| Larch(Larix principis-rupprechtii)is one of the main tree species in subalpine forest types in the warm temperate zone of China,which is widely distributed in North China.To study forest soil physicochemical properties,soil nutrient and microbial characteristics of natural larix principis-rupprechtii with different stand densities has great significance for realizing sustainable management of Larix principis rupprechtii natural forest and improving the speed and quality of natural forest restoration and maintaining the stability of forest ecosystem in North China.This paper compared the soil physical and chemical properties,soil microbial biomass carbon and nitrogen,and soil respiration of natural larix principis-rupprechtii with different stand densities in the Mount Wut ai area by using plot investigation and sampling analysis methods.In order to provide a reference for sustainable management of natural larix principis-rupprechtii in Mount Wutai area from the perspective of soil nutrient and sustainable management of forest ecosystem.The characteristics of soil physical properties,nutrients,microbial biomass carbon and nitrogen and soil respiration in different stand densities of natural larix principis-rupprechtii forests were further analyzed.The main results of the research are as follows:(1)Soil bulk density,soil porosity and soil moisture content in the soil under natural larix principis-rupprechtii forests in the range of 0--30cm are not significant,but the bulk dcensity of the surface soil is slightly higher than that of the middle and the bottom.Soil p44,soil total carbon,total nitrogen,total phosphorus,ammonium nitrogenand microbial biomass carbon and nitrogen decreased with the increase of soil depth.There was no significant difference between soil nitrate nitrogen in soil layer,but also decreased with the increase of soil depth.In the mature and stable natural larix principis-rupprechtii forests,there is no significant difference in soil physical properties of 0-30cm under forest due to the long-term effect of Larix principis rupprechtii root distribution on soil.(2)Soil bulk density,soil total carbon and nitrate nitrogen contents in natural larix principis-rupprechtii forests showed a trend of increasing first and then decreasing in the density range of 576 plant·hm-2-1568 plant·hm-2.The corresponding soil porosity shows a trend of decreasing and then increasing.Soil water content,pH value,total phosphorus,ammonium nitrogen,microbial biomass carbon and nitrogen content and soil respiration did not show a significant change on the whole.The total nitrogen content of soil has a less trend with the increase of the stand density.The carbon fixed level and nitrogen release ability in the soil under natural larix principis-rupprechtii forests with medium density were higher.(3)By calculating the main component score in the system,the order of soil quality evaluation of 9 different stand densities in the natural larix principis-rupprechtii forests was obtained:896 plant·hm-2>1072 plant·hm-2>576 plant·hm-2>1312 plant·hm-2>848 plant·hm-2>656 plant·hm-2>1488 plant·hm-2>1568 plant·hm-2>1216 plant·hm-2.The stand density of relatively high soil quality was 896 plant·hm-2—1072 plant·hm-2.The soil condition of natural larix principis-rupprechtii forests with medium density is better than that of Larix principis rupprechtii natural forest with low and high density in the density range of 576 plant·hm-2-1568 plant·hm-2. |
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