吉林东部天然次生林下光强衰减的空间分布特征

The spatial distribution characteristics of light intensity attenuation under natural secondary forests in eastern Jilin Province, China

【目的】探究长白山北坡不同林型天然次生林下空间尺度及方位间的光强衰减特征。【方法】以吉林东部长白山北坡天然次生林5块0.6 hm^(2)样地为研究对象,调查了样地内乔木生长及光强衰减状况,对林型、空间尺度及方位进行划分,采用移动窗口法分析不同空间尺度下森林群落结构对林下光强衰减的影响。【结果】吉林东部天然次生林乔木胸高断面积与林下光强衰减率相关性显著(P<0.01)。随着空间尺度增大,乔木胸高断面积与光强衰减率的相关系数逐渐增大,大部分林型在内侧窗口达到10 m×10 m时,光强衰减率与乔木胸高断面积显著正相关(P<0.01),在25 m×25 m尺度时相关系数最大,内侧窗口周围10 m内的乔木也与内侧窗口下的光强衰减率显著正相关(P<0.01)。东侧、南侧的树木对于内侧窗口下的光强衰减率影响比西侧、北侧影响更大。【结论】通过移动窗口法可以分析不同林型乔木对于林下光强衰减的影响范围,与耐阴树种相比,喜光树种乔木胸高断面积与光强衰减率在更多尺度下显著相关;在(10 m×10 m)~(40 m×40 m)的尺度范围内,多数林型乔木胸高断面积与光强衰减率显著正相关(P<0.01)。不同方位的乔木对于光强衰减的影响也存在差异。

【Objective】 The study explored the characteristics of light intensity attenuation among different forest types, spatial scales, and orientations of natural secondary forests in eastern Jilin Province, China. 【Method】 The tree growth and light intensity attenuation were investigated in five plots of 0.6 hm~2 each by dividing them according to forest types, spatial scales, and orientations, and the moving window method was then used to analyze the effect of forest community structure on understory light. 【Result】 In the natural secondary forests of eastern Jilin, the arbor basal area was significantly correlated with the understory light intensity attenuation rate(P<0.01). With increasing spatial scale, the correlation coefficient between the arbor basal area and light intensity attenuation rate also increased gradually. When the inner window of most forest types reached 10 m × 10 m, the light intensity attenuation rate was positively significantly related to the arbor basal area(P<0.01). The maximum correlation coefficient was at a scale of 25 m × 25 m. The presence of trees within 10 m of the inner window was also positively significantly related to the light intensity attenuation rate under the inner window(P<0.01). The trees on the east and south sides had a greater impact on the light intensity attenuation rate under the inner window than those on the west and north sides. 【Conclusion】 The moving window method can be used to analyze the range of influence exerted by different forest types on the light intensity attenuation. Light-loving tree species demonstrated a highly significant correlation between the arbor basal area and the light intensity attenuation rate at a greater range of scales than shade-tolerant species. In the scale range of(10 m×10 m)-(40 m×40 m), the arbor basal area of most forest-type trees was significantly positively correlated with the light intensity attenuation rate(P<0.01). Differences in the orientation of trees also affect the attenuation of light intensity.