树种结构,构建健康、稳定、高效的森林生态系统。本文拟通过建立松树纯林改造过程中草本层、各类树冠、多种干扰等多类事物间关联,分析林分质量趋势和驱动机制。将芒萁(Dicranopteris dichotoma)的出现和扩散视为林分趋于低质化的一种指示;应用扩展点格局的方法,将调查样地芒萁、针叶树冠、常绿阔叶树冠、落叶阔叶树冠、人迹干扰、林窗干扰、边坡干扰归类并调查绘制矢量图;建立栅格数据库后进行格局关联分析。结果显示样地范围内0~40 m空间尺度内芒萁与人迹干扰、边坡干扰、针叶树种呈空间格局显著正关联;芒萁与林相改造过程中形成的人工林窗、常绿阔叶树显著负关联,芒萁斑块与落叶阔叶树种斑块在0~40 m空间尺度上斑块间关联不显著。研究亦发现可以通过扩展点格局的方法建立林分改造和利用过程中多种事物关联关系,分析干扰对林分质量的影响。在林地里增设户外运动场地和边坡的形成会促进芒萁种群形成和扩散,使林分趋于低质;在过熟松林中开拓林窗和在林窗下种植常绿阔叶树,针叶林“针改阔”改造可抑制芒萁种群的扩散,是促进林分质量提升的营林措施。

All provinces in southern China are speeding up the transformation project of pure pine forest,reducing the proportion of pure pine forest dominated by Pinus masonniana and Pinus.elliottii.This paper intends to analyze the trend and driving mechanism of stand quality by establishing the correlation between herb layer,canopy and disturbance in the process of pure pine forest transformation.The appearance and diffusion of Dicranopteris dichotoma are regarded as an indication of the tendency of stand to be degraded.Using the method of extended point pattern,the data of D.pedata,coniferous canopy,evergreen broad-leaved canopy,deciduous broad-leaved canopy,human-disturbance,forest-gap disturbance and slope-disturbance were classified and vector maps were drawn.The results showed that the data were positively correlated with human-track disturbance,slope disturbance and conifer species at the spatial scale of 0~40m.The data were negatively correlated with the plantation-gaps and evergreen broad-leaved trees formed in the process of forest facies transformation,while the data were not significantly correlated with deciduous broad-leaved tree species patches at the spatial scale of 0~40m.We can use the method of extended point pattern to establish the relationship between various things in the process of stand reconstruction and utilization,r to analyze the influence of disturbance on stand quality.The formation of outdoor sports field and slope in forestland can promote the formation and diffusion of D.pedata and make the stand tend to be low quality.Gaps and planting evergreen broad-leaved trees in overmature pine forests and transforming coniferous forests from needle to broad-leaved trees can inhibit the spread of D.pedata and promote the improvement of stand quality.