Soil animals and nitrogen mineralization under sand-fixation plantations in Zhanggutai region,China

The effects of soil animals on soil nitrogen (N) mineralization and its availability were studied by investigating soil animal groups and their amounts of macro-faunas sorted by hand, and middle and microfaunas distinguished with Tullgren and Baermann methods under three Pinus sylvestris var. mongolica Litv. plantations in Zhanggutai sandy land, China. In addition, soil N mineralization rate was also measured with PVC closed-top tube in situ incubation method. The soil animals collected during growing season belonged to 13 orders, 5 groups, 4 phyla, whose average density was 86 249.17 individuals·m^(-2). There were significant differences in soil animal species, densities, diversities and evenness among three plantations. Permanent grazing resulted in decrease of soil animal species and diversity. The average ammonification, nitrification and mineralization rates were 0.48 g·m^(-2)·a^(-1), 3.68 g·m^(-2)·a^(-1) and 4.16 g·m^(-2)·a^(-1), respectively. The ammonification rate in near-mature forest was higher than that in middle-age forests, while the order of nitrification and net mineralization rates was: middle-age forest without grazing < middle-age forest with grazing < near-mature forest with grazing (P<0.05). Soil N mineralization rate increased with soil animal amounts, but no significant relationship with diversity. The contribution of soil animals to N mineralization was different for different ecosystems due to influences of complex factors including grazing, soil characteristics, the quality and amount of litter on N mineralization.

ECOLOGICAL SERIES OF SOIL ANIMALS IN DARLIDAI MOUNTAIN

The ecological series of soil animals under the broad-leaved and pine mix ed forest in Darlidai Mountain was studied.Seven sample plots were selected according to different altitude gradients,which belong to dif ferent vegeta-tion types.By investigating and analyzing soil animals in every sample p lot it is found that there are 45group s and 1956individuals,which are involved in 3phylums,7classes,16orders,respectively.The altitude is a key factor which af-fects ecological series of soil anim als.Both the groups and individuals of soil animals increase with altitu de increasing under certain conditions,which con trastes with ordinary cases,resulting from special micro-climate in studied area.The groups and individuls of soil animals are the most under the broad-leaved and pine forest on the top of the mount ain,and the least under Picea-Abies forest in the foot of the mountain.

Studies on the diversity of soil animals in Taishan Mountain

Taishan Mountain has diverse habitats and abundant groups of soil animals. Five habitats,Platycladus orientalis forest,Pinus densiflora forest,Robinia pseudoacacia forest,Pinus tablaerormis forest and Grassland, were selected and the diversity of soil animals in different habitats in Mt. Taishan were investigated and studied in 1997–1999. Totally 52 groups of soil animals were found, belonging separately to 7 Phyla, 11 Classes, 25 Orders and 28 suborders or families. There exists remarkable difference in groups, quantity and diversity of soil animals among the five habitats. Grassland habitat was the highest andPinus densiflora forest was the lowest in groups, quantities, Density-group index (DG) and Diversity index of comparing many communities (DIC) of soil animals. Shannon-Wiener’s diversity index (H′) for soil animals of different habitats was in order ofPlatycladus orientalis forest>Pinus densiflora forest>Pinus tablaerormis forest>Grassland>Robinia pseudoacacia forest, Pielou’s equality index (J′) wasPlatycladus orientalis forest>Pinus densiflora forest>Grassland>Pinus tablaerormis forest>Robinia pseudoacacia forest, and Simposn’s dominant index (C) was Grassland>Robinia pseudoacacia forest>Pinus tablaerormis forest>Pinus densiflora forest>Platycladus orientalis forest. The H index and J index of macro-soil animal all were larger than that of mid-small soil animal. Clustering analysis for five soil animal communities and ordination analysis for community structure by multidimensional scaling (MDS) were made and completely identical results were obtained. Soil animal communities of five habitats were divided into 3 groups.

Effect of organophosphorus pesticide pollution on soil animals

This paper studied the change in soil animal community in contaminated and irrigated area by organophosphorus pesticide waste water and its mechanism was discussed. The results showed that the species and quantities of soil animals decreased with organophosphorus pesticide pollution degree increasing. The species of soil animals decreased with average and rare population mainly decreasing, while the amount change was associated with that of the dominant population of Acarina, Collembola and Nematoda. Toxicity experiment demonstrated that the respiration intensity of soil animal was restrained obviously by pesticide pollution. After observation of SEM, the effect of pesticide pollution on the earthworm (\%Pheretima robusta)\% stomach intestinal mucosa damage has been observed, which showed the pesticide contamination may damage the earthworms bodies. Ulcerous focus and perforation on stomach mucosa were usually seen. The stomach microvilli appeared atrophic and disordered especially in the bodies of these earthworms growing in seriously polluted soil, bad atrophic phenomena were seen not only on the stomach mucosa microvilli but also on the cilia of the intestinal mucosa which appeared swollen as a spheroid. Under TEM, RER and Golgi compound dilatation, chondrisome swell and ridge disappearance were observed on cells of stomach epithelium mucosa of \%P.robusta\% collected from heavy polluted area. By calculation, the safety concentration of earthworm in methamidophos pesticide is 0\^2517 ml/L.

Ecogeographical characteristics of forest soil animal in mountainous districts of the eastern China

In this paper ecogeographical characteristics of forest soil animal i n mountainous districts of the eastern China was analyzed, and results show that soil fauna was very rich in diversified forest habitat, moreover, as times and spaces varied, their compositions and abundance changed obviously too. Forest so il animal decreased gradually in taxa and individual number from the tropics to cold-temperature zone, and they are higher in zonal forest habitat than in other ones on the same mountain. Forest soil animal also got gradually less with incr easing of depth in soil layer, and distributed principally in surface layer. The activities of human had strong affection on faunal composition and diversity of soil animal. On the tropics and subtropics mountains, forest soil animal are le ss in spring-summer than in autumn-winter, whereas they are more in summer-autum n than in winter-spring from warm-temperate zone to cold-temperate zone.

Deforestation effects on biological and other important soil properties in an upland watershed of Bangladesh

Deforestation occurs at an alarming rate in upland watersheds of Bangladesh and has many detrimental effects on the environment. This study reports the effects of deforestation on soil biological proper- ties along with some important physicochemical parameters of a southern upland watershed in.Bangladesh. Soils were sampled at 4 paired sites, each pair representing a deforested site and a forested site, and having similar topographical characteristics. Significantly fewer （p〈0.001） fungi and bacteria, and lower microbial respiration, active microbial biomass, metabolic and microbial quotients were found in soils of the deforested sites. Soil physical properties such as moisture content, water holding capacity, and chemical properties such as organic matter, total N, avail- able P and EC were also lower in deforested soils. Bulk density and pH were significantly higher in deforested soils. Available Ca and Mg were inconsistent between the two land uses at all the paired sites. Re- duced abundance and＇biomass of soil mesofauna were recorded in defor- ested soils. However, soil anecic species were more abundant in defor- ested soils than epigeic and endogeic species, which were more abundant in forested soils than on deforested sites.

Dynamics of Soil Fauna in Da Hinggan Mountains, Northeast China

The dynamics of soil animals was studied in seven representative forest communities in the north of the Da Hinggan Mountains, Northeast China. The results indicate that it was distinctive in the changes of the numbers of soil animals and groups and diversity in relationship with seasons for macrofauna and meso-micro fauna in the study area. The numbers of the observed soil animals in different months were: October>August>June. Group number was larger in August and October, but smaller in June. The change of diversity index in different months was: August>June>Oc- tober. The biomass for macrofauna in different months was: October>June>August. The composition and number of each functional group was relatively stable. In the community of the predominant soil environment, the percentage of saprophagous animals was higher than carnivorous animals and herbivorous animals. The dynamics changes of sapro- phagous and carnivorous animals were distinctive, increasing from June to October, while the change of herbivorous animals was unremarkable.

Composition and ecological distribution of forest soil animalin Confucian graveyard of Qufu

Soil animal communities of Secondary forest,Platycladus forest andQuercus acutissima forest in Confucian graveyard of Qufu were investigated. 3583 specimens were collected, belonging separately to 5 Phylums, 11 Classes and 23 Orders. Two dominant groups and 9 common groups account for 94.45% of the total numbers. The soil animals in these three forest habitats differ in composition, ecological distribution and important indices. The dominant groups of soil animals in the three forests were the same, but other groups differ more greatly. Diversity index (H′) and evenness index (E) of soil animal in Secondary forest are the highest, and yet dominance index (C) inQuercus acutissima forest is the highest. Most soil animals in each forest habitats congregate to the surface soil layer. Their sorts and individual numbers are all layer I>II>III. It is very similar for composition of soil animals in the three forests.

Dietary characteristics of the Malayan Night Heron (Gorsachius melanolophus) in the Yaeyama Islands,southern Japan

The Malayan Night Heron (Gorsachius melanolophus) inhabits a range of tropical and subtropical zones in South,Southeast and East Asia.As this heron breeds singularly in dense forests,its detailed ecology is not well known and only piecemeal information on its diet is available.Thus,we quantitatively estimated its diet menu with an analysis of pellets and stomach contents in the subtropical Yaeyama Islands of southern Japan.The results showed that the heron frequently foraged on land snails,arachnids,freshwater crabs and insects;no fish were detected.Although the earthworm was believed to be a primary dietary source of this species,it was not detected in our results,as it does not remain in pellets due to its high digestibility.This indicated that this bird dominantly depends on soil animals that inhabit humid forest floors.While the heron does not directly utilize aquatic habitats,they likely prefer moist forests caused by watery environments such as streams and swamps.Wet forests should be conserved for maintaining populations of this heron species.

Soil animal communities at five succession stages in the litter of the evergreen broad-leaved forest in Tiantong,China

Soil animals are abundant in forest litter layer,but little attention has been paid to the vertical distribution of community structure of soil animals in the layers at different plant community succession stages.The forest litter layer can be divided into fresh litter layer(L),fermentation layer(F)and humus layer(H),which may represent different litter decomposition stages.The aim of the study is to ascertain the vertical distribution features of soil animal communities among the three litter layers and the change in the succession process of the Evergreen Broad-Leaved Forest(EBLF)in Tiantong,Zhejiang Province,China.Soil animal communities in the five plant communities at different succession stages were investigated during the 2003 winter.Soil animals,which were collected by using Tullgren funnels,amounted to a total of 13381 individuals falling into 2 phyla,8 classes and 20 orders.The dominant groups were Acarina and Collembola,accounting for 94.24%of the total individuals,with the number of Acarina individuals 7.66 times than that of Collembola.The common group was Diptera.The results indicated that there was a distinctive vertical distribution of the soil animal communities in the forest litter layer,but it differed from that in soil below the litter layer.In contrast to those in the soil,the soil animals in the litter layer generally tended to increase in both group abundance and density from the top fresh litter layer to the bottom humus layer.Altogether 19 groups and 59.03%of total individuals were found in the bottom layer,while only 8 groups and 5.35%of the total individuals in the top.Moreover,there were some variations in the distribution of the soil animals at different plant succession stages.85.19%of Homoptera and 100%of Symphyla were found in the litter layer at the climax succession stage,while 75.61%of Thysanoptera at the intermediate succession stage.Therefore,these groups might be seen as indicative groups.The total numbers of soil animal groups and individuals in the litter layers greatly changed in the succession process of the EBLF.They both were greatest at the climax,moderate at the intermediate and smallest at the primary succession stage.However,the main soil animal groups in the litter at the different succession stages were essentially the same.They were Acarina,Collembola,Diptera and Lepidoptera.Although similarity analysis revealed that the soil animal communities in the litter at the intermediate succession stage were most similar to those at the climax succession stage,they differed greatly from each other in the Shannon-Wiener diversity index.The Shannon-Wiener index was highest at the climax succession stage and lowest at the intermediate succession stage.Finally,the paper discusses the following three questions:the role of soil animals as indicators for plant community succession;the role of different soil animal groups in the litter decomposition at different stages;and the major factors affecting the composition and distribution of soil animals in the litter.This paper provides a new perspective for the research on the succession mechanism of plant communities and the decomposition functions of soil animals.

Biological transfer of silver under silver nanoparticle exposure and nitrogen transfer via a collembolan- predatory mite food-chain and ecotoxicity of silver sulfide

The development of nanotechnology has accelerated the use of silver nanoparticles(AgNPs)in household chemicals and the accumulation of Ag in sewage treatment systems.The application of sewage sludge products to soils raises concerns over the safety of Ag in the function and biogeochemical cycles of the soil belowground ecosystem.Here,we assess the potential risk of the accumulation and transfer of Ag under AgNPs exposure and its effects on the trophic transfer of nitrogen(N)through a soil animal food chain(Folsomia candida–Hypoaspis aculeifer).The formation of stable silver sulfide(Ag_(2)S)was also studied via a single species test using F.candida.Concentrations of Ag in F.candida increased with increasing AgNPs concentration,as did those in the predator H.aculeifer,but the Ag bioaccumulation factors of both animals were<1.Folsomia candida body tissue 15 N abundance declined markedly compared with that of H.aculeifer.Silver sulfide did have adverse effects on the survival and reproduction of F.candida.The Ag concentrations of F.candida increased with increasing Ag_(2)S concentration in sludge-treated soils.Silver sulfide showed ecotoxicity to the collembolan,therefore ecotoxicity resulting from the transformation and fate of AgNPs in soils needs to be considered before biosolid products are applied to agricultural soils.

Interspecific interactions between burrowing dung beetles and earthworms on yak dung removal and herbage growth in an alpine meadow

Interspecific interactions between two spatiotemporally co-occurred species sharing a single resource are considered to be either competitive or facilitative.This study examined the possible interspecific interactions between a dung-tunneling beetle species(Onthophagus yubarinus)and an earthworm species(Aporrectodea noctuma),two major detritivores responsible for dung removal in a Tibetan alpine meadow.We conducted a two-way,factorial field experiment using replicated chambers,and measured the performances of beetles and earthworms,as well as yak dung removal,soil properties and aboveground plant biomass over two months.Earthworm presence significantly decreased the body size of beetle larvae and the weight of tunnel dung that beetle larvae live on.In contrast,beetle presence did not affect the performance of earthworms.Beetles,earthworms and their interaction significantly increased dung removal and soil organic carbon concentration at the end of the experiment.Beetles alone significantly increased soil total N and P,soluble N and P concentrations,but earthworms alone had nonsignificant effects on these nutrient variables.Beetles and earthworms additively enhanced soluble N and P concentrations,and aboveground plant biomass at the end of the experiment.These results indicate 1)there was a one-sided negative relationship between dung-tunneling beetles and earthworms,resulting from the consumption of earthworms on food resource of beetle larvae;and 2)the coexistence of beetles and earthworms facilitated dung removal interactively and plant growth additively by increasing nutrient availability.