Influence Of Forest Management Measures On Soil Faunal Communities In Larch Plantations

Larch(Larix principis-rupprechtii) plantation was the main forest ecotypes in north China. It plays an irreplaceable role in water conservation, biodiversity protection and forest ecosystem maintenance. But, constructing pure and single-layered forests caused soil degradation and unstable ecosystem. Scientific management measures not only enhance the productivity and stability of forest, but also improve the composition and properties of litter type. Forest managements also conducive to maintaining soil quality and higher diversity. Soil fauna is an important component in forest ecosystems, due to their functional role in nutrient cycling and decomposition of organic matter. The diversity of soil fauna can be used as bio-indicator for assessing forest environmental change. Stand structures and vegetation types would be changed by forest managements, and the corresponding soil faunal communities would be created. This master’s thesis researched the influences of different managements on soil faunal community structures, biodiversities and functional groups in the mountain area of Northern Hebei, the results would provide theoretical foundation and basic data to ecosystem restoration and sustainable management of plantations.The study was conducted in the larch plantation of the mountain area of Northern Hebei. Five forest managements were practiced(EC: Enclosure forest, M1: young even-aged larch and birch mixed forest, M2: uneven-aged larch and birch striped mixed forest, M3: selected cutting regeneration forest, UC: unenclosed forest) in 2007. Investigations on soil faunal composition, structure and distribution were conducted by using hand pick and Tullgren technique in 2013. Soil fauna was divided into four functional groups, saprophagous, predacity, phytophagous and omnivorous, based on their feeding habits. SPSS 18.0、forstat and CANOCO 5.0 were applied to compare and analysis the effect of different managements on community composition, structure, biodiversity, functional groups and seasonal dynamics of soil faunal. As the same time, combining with the survey of soil physicochemical properties to reveal the influence rule of different managements on soil fauna structure and biodiversity. The main results are as follows:(1) A total of 45 933 individuals were extracted and identified, belonging to 86 groups, 19 Orders, 7 Classes and 3 Phyla, including 1 995 macro-fauna specimens in 68 groups and 43 938 meso- and micro-fauna in 57 groups. Formicidae, Curculionidae, Nematocera, and Lumbricidae were dominant groups in the macro-fauna community, while Acarina and Collembola were dominant groups in the meso- and micro-fauna community(94.93%). Group numbers of macro-fauna(P = 0.001) and meso- and micro-fauna(P < 0.001) were significantly decreased with soil profile as well as density of meso- and micro-fauna. On the contrary, in 0—10 cm of macro-fauna density was significantly higher then litter layer and 10—20 cm layer(P < 0.05). Different groups also have specific vertical distribution. Predacity has the most group numbers(33), while the density rate of saprophagous was highest(96.68%).(2) Group numbers and density of soil fauna were increased in enclosure forest. Density of Acarina(P = 0.003) and Bostrychidae(P = 0.024) were increased significantly. Numbers of rare groups were increased, too. After enclosed, biodiversity index were enhanced. DG in July and September were significantly higher then UC. May showed the lowest group numbers, density, biodiversity indexes and were significantly of H、J in EC(P < 0.05). Group numbers showed significantly positive correlation with water content and total nitrogen. DG showed significantly positive correlation with water content.(3) Species composition and distribution of soil fauna were changed significantly after managing. The ratio of density of dominant species in macro-fauna community was rising, while in meso- and micro-fauna community was declining. After managing, group numbers of macro-fauna community increased significantly. Different managements showed different impacts on various soil faunal communities. Group numbers of soil fauna in M3(P = 0.002) and M2(P < 0.001) were significantly higher then that in M1 in July. Density of M3 was significantly lower than the other stands(P < 0.05) in September. Some rare groups had indicated function on managements. All the three management stands have higher H and DG compared with EC. To be specific, M1 had the maximum H and J in each month, and its J was significantly higher than EC(P = 0.031) and M3(P = 0.007) in May. M2 had the maximum of DG in average and July and September. And was significantly higher than EC(P = 0.003) and M1(P = 0.014) in July.(4) The distribution of functional groups was due to different managements. But beyond that, group numbers of four functional groups were higher in management stands, except group numbers of saprophagous in M1 were slightly less than EC. Group numbers of saprophagous, predacity, and phytophagous in M2 were significantly higher than EC(P < 0.05). After managing, density of phytophagous in September increased significantly(P < 0.05). After managing, DG indexes of saprophagous, predacity, and phytophagous were all higher than those in EC, and DG of predacity increased significantly(P < 0.05). The effects of managements on H and J of different functional groups were different. The maximum H and J of saprophagous was found in M1; the maximum H of predacity was found in M2; the maximum H of was found in M3. The minimum values were in M3, M1 and M2, respectively.(5) Seasonal dynamic of group numbers, density, functional groups, and biodiversity indexes of soil fauna were different in different managements. The maximum of group numbers were in July in EC and M2, while, in May in M1 and M3. Seasonal dynamic of density in M1 and M2 had the same trends as that in EC, and M3 had reverse trend. Some rare groups could be used as season indicater. Seasonal dynamic of H and J in management stands were reduced. DG was more sensitive to managements. The maximum of DG in EC was found in September, while in M2 it was significantly higher in July(P = 0.006). For four functional groups, density of saprophagous in May was significantly higher than September(P = 0.008) and July(P = 0.007) in M3. Group numbers of predacity in September were significantly higher than May(P < 0.05). The difference of predacity H in M2 and M3, J in M3 was significantly with different seasons. The effects of managements were larger on phytophagous, such as density in M1(P = 0.024), DG(P = 0.046) and density(P = 0.025) in M2, group numbers(P = 0.047) and DG(P = 0.020) in M3.(6) Physicochemical properties of soil were significantly influenced by forest managements. Soil bulk density was significantly decreased in management stands(P < 0.05). Correlation analyses showed that the distributions of soil fauna in litter layer were less influenced by soil physicochemical properties, except DG showed significantly correlations with organic matter. On the contrary, the distributions of soil fauna in soil layer was affected by soil physicochemical properties obviously. Redundancy Analysis(RDA) showed that soil fauna in soil layer were obviously correlated with soil bulk density(P = 0.002) and organic matter(P = 0.026). Staphylinidae, Cantharidae, and Thomisidae etc. tended to lower soil bulk density. Curculionidae, Phalangida etc. tend to higher organic matter. Geophilomorpha, Araneidae etc. which closely to the origin show widely adaptability to various soil environments.Through the research on soil faunal community of different managements of larch plantation, the results showed that enclose management was advantageous to the recovery of soil fauna by reducing soil bulk density as the decrease of human disturbance, and the group numbers, density and diversity of soil fauna increased in enclosed stands. Uneven-aged larch and birch striped mixed forest was advantageous to the development of soil fauna as the increased heterogeneity resulted by the introduction of birch and adjustment of forest structure reflected in the higher group numbers, density and diversity of soil faunal. Key words: soil fauna; Larch plantations; forest management measures; community...