Effects Of Different Succession Stages Of Deciduous Pine Forest On Soil Habitat Quality In The Greater Xing'an Mountains

Soil is an indispensable substrate for forest growth.The effects of climate,vegetation and land cover on its physical and chemical properties have been paid more and more attention.As an ecological barrier in the northeast of China,the Greater Xing'an Mountains'forest region plays an important role in the material circulation and dynamic change of the global forest ecosystem.Taking forest succession and community development sequence(forest type and forest age)of the Greater Xing'an Mountains as the object,this paper systematically studied the changes of various habitat factors of forest soil,and analyzed the effects of succession or forest type transformation on soil habitat quality and habitat obstacle factors,in order to provide theoretical support for forest management and sustainable development of forestry.The results are as follows:(1)In the growing season,the soil water availability of different succession sequences is not limited.Soil nitrogen(N),phosphorus(P)availability,oxygen supply,temperature environment,acid and alkali environment,root standing and other habitat functions were shown to be lower in the succession sequence of wet and middle wet,and significantly higher in the intermediate sequence.In the same soil layer,the comprehensive habitat quality index(SQI)value of mesogenetic succession sequence was the highest,followed by the SQI value of mesogenetic succession sequence,and the SQI value of mesogenetic succession sequence was the lowest.(2)Soil water availability was not restricted in the early stage,pioneer stage and climax stage of different succession sequences,and there was no significant difference between different succession stages.The availability of soil N and the availability of o-layer P were significantly higher in the early stage and pioneer stage than in the climax stage,but there was no significant difference in the availability of mineral soil P in each succession stage.The potassium(K)availability of o-layer decreased successively from the early stage,pioneer stage to the climax stage,and there was no significant difference in the availability of mineral soil layer K in each succession stage.Soil habitat functions tend to deteriorate with the progression of succession to the top stage,so the SQI value of the top stage of different succession sequences is lower than that of the early stage and the pioneer stage,that is,the soil habitat quality tends to deteriorate with the progression to the top stage.(3)For the top-level stage of different succession sequences,the variation trend of different age segments was basically the same.There was no difference in water availability of different soil layers in different age groups.In the stage of young forest,soil N availability was relatively high.With the development of stand to medium age forest,near-mature forest and mature forest,soil N availability tended to decrease,while in the stage of over-mature forest,soil N availability tended to rise again.The change rule of soil P availability is similar to that of N,but less obvious than that of N.The variation trend of soil oxygen supply and soil temperature environment membership degree was similar to that of nutrients,that is,it was relatively high in the stage of young forest and overripe forest,and relatively low in the stage of mid-mature forest,near-mature forest and mature forest.The change of membership degree of soil acid-base environment is mainly reflected in the o-layer and the 0-10cm soil layer,and the change trend is similar to the nutrient,aeration and temperature environment.The comprehensive habitat quality index(SQI)and root standability of different soil layers at different forest ages also showed the highest at the young stage,and the lower at the middle,near and mature stage,and the higher at the overripe stage.