| Pinus massoniana is an important afforestation pioneer and timber tree species in southern my country,and it is also an important part of the ecological security barrier construction and forestry ecological economy in the upper reaches of the Yangtze River.Various ecological problems of inefficient Pinus massoniana plantation directly affect its overall service function.Therefore,comprehensively improving the overall service function of the low-efficiency artificial forest ecosystem of Pinus massoniana is an important part of the construction of the ecological safety barrier in the upper reaches of the Yangtze River and the forestry ecological economy.Forest gap reconstruction is an important measure to improve the overall service function of the degraded ecosystem of Pinus massoniana plantation.In order to reveal the response of soil animal communities in this process,7 forest gaps of different sizes(G1:10×10 m、G2:15×15 m、G3:20×20m、G4:25×25 m、G5:30×30 m、G6:35×35 m、G7:40×40 m)were selected and treated with Pinus massoniana pure forest as a control.Separation of small and medium-sized soil animals by wet and dry funnel method.Study the ecological characteristics of soil animal community composition,dominant groups,seasonal dynamics,vertical distribution,etc.,and on this basis,analyze the characteristics of soil animal diversity and functional groups,and the results showed:(1)There were 9 859 individuals of meso and micro-soil fauna,belonging to 5 phyla,18 classes,195 families.The dominant taxon is Nematoda.The common taxa are Formicidae,Poduridae,Nothridae and so on.(2)Forest gap reconstruction affected the horizontal distribution of small and medium-sized soil animals,among which G4,G5 and G6 significantly increased their average density(P<0.05).The group number of forest gap reconstruction treatment increased significantly(P<0.05).The horizontal distribution of the number of habitats and the number of groups shows obvious seasonal dynamics.The maximum average density occurs in summer,and the number of groups is more abundant in Autumn and Spring than in Summer and Winter.(3)The effects of different reconstruction measures on the vertical distribution and seasonal dynamics of soil animals in Pinus massoniana plantation were consistent.The average density was ranked as 0～5 cm layer>5～10 cm layer>10～15 cm layer>litter layer,which had obvious soil surface clustering characteristics.The ranking of group number was litter layer>0～5 cm layer>5～10 cm layer>10～15 cm layer.The average density and group number of small and medium-sized soil animals were significantly different among the four levels(P<0.01).The average density of the three soil layers was more in June(summer),while the litter layer was more in September(autumn).The litter layer group number changed most obviously with the season,while the 10～15 cm layer group number did not change significantly,indicating that the influence of season on the small and medium-sized soil animal group number decreased with the increase of depth.(4)Forest gap reconstruction treatment significantly increased the richness index of small and medium-sized soil animals(P<0.05).G4,G5,G6 and G7 significantly reduced the evenness index of small and medium-sized soil animals(P<0.05).G5 significantly improved the dominance index of small and medium-sized soil animals(P<0.05).However,the effect of forest gap reconstruction on the diversity index of small and medium-sized soil animals was not significant(P>0.05).Among them,G5 dominance index is the highest and evenness index is the lowest.(5)The diversity index,dominance index and richness index of shrub layer were all G4,G5,G6 and G7 higher than CK,G1,G2 and G3.The diversity index,dominance index and richness index of herb layer were all the highest with G4.The evenness index of CK was the highest,and the difference between the evenness index of different treatments was not significant(P>0.05).The results showed that the transformation area of 625～900 m~2had a positive effect on the enrichment of undergrowth vegetation.At the same time,the diversity index of soil animals collected from the 625～900 m~2 transformed area was relatively large,among which nematodes were the most obvious,indicating a positive correlation between soil animal diversity and plant diversity.(6)There was an incomplete correlation between the physical and chemical properties of soil,among which,the total nitrogen content of soil was positively correlated with the organic carbon content,total phosphorus content and soil bulk density(P<0.05),while the soil bulk density was negatively correlated with the soil water content(P<0.01).Small and medium-sized soil animal density was significantly correlated with soil p H value(P<0.05),and was significantly correlated with the number of soil animal groups(P<0.01),while other indicators were not significantly correlated with soil animal(P>0.05).In summary,the meso and micro-soil faunal community investigated in this experiment are rich in groups and large in number of individuals.Forest gap reconstruction measures have an effect on the community structure of small and medium-sized soil animals,and also on plant diversity and soil physical and chemical characteristics.Among them,G5 has the greatest influence on the transformation of Pinus massoniana plantation,which is the most stable and the best improvement measure. |
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