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Historical land use provides long-term field experiments that give valuable clues for ecosystem management and habitat restoration. We hypothesized that remnants of a small-scale charcoal-ore industry that ceased more than a century ago still affect soil properties and the litter-dwelling fauna of a beech forest on rendzina soil (pH 4–6.5). We sampled the remains of charcoal kilns, small mining pits, and mounds of dugout material. Soils from kilns displayed increased carbon and nutrient contents and soils from kilns and in pits tended to be moister than that from all other locations. Leaf litter accumulated in the pits. Most mesofauna taxa occurred independent of the modifications, whereas larger-sized Collembola and many macrofauna taxa (Aranea, Chilopoda, Diplopoda, Isopoda, Coleoptera, and Gastropoda) were more abundant in the pits. Snails are highly sensitive to microclimatic fluctuations and structural changes and thus were used to compare man-made structures with natural ones: assemblages from kilns equaled those from the unmodified forest floor, assemblages from pits resembled those from adjacent to coarse woody debris (CWD), and assemblages from mounds resembled those from outcrops and tree bases. The outcrops were the local keystone structure, but mining pits and CWD added to species richness as they provided shelter for hygrophilous species. We thus recommend maintaining or creating a diversified soil surface structure in post-mining land reclamation to accumulate organic matter and nutrients and to buffer microclimatic extremes.

The open-cast lignite mine “Hambach” (NW-Germany) and the accompanying land reclamation replace a large ancient forest. Reclamation of an 1000 ha large overburden dump started 25 years ago and is still in progress. Reclamation methods comprise combinations of different topsoil dumping techniques and reclamation measures such as seeding or afforestation. In accordance with the spatial heterogeneity hypothesis, we hypothesize that beetle assemblages from sites where the topsoil was left structured are more diverse than those from sites with levelled topsoil, and that richly structured mid-successional sites harbour more heterogeneous assemblages than afforested sites. We tested the influence of environmental variables on assemblage characteristics of pitfall-trapped beetles from 17 sites on the overburden dump. The results are based on 35,588 individuals from 339 species. Species assemblages differed significantly between almost all sites. Habitat age did not affect assemblage characteristics, while species richness was significantly influenced by surface structure. Sites that were not levelled and that additionally included pits that slope down for several meters exhibited the highest species richness. Abundance of beetles increased in parallel to the canopy cover, whereas assemblage heterogeneity (MVDISP) decreased. Successional and grassland sites usually exhibited higher diversity (Fisher's α) than afforested sites, but diversity was not significantly predicted by a single environmental factor. Instead, diversity increased along with increasing MVDISP-values. Afforestations speed up the successional process and some euryecious forest species are already well established, but stenecious forest specialists have not yet been found.

We studied the leaf litter-dwelling fauna of managed deciduous forests and primeval reference sites in Western and Central Europe and addressed the questions if the higher overall species richness close to downed coarse woody debris (CWD) is related to intra-specific or inter-specific aggregation, if the aggregation pattern changes with the amount of CWD on the forest floor, and how much CWD is needed for different taxa. The analysis is based on shelled Gastropoda, Diplopoda/Isopoda, Chilopoda and Coleoptera. Among-sample heterogeneity was lower close to CWD than distant from CWD. This was most pronounced in Diplopoda/Isopoda and Gastropoda. Diplopoda/Isopoda are comparatively mobile and assemblages were already quite homogenous close to CWD at levels above 5 m3 downed deadwood ha−1. Gastropoda have a low mobility, and more than 20 m3 downed deadwood ha−1 is needed for assemblage homogeneity. We further focused on the Gastropoda as sensitive indicators. Enhanced densities and species richness close to CWD were not a simple function of leaf litter weight, thus effects of densities on heterogeneity are not solely driven by leaf litter accumulation close to CWD. In contrast to euryecious litter-dwellers such as the Punctidae, stenecious slow active dispersers such as the Clausiliidae clearly require more than 20 m3 CWD ha−1 for an even distribution. Specialists depending on CWD even seem to have gone extinct in some managed forests. For conserving the litter-dwelling fauna, we propose a target of at least 20 m3 downed CWD ha−1 in already managed forests and rigorous restrictions for deadwood removal from still (almost) pristine systems.

Summary 1. In long-term laboratory studies, the influence of different food materials on parameters of population dynamics was compared in the sympatric woodlice, Porcellio scaber and Oniscus asellus, as a measure of interspecific differences in the utilization of food. 2. Freshly fallen leaf litter of different tree species had been acidified and microbially inoculated prior to the experiments. By analysing the influence of pH level, density and activity of litter-colonizing microbiota and several physico-chemical characteristics of the leaf litter, we obtained information on those factors that determine food quality. 3. The studied species responded similarly to different leaf litter species in that both P. scaber and O. asellus performed better on litter with low C:N ratio. Overall, both isopod species reproduced more successfully on litter with higher pH levels, containing half the levels of tannins and other phenolics. 4. Interspecific differences were obvious with respect to the significance of litter-colonizing microbiota, and the dependence of juveniles on particular food parameters. While the performance of adult P. scaber was influenced by both litter-colonizing microbiota and physico-chemical characteristics of the leaf litter, adult O. asellus were influenced by leaf litter characteristics, but not by litter-colonizing microbiota. Juvenile mortality was affected by the tested food parameters in O. asellus, but not in P. scaber. Growth rates of juveniles of both species were influenced by physico-chemical characteristics of the leaf litter. Additionally, leaf litter microbiota had a significant influence on growth rates in juvenile P. scaber, but not in juvenile O. asellus. 5 Reasons for, and consequences of, similarities and differences between the observed sympatric species, and intraspecific differences between ontogenetic stages, are important aspects of soil ecology and may help explain the sympatric coexistence of two species belonging to the same guild of saprophagous soil animals.

Giant knotweeds (Reynoutria spp.) are highly productive and aggressive invaders in riparian wetlands of Europe and North America. We sampled ground-dwelling beetles by pitfall traps from six sites comparing monotypic Reynoutria stands with the invaded native Urtica-dominated stands. Three sites were located in a semi-natural softwood forest and three sites were on a ruderal embankment. The analyses are based on a total of 13,244 individuals from 218 species. Location and site significantly influenced beetle assemblages. Moreover, there were pronounced differences between vegetation stands. The monotypic Reynoutria stands exhibited lower beetle abundance, species richness and rarefaction diversity irrespective of location. However, the negative effect on species richness, abundance and assemblage similarities were stronger on the transformed ruderal embankment than in the semi-natural softwood forest. Reynoutria invasion seems to influence microclimatic conditions. We found a higher abundance of silvicolous and a lower abundance of xerophilous ground beetles in the Reyountria stands than in the Urtica-dominated stands. Feeding guilds reacted differently to Reynoutria invasion that reduced the abundance of predators and herbivores but enhanced that of detritivores. Detritivores assumingly profit from the perennial presence of the large quantities of Reynoutria litter. We conclude that highly productive invaders pauperise the arthropod fauna and alter link strengths in trophic cascades shifting primary producer-based food webs to detritus-based food webs.

Base cation depletion due to soil acidification is a major environmental problem which can disrupt proper ecosystem functioning. We investigated nine mesic broad-leaved forests growing on Devonian sediments of the Rhenish Shield (Germany) and investigated the effect of coarse woody debris (CWD). The forests grow on soils originating from different parent material (graywacke, slates, dolostone) with upper soil pH-values ranging from 3.0 to 7.0. We analyzed soil chemistry, soil microbial parameters and the density of litter-dwelling detritivores (snails, slugs, woodlice and millipedes) to assess the influence of both acidification and CWD. The forests were classified according to their (Ca + Mg + K)/Al molar ratios into groups with ratios of either 2+ and Mg 2+ availability and an improved (Ca + Mg + K)/Al molar ratio. The presence of CWD also enhanced soil microbial biomass, the density of detritivores and species richness of snails, slugs and millipedes. Consequently, coarse woody debris influences nutrient fluxes and decreases the acidification-related risk of tree damage.

Many forest ecosystems have been extensively degraded by acidifying pollutants over the last decades. There is also widespread concern about population decline of a number of songbirds due to acidification-driven calcium limitation. We hypothesize that the carrying capacity of forests decreases with reduced soil calcium content. We analyzed songbird assemblage/habitat relationships by territory mapping at 30 sites in a total of five managed beech forests. The sites harbored 38 songbird species. A canonical correspondence analysis showed that soil acidification, represented by soil calcium content, had a significant influence on the species assemblages of the 14 most frequent songbirds. The vertical complexity of the canopy additionally influenced the assemblages. Multiple regressions revealed that the density of the territories of song thrush (Turdus philomelos) and nuthatch (Sitta europaea) were positively correlated to calcium content. Blackbirds (Turdus merula) seemed to compensate for the negative effect of acidification by selecting breeding sites close to forest edges to forage in less acidified agricultural habitats. In contrast, the territorial density of robin (Erithacus rubecula), chaffinch (Phylloscopus collybita) and coal tit (Parus ater) increased with increasing soil acidification. Contrary to our hypothesis, the overall carrying capacity of songbird was not reduced in forests with acidified soils. However, the nesting success of song thrush and blackbird, as determined by the number of fledglings, was higher in the forest with the highest calcium content when compared to the forest with the lowest calcium content. We conclude that some species are severely affected by acidification, whereas others seem to have evolved successful strategies to meet their calcium demand even in acidified habitats.

The highly invasive giant knotweed (Reynoutria spp.) often displaces nettle (Urtica dioica) dominated stands in European floodplains. Urtica-dominated stands differ from the monospecific Reynoutria stands in plant species richness and stand structure. We thus hypothesize that Reynoutria invasion profoundly alters ecosystem structure and function, with negative effects cascading up through the food chain. We performed a paired sampling design in six sites belonging to two different locations and studied effects on the soil and the litter-dwelling fauna. Reynoutria stands differed in habitat structure and were characterized by decreased soil pH and potassium depletion. The faunal analysis is based on model groups of herbivore generalists (Gastropoda), detritivores (Isopoda and Diplopoda), and predators (Opiliones). The gastropod assemblages from Reynoutria stands were severely impoverished subsets of those from Urtica stands with reduced densities, species richness and diversity. In general, snails were more sensitive to Reynoutria invasion than slugs such as the invasive Arion 'lusitanicus’. Among detritivores, the abundance of the Isopoda decreased, whereas Diplopoda were not affected by Reynoutria invasion. Yet, the relative abundance of detritivores was significantly higher within the Reynoutria stands. Abundance, species richness and diversity of the predatory Opiliones were higher in the relatively sparse Reynoutria stands. We conclude that ecosystem changes associated with Reynoutria invasion are characterized by shifts from a plant-based to a detritus-based food chain and that Reynoutria invasion primarily enhances predators that profit from the simplified vegetation structure.

We studied the snail fauna of four primeval forests of Central Slovakia and focused on the influence of forest type and coarse woody debris (CWD) on species assemblages. We found a total of 3281 individuals from 39 species. Species assemblages differed between the forests. In SW-facing oak forests, CWD enhanced the proportion of forest species such as the wood-grazing Cochlodina laminata and decreased the proportion of euryecious species like the litter-dwelling Punctum pygmaeum. In NE-facing beech forests, hygrophilous species such as Carychium tridentatum dominated the assemblages. This litter-dwelling snail was especially abundant close to CWD. The NE-facing beech forests harbored more species and individuals than the SW-facing oak forests did. CWD enhanced snail abundance, species richness and biodiversity, irrespective of forest type. We found positive correlations for

We investigated the distribution pattern of centipedes (Chilopoda) in four primeval forests of the western Carpathians, central Slovakia. The forests are located in two different mountain ranges (Kremnicke vrchy and Pol’ana Mountains), which are exposed on either the southern (Boky, Rohy) or northern slopes (Pol’ana, Badin). In these forests, the influence of coarse woody debris (CWD) on centipede distribution was studied, by distinguishing sampling sites on the forest floor, close to CWD (c-CWD) and distant from CWD (d-CWD). In total, we collected 2,706 individuals from 20 species of centipedes. Average species richness and number of individuals per forest ranged from 8 to 12 species/m2 and from 244 to 486 individuals/m2. The oak forests on south facing slopes harboured several species, which did not occur in the more northern exposed fir-beech forests. Number of species as well as individuals, however, varied more within than between individual forests. Increase of species number and density was mainly caused by CWD and was more pronounced on the southern slopes (P

We collected 1605 isopod individuals (eight species) and 671 diplopod individuals (17 species) in four primeval forests of the Western Carpathians, Central Slovakia, by leaf litter extraction. The forests are of different temperate deciduous forest types varying in tree species, aspect, elevation and soil characteristics. The oak forests, established on southwest oriented slopes at an elevation of 280–600 m, were characterized by Hyloniscus riparius , Porcellium conspersum , Enantiulus nanus and Ophioiulus pilosus . The beech forests, established on northeast oriented slopes at an elevation of 700–1100 m, were characterised by Ligidium hypnorum , Trachysphaera costata and Polyzonium germanicum . A remarkable increase of the total number of species and individuals occurred in both forest types adjacent to coarse woody debris (CWD). Woodlice density close to CWD was between 200 and 630 individuals m −2 (35–130 individuals m −2 distant from CWD); millipede density close to CWD ranged from 60 to 230 individuals m −2 (15–75 individuals m −2 distant from CWD). Species richness of both taxa close to CWD varied from 13 to 16 species m −2 (7–12 species m −2 distant from CWD). Thus, CWD has a significant influence on saprophages. However, structural components such as CWD and the amount of leaf litter did not significantly alter species assemblages. Species at sites distant from CWD were a subset of species at sites close to CWD. According to a canonical correspondence analysis (CCA), ‘forest type’ and ‘elevation within a slope’, as well as chemistry of the upper soil layer, i.e. ‘acidification’ and ‘nutrition’, strongly influenced species assemblages.

In sloping oak forests of the German low mountain range high wild boar (Sus scrofa) and red deer (Cervus elaphus) population densities may affect soil ecological processes by grubbing, grazing, trampling and dunging. We simulated wild boar grubbing in a fenced exclosure and an unfenced replicate and established two adjacent control plots, one fenced, the other unfenced. We evaluated if repeated soil bioturbation and game exclusion by fencing influence soil texture, soil chemical and soil biotic properties in the upper soil over a time period of 2 years. Soil bioturbation was conducted in November 2000 and 2001 creating a grubbing pattern similar to that found in naturally grubbed areas. Soil and fauna sampling was performed in spring and fall of the years 2001 and 2002. Soil bioturbation did not affect soil texture, pH and the contents of organic carbon and nitrogen. In contrast, the contents of potassium and magnesium, the microbial activity and the abundance of saprophageous and predatory soil arthropods were generally lower in grubbed plots compared to ungrubbed control plots (p≤0.05). The exclusion of game did not improve soil quality. On the contrary, microbial activity and the contents of organic carbon and total nitrogen were elevated outside the fenced exclosure (p≤0.05) which may be related to the deposition of urine and dung. Our study found that large mammals affect soil nutrient cycling in sloping oak forests either directly by the deposition of urine and dung or indirectly by accelerating nutrient leaching and disturbing the decomposer system in the soils.

We studied Coleoptera emerging from deadwood in a broadleaved forest that has been managed with nature-oriented forestry since 1990 and in which an accumulation of 10 m3 deadwood/ha has been achieved. We sampled a total of 11 m3 of deadwood from oak and beech trees and yielded 32,477 individuals pertaining to 342 species. The number of species emerging from oak deadwood was significantly higher than that from beech. Significantly more species emerged from deadwood with medium size (15–21 cm) diameter than from smaller (5–7 cm) or larger (40–60 cm) diameters. The stage of decay did not influence the number of species during the first 6 years of decomposition. Species richness strongly increased with the amount of deadwood sampled. Species–area regressions yielded z-values of 0.81 for oak and 0.87 for beech deadwood. The beetle assemblage was characterized by a low number of xylophagous species and a high number of mobile zoophagous species. However, two-thirds of the individuals sampled pertained to nine species of Scolytidae. This is why Shannon–Wiener diversity (H) and evenness-indices (E) greatly decreased with increasing number of scolytids. The species and individuals yielded from the sun-exposed deadwood outnumbered those from shaded areas. Namely the scolytid Taphrorychus bicolor reached remarkably high densities in the sun-exposed beech deadwood (>800 individuals/m2). In contrast, oak deadwood never harboured such high numbers of scolytids. Felling of moribund trees had decreased the number of scolytids but it had also considerably reduced the number of rare and endangered species.

In a 2-year study we investigated soil macro-arthropods (Opilionida, Araneida, Pseudoscorpionida, Isopoda, Diplopoda, Chilopoda, Coleoptera) in a forest where forestry management is nature oriented and includes the accumulation of about 10 m 3 deadwood per ha. We focused on soil arthropod density close to (c-CWD) or distant from coarse woody debris (d-CWD) in different locations of the forest stand (interior location versus edge zone) and in different seasons (summer versus winter). We found twice as many individuals of almost all taxa at c-CWD sites compared to d-CWD sites. The influence of CWD on most taxa of soil arthropods was more pronounced in the edge zone than in the interior location. In the edge zone c-CWD sites yielded significantly higher numbers of all taxa in both seasons. In the interior location seasonal effects occurred. For example, Pseudoscorpionida and Coleoptera-Larvae preferred c-CWD sites only in summer, whereas Araneida preferred c-CWD sites only in winter. A three-way ANOVA, regarding site, location and season as the main factors, emphasised the dominant influence of CWD on the density of all taxa. Consequently, CWD is an important structural component that serves as a habitat for many saprophagous species and thus locally improves the nutritional situation of a forest stand. CWD also may reduce the pest species problem because it harbours many zoophagous soil macro-arthropods as well. # 2004 Elsevier B.V. All rights reserved.

Cold-season beetles, Catops nigricans Spence, Choleva agilis Illiger and Choleva elongata Payk., i.e. beetles which start to lay eggs in autumn, which are active during the winter in the adult stage and develop from the egg stage to the adult stage mainly during the winter months, were collected from various locations in north-western Europe and reared in the laboratory at varying temperatures and photoperiods.Reproduction of all species started in autumn and continued during the winter months. Highest reproductive and survival rates occurred at low temperatures and within a small thermal window ranging from 5° to 10°C: The fitness of individuals decreased at higher and lower temperatures. The lower thermal threshold for all developmental stages was in the range from -5°C to +2°C. The metabolisms of the species were independent of temperature in both dormant and non-dormant stages and were elevated in the low temperature range in comparison to other species which show a temperature-dependent reaction pattern.Optimal dates for reproduction were determined by the duration of an obligatory adult summer diapause. In C. nigricans, which favours the litter layer of deciduous forests, this duration was fine-tuned by exogenic factors, such as photoperiod and temperature. In contrast, the soil-inhabiting species Ch. elongata showed a homeostatic response pattern, independent of temperature and photoperiod. Heritability (h2) of the duration of diapause was approximately 0.26 in C. nigricans, less pronounced in Ch. agilis (ca. 0.12) and not evident in the subterranean species Ch. elongata.All three species compensated for the vagaries of climate through bet-hedging tactics. Bet-hedging is so pervasive that a recent substantial increase in temperature seems to have a negligible effect on the distribution pattern of all three species. Based on life-history data it is conceivable that both soil-inhabiting Choleva species, which require a relatively low thermal sum for their development, were already present in western Europe during the sub-arctic conditions when ice shields reached their maximum extension during glacial periods by shifting their activity from the cold to the warm season. The Atlantic fringe north of the Pyrenees, where the climate was not cold enough for permafrost during glacial stages, was probably the only refuge where Ch. elongata might have survived. In contrast, the Mediterranean region should have been the northernmost refuge for C. nigricans during glacial periods. This species has relatively high day-degree requirements (= 1150 d°) for individual development when compared to both Choleva species (= 700 d°).

Herbivorous beetles were sampled in central Slovakia and in the Tatra Mountains of northern Slovakia from seven different Salix species which are partly characterized by smooth leaves containing phenolic glycosides and partly by hairy leaves containing tannins. The collection included about 8000 individuals representing 129 species. Of the 129 species, 77 species are able to use the willows as hosts; the remaining 52 ‘tourist’ species comprise less than 3% of the collected individuals. The data on species richness and abundance did not generally support the ‘feeding specialization’ hypothesis. The proportion of specialized (= monophagous and oligophagous) beetles feeding on willows of both morphological and biochemical groups was in the same range. Host plants of the two groups could support high diversity and high evenness values, even when leaf characteristics and plant chemicals largely influenced species assemblage. The region in which the willow trees grow had a considerable impact on host plant use. Generalist beetle species predominated in central Slovakia. By contrast, in the Tatra Mountains, specialist feeders which are able to use phenolic glycosides to their advantage were predominant. The number of species and the total density of individuals collected from willows containing phenolic glycosides (S. fragilis and S. purpurea) did not usually vary between the two regions. In contrast, fewer species and individuals were found in the Tatra Mountains when they settled on willow species containing tannins (S. caprea and S. cinerea). Also, the phylogenetic status of host plants affected species assemblages. In central Slovakia willow species of the subgenus Vetrix (S. purpurea, S. caprea and S. cinerea) generally showed a higher beetle diversity (Hs) than species of the subgenus Salix (S. fragilis, S. alba and S. triandra), although both subgenera comprise species of both morphological and biochemical groups. Furthermore, when the analysis was restricted to beetles of central Slovakia, which should be most adapted to their host plants (i.e. catkin feeders and phyllophages in the adult and larval stage), the phylogenetic status was found to be more important than any single leaf character measured.

The jumping plant-lice fauna of seven different willow species growing adjacent to the Rhine River and nearby was investigated in a two-year study. In four of five distinct sites all the seven plant-lice species were found, which feed on willows in central Europe. Number and density of species per host varied tremendously depending on the year, host plant species and site. There was no plant-lice species which characterised a distinct host or a distinct site. Cacopsylla pulchra (Zetterstedt 1838) was the most common psyllid species: it dominated at four of the five sites studied, and preferred either Salix viminalis, S purpurea or S alba at each site, even when the other host plants were also present. The canonical correspondence analysis (CCA), which takes the year of study, the site and the host plant species including secondary plant chemistry into account, resulted in 45% of the variance in psyllid diversity, leaving up to 55% to unexplained variance which could potentially be accounted for by a stochastic dispersion pattern and the low ability to find host plants. The number of species and individuals of the Salix-feeding psyllids usually surpassed that one of the tourist species. However, several examples of this study exhibited higher tourist guild inputs than of psyllid species associated with their hosts. This was found not only for single host trees but also for total groups of single willow species growing at a site. The study clearly demonstrates that plant-lice assemblages and herbivory are dynamic processes that reflect influences of variable environmental conditions and erratic colonization.

In April 1996, we collected soil samples in thevicinity of a magnesite plant at Lubenik, southernSlovakia, and screened them for soil microbial biomassand activity. Six investigated sites were chosen alonga transect, with distances ranging from 600 to 8000 mfrom the plant, to represent a gradient ofintoxication. Soil microbial cellulase activity,respiration, biomass, metabolic quotient of the soilmicrobiota, and numbers of platable fungi increasedwith increasing distance from the plant, i.e.decreasing degree of intoxication. The observedgradients of soil microbial characteristics of theinvestigated sites reflect the physico-chemical soilparameters and the floristic characteristics of thesesites, and may be used to predict transitory changesduring amelioration.

Summary Long-term observations of Trichoniscus pusillus revealed that chemical composition and microbial activity of the leaf litter serving as food influenced the reproductive success of females and the mortality rates of juveniles as well. Of the food sources investigated, only alder litter, exhibiting high microbial activity, allowed the maintenance of a stable population with frequently reproducing females. This study concludes that the food type is a significant factor for population parameters of this parthenogenetic isopod. Our results on T. pusillus, belonging to the taxon Synocheta, are compared with data on terrestrial isopod species of the taxon Crinocheta.

Summary We analysed field data on the occurrence of woodlice and millipedes in abandoned grassland in southwestern Germany using multivariate ordination statistics to extract information on single environmental factors influencing the distribution of particular species in the field. Different methods (DECORANA, CANOCO) revealed slightly different patterns of ordination, but led to similar conclusions. These conclusions coincide with previously observed ecophysiological requirements of isopods, and confirm the significance of the soil pH for their distribution. Howewer soil pH did not appear to be significant for diplopods. The distribution of diplopod species mainly corresponds with mean annual air temperature. Besides assigning particular species to single study sites that are characterised with respect to environmental factors, we statistically associate a group of three isopod species having similar ecological requirements.

Field studies on microbial populations and their activity in soil and litter layers of different sites revealed statistically significant correlations with climatic factors, soil characteristics and the number of terrestrial isopods (Isopoda: Oniscidea). The number of captured Porcellio scaber was negatively correlated with the density of soil microbiota, but positively correlated with both respiration and cellulolytic activity of litter-colonizing microorganisms. By contrast, the number of Oniscus asellus was positively correlated with soil microbial density and respiration, and cellulolytic and respiratory activity of the litter. These interspecific differences were unexpected between species that frequently occur sympatrically, and, thus, probably have similar ecological requirements. Hence, the results suggested species-specific interactions of these species with soil and litter-colonizing microbiota. However, further field studies are required to prove this.

Choleva agilis Illiger 1789 is a cold season species which reproduces and develops in winter months and obligatorily aestivates in the early adult stage from IV until IX. Aestivation delays, and tends to synchronize, the developmental cycle with the season rather than avoids deteriorating climatic conditions. Females [FF] oviposit for about 150 days. However, at the end of pre-imaginal development in the spring the adults emerge within a relatively narrow time interval of about 35 days. Synchronisation of individual development within the population is caused by the differences in thermal thresholds in subsequent pre-imaginal stages, and by the changing temperatures during winter months as well. The narrow time interval of adult emergence is not maintained until the age of first reproduction. By contrast, diapause intensity varies and gives the capability to spread the onset of reproduction over a time interval of more than 200 days, even between full sibs. Spreading the age at first reproduction even within families, and the relatively low heritabi-lity in the duration of diapause (h 2 = 0.12 + 0.018), are interpreted as bet-hedging mechanisms to cope with the vagaries of weather conditions in an unpredictable environment. Temporal spreading of reproduction is so pervasive that it provides the opportunity for at least some daughters of each single dam to match the correct date of oviposition, independently of birth dates and weather conditions which could be expected in the area of study. There is insufficient synchronisation of the developmental cycle with the season by diapause intensity when (a) oviposition is very early in the season, and (b) the entire pre-imaginal development occurs at extremely high temperatures. Under these circumstances an ecological tuning by photoperiod and temperature is neccessary.

We compared Quercus petraea monocultures with adjacent mixed oak-hazel (Corylus avellana) stands at gentle (14°) and steep (25°) slopes of the Ahr-Eifel. The influence of hazel on forest floor mass, soil nutrients, microbial properties and on the abundance of Lumbricidae was studied. Litter mass was greater in mixed stands than in oak monocultures, resulting in a thicker Ah-horizon. Additionally, the PO43-, Ca2+- and Mg2+-contents were higher and the Al3+-content lower in the upper soil of mixed stands. In contrast, the contents of organic carbon , total nitrogen and the C/N ratio did not differ between the two soils. Basal respiration, specific microbial activity (qCO2) and carbon mineralisation (Cmin) were higher in mixed stands than in oak monocultures. Lumbricidae showed low densities in three of the stands studied (15-21 ind./m2) and were almost absent at the oak monoculture on the steep terrain (2 ind./m2)., Le noisetier améliore la qualité du sol des peuplements de chênes de basse montagne en Allemagne. Nous avons comparé des monocultures de type Quercus petraea avec des cultures adjacentes mixtes composées de chênes et de noisetiers (Corylus avellana) situées sur des pentes (14°/25°) différentes. L'influence du noisetier sur la masse de litière, les substances nutritives du sol, les propriétés microbiennes et l'abondance de Lumbricidae at été étudiée. Cette étude a montré que la masse de litière est plus élevée dans les cultures mixtes que dans les monocultures de chênes ; il en résulte un épaississement de l'horizon Ah. En outre, les teneurs en PO43- -P, Ca2+ - et Mg2+ - sont plus élevées et les teneurs en Al3+ -plus faibles dans les couches supérieures des sols de cultures mixtes. Par contre, la teneur en carbone organique, en azote total ainsi que la relation C/N ne diffèrent pas. La respiration de base, l'activité microbienne spécifique (qCO2) et la minéralisation carbonique (Cmin) sont plus élevées dans les cultures mixtes que dans les monocultures de chênes. Les Lumbricidae présentent des densités faibles dans trois des cultures étudiées (15-21 ind./m2), tandis qu'ils sont pratiquement absents dans les monocultures de chênes en terrain escarpé (2 ind./m2).

The sandy beaches of British Columbia are inhabited by a small number (11 species) of indigenous Staphylinidae which live near the drift line in the mid to upper littoral zone. They prefer fine-grained sandy beaches and most species feed on other intertidal invertebrates. All species investigated survived submersion in seawater by becoming quiescent, thereby reducing their metabolic rate. Oxygen consumption in seawater was greatly reduced. On re-exposure to air, a large overshoot in oxygen consumption occurred (in Thinopinus pictus), signifying a prior oxygen debt. In Cafius canescens, Cafius seminitens, and Hadrotes crassus the time required to reach full recovery was directly related to the duration of submersion, with 50% mortality in the population when recovery time exceeded 25 min. At a seawater temperature of 10 °C, LT50 was reached at 12–16 h submersion and at 20 °C, after 6.5 h. In Thinopinus pictus, however, recovery time was independent of duration of submersion, although the mortality curves were almost the same as for the three previously mentioned species, with LT50 occurring at 13 h at 10 °C and 7–8.5 h at 20 °C. Bledius monstratus showed symptoms of oxygen depletion only after a considerable time lag. Experimental submersion of this beetle resulted in an LT50 of 18 h at 20 °C.