不同郁闭度控制下马尾松（Pinus massoniana）人工林土壤动物群落特征

采用郁闭度控制方法,形成马尾松人工林郁闭度梯度(0.5,0.6,0.7,0.8,0.9)试验样地,研究不同郁闭度下土壤动物群落特征。运用手捡法、Tullgren法和Baermann法进行土壤动物群落调查。结果显示,1)共捕获土壤动物8 860只,隶属于4门11纲25目111科,其中大型土壤动物589只,以蜚蠊、疣和康叭为优势类群;中小型土壤动物8271只,以等节和丽甲螨为优势类群。2)大型土壤动物以杂食性为主,杂食性在0.9郁闭度显著增加,捕食性显著减少;中小型土壤动物以菌食和腐食性为主,腐食性土壤动物随郁闭度增大逐渐增加,菌食性逐渐减少。中小型捕食性土壤动物在郁闭度0.5—0.7显著增加,0.7—0.9无显著变化。3)大型土壤动物仅5—10 cm土层类群数在0.9郁闭度显著增加;中小型土壤动物总个体数及枯落物层个体数、5—10 cm土层类群数显著增加(0.5—0.7)后减少(0.7—0.9);中小型土壤动物总类群数在郁闭度0.5—0.6显著增加,枯落层类群数在郁闭度0.5—0.8显著增加,0.8—0.9显著减少。4)大型、中小型土壤动物多样性在土层中差异显著。中小型土壤动物Simpson优势度指数随郁闭度增大而减小,Shannon-Wiener多样性指数、Pielou均匀性指数则显著增大,Margalef丰富度指数先显著增高(0.5—0.6)后趋于平稳(0.6—0.9);大型土壤动物Jaccard相似性指数低于中小型。5)CCA分析表明,不同类群土壤动物对环境因子响应不同,郁闭度、含水量、有机质及全P对土壤动物类群影响显著。研究表明,0.7郁闭度马尾松人工林下土壤动物优势度、丰富度适中,林下植被恢复情况较好,该郁闭度可能更有利于土壤动物多样性和群落稳定性。

Community characteristics of soil fauna for different canopy density of a Pinus massoniana plantation

Soil fauna is critical to the nutrient cycling, litter decomposition promoting and soil structure formation. The relationship between underground biota especially soil fauna and aboveground vegetation are beneficial to the forest ecosystem stability. Therefore, we studied the community structure of soil fauna in Pinus massoniana plantation controlled by different sized canopy density (proportion of the forest floor covered by the tree crowns'' vertical projection: 0.5, 0.6, 0.7, 0.8, 0.9). In October 2014, we used the hand picking up method, Tullgren funnel method and Baermann technique to collect macro, meso or micro soil fauna in the upper Yangtze River at Yibin. The results revealed that a total of 8860 individuals soil fauna were collected, belonging to 4 phyla, 11 classes,25 orders and 111 families. These include 588 macro individuals with Blattidae, Neanuridae and Campodeidae as the dominant species and with omnivorus as the main feeding habit. Besides, the rest of 8271 individuals were meso or micro fauna with Isotomidae and Liacaridae as the dominant species, the feeding habits were mainly fungivorous forms and saprozoic. Meanwhile, the percentage of macro omnivorous soil fauna increased significantly in 0.9 canopy density and predators decreased conversely. Soil fauna of meso or micro sized predators increased significantly in 0.5-0.7 canopy density and then had no significant change along with canopy density. The proportion of meso or micro saprozoic soil fauna increased significantly with canopy density increasing but opposite trend we found for fungivorous forms. In addition, canopy density treatments only impacted on the number of macro soil fauna groups, which significant increase in 0.9. With increasing canopy density, all of the total individuals, little layer individuals and 5-10 cm layer groups number of soil meso or micro fauna increased (0.5-0.7) and subsequently decreased (0.7-0.9) significantly. The total group number of meso or micro soil fauna increased in 0.5-0.6 canopy density. In litter layer the group number of meso or micro soil fauna also increased in 0.5-0.8 significantly and 0.8-0.9 decreased. We had also take diversity feature into consideration. The diversity value of macro, meso or micro soil fauna were significantly different with soil layer. Following the canopy density increased, the value of Simpson index of meso or micro soil fauna decreased although the Shannon-Wiener index and Pielou index were significantly increased. Simultaneously the Margalef abundance index were significantly higher firstly (0.5-0.6) and decreased (0.6-0.9) subsequently. Furthermore, macro soil fauna Jaccard similarity coefficient is lower than the meso or micro sized. Finally, the CCA (canonical correlation analysis) results showed that different response to environmental factors for different groups of soil fauna. Canopy density, moisture content, organic matter and total phosphorus have significant effects on these groups. So based on our research, we proposed that Pinus massoniana plantation with 0.7 canopy density has relatively abundant soil fauna diversity and stable community.