Characteristics Of Light Intensity Attenuation Under Natural Forest And Its Effect On Above-ground Shrub Biomass In Eastern Jilin

The purpose of this study was to explore the characteristics of light intensity attenuation among different forest types,different spatial scales,and different orientations and the characteristics of understory above-ground shrub biomass under natural secondary forests in eastern Jilin.Based on the tree data,light attenuation data,and understory above-ground shrub biomass data obtained from the survey of five 0.6 hm2 plots,different forest types,spatial scales,and orientations were divided,and the moving window method was used to analyze the impact of forest community structure on understory at different spatial scales.Effects of light intensity attenuation and forest community structure and understory light attenuation on understory above-ground shrub biomass.Research indicates:(1)In the natural secondary forest in eastern Jilin,the correlation between the arbor basal area and the understory light intensity attenuation rate was significant(P < 0.01).With the increase of the scale,the correlation coefficient between the arbor basal area and the light intensity attenuation rate gradually increased.When the inner window of most forest types reached 10 m × 10 m,the light intensity attenuation rate was significantly positively correlated with the arbor basal area(P < 0.01),the absolute value of the correlation coefficient increased with the increase of the scale and reaches a peak at the scale of 25 m × 25 m.The trees within10 m around the medial window were also significantly positively correlated with the light intensity attenuation rate under the medial window(P < 0.01).The goodness of fit of the linear regression model between the trees on the south and east sides and the light intensity attenuation rate is better than that on the north and west sides.(2)The absolute value of the correlation coefficient between the above-ground shrub biomass and understory light intensity attenuation rate increases with the scale increase(P <0.01).The correlation coefficient is always optimistic in the pure Larch forest,and the correlation coefficient gradually decreases to negative under the mongolica forest.And were consistently negatively correlated under other forest types(P < 0.01).The absolute value of the correlation coefficient between the biomass of understory shrubs and the sectional basal area increases with the increase of scale and tends to be stable at the scale of 25 m × 25 m.The influence range of trees is the same as the attenuation rate of light intensity.The goodness of fit of the linear regression model between the above-ground shrub biomass and the above-ground shrub biomass on the north and east sides was better than that on the south and west sides.The fitting results of multiple factors and understory above-ground shrub biomass were better than those of a single factor.The moving window method can be used to analyze the influence of different forest types’ dominant layer trees on the understory light intensity attenuation and understory above-ground shrub biomass.Correlations of above-ground shrub biomass were enhanced.For the light intensity attenuation and above-ground shrub biomass in the same range,the difference in orientation will also lead to differences in the goodness of fit between the model of arbor basal area and the above-ground shrub biomass.Exploring the effects of trees at different scales on the understory light intensity attenuation rate and above-ground shrub biomass will help to further improve the accuracy of understory environment simulation and provide guidance for actual production.