Seasonal changes in soil arthropod abundance in the dry evergreen forest of north-east Thailand,with special reference to collembolan communities

A soil arthropod community was studied in a dry evergreen forest over a 3-year period from May 1998 to April 2001. Population abundance, species composition, and community structure were investigated over the 3-year study period. The soil arthropods consisted of Acari (75.38%), Collembola (16.11%), and others (8.51%), and their abundances showed a clear difference between the rainy and dry seasons. Population abundance of Collembola and Acari were low during drought conditions. The humidity was the most important factor determining distribution, abundance, and survival of soil Collembola in this tropical forest. High predation and low accumulation of organic matter caused low population abundance of Collembola in the tropical habitat. The collembolan community was dominated by a few dominant species over the study period. The pattern of seasonal changes in numbers of Collembola was similar over the 3-year study period. The species composition of the collembolan community was constant and persistent throughout a 3-year study period. Thus, the collembolan community showed constancy in its species composition with seasonal variability over the 3-year study period.     

Classification and ordination of communities of soil arthropods in an urban park of Osaka City

To assess the effect of management of a park on soil arthropods, communities of Oribatida and Collembola were analyzed at 11 sites of different vegetation in Tsurumi Park, an urban park of Osaka City. The type of canopy layer and soil density strongly affected the community parameters, such as species diversity. Ordination revealed that soil density, contents of organic matter, and shrub layer were important for variety in the oribatid community; the shrub layer was important for the collembolan community. Species richness of both arthropod groups was highest in a mixed forest and lowest on bare land, while the abundance of Collembola was highest on a lawn site. Areas of a common vegetation type had a similar oribatid community;Trichogalumma nipponica dominated in deciduous forests,Eohypochthonius crassisetiger in mixed forests and one of coniferous forests. On the other hand, collembolan communities did not correspond with the vegetation.Sminthurinus sp. was collected from every site, and the most abundant species wasCryptopygus thermophilus that exhibited an outbreak on lawn sites. A significant correlation existed between species diversities but not between abundances of Oribatida and Collembola.     

Alginate films for delivery of root-knot nematode inoculum and evaluation of microbial interactions

A method was developed for utilizing alginate films to deliver inoculum into soil and evaluate microbial antagonistic activity against nematode eggs. Eggs of Meloidogyne incognita were harvested from galled tomato roots (Lycopersicon esculentum), surface disinfested, suspended in 2% (w/v) aqueous sodium alginate, and applied to 2.5 × 5.0 cm polyvinyl chloride coated fiberglass screens (1.5 mm² mesh size) at a uniform thickness of 0.5 mm. The alginate solution was gelled by dipping in 0.25 M CaCl₂. Films containing eggs were observed in vitro and egg development was evaluated. The number of immature eggs and eggs with first stage juveniles declined linearly over time while the number of empty eggs shells, and hatched juveniles increased over time, indicating that the alginate gel did not inhibit development and motility of M. incognita juveniles. In a greenhouse experiment using cucumber (Cucumis sativus) the number of galls g^-1 root was correlated with the number of eggs in alginate films placed in each pot at planting. Films containing M. incognita eggs were buried in field soil containing organic amendments, incubated, removed from soil, rinsed with water, and observed. The number of immature eggs in grids from soil amended with chitin or flax seed meal were lower than in untreated soil; percent parasitized eggs was also greater in films from amended soil than from untreated soil.     

Effects of fuel reduction burning on epigeal arthropods and earthworms in dry sclerophyll eucalypt forest of west-central Victoria

The effects of prescribed low-intensity burning during spring and autumn on invertebrates in litter/upper soil were assessed in dry sclerophyll mixed eucalypt forest near Daylesford, west–central Victoria. The 4-year study was based on 68 848 arthropod specimens representing 29 ordinal or lower level taxa contained in 1980 pitfall trap samples, and on in situ counts of earthworms (Annelida) in 2220 litter/upper soils samples. The spring bum caused short-term reductions in activity among the common ‘major’ taxa Collembola (springtails) and Diptera (flies), and among the rarely trapped ‘minor’ taxa Opilionida (harvestmen), Lepidoptera (moths) and Apocrita (parasitic wasps) for up to one year. These reductions were associated with low fine fuel loads in the first year after the fire. Populations of earthworms also declined substantially, but recovered within 3 years of the burn. The autumn burn suppressed the Collembola and the ‘minor’ taxa Blattodea, Polydesmida, Thysanura and Tettigoniidae for up to 10 months. Earthworms were not affected. Very dry soil conditions were associated with depressed collembolan activity at study sites irrespective of burning. Given the importance of Collembola, larval Diptera and earthworms among decomposers in forest litter, it appears that the spring burn, and to a lesser extent the autumn burn, may have temporarily reduced the decomposer cycle. Further research on individual species is required to substantiate this conclusion, and also on the effects of high frequency burning. In the interim, any broadscale fuel reduction burning in forest ecosystems similar to that studied here should be scheduled for autumn rather than spring to protect earthworms and no burning should be permitted during drought periods, to minimize adverse impacts on the overall invertebrate fauna inhabiting litter/upper soil.     

Drought and its legacy modulate the post‐fire recovery of soil functionality and microbial community structure in a Mediterranean shrubland

The effects of drought on soil dynamics after fire are poorly known, particularly its long‐term (i.e., years) legacy effects once rainfall returns to normal. Understanding this is particularly important for nutrient‐poor soils in semi‐arid regions affected by fire, in which rainfall is projected to decrease with climate change. Here, we studied the effects of post‐fire drought and its legacy on soil microbial community structure and functionality in a Cistus‐Erica shrubland (Spain). Rainfall total and patterns were experimentally modified to produce an unburned control (natural rainfall) and four burned treatments: control (natural rainfall), historical control (long‐term average rainfall), moderate drought (percentile 8 historical rainfall, 5 months of drought per year), and severe drought (percentile 2, 7 months of drought). Soil nutrients and microbial community composition (ester‐linked fatty acid approach) and functionality (enzyme activities and C mineralization rate) were monitored during the first 4 years after fire under rainfall treatments, plus two additional ones without them (six post‐fire years). We found that the recovery of burned soils was lower under drought. Post‐fire drought increased nitrate in the short term and reduced available phosphorus, exchangeable potassium, soil organic matter, enzyme activities, and carbon mineralization rate. Moreover, drought decreased soil total microbial biomass and fungi, with bacteria becoming relatively more abundant. Two years after discontinuing the drought treatments, the drought legacy was significant for available phosphorus and enzyme activities. Although microbial biomass did not show any drought legacy effect, the proportion of fungi and bacteria (mainly gram‐positive) did, being lower and higher, respectively, in former drought‐treated plots. We show that drought has an important impact on soil processes, and that some of its effects persist for at least 2 years after the drought ended. Therefore, drought and its legacy effects can be important for modeling biogeochemical processes in burned soils under future climate change.     

Disentangling the Litter Quality and Soil Microbial Contribution to Leaf and Fine Root Litter Decomposition Responses to Reduced Rainfall

Climate change-induced rainfall reductions in Mediterranean forests negatively affect the decomposition of plant litter through decreased soil moisture. However, the indirect effects of reduced precipitation on litter decomposition through changes in litter quality and soil microbial communities are poorly studied. This is especially the case for fine root litter, which contributes importantly to forests plant biomass. Here we analyzed the effects of long-term (11 years) rainfall exclusion (29% reduction) on leaf and fine root litter quality, soil microbial biomass, and microbial community-level physiological profiles in a Mediterranean holm oak forest. Additionally, we reciprocally transplanted soils and litter among the control and reduced rainfall treatments in the laboratory, and analyzed litter decomposition and its responses to a simulated extreme drought event. The decreased soil microbial biomass and altered physiological profiles with reduced rainfall promoted lower fine root—but not leaf—litter decomposition. Both leaf and root litter, from the reduced rainfall treatment, decomposed faster than those from the control treatment. The impact of the extreme drought event on fine root litter decomposition was higher in soils from the control treatment compared to soils subjected to long-term rainfall exclusion. Our results suggest contrasting mechanisms driving drought indirect effects on above-(for example, changes in litter quality) and belowground (for example, shifts in soil microbial community) litter decomposition, even within a single tree species. Quantifying the contribution of these mechanisms relative to the direct soil moisture-effect is critical for an accurate integration of litter decomposition into ecosystem carbon dynamics in Mediterranean forests under climate change.     

Soil microarthropods respond differently to simulated drought in organic and conventional farming systems

In Central Europe, summer droughts are increasing in frequency which threatens production and biodiversity in agroecosystems. The potential of different farming systems to mitigate detrimental drought effects on soil animals is largely unknown. We investigated the effects of simulated drought on the abundance and community composition of soil microarthropods (Collembola and Oribatida and Meso‐, Pro‐, and Astigmata) in winter wheat fields under long‐term conventional and organic farming in the DOK trial, Switzerland. We simulated drought by excluding 65% of the ambient precipitation during the wheat‐growing season from March to June 2017. The abundance of Collembola and Oribatida declined more consistently in conventionally managed fields compared to organically managed fields under simulated drought. The abundance of Collembola as well as Meso‐, Pro‐ and Astigmata, but not the abundance of Oribatida, increased in deeper soil layers due to simulated drought, suggesting vertical migration as a drought avoidance strategy. The species composition of Oribatida communities, but not of Collembola communities, differed significantly between drought treatments and between farming systems. Soil carbon content was a major factor structuring Oribatida communities. Our results suggest that organic farming buffers negative effects of drought on soil microarthropods, presumably due to higher soil carbon content and associated higher soil moisture and improved soil structure. This potential of organic farming systems to mitigate consequences of future droughts on soil biodiversity is promising and needs further exploration across larger climatic and spatial scales and should be extended to other groups of soil biota.     

Response of collembolan communities to land-use change and grassland succession

This study focuses on the long-term changes of collembolan communities occurring after the conversion of arable land to managed grassland. We analysed collembolan communities at grassland sites of different age that had been gradually converted over a period of 50 yr. Abundance and biomass responded rapidly and very positively to the conversion of arable land to grassland, while species richness was not affected. Collembolan assemblages changed only little during grassland maturation. The impact of land-use change on community structure was more obvious at the functional level because the colonization processes observed in our study mostly relied on hemiedaphic species. Vegetation and soil parameters were good predictors of collembolan community structure during development of managed grassland. The present study demonstrated that past landscape patterns and processes like land-use conversion and subsequent succession had a considerable impact on the present day pattern of species richness and community composition of Collembola within a landscape. Our results strongly differ from those obtained for other invertebrate groups, highlighting on the one hand the very diverse reactions of invertebrates to a common factor, and on the other hand the need to survey more than one taxa in order to draw conclusions on effects of land-use change on faunistic communities.     

Agro-ecology of onion couch (Arrhenathemm elatius var. bulbosum).

The agro-ecology of onion couch (Arrhenatherum elatius var. bulbosum), a well known weed of arable land is studied. Contribution of seeds from onion couch and a more widespread variety of Arrhenatherum elatius: tall oat-grass, towards future ingress of onion couch in arable fields has indicated that the tall oat-grass variety is not a potential weed of arable land. It appears that vegetative propagules rather than the seeds are the effective means of propagation of the onion couch variety in arable fields. An experiment performed to test any modifying effect of the soil texture indicated that onion couch is restricted to loamy soils and there is a complete absence from heavy clays and sandy soils. This could be due to the moist and protective micro-environment provided by the texture of the soils to partially buried vegetative propagules of onion couch, which are susceptible to drought.     

New insight into the systematics of Tomoceridae (Hexapoda,Collembola) by integrating molecular and morphological evidence

Tomoceridae is common but among the most problematic groups of Collembola. Its position within Collembola and the relationships within the family remain obscure. This also extends to the generic division of the subfamily Tomocerinae that remains controversial. This study examines these issues by integrating both molecular and morphological evidence. Our molecular phylogeny based on rDNA sequences supports the monophyly of Tomoceridae and the sister relationship between Tomocerinae and Lepidophorellinae. Reconstructions and tree topology tests constraining monophyly did not resolve the relationships between Tomoceridae and other collembolan groups. We also examined the morphology of the first instar (primary) larvae, which has significant phylogenetic value among higher Collembola. Mapping primary chaetotaxy onto our molecular phylogeny provided further evidence for the unique position of Tomoceridae within Entomobryomorpha and Collembola. The monophyly and subfamilial classification within Tomoceridae were validated here, whereas its position among Collembola will need further studies in a broader consideration across the major collembolan orders. Within Tomocerinae, the monophyly of Pogonognathellus was demonstrated, but the status of Tomocerus and Tomocerina is still to be resolved.     

长白山地典型农田生态系统土壤跳虫群落结构及其生态分布特征

为了解长白山地不同地貌类型典型农田生态系统土壤跳虫群落结构及其分布,探讨不同地貌类型对土壤跳虫群落结构和分布及其季节动态的影响,于2015年春季(5月)、夏季(7月)、秋季(9月)分别对长白山地玄武岩台地、花岗岩低山、花岗岩丘陵三种地貌类型玉米田土壤跳虫进行了研究。研究表明,3个生境共获土壤跳虫881头,隶属10科16属22种。其中,玄武岩台地土壤跳虫个体密度是1 760头/m~2,17种;花岗岩低山个体密度是2 206.67头/m~2,13种;花岗岩丘陵个体密度是1 906.67头/m~2,18种。地貌及取样时间的差异对土壤跳虫个体密度、物种数、多样性指数均有一定的影响。花岗岩低山与花岗岩丘陵的个体密度和物种数大小为秋季春季夏季,而玄武岩台地的个体密度和物种数表现出随季节变化呈递增的趋势(P0.05)。不同地貌土壤跳虫多样性均在秋季达到最大,夏季玄武岩台地多样性指数显著高于花岗岩低山和花岗岩丘陵,秋季,玄武岩台地丰富度指数和均匀度指数显著高于花岗岩低山,玄武岩台地优势度指数显著低于花岗岩低山(P0.05)。不同土壤环境因子对跳虫的影响不同,土壤温湿度、有机质、全氮、速效氮和全磷与土壤跳虫的群落结构、生态分布有明显的相关性。综上可知,长白山地农田生态系统土壤跳虫群落结构和生态分布因地貌类型不同而存在差异,季节变化也对其影响明显。     

Population Changes of Tylenchulus semipenetrans Under Localized Versus Uniform Drought in the Citrus Root Zone

Population development of Tylenchulus semipenetrans in dry soil was investigated in a greenhouse study. Citrus seedlings were grown in sandy soil in vertical tubes with upper and lower sections. Nematode population densities in the upper tubes were measured at 16, 23, and 37 days, post-treatment. Three treatments consisted of i) irrigating both tubes when soil water potential reached -1 5 kPa (non-drought), ii) irrigating only the bottom tube (local drought), and iii) no irrigation (uniform drought). Soil water potential in the upper tubes did not differ under local and uniform drought during the first 16 days post-treatment, when it approached - 125 kPa. Thereafter, the water potential of soil under uniform drought continued to decrease, while that under local drought stabilized at approximately -150 kPa. Treatments had no consistent effects on female T. semipenetrans counts from soil or roots. However, after 37 days, numbers of eggs, juvenile, and male nematodes per gram of root under local drought were more than 2.4-fold greater than those under non-drought or uniform drought. Numbers of juvenile and male nematodes in soil were 6.5 times higher under local drought than under non-drought after 37 days. Nematodes did not survive in soil under uniform drought. Most of the eggs recovered on each date, from roots under local and non-drought, hatched within 35 days. Sixteen days of uniform drought reduced cumulative egg hatch to 51%, and almost no eggs hatched after 23 and 37 days of uniform drought. Thus, the response of T. semipenetrans to dry soil is fundamentally different, depending on whether all or part of the rhizosphere experiences drought. These data and field observations suggest that hydraulic lift via the root xylem may prolong the activity of some nematodes and possibly other rhizosphere-inhabiting organisms in dry soil.     

Egg size and offspring fitness in a bdelloid rotifer

To test if the quality of offspring is affected by egg size and whether it increases with the amount of resources allocated to an individual egg, we compared the offspring hatched from small and large eggs of Macrotrachela quadricornifera(Rotifera, Bdelloidea). Differently sized eggs were obtained by feeding mothers with different food concentrations. Large eggs were expected to provide better offspring in terms of (1) development time of the embryos, (2) age at first reproduction of the juveniles and (3) recovery after desiccation of the newborns. The comparison between offspring hatched from large vs. small eggs of the same bdelloid species revealed that animals hatched from large eggs had shorter embryonic development and earlier age at first reproduction than animals hatched from small eggs. In contrast, the capacity to survive stress, like desiccation, was not affected by egg size. Thus, offspring hatched from larger eggs had shorter generation times, but were not favoured under harsh circumstances.     

Mean annual population density of Collembola and Acari in the soil and litter of three indigenous South Australian forests

A quantitative study of the soil and litter fauna of three South Australian low open forests was made for two years. The soil and vegetation of the sites were similar but the mean annual rainfall of the areas differed; 635, 690 and 1050 mm/y, respectively for the ‘dry’, ‘medium’ and ‘wet’ sites. Monthly samples were taken of litter, and the upper 0–4 cm and lower 4–8 cm soil layers, and the method used to estimate the numbers of active animals is also described. Mean annual population densities of Collembola and Acari were greatest at the medium site (9.5 and 48.6 × 10³/m², respectively) and least at the dry site (4.9 and 35.1 × 10³/m², respectively) and values are discussed in relation to site organic carbon content. Over all the sites, between 11–21, 67–75 and 10–15% of the collembolan populations, and 10–13, 66–72 and 16–21% of the acarine populations inhabited the litter layer and upper and lower soil layers respectively. Isotomidae were the most abundant collembolan family in each level at each site, but the overall proportion of Entomobryidae increased from the dry to wet site. Prostigmata were the most abundant acarine order in each level at two sites. Cryptostigmata were dominant in the litter layer of the wet site, and their overall proportion increased from the dry to wet site. Seasonal density changes were similar on all sites with minima in the summer and maxima in the winter months. The results obtained here combined with those from other published investigations indicate a trend of faunal population change over various ecosystems in Australia. Prostigmatid mites and iso-tomid Collembola dominate at arid sites. As sites become less arid and the amount of soil organic matter increases, the proportion of cryptostigmatid and mesostigmatid mites increases, and other groups of Collembola, particularly Entomobryidae, become more frequent.     

Invertebrate biodiversity affects predator fitness and hence potential to control pests in crops

Natural enemies that control pests usually allow farmers to avoid, or reduce, the use of pesticides. However, modern farming practices, that maximize yields, are resulting in loss of biodiversity, particularly prey diversity. Does this matter? Pests continue to thrive, and without alternative prey the predators should, perforce, concentrate their attentions upon the pests.We showed that a diverse diet significantly enhances predator fecundity and survival. Experiments were conducted using common generalist predators found in arable fields in Europe, the carabid beetle Pterostichus melanarius (Coleoptera: Carabidae) and the linyphiid spider Erigone atra (Araneae: Linyphiidae). We tested the hypothesis that mixed species diets were optimal, compared with restricted diets, with respect to parameters such as predator weights, egg weights, numbers of eggs laid, egg development times, egg hatching rates and predator survival. In carabids, an exclusive earthworm diet was as good as mixed diets containing earthworms for egg production and hatching, but less good than such mixed diets for increase in beetle mass and sustained egg laying. For spiders, aphids alone (Sitobion avenae) or with the Collembola Folsomia candida, drastically reduced survival. Aphids plus the Collembola Isotoma anglicana improved survival but only aphids with a mixed Collembola diet maximized numbers of hatching eggs.Predators offered only pests (slugs or aphids) had lowest growth rates and fecundity. We therefore demonstrated that conservation of a diversity of prey species within farmland, allowing predators to exploit a diverse diet, is essential if predators are to continue to thrive in crops and regulate agricultural pests.     

Western myall groves (Acacia papyrocarpa) determine the fine‐scale distribution of soil Collembola in semi‐arid South Australia

Vegetation can exert a strong influence on the distribution and activity of biotic communities across a broad range of spatial scales, especially in arid and semi‐arid ecosystems. At fine spatial scales, patches created by individual plants can support different faunal and floral communities even at locations distant from the plant. These differences can have profound effects on a range of ecosystem processes, including seed dispersal, nutrient cycling and resource distribution. In semi‐arid Australia, areas surrounding groves of western myall (Acacia papyrocarpa) trees are largely devoid of vegetation, being referred to as ‘halos’. Here, we investigate the soil‐dwelling Collembola in groves of western myall trees, the surrounding halos and nearby chenopod shrubland. We also investigated whether the abundance of Collembola was influenced by soil depth (0–5 cm layer vs. 6–10 cm layer) in groves. We found that collembolan density was approximately nine times lower and taxonomic richness half that in a halo compared with the grove and chenopod vegetation. Furthermore, analyses at finer taxonomic levels indicate that vegetation patches differed in species composition, with some species restricted to or preferring particular patches. In the grove, we found a higher abundance of Collembola in the 0–5 cm soil layer compared with the 6–10 layer. Our results indicate vegetation patches strongly influence collembolan abundance and species composition in bare patches around western myall. As patches created by vegetation are a common feature of semi‐arid and arid regions, we suspect that these effects are widespread although seldom reported. Furthermore, as Collembola are involved in the decomposition process, Acacia papyrocarpa patches will be influencing nutrient cycling through their effects on the soil biota. Our results also emphasize that comprehensive fauna survey and management of woodland ecosystems need to consider fine‐scale processes.     

Assessment of Tannery Waste in Semi-arid Soils Under a Simulated Rainfall System

The use of tannery sludge in arid soils could be promising due to the high content of organic carbon and nitrogen. However, tannery waste also contains high amounts of Cr and salts that could leach into drainage water in response to rainfall. In order to study the effects of two tannery wastes as organic fertilizers on two types of semi-arid soils, simulated rainfall experiments were carried out. Soils collected from under and outside a mesquite tree canopy were amended with fleshing waste and/or tannery sludge and incubated 0 to 6 months prior to being subjected to simulated rainfall. The parameters measured were: infiltration, runoff, soil and Cr losses, and NH₄⁺-N and NO₃^?-N released after a rainfall event. Results showed that fleshing waste added to soils from outside the canopy tree was the most effective treatment for decreasing runoff, soil losses, and Cr, NH₄⁺-N and NO₃^?-N loss in runoff and infiltration, in general. However, the same treatment had the opposite results for soil under the canopy. These results indicate that the types of waste and soil must be taken into consideration when attempting to improve physical and chemical characteristics of semi-arid soils. Thus, the use of tannery waste represents a potential hazard, not only causing soil erosion but also Cr contamination in adjacent sites and aquifers.     

Hatching from cysts and egg sacs of Heterodera cruciferae and effects of temperature on hatching and development on oilseed rape

Juveniles hatched readily from field cysts and very readily from eggs in egg sacs of Heterodera cruciferae, when exposed to oilseed rape root diffusate. They hatched very poorly, however, from white or brown females from which the above egg sacs had been removed. Some hatching occurred at 8 ^oC but much more occurred at 12 , 16, 20 and 24 ^oC, with most at 16 ^oC. Development of juveniles in roots of oilseed rape occurred throughout the range 8–24 ^oC, and proceeded faster the higher the temperature. The basal development temperature was taken as 5 ^oC and the number of day degrees above this temperature required to reach each stage of development was calculated. From invasion of roots to the hatching of F₁ juveniles required an average of 680 day degrees, but only 210 day degrees were required for the first appearance of egg sacs on adult females. On this basis, two consecutive generations of H, cruciferae would be possible on autumn-sown oilseed rape in southern England, but the second would mature fully only after the crop was harvested. In Scotland, two consecutive generations could also occur but the second would be much less mature by harvest: only about 850 day degrees are available compared to almost 1100 in southern England. In practice, however, overlapping generations probably occur due to flushes of hatching of juveniles (i) at sowing, (ii) when soils warm up after winter and (iii) when the first generation completes its development. The proportion of eggs found in egg sacs was never more than 37% and some field cysts contained about 220 eggs; their egg sacs may, therefore, have contained as many as 150 eggs. Any study of population dynamics or damage assessment will require a quantification of the contribution of eggs in egg sacs to population density. Oilseed rape is direct drilled and may, therefore, be more sensitive to a given population density of the nematode than host crops which are transplanted.     

Seasonal exposure to drought and air warming affects soil collembola and mites

Global environmental changes affect not only the aboveground but also the belowground components of ecosystems. The effects of seasonal drought and air warming on the genus level richness of Collembola, and on the abundance and biomass of the community of Collembola and mites were studied in an acidic and a calcareous forest soil in a model oak-ecosystem experiment (the Querco experiment) at the Swiss Federal Research Institute WSL in Birmensdorf. The experiment included four climate treatments: control, drought with a 60% reduction in rainfall, air warming with a seasonal temperature increase of 1.4°C, and air warming + drought. Soil water content was greatly reduced by drought. Soil surface temperature was slightly increased by both the air warming and the drought treatment. Soil mesofauna samples were taken at the end of the first experimental year. Drought was found to increase the abundance of the microarthropod fauna, but reduce the biomass of the community. The percentage of small mites (body length [Formula: see text] 0.20 mm) increased, but the percentage of large mites (body length >0.40 mm) decreased under drought. Air warming had only minor effects on the fauna. All climate treatments significantly reduced the richness of Collembola and the biomass of Collembola and mites in acidic soil, but not in calcareous soil. Drought appeared to have a negative impact on soil microarthropod fauna, but the effects of climate change on soil fauna may vary with the soil type.     

Fine structure of the egg envelopes of one proturan and two Collembolan genera (apterygota)

The eggs of one proturan and two representatives of Collembola (Heteromurus nitidus and Hypogastrura succinea) were studied by scanning and transmission electron microscopy. The proturan (Eosentomon) eggs are covered by 2 envelopes. The surface of the outer one is equipped with numerous hemispherical projections. The eggs of H. nitidus possess an envelope, which is studded with numerous granules. In H. succinea, eggs are covered with 2 envelopes. The outer is studded with characteristic complex structures. Neither micropyles nor aeropyles were observed in either proturan or collembolan eggs.