| Pinus massoniana is the main afforestation tree species in the hilly areas of the upper reaches of the Yangtze River.Long-term single pure forest management has caused ecological problems such as soil fertility decline and forest ecological function decline,which seriously affects the sustainable development of forests.This study selects 7 masson pine plantation forest oil camphor patches with different area scales in Yibin area as the research object.Using the method of soil chemical analysis,the soil aggregate organic carbon,soluble organic carbon,and easy to oxidize in different area of forest gap patches are determined.The content of organic carbon,microbial biomass carbon,ammonium nitrogen and nitrate nitrogen.At the same time,soil animals were collected in the field,and the soil animals were separated by dry funnel separation method to study the composition,density and number of soil animal communities in different forest gap areas.The impact of diversity,and the relationship between soil animals and soil nutrients.Research indicates:(1)Replanting Cinnamomum camphora after the gap is formed can increase the proportion of large aggregates in the soil and reduce the acidity of the soil.Patch area,patch location and particle size have significant effects on dissolved organic carbon,easily oxidizable organic carbon,organic carbon,and nitrate nitrogen;patch area and patch location have significant effects on microbial biomass carbon content;patches The area and particle size have a significant effect on the content of ammonium nitrogen.(2)The edge of the small gap patch(G2)and the center of the middle patch(G4)have the highest soil organic carbon content;the edge of the small gap patch(G2)and the large gap patch(G6,G7)Has the highest soluble carbon content in the central soil,and organic carbon and soluble carbon tend to accumulate in micro-aggregates.The microbial biomass carbon content is higher in the edges of medium-sized canopy gap patches(G4)and the center of small canopy gap patches(G2),and the microbial carbon content is higher in large aggregates in the center of large canopy gap patches.(3)In general,the content of soil ammonium nitrogen is higher than that of nitrate nitrogen.The patch area and particle size have a significant effect on the content of soil ammonium nitrogen and nitrate nitrogen.The larger the patch area,the more ammonium nitrogen in the soil.The higher the content of nitrate and nitrate nitrogen,and both are higher than those under the forest.The content of soil nitrate nitrogen is the highest in the middle of the middle canopy patch(G4)and the edge of the large canopy patch(G7),and the content is in the micro aggregate Higher,the content of soil ammonium nitrogen in each canopy patch decreases with the increase of the particle size.(4)A total of 2,629 soil animals were collected in the wild,belonging to 2 phyla,8 classes and 18 orders.Among them,G2 has the highest soil animal density,G4 has the most abundant soil animal population,and the large forest gap patch(G7)has the highest soil animal diversity index,evenness index and richness index.According to the analysis of grey correlation method,soil p H and water content contribute the most to the distribution of soil animal density and group number.Replanting Cinnamomum camphora in forest gaps can better improve soil quality and soil fertility.Small gap patches(G2:225 m~2)and medium gap patches(G4:625 m~2)can improve soil fertility and soil animals.The community construction effect is good.It is recommended that the window area be set to 225 m~2or 625 m~2,and the masson pine cluster-like mixed mode should be constructed by replanting oil camphor to promote the management of the pure masson pine plantation. |
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