Short-term effects of thinning on the understory natural environment of mixed broadleaf-conifer forest in Changbai Mountain area, Northeast China

Abstract

Background The understory natural environment is critical in affecting the succession and recovery process of vegetation, stand structure, and species composition of forest. The thinning intensity could significantly change the forest microclimates and soil properties, therefore, to analyze the effects of thinning intensity on the understory natural environment of forest is of important significance for promoting the ecological benefits of thinning. Methods A total of 16 fixed sample plots with different thinning intensities were established in the mixed broadleaf-conifer forest in Jiaohe, situated in Changbai Mountain area, Northeast China, and the forest microclimates and soil properties were investigated after 4 years since the establishment of the sample plots. Results The results showed that the high intensity thinning significantly decreased the leaf area index from 4.13 (unthinned plot) to 2.21 (high intensity thinned plot), and the air temperature was increased by thinning from May to July. Comparing with the unthinned plot, thinning caused a rise of temperature (ranging from 2.11 to 6.74 °C, depending on the intensity of thinning) in May. However, it showed cooling effect in September and October. Besides, the air moisture of thinning plots was lower than the control plot in May and October, when the density of leaves is lower in the forest, and it even decreased 20.27% after thinning. The thinning intensity had no significantly effect on water content and organic carbon in forest soils, and only the bulk density in the top-layer soils in high intensity thinning plot was remarkably increased. Total nitrogen in soil was increased by different intensities of thinning, and the availability of nutrients for nitrogen, phosphorus and potassium in some soils were also affected.

Effect of Forest Thinning on Soil Phosphorus Stocks and Dynamics on a Global Scale

“…(2) The sample size of broadleaf forests was very limited (only 27), which led to a limitation in our group analysis. (3) The change in soil P stocks is affected by litter, understory plant diversity, microbial activity, and other factors [23,36,43]. However, this study did not discuss the mechanism of soil P stock change from the perspective of environmental factors; therefore, it is necessary to strengthen the relevant research in the future to address this deficiency.…”

“…The forest soil nutrient content is an important part of terrestrial ecosystems, and is easily affected by forest thinning [35,36]. Research on the effects of thinning on soil P stocks and dynamics is of great significance for an in-depth understanding of soil nutrient cycling and sustainable forest management [9,37].…”