A review on the eco-geography of soil fauna in China

This review summarizes main research findings in soil fauna eco-geography in China in the past 30 years. The subject areas and main results were overviewed including biodiversity and eco-geological distribution of soil fauna communities. Studies of ecological distributions of soil fauna and dynamic ranges in space from tropical, subtropical to temperate regions, and in categories from forest, grassland, desert, wetland, farmland to urban ecosystems, the responses and indications of soil fauna to soil environments. Effects of intensive disturbance such as fire, grazing, farming, fertilization on soil fauna include sensitive （e.g. nematode） and rare groups and community indexes. The functions of soil fauna were discussed including environmental construction, environmental purification, litter decomposition and elements cycling. Interactions between soil fauna and other biota in soil ecosystems and linking between aboveground and belowground diversity and the effects of global change on soil fauna community in China were also included. Finally, the authors pointed out common interests in soil fauna eco-geographical studies, which include application of molecule biology into soil fauna taxa; function and mechanism of soil fauna community diversity; interaction between aboveground and belowground ecosystems; effects of disturbance, pollution, biological invasion, and global change on soil fauna community and function. The review is to provide a scientific basis for promoting soil fauna eco-geographical studies in China.

Response of soil fauna to simulated nitrogen deposition: A nursery experiment in subtropical China

We studied the responses of soil fauna to a simulated nitrogen deposition in nursery experimental plots in Subtropical China. Dissolved NH4NO3 was applied to the soil by spraying twice per month for 16 months, starting January 2003 with treatments of 0, 5, 10, 15 and 30 gN/（m^2·a）. Soil fauna was sampled after 6, 9, 13 and 16 months of treatment in three soil depths （0-5 cm, 5-10 cm, 10-15 cm）. Soil available N increased in correspondence with the increasing N treatment, whereas soil pH decreased. Bacterial and fungal densities were elevated by the N treatment. Soil fauna increased in the lower nitrogen treatments but decreased in the higher N treatments, which might indicate that there was a threshold around 10 gN/（m^2·a） for the stimulating effects of N addition. The N effects were dependent on the soil depth and sampling time. The data also suggested that the effects of the different N treatments were related to the level of N saturation, especially the concentration of NO3^- in the soil.

Preliminary Response of Soil Fauna to Simulated N Deposition in Three Typical Subtropical Forests

A field-scale experiment arranged in a complete randomized block design with three N addition treatments including a control (no addition of N), a low N (5 g m-2 year-1), and a medium N (10 g m-2 year-1) was performed in each of the three typical forests, a pine (Pinus massoniana Lamb.) forest (PF), a pine-broadleaf mixed forest (MF) and a mature monsoon evergreen broadleaf forest (MEBF), of the Dinghushan Biosphere Reserve in subtropical China to study the response of soil fauna community to additions of N. Higher NH4+ and NO3- concentrations and a lower soil pH occurred in the medium N treatment of MEBF, whereas the NO3- concentration was the lowest in PF after the additions of N. The response of the density, group abundance and diversity index of soil fauna to addition of N varied with the forest type, and all these variables decreased with increasing N under MEBF but the trend was opposite under PF. The N treatments had no significant effects on these variables under MF. Compared with the control plots, the medium N treatment had significant negative effect on soil fauna under MEBF. The group abundance of soil fauna increased significantly with additions of higher N rates under PF. These results suggested that the response of soil fauna to N deposition varied with the forest type and N deposition rate, and soil N status is one of the important factors affecting the response of soil fauna to N deposition.

Dynamics and Relationships of Ca,Mg,Fe in Litter,Soil Fauna and Soil in Pinus koraiensis-Broadleaf Mixed Forest

The Liangshui Natural Reserve in Heilongjiang Province of China was selected as the study area. The authors collected the samples of forest litter （Tilia amurensis, Fraxinus mandshurica, Pinus koraiensis, Acer mono, Betula costata, and mixed litter）, soil in humus horizon （0--5cm） and soil horizon （5-20cm）, and soil macrofauna （Oligochaeta, Geophiloporpha and Juliformia） from 2001 to 2002. The role of soil macrofauna in the material cycle was analyzed through comparing the macro-element contents among various parts of the subsystems and using enrichment index （El）. The results indicate that dynamic changes of various litters are very complicated. The contents of Fe in each kind of litter increase firstly, and then decrease in the study period. The changes of macro-element contents are greater in the broad-leaf litter than in the coniferous litter, and the mixed litter is in the middle level, but the differences among them are not significant. The contents of Mg and Fe in humus are higher than those in soil, but the contents of Ca in soil are higher than that in humus. The dynamic changes of macro-element contents in soil and soil fauna are not consistent with those in litter. The diplopod presented obvious enrichment of Ca and Mg （E1〉1）, but it does not significantly enrich Fe. Earthworm has a stronger enrichment ability of Fe than diplopod and scolopendra, but E1〈1. Soil fauna can make great influences on the material cycle of the subsystems.

Differentiation of Soil Fauna Populations in Conventional Tillage and No-Tillage Red Soil Ecosystems

In a field experiment, the populations of major soil fauna groups including earthworms, enchytraeids,arthropods and nematodes were examined in conventional tillage (CT) and no-tillage (NT) red soil ecosystems to evaluate their responses to tillage disturbance. Earthworms, macrry and micro-arthropods were stimulated under NT with earthworms showing the highest population increase by four times, while enchytraeids and nematodes favored CT system, predicting certain adaptability of these animals to plow-disturbed soil environment. On the basis of relative response index it was found that soil fauna was more sensitive to tillage than soil resource base (C and N pools) and microflora. The population structure of soil fauna was also affected by tillage treatments. Analysis on nematode trophic groups showed that bacteria-feeding and plant parasitic nematodes were more abundant in CT soil whereas the proportions of fungivores and omnivorepredators increased in NT soil. Possible reasons for the differentiation in both size and structure of the fauna population were discussed and the ecological significance involved in these changes was emphasized.

Impacts of Soil Fauna on Litter Decomposition at Different Succession Stages of Wetland in Sanjiang Plain,China

Litter decomposition is the key process in nutrient recycling and energy flow. The present study examined the impacts of soil fauna on decomposition rates and nutrient fluxes at three succession stages of wetland in the Sanjiang Plain, China using different mesh litterbags. The results show that in each succession stage of wetland, soil fauna can obviously increase litter decomposition rates. The average contribution of whole soil fauna to litter mass loss was 35.35%. The more complex the soil fauna group, the more significant the role of soil fauna. The average loss of three types of litter in the 4mm mesh litterbags was 0.3-4. l times that in 0.058ram ones. The decomposition function of soil fauna to litter mass changed with the wetland succession. The average contribution of soil fauna to litter loss firstly decreased from 34.96% （Carex lasiocapa） to 32.94% （Carex rneyeriana）, then increased to 38.16% （Calamagrostics angustifolia）. The contributions of soil fauna to litter decomposition rates vary according to the litter substrata, soil fauna communities and seasons. Significant effects were respectively found in August and July on C. angustifolia and C. lasiocapa, while in June and August on C. meyeriana. Total carbon （TC）, total nitrogen （TN） and total phosphorus （TP） contents and the C/N and C/P ratios of decaying litter can be influenced by soil fauna. At different wetland succession stages, the effects of soil fauna on nutrient elements also differ greatly, which shows the significant difference of in- fluencing element types and degrees. Soil fauna communities strongly influenced the TC and TP concentrations of C. meyeriana litter, and TP content of C. lasiocapa. Our results indicate that soil fauna have important effects on litter decomposition and this influence will vary with the wetland succession and seasonal variation.

Contribution of soil fauna to the degradation of recalcitrant components in Cinnamomum camphora foliar litter in different-sized gaps in Pinus massoniana plantations

Forest gaps are important in forest dynamics and management, but little is known about how soil fauna influence the degradation of recalcitrant litter components in different-sized forest gaps. This investigation uses litterbags with two different mesh sizes (0.04 and 3 mm) to control the meso- and microfauna entering the bags to quantify the contribution of soil fauna to the degradation of recalcitrant components (including condensed tannins, total phenol, lignin and cellulose) during litter decomposition. The experiment was conducted in seven different forest gap sizes in Pinus massoniana plantations over 1 year. One closed-canopy site (CC) and forest gap sizes of 100, 225, 400, 625, 900, 1225 and 1600 m^2 were created in a P. massoniana plantation in the Sichuan basin of China;the CC was treated as the control. Cinnamomum camphora foliage from local native trees was used in all forest gap experiments. We found the following:(1) Gap size had significant effects on the degradation rates (E) of condensed tannins and lignin and on the contributions of soil fauna;medium-sized gaps also presented high degradation rates. Soil fauna obviously contributed to the degradation of recalcitrant foliar litter components in medium-sized gaps.(2) The highest contribution to degradation (40.98%) was recorded for lignin, and the lowest contribution (0.29%) was recorded for condensed tannins. The results indicate that medium-sized gaps (900 m^2) were conducive to the degradation of recalcitrant litter components by soil fauna.

Effects of gap size on diversity of soil fauna in a Cunninghamia lanceolata stand damaged by an ice storm in southern China

Cunninghamia lanceolata （Lamb.） Hook. is economically the most important tree species in southern China and has been cultivated in plantations on a large scale. This species is widely used in construction, furniture, utensils and shipbuilding. Soil fertility of C. lanceolata stands affects soil structure, porosity and nutrient availability, which causes changes in fauna activity. During January to February 2008, an ice storm caused extensive damage to C. lanceolata stands. Despite the environmental importance of soil fauna, basic information on the distribution and diversity of soil fauna in C. lanceolata stands after ice storm damage is lacking. To assess the response of soil fauna diversity and distribution to forest gaps following the ice storm, five small gaps （each 30-40 m^2）, five large gaps （each 80-100 m^2） and five canopy cover plots were selected within a 2-ha C. lanceolata stand. Soil samples were collected from 0 to 10 cm depth in March 2011 to measure soil fauna diversity and abundance. The abundance and community composition of the soil fauna varied with gap size. In canopy cover sites, the number of individuals was 2.0 and 5.2 times greater than in the small gaps and large gaps. Three taxa （Nematoda, Oribatida and lnsecta） of soil inver- tebrates occurred commonly, and Nematoda dominated the communities in all three habitat types. The Shannon-Wiener diversity index, Margalef diversity index, and Pielou evenness index were high in the small gaps, indicating that they harbored the most species, with the most even distribution, and the highest diversity. Our results indicated that gap size apparently affected abundance and community composition of the soil fauna.

Effects of of Habitats and Pesticides on Aerobic Capacity and Survival of Soil Fauna

Objective Faunal health is largely dependent on their soil environment and available litter quality. So the effects of different soil habitats and pesticides on citrate synthase (CS) activity of soil fauna and its population were studied. Methods The soil animals were collected from different pedoecosystems for habitat study. Whereas Vigna radiata based system was selected for pesticidal observations. The field was divided into five equal plots for control and treatment of γ-BHC, quinalphos, carbaryl and cypermethrin. Soil fauna was collected by quadrat method and extracted by Tullgren funnel. Individuals of a species having similar sizes were collected for the estimation of CS activity. They were homogenized and fractions were obtained by differential centrifugation. The activity of CS was assayed spectrophotometrically. Results Citrate synthase (CS) activity of beetle (Rasphytus fregi), woodlouse (Porcellio laevis) and centipede (Scolopendra morsitans) varied significantly with respect to changes in different soil habitats. Though the CS activity of R. fregi, P. laevis, and S. morsitans differed among themselves but the highest activity of CS in these animals was in V. radiata and lowest in A. nilotica based pedoecosystem. The aerobic capacity of centipede was maximum followed by woodlouse and beetle. The treatment of γ-BHC, quinalphos, carbaryl and cypermethrin significantly reduced the CS activity of these animals. γ-BHC showed maximum reduction in CS activity indicating highly toxic effect of organochlorine on aerobic metabolism of soil fauna. However, minimum reduction was observed in response to carbaryl (in beetle) or cypermethrin (in woodlouse/centipede) leading to impairment of aerobic capacity. The differences in pesticide effects might be assigned to the differences in chemical nature of pesticides and their interactions with below-ground fauna. Treatment of γ-BHC and quinalphos reduced the population of Acari, Coleoptera, Collembola, other arthropods as well as total soil fauna. Acari was least affected by γ-BHC and maximally affected (72%) in response to quinalphos. The effect of γ-BHC was fairly similar on Coleoptera, Collembola, other arthropod and total soil fauna suggesting almost similar sensitivity to this pesticide. Likewise, quinalphos was similarly effective on Collemobola and other soil arthropods. Application of carbaryl decreased Acari and Coleoptera population but increased Collembola, other arthropods and total faunal populations. However, application of cypermethrin significantly reduced the population of Acari, Coleoptera, Collembola and total soil fauna and increased the population of other soil arthropods. In both the cases, acarine population was least affected. Conclusion The observations show the habitat-specific variation in aerobic capacity of soil fauna. However, pesticide-dependent loss in population might be due to impairment of aerobic capacity of soil inhabiting animals in desert.

Responses of Soil Fauna Structure and Leaf Litter Decomposition to Effective Microorganism Treatments in Da Hinggan Mountains,China

Microorganisms are nutritious resources for various soil fauna.Although soil fauna grazing affects microorganism composition and decomposition rate,the responses of soil fauna and leaf litter decomposition to added microorganism is little understood.In this study,in the coniferous and broad-leaved mixed forest of Tahe County in the northern Da Hinggan Mountains,China,three sampling sites(each has an area of 10 m2) were selected.The first two sites were sprinkled with 250 times(EM1) and 1000 times(EM2) diluted effective microorganism(EM) preparations evenly,and the third site was sprinkled with the same volume of water as a control site.The responses of soil fauna structure and leaf litter decomposition to EM treatment were conducted during three years.The results revealed that EM treatment resulted in significant increase of soil organic matter.The number of soil fauna in the EM1 and EM2 sites increased by 12.88% and 2.23% compared to the control site,and among them springtails and mites showed the highest increase.However,the groups of soil fauna in the EM1 and EM2 sites decreased by 6 and 9,respectively.And the changes in the diversity and evenness index were relatively complicated.EM treatment slowed the decomposition of broad-leaved litter,but accelerated the decomposition of coniferous litter.However,the decomposition rate of broad-leaved litter was still higher than that of coniferous litter.The results of this study suggested that the added microorganisms could help individual growth of soil fauna,and this method led to a change in the process of leaf litter decomposition.This paper did not analyze the activity of soil microorganisms,thus it is difficult to clearly explain the complex relationships among litter type,soil fauna and soil microorganisms.Further research on this subject is needed.

The Diversity of Soil Fauna Communities in the Karst Cave Wetland of Maolan Nature Reserve

From March 2014 to February 2015, the soil fauna community in the karst cave wetland of Maolan Nature Reserve was investigated. A total of 3,820 soil fauna was obtained, belonging to 31 orders, 11 classes, and 3 phyla. The dominant groups were Araneae, Coleoptera and Hymenoptera, accounting for 48.90% of the total catch. There were 18 common groups and 10 rare groups. The diversity analysis showed that the Banzhai karst cave wetland had the largest soil fauna community diversity index and evenness index and that the Dongsai karst cave wetland had the largest number of groups and individuals. The seasonal variation of the soil fauna in the karst cave wetlands was analyzed: the number of soil fauna individuals showed a downtrend in summer, autumn, spring and winter; there were the highest number of phytophagous soil fauna, followed by predatory soil fauna and saprophagous soil fauna.

Impact of Long-Term Fertilization on Cropland Soil Fauna Community at Loess Soil, Shannxi, China

The relationship between long-term fertilization and cropland network for soil fertility and fertilizers in Loess soil of Shannxi soil fauna was studied at the station＇s experiment research Provincefrom Jul. 2001 to Oct. 2002. Six types of long-term fertilizer were carried out for this study including non-fertilizer （CK）, abandonment （ABAND）, nitrogenous and phosphors and potassium fertilizers combined （NPK）, straw and NPK （SNPK）, organic material and NPK （MNPK） and 1.5 times MNPK （1.5MNPK）. 72 soil samples were collected and 5 495 species of cropland soil fauna obtained by handsorting and Cobb methods at 4 times, belonging to 6 Phyla, 11 Classes, 22 Orders, 2 Superfamilies, 61 Families and 35 Genera. The result showed that different fertilizer had significantly impacted on the cropland soil fauna （F = 2.24, P〈0.007）. The number of the cropland soil fauna was related to the soil physicochemical properties caused by long-term fertilization. The result by principal component analysis, focusing on the number of 15 key soil fauna species group＇s diversity, evenness of community and the total soil fauna individuals indicated that the effects of SNPK, NPK, MNPK and 1.5MNPK were significantly different from that of the cropland soil fauna, in which, SNPK and NPK had the positive effect on cropland soil fauna, and MNPK and 1.5 MNPK had the negative affect, others could not be explained. By principal component I, the synthetic effect of different fertilization on the total soil fauna individuals and the group was most significant, and the effect was little on evenness and diversity. By value of eigenvectors, the maximum one was 9.6248, and the minimum one was - 1.0904, that means the 6 types of fertilization did not affect evenly the cropland soil fauna.

Leaf litter and crop residue decomposition in ginkgo agroforestry systems in eastern China: Soil fauna diversity and abundance,microbial biomass and nutrient release

The response of soil fauna to the litter decomposition process has received considerable attention,but this effect has not been fully examined in agroforestry systems.A 1-year in situ decomposition experiment was carried out in a pure ginkgo plantation and two ginkgo agroforestry systems using a litterbag method(11 different treatments were tested in three systems).We found that the application of different organic materials(crop residues)produced positive effects on the number of soil fauna in the ginkgo planting systems;the mixture of ginkgo leaves and corn leaves was the best performing treatment.Collembola and Acarina were the predominant groups in the litter bags and were mainly responsible for the differences among the treatments.Litter mixing promoted the abundance,richness,and diversity of soil fauna,and significant differences regarding the Shannon–Wiener index of the soil fauna were observed among the 11 treatments in July.Significantly higher soil MBC(microbial biomass carbon)and MBN(microbial biomass nitrogen)were observed in agroforestry systems than in pure ginkgo plantations.These results suggest that the practice of intercrop residue application plays an important role in enhancing soil ecosystem function in ginkgo agroforestry systems and may ultimately contribute to sustainable intercrop production,soil fertility,and local economic diversity.

Fauna-associated Changes in Chemical and Biochemical Properties of Soil

Objective To study the impacts of abundance of woodlice, termites, and mites on some functional aspects of soil in order to elucidate the specific role of soil fauna in improving soil fertility in desert. Methods Fauna-rich sites were selected as experimental sites and adjacent areas were taken as control, Soil samples were collected from both sites. Soil respiration was measured at both sites. The soil samples were sent to laboratory, their chemical and biochemical properties were analyzed. Results Woodlice showed 25% decrease in organic carbon and organic matter as compared to control site. Whereas termites and mites showed 58% and 16% decrease in organic carbon and organic matter. In contrast, available nitrogen （nitrate and ammonical both） and phosphorus exhibited 2-fold and 1.2-fold increase, respectively. Soil respiration and dehydrogenase activity at the sites rich in woodlice, termites and mites produced 2.5-, 3.5- and 2-fold increases, respectively as compared to their control values. Fauna-associated increase in these biological parameters clearly reflected fauna-induced microbial activity in soil. Maximum decrease in organic carbon and increase in nitrate-nitrogen and ammonical-nitrogen, available phosphorus, soil respiration and dehydrogenase activity were produced by termites and minimum by mites reflecting termite as an efficient soil improver in desert environment. Conclusion The soil fauna-associated changes in chemical （organic carbon, nitrate-nitrogen, ammonical-nitrogen, phosphorus） and biochemical （soil respiration, dehydrogenase activity） properties of soil improve soil health and help in conservation of desert pedoecosystem.

Effects of soil fauna on leaf litter decomposition under different land uses in eastern coast of China

Soil fauna decompose litter, whereas land use changes may significantly alter the composition and structure of soil fauna assemblages. However, little is known of the effects of land-use on the contribution of soil fauna to litter decomposition. We studied the impacts of soil fauna on the decomposition of litter from poplar trees under three different land uses （i.e. poplar-crop integrated system, poplar plantation, and cropland）, from December 2013 to December 2014, in a coastal area of Northern Jiangsu Province. We collected litter samples in litterbags with three mesh sizes （5, 1 and 0. 01 mm, respectively） to quantify the contribution of various soil fauna to the decomposition of poplar leaf litter. Litter decomposition rates differed significantly by land use and were highest in the cropland, intermediate in the poplar-crop integrated system, and lowest in the poplar plantation. Soil fauna in the poplar-crop integrated system was characterized by the highest numbers of taxa and individuals, and highest Margalef＇s diversity, which suggested that agro-forestry ecosystems may support a greater quantity, distribution, and biodiversity of soil fauna than can single-species agriculture or plantation forestry. The individuals and groups of soil fauna in the macro-mesh litterbags were higher than in the meso-mesh litterbags underthe same land use types. The average contribution rate of meso- and micro-fauna to litter decomposition was 18.46%, which was higher than the contribution rate of macro-fauna （3.31%）. The percentage of remaining litter mass was inversely related to the density of the soil fauna （P 〈 0.05） in poplar plantations; however, was unrelated in the poplar-crop integrated system and cropland. This may have been the result of anthropogenic interference in poplar-crop integrated systems and croplands. Our study suggested that when land-use change alters vegetation types, it can affect species composition and the structure of soil fauna assemblages, which, in turn, affects litter decomposition.

Responses of soil fauna community under changing environmental conditions

Soil faunas account for 23%of known animal species and play a crucial role in ecosystem processes such as mineralizing nutrients,regulating microbial community composition,forming soil aggregates,and enhancing primary productivity.However,due to global climate change,population density,community composition,and distribution patterns of soil fauna vary.Understanding the responses of soil fauna to major environmental change facilitate the conservation of biodiversity.Therefore,a review work of recent researches for analysing the effects of key environmental factors on soil fauna,such as warming,drought,food quality,and soil physical-chemical properties was studied.For most species,warming may exert a positive effect on their abundance and population development,however,it can inhibit the survival and reproduction of hibernating species.Drought leads to low soil porosity and water holding capacity,which reduces soil fauna population and changes their community composition.Drought also can reduce the coverage of flora and alter microclimate of the soil surface,which in turn indirectly reduces fauna abundance.Climate warming and elevated atmospheric carbon dioxide can reduce litter quality,which will force soil fauna to change their dietary choices(from higher-quality foods to poor quality foods)and reduce reproduction for survival.However,it is still predicted that enhanced species richness of plant(or litter)mixtures will positively affect soil fauna diversity.Habitat loss caused by the deterioration of soil physical-chemical property is primary factor affecting soil fauna.We mainly discuss the threats of increased salinity(a major factor in arid land)to soil fauna and their potential responses to anthropogenic disturbance in saline soils.The increase in soil salinity can override other factors that favour habitat specialists,leading to negative effects on soil fauna.Moreover,we find that more studies are needed to explore the responses of soil fauna in saline soils to human activities.And the relationship of important ecological processes with soil fauna density,community structure,and diversity needs to be redefined.

Impacts of Micro- and Nano-Plastics on Soil Properties and Plant Production in Agroecosystems: A Mini-Review

Micro- and nano-plastics (MNPs) are tiny plastic particles resulting from plastic product degradation. Soil MNPs have been identified as potential influential factors affecting various soil properties and crop biomass productivity. This mini-review provides a synthesis of recent findings concerning their effects on soil physicochemical properties, microorganisms, organic carbon content, soil nutrients, greenhouse gas emissions, soil fauna, and their impacts on plant ecophysiology, growth, and production. The results indicate that MNPs may markedly impede soil aggregation ability, increase porosity, decrease soil bulk density, enhance water retention capacity, influence soil pH and electrical conductivity, and escalate soil water evaporation. Exposure to MNPs may predominantly induce changes in soil microbial composition, reducing the diversity and complexity of microbial communities and microbial activity while enhancing soil organic carbon stability, influencing soil nutrient dynamics, and stimulating organic carbon decomposition and denitrification processes, leading to elevated soil respiration and methane emissions, and potentially decreasing soil nitrous oxide emission. Additionally, MNPs may adversely affect soil fauna, diminish seed germination rates, promote plant root growth, yet impair plant photosynthetic efficacy and biomass productivity. These findings contribute to a better understanding of the impacts and mechanistic foundations of MNPs. Future research avenues are suggested to further explore the impacts and economic implications.

毛竹林扩张后土壤动物群落及与土壤细菌多样性的关系

为探究毛竹(Phyllostachys edulis)扩张过程中,土壤动物群落结构的变化特征,以凤阳山地区毛竹向杉木(Cunninghamia lanceolata)林扩张不同阶段的林分为研究对象,采用Tullgern干漏斗法对土壤动物进行分离,并调查其功能种团和分布密度,分析土壤动物与土壤理化性状、土壤细菌多样性之间的关系。结果表明:长期扩张演替形成的毛竹林中,腐食性土壤动物和植食性土壤动物的分布密度显著高于未受侵入的杉木林。土壤有机碳质量分数在林地扩张形成混交林后显著提高,但林地演替为毛竹纯林后,又会显著降低,而毛竹林地中土壤pH显著高于杉木林和混交林。林地中土壤pH及有效磷质量分数等指标与蜱螨目(Acarina)中气门亚目(Mesostigmata)、前气门亚目(Prostigmata)呈正相关关系,土壤有机碳质量分数与蜱螨目甲螨亚目(Oribatida)、鞘翅目(Coleoptera)等土壤动物均呈显著负相关,但与弹尾目(Collembola)等节跳科(Isotomidae)呈显著正相关。土壤动物优势类群甲螨亚目、中气门亚目在毛竹林分布较多,且与土壤细菌多样性指数呈显著正相关,而等节跳科在竹-杉混交林分布较多。甲螨亚目与norank_f__norank_o__Rokubacteriales属、norank_f__norank_o__norank_c__TK10属、芽孢杆菌属(Bacillus)、norank_f__Gemmatimonadaceae属均呈显著正相关,而等节跳科与norank_f__norank_o__Elsterales属等土壤肥力相关的细菌呈显著正相关。土壤动物分布密度与其生境条件密切相关,毛竹向杉木林的长期扩张有利于林地中土壤动物的生存和活动。

关帝山杨桦混交林土壤动物功能群海拔梯度分布格局及其环境驱动因素

为探究关帝山不同海拔梯度下杨桦混交林土壤动物功能群的分布格局及环境驱动因素,以山西省关帝山林区典型森林生态系统“山杨-桦树”混交林为调查对象,设置4个海拔梯度(1600 m、1800 m、2000 m、2200 m),于2022—2023年的5月、7月、10月对杨桦林中土壤动物进行采样调查,采用多因素方差分析对不同海拔、月份、土层及其交互作用进行检验,采用单因素方差分析(One-way ANOVA)和最小差异显著法(LSD)分析不同海拔、采样季节、土壤各土层间的土壤动物功能群的动态响应;运用Mantel检验、冗余分析以明确环境因素对土壤动物功能群时空分布格局的影响。研究结果表明:关帝山不同海拔共获得土壤动物24434只,隶属于3门11纲34目(亚目)127个类群,其中菌食性3类、杂食性13类、植食性23类、捕食性30类、腐食性54类,数量占比分别为19.66%、4.33%、8.95%、10.08%、56.98%;随海拔上升,土壤动物功能群类群和个体数下降,菌食性类群数最少,腐食性类群数和数量最多,在时间动态上,土壤动物功能群总类群数随月份变化先上升后下降,变化趋势为7月>5月>10月,总个体数随时间逐渐下降,变化趋势为5月>7月>10月;在垂直分布上,总类群数和个体数随土层加深逐渐变少,变化趋势为同一海拔凋落物层>0—10 cm层>10—20 cm层>20—30 cm层。此外,腐食性土壤动物类群数、个体数均高于其它功能群。土壤温度、湿度、土壤酸碱度、电导率、速效氮、速效磷、速效钾是决定关帝山土壤动物功能群群落时空分布格局的主要环境因子。研究结果可为关帝山林区土壤动物的多样性监测与保护提供科学参考。

基于文献计量分析的土壤动物研究现状和发展趋势

文章基于Web of Science(WoS)核心数据库中2709篇和中国知网(CNKI)数据库中2012篇土壤动物领域文献,统计2003—2023年该领域发文数量、发文国家合作情况、研究机构、高频关键词等,分析对比土壤动物领域国内外研究现状。运用VOSviewer和CiteSpace两种可视化软件,旨在探讨该领域的研究重点和发展趋势。结果显示,我国在土壤动物领域的研究能力不断提高;国际合作研究在该领域存在不平衡的特点,中国研究机构与德、美等国的合作较为密切;国内外相关研究机构主要集中在高校,中国的研究机构在发表论文方面处于国际领先地位,但文献质量有待提升;国内文献多从生物多样性、群落结构功能与土壤理化性质之间的关系等方面展开,在凋落物降解、碳循环等方面的研究较少。二十多年来,土壤动物方面的研究逐渐受到重视和广泛关注,对该领域生态学问题的研究也逐步受到重视。