Aboveground Community Research Articles

Soil nematode assemblages as bioindicators of primary succession along a 120-year-old chronosequence on the Hailuogou Glacier forefield, SW China

Successional dynamics in terrestrial ecosystems is important for interactions between aboveground and belowground subsystems. In this study, nematode communities in a Hailuogou Glacier Chronosequence from seven stages were investigated to determine whether changes in soil phosphorus (P) and nematode assemblages parallel those observed in aboveground communities, and whether the primary succession in this chronosequence has entered a retrogressive phase after 120 years of succession. The initial 40-year succession, including stages 2, 3 and 4, can be viewed as a build-up phase. Especially at stage 3, vegetation succession from grassland to forest accelerated the accumulation of plant litter and bioavailable P, paralleled with a sharp increase in nematode abundance. The mature phases covering stages 5, 6 and 7 displayed most balanced nematode communities, in which abundance, taxon richness, maturity index and structure index were at highest. However, the last stage 7 appeared to show some retrogressive characteristics, as suggested by the reduced bioavailability of P and a significant decrease in nematode densities, along with the disappearance of some rare genera of nematodes from higher trophic guilds, resulting in decreases in the nematode channel ratio, plant parasite index and enrichment index. Thus, the Hailuogou Glacier Chronosequence may enter its retrogressive phase during the next decade or century. A bacterial-based nematode energy channel dominated the chronosequence during the development; by contrast, a fungivore-based channel was activated at the early and late stages, because fungivores are better adapted to nutrient-poor environments. Our results demonstrated that different nematode guilds have contrasting responses to chronosequence stages, possibly due to their different responses to bottom-up and top-down controls. Furthermore, soil nematode communities could be used as sensitive bioindicators of soil health in glacial-retreat areas.

Seed bank composition varies along invasion and inundation gradients in vernal pool wetlands

Environmental filters are well-known influences on aboveground vegetation community structure; however, less is known about their role on belowground seed banks. Understanding the influence of environmental filters on the composition of seed banks can reveal community dynamics across known environmental gradients and facilitate restoration efforts. We examined the influence of environmental filters on seed banks of vernal pools by characterizing seed density and diversity along seasonal inundation gradients. We also sampled seed banks from both naturally occurring and restored vernal pools that differed in their aboveground communities (invasive or native species dominated) in a long-term field study in Solano Co., California, USA. We found that the highest seed densities were associated with the longest inundation period and in the naturally occurring pools. Inundation gradients within a pool had little influence on seed bank diversity, yet among the pool types diversity and community metrics varied. The naturally occurring pools, regardless of invasion status, displayed a greater species richness and diversity than constructed pools. Our greenhouse germination trials did not show a strong relationship of inundation depths influencing species and total germination. Overall, we found that local position in the field along inundation gradients within a pool strongly affected soil seed bank density, while seed bank diversity varied more across pool types. Environmental filters may be limiting germination with the pool bottoms having the highest inundation and maintain the densest seed bank, but our lack of difference in the germination trials suggests alternative mechanisms other than inundation may be hindering germination.

Early recovery signs of an Australian grassland following the management of Parthenium hysterophorus L.

Parthenium weed (Parthenium hysterophorus L.) is believed to reduce the above- and below-ground plant species diversity and the above-ground productivity in several ecosystems. We quantified the impact of this invasive weed upon species diversity in an Australian grassland and assessed the resulting shifts in plant community composition following management using two traditional approaches. A baseline plant community survey, prior to management, showed that the above-ground community was dominated by P. hysterophorus, stoloniferous grasses, with a further high frequency of species from Malvaceae, Chenopodiaceae and Amaranthaceae. In heavily invaded areas, P. hysterophorus abundance and biomass was found to negatively correlate with species diversity and native species abundance. Digitaria didactyla Willd. was present in high abundance when P. hysterophorus was not, with these two species, contributing most to the dissimilarity seen between areas. The application of selective broad leaf weed herbicides significantly reduced P. hysterophorus biomass under ungrazed conditions, but this management did not yet result in an increase in species diversity. In the above-ground community, P. hysterophorus was partly replaced by the introduced grass species Cynodon dactylon L. (Pers.) 1 year after management began, increasing the above-ground forage biomass production, while D. didactyla replaced P. hysterophorus in the below-ground community. This improvement in forage availability continued to strengthen over the time of the study resulting in a total increase of 80% after 2 years in the ungrazed treatment, demonstrating the stress that grazing was imposing upon this grassland-based agro-ecosystem and showing that it is necessary to remove grazing to obtain the best results from the chemical management approach.

Vegetation Community Convergence of Pastoralists' Pasture at Different Economic Levels in Desert Steppe

Vegetation characteristics of pastoralist households' pastures at different economic levels were quantified to compare the grassland conditions in Sunite Right Banner, Inner Mongolia, China in 2011 and 2012. The results showed that the heights of Stipa klemenzis and Cleistogenes songorica were similar among economic treatments. And the height of Allium polyrhizm had no significant differences between high-economic-level (HEL) and low-economic-level (LEL) treatments. There were no significant difference among treatments in the canopy cover of C. songorica. The densities of dominant species (S. klemenzis, C. songorica and A. polyrhizm) were significantly similar among treatments. Aboveground community biomass in reference area (CK) was higher than that in other three treatments in 2011, but their biomass showed no significant difference among three economic treatments; for 2012, biomass in HEL was higher than low-economic-level treatment (LEL), while the biomass in middle-economic-level treatment (MEL) and CK was similar to that in HEL and LEL, respectively. Aboveground biomass of S. klemenzis and C. songorica was similar among treatments in both 2011 and 2012. Biomass of A. polyrhizum had no significant difference between HEL and MEL. Households of LEL had rented out excess lands and those of HEL had leased their available lands thus resulting uniform utilization and convergence of pastoralist households' pastures across all economic levels.

Co-occurrence patterns of above-ground and below-ground mite communities in farmland of Sanjiang Plain, Northeast China

One of the fundamental questions in community ecology is whether communities are random or formed by deterministic mechanisms. Although many efforts have been made to verify non-randomness in community structure, little is known with regard to co-occurrence patterns in above-ground and below-ground communities. In this paper, we used a null model to test non-randomness in the structure of the above-ground and below-ground mite communities in farmland of the Sanjiang Plain, Northeast China. Then, we used four tests for non-randomness to recognize species pairs that would be demonstrated as significantly aggregated or segregated co-occurrences of the above-ground and below-ground mite communities. The co-occurrence pattern of the above-ground mite community was significantly non-random in October, suggesting species segregation and hence interspecific competition. Additionally, species co-occurrence patterns did not differ from randomness in the above-ground mite community in August or in below-ground mite communities in August and October. Only one significant species pair was detected in the above-ground mite community in August, while no significant species pairs were recognized in the above-ground mite community in October or in the below-ground mite communities in August and October. The results indicate that non-randomness and significant species pairs may not be the general rule in the above-ground and below-ground mite communities in farmland of the Sanjiang Plain at the fine scale.

Effects of Soil Amendments on the Abundance of a Parasitic Weed, Yellow Rattle (Rhinanthus minor) in Hay Fields

Yellow rattle is a hemiparasitic weed that is becoming increasingly problematic in hay fields in the northeastern United States. The biomass of yellow rattle was assessed in two experiments in which commercially available soil amendments were applied to an infested hay field under no-till management. The amendments were applied in the fall of 2010 and 2011 and included wood ash, biochar, hardwood sawdust, lime, and K. Wood ash applied at a rate of 8,967 kg ha−1 (4 tons per acre) had the greatest suppressive effect and reduced yellow rattle biomass the following summer by 86 and 92% relative to the untreated control in Experiments 1 and 2, respectively. Two additional treatments included in Experiment 2, a doubled rate of wood ash and sawdust applied at a rate of 13,450 kg ha−1, also reduced yellow rattle biomass. No other treatments affected yellow rattle biomass. A partial least-squares regression (PLSR) analysis that included aboveground plant community and soil biochemical data explained only 42.4% of the variation in yellow rattle biomass, suggesting that the mechanisms responsible for the suppression of yellow rattle by wood ash and sawdust are complex. Amending hay fields with wood ash or sawdust may be an effective nonherbicide strategy for managing yellow rattle infestations. Additional research will be required to determine the mechanisms and generality of yellow rattle suppression by wood ash and sawdust amendments to the soil.

Rapid recovery of soil bacterial communities after wildfire in a Chinese boreal forest

Fires affect hundreds of millions of hectares annually. Above-ground community composition and diversity after fire have been studied extensively, but effects of fire on soil bacterial communities remain largely unexamined despite the central role of bacteria in ecosystem recovery and functioning. We investigated responses of bacterial community to forest fire in the Greater Khingan Mountains, China, using tagged pyrosequencing. Fire altered soil bacterial community composition substantially and high-intensity fire significantly decreased bacterial diversity 1-year-after-burn site. Bacterial community composition and diversity returned to similar levels as observed in controls (no fire) after 11 years. The understory vegetation community typically takes 20–100 years to reach pre-fire states in boreal forest, so our results suggest that soil bacteria could recover much faster than plant communities. Finally, soil bacterial community composition significantly co-varied with soil pH, moisture content, NH4+ content and carbon/nitrogen ratio (P < 0.05 in all cases) in wildfire-perturbed soils, suggesting that fire could indirectly affect bacterial communities by altering soil edaphic properties.

Progressive and retrogressive ecosystem development coincide with soil bacterial community change in a dune system under lowland temperate rainforest in New Zealand

It is established that plant communities show patterns of change linked to progressive and retrogressive stages of ecosystem development. It is not known, however, whether bacterial communities also show similar patterns of change associated with long-term ecosystem development. We studied soil bacterial communities along a 6,500 year dune chronosequence under lowland temperate rain forest at Haast, New Zealand. Pyrosequencing of 16S rRNA genes was used to observe structural change in bacterial communities during the process of pedogenesis and ecosystem development. Bacterial communities showed patterns of change during pedogenesis, with the largest change during the first several hundred years after dune stabilization. The most abundant bacterial taxa were Alphaproteobacteria, Actinobacteria and Acidobacteria. These include taxa most closely related to nitrogen-fixing bacteria, and suggest heterotrophic nitrogen input may be important throughout the chronosequence. Changes in bacterial community structure were related to changes in several soil properties, including total phosphorus, C:N ratio, and pH. The Bacteroidetes, Actinobacteria, Cyanobacteria, Firmicutes, and Betaproteobacteria all showed a general decline in abundance as pedogenesis proceeded, while Acidobacteria, Alphaproteobacteria, and Plantctomycetes tended to increase as soils aged. There were trends in the dynamics of bacterial community composition and structure in soil during ecosystem development. Bacterial communities changed in ways that appear to be consistent with a model of ecosystem progression and retrogression, perhaps indicating fundamental processes underpin patterns of below and above-ground community change during ecosystem development.

Complex restoration challenges: Weeds, seeds, and roads in a forested Wildland Urban Interface

Federal policies in the US strongly emphasize reducing hazardous fuels at the Wildland Urban Interface (WUI). However, these areas present restoration challenges as they often have exotic weeds, frequent human disturbance, and the presence of roads. Understanding seed banks is important in planning for desirable post-disturbance community conditions, developing integrated weed management programs, and complying with State and Federal regulations. We characterized the aboveground vegetation and seed bank in a WUI composed of mixed age dry-mixed conifer forest stands in central Washington State, and examined patterns and relationships between aboveground vegetation and seed bank germinant abundance in relation to distance to road, seed bank layer, and herbicide treatments. Noxious weed frequency, as well as exotic weed and annual native forb cover, significantly decreased with distance from road, while native graminoid cover increased, declining beyond 20m. Herbicides did not affect composition of the aboveground community in the short term. Six hundred and thirty seeds germinated from litter and mineral soil samples over a 5 month trial, and 43 species were identified. Most germinants (77%) and species (36 species) emerged from the litter layer compared to mineral soil, and the majority were annual forbs, followed by perennial forbs, native graminoids and exotic species. Little similarity was found between the extant vegetation and seed bank floras. Fourteen percent of germinants were exotic species, and were found in similar abundances regardless of proximity to road or herbicide treatment. Findings from our study suggest that (1) roads strongly influenced aboveground vegetative cover and species composition; (2) seed bank contributions to desirable post-disturbance understory development may be relatively low, especially if activities remove the litter layer; (3) weed populations were largely confined to near road environments, but the weed seed bank, which is a substantial part of the total seed bank, was not; and (4) herbicide treatments were ineffective and did not impact seed banks in the short term.

Banking on the past: seed banks as a reservoir for rare and native species in restored vernal pools

Soil seed banks serve as reservoirs for future plant communities, and when diverse and abundant can buffer vegetation communities against environmental fluctuations. Sparse seed banks, however, may lead to future declines of already rare species. Seed banks in wetland communities are often robust and can persist over long time periods making wetlands model systems forstudyingthe spatialand temporal links between above- and belowground communities.Usingcollectedsoilsandgerminationtrials,weassessedspeciesdiversityanddensityintheseedbanksof restored, ephemeral wetlands (vernal pools) in California's Central Valley, USA. Using long-term vegetation surveys, we compared the community structure of seed banks to that of aboveground vegetation and assessed the temporal links between below- and aboveground communities. We also compared the proportional abundances of different cover classes as well as the abundance of native plants in seed banks to aboveground communities. The proportional abun- dances of both rare and native species were greater in seed bank samples than in aboveground samples, yet the seed bank had lower species richness than aboveground vegetation. However, the seed bank had greater levels of differen- tiation among pools (beta diversity;b) than aboveground samples. Additionally,the seed bank was more similar to the earlier(2003-06)abovegroundcommunitythanthemorerecent (2007-10)abovegroundcommunity.Thecorrelation ofspeciescompositioninthecurrentseedbanktoanearlierabovegroundcommunitysuggeststhatseedbanksexhibit storage effects while aboveground species composition in this system is not driven by seed bank composition, but is perhapsduetoenvironmentalfiltering.Weconcludethattheseedbankofthesepoolsisneitherpronetothesametem- poral rates of invasion as the aboveground community, nor is seed abundance presently a limiting factor in the above- ground frequency of native species or a promoting factor in plant invasions of these restored habitats.

Belowground induction by Delia radicum or phytohormones affect aboveground herbivore communities on field-grown broccoli.

Induced plant defence in response to phytophagous insects is a well described phenomenon. However, so far little is known about the effect of induced plant responses on subsequently colonizing herbivores in the field. Broccoli plants were induced in the belowground compartment using (i) infestation by the root-herbivore Delia radicum, (ii) root application of jasmonic acid (JA) or (iii) root application of salicylic acid (SA). The abundance of D. radicum and six aboveground herbivores displaying contrasting levels of host specialization were surveyed for 5 weeks. Our study showed that the response of herbivores was found to differ from one another, depending on the herbivore species, its degree of specialization and the root treatment. The abundance of the root herbivore D. radicum and particularly the number of emerging adults was decreased by both phytohormone treatments, while the number of D. radicum eggs was increased on conspecific infested plants. The root infestation exhibited moderate effects on the aboveground community. The abundance of the aphid Brevicoryne brassicae was strongly increased on D. radicum infested plants, but the other species were not impacted. Root hormone applications exhibited a strong effect on the abundance of specialist foliar herbivores. A higher number of B. brassicae and Pieris brassicae and a lower number of Plutella xylostella were found on JA treated plants. On SA treated plants we observed a decrease of the abundance of B. brassicae, Pi. rapae, and P. xylostella. Surprisingly, generalist species, Mamestra brassicae and Myzus persicae were not affected by root induction treatments. Finally, root treatments had no significant effect on either glucosinolate (GLS) profiles of the heads or on plant quality parameters. These results are discussed from the perspective of below- aboveground interactions and adaptations of phytophagous insects to induced plant responses according to their trophic specialization level.

Similarity between grassland vegetation and seed bank shifts with altered precipitation and clipping, but not warming

Similarity between seed bank and aboveground vegetation is frequently studied in order to better understand how community composition is affected by factors such as disturbance and succession. Grassland plant communities are known to be sensitive to shifts in precipitation and increases in temperature associated with climate change, but we do not know if and how these factors interact to affect the similarity between seed bank and aboveground vegetation. Also unknown is how the impact of grazing, the dominant land-use in grasslands, will interact with climatic conditions to affect similarity. We manipulated precipitation and temperature, and cut vegetation (as a proxy for grazing) at a grassland site for three years. Percent cover of aboveground vegetation was estimated in the third year, and compared with persistent seed bank samples taken in the year prior from the same plots. Similarity increased with reduced precipitation, was unresponsive to warming, and decreased with clipping. The aboveground community responded strongly to the treatments, while the seed bank community did less so, suggesting similarity responses were largely driven by changes in aboveground vegetation. Because of the importance of the seed bank in vegetation regeneration, understanding the relationship between seed bank and aboveground vegetation will improve our understanding of plant community dynamics under climate change and varied management (grazing) intensities.

Disturbance intensity, timing and history interact to affect pasture weed invasion

Past disturbance events shape future community trajectories if their ecological legacies interact with contemporary disturbance regimes to affect recruitment and reproduction. In pastures, large-scale disturbance events can become undetectable in aboveground community components but persist as augmented weed seedbanks, suggesting disturbance history may be a predictor of weed invasion magnitude following subsequent disturbance. Using a randomized block factorial design, we investigated how soil disturbance intensity, timing and history interact to affect weed recruitment, diversity and reproduction by implementing a range of disturbance intensities in April and June 2004 in pastures of differing disturbance history. Response variables were followed for two years. Disturbance timing interacted with disturbance intensity and history to affect recruitment, with some June treatment combinations having ≥48% higher weed abundance than those in April. Relative to undisturbed controls, low to intermediate disturbance intensity facilitated recruitment by ≥117% but high intensity disturbance had highest recruitment, particularly in previously disturbed pastures (≥543% increase). In both years, weed species richness was highest in intense disturbances in previously disturbed pastures. Importantly, weed reproduction was nearly one order of magnitude higher in intense disturbance patches, especially in previously disturbed pastures, and increased through time by ≥243%. These findings indicate weed recruitment, diversity and reproductive output are seed- and microsite-limited, and that intense soil disturbance may result in high long-term weed abundance. Although moderate disturbance facilitated recruitment, reproduction here was low, suggesting modest disturbance will not appreciably increase weed abundance. The most common species were Taraxacum officinale and Poa pratensis, both of which can benefit forage-livestock production, but most establishing species were of low palatability. We recommend grassland managers explicitly integrate disturbance history into dynamic management planning, consider augmenting seedbanks with ‘desirable’ weed species to help communities recover following inevitable disturbance events and do not rely exclusively on aboveground characters to evaluate their system's vulnerability to undesirable plant establishment and persistence.

Influence of aboveground vegetation on seed bank composition and distribution in a Great Basin Desert sagebrush community

The quantity, composition, and spatial dispersion of seed banks can greatly affect community dynamics. While seed banks of hot deserts have been studied extensively, little is known about seed banks in cold deserts, in particular the relationship between the seed bank and the aboveground vegetation. We investigated the relationship between the seed bank and aboveground vegetation and the effect of microhabitat (shrub interspace or beneath shrub) and aboveground community phase (high or low perennial bunchgrass cover) on the seed bank of a Great Basin Desert sagebrush community. The seed bank and aboveground vegetation differed in their most dominant species, resulting in moderately dissimilar species compositions as determined by Sørensen's similarity index and Bray–Curtis distance. In contrast, comparing the seed bank species composition to the aboveground vegetation structure (functional groups) using non-metric multidimensional scaling (NMDS) revealed a correspondence between the two communities. Shrub seed densities were higher beneath shrubs. Neither microhabitat nor community phase explained variation in total seed density or species richness. Therefore, our measures of the aboveground vegetation did not influence seed density across functional groups or species richness, and the similarity between the seed bank and aboveground vegetation varied depending on the aboveground organizational level used in comparisons.

Response of the soil microbial community to changes in precipitation in a semiarid ecosystem.

Microbial communities regulate many belowground carbon cycling processes; thus, the impact of climate change on the structure and function of soil microbial communities could, in turn, impact the release or storage of carbon in soils. Here we used a large-scale precipitation manipulation (+18%, -50%, or ambient) in a piñon-juniper woodland (Pinus edulis-Juniperus monosperma) to investigate how changes in precipitation amounts altered soil microbial communities as well as what role seasonal variation in rainfall and plant composition played in the microbial community response. Seasonal variability in precipitation had a larger role in determining the composition of soil microbial communities in 2008 than the direct effect of the experimental precipitation treatments. Bacterial and fungal communities in the dry, relatively moisture-limited premonsoon season were compositionally distinct from communities in the monsoon season, when soil moisture levels and periodicity varied more widely across treatments. Fungal abundance in the drought plots during the dry premonsoon season was particularly low and was 4.7 times greater upon soil wet-up in the monsoon season, suggesting that soil fungi were water limited in the driest plots, which may result in a decrease in fungal degradation of carbon substrates. Additionally, we found that both bacterial and fungal communities beneath piñon pine and juniper were distinct, suggesting that microbial functions beneath these trees are different. We conclude that predicting the response of microbial communities to climate change is highly dependent on seasonal dynamics, background climatic variability, and the composition of the associated aboveground community.

Alien and endangered plants in the Brazilian Cerrado exhibit contrasting relationships with vegetation biomass and N : P stoichiometry

Although endangered and alien invasive plants are commonly assumed to persist under different environmental conditions, surprisingly few studies have investigated whether this is the case. We examined how endangered and alien species are distributed in relation to community biomass and N : P ratio in the above-ground community biomass in savanna vegetation in the Brazilian Cerrado. For 60 plots, we related the occurrence of endangered (Red List) and alien invasive species to plant species richness, vegetation biomass and N : P ratio, and soil variables. Endangered plants occurred mainly in plots with relatively low above-ground biomass and high N : P ratios, whereas alien invasive species occurred in plots with intermediate to high biomass and low N : P ratios. Occurrences of endangered or alien plants were unrelated to extractable N and P concentrations in the soil. These contrasting distributions in the Cerrado imply that alien species only pose a threat to endangered species if they are able to invade sites occupied by these species and increase the above-ground biomass and/or decrease the N : P ratio of the vegetation. We found some evidence that alien species do increase above-ground community biomass in the Cerrado, but their possible effect on N : P stoichiometry requires further study.

Abiotic drivers and plant traits explain landscape‐scale patterns in soil microbial communities

The controls on aboveground community composition and diversity have been extensively studied, but our understanding of the drivers of belowground microbial communities is relatively lacking, despite their importance for ecosystem functioning. In this study, we fitted statistical models to explain landscape-scale variation in soil microbial community composition using data from 180 sites covering a broad range of grassland types, soil and climatic conditions in England. We found that variation in soil microbial communities was explained by abiotic factors like climate, pH and soil properties. Biotic factors, namely community-weighted means (CWM) of plant functional traits, also explained variation in soil microbial communities. In particular, more bacterial-dominated microbial communities were associated with exploitative plant traits versus fungal-dominated communities with resource-conservative traits, showing that plant functional traits and soil microbial communities are closely related at the landscape scale.

Fear of Predation Slows Plant-Litter Decomposition

Aboveground consumers are believed to affect ecosystem functioning by regulating the quantity and quality of plant litter entering the soil. We uncovered a pathway whereby terrestrial predators regulate ecosystem processes via indirect control over soil community function. Grasshopper herbivores stressed by spider predators have a higher body carbon-to-nitrogen ratio than do grasshoppers raised without spiders. This change in elemental content does not slow grasshopper decomposition but perturbs belowground community function, decelerating the subsequent decomposition of plant litter. This legacy effect of predation on soil community function appears to be regulated by the amount of herbivore protein entering the soil.

Effects of Targeted Grazing and Prescribed Burning on Community and Seed Dynamics of a Downy Brome (Bromus tectorum)–Dominated Landscape

AbstractDowny brome (Bromus tectorumL.)—dominated communities can remain as stable states for long periods, even with frequent disturbance by grazing and fire. The objective of this study was to determine the effectiveness of using targeted cattle grazing and late-season prescribed burning, alone and in combination, to reduceB. tectorumseed bank input and seed bank density and thus alter aboveground community dynamics (species composition) on aB. tectorum–dominated landscape in northern Nevada. Cattle removed 80 to 90% of standing biomass in grazed plots in May of 2005 and 2006 whenB. tectorumwas in the boot (phenological) stage. Grazed and ungrazed plots were burned in October 2005 and 2006. The combined grazing–burning treatment was more effective than either treatment alone in reducingB. tectorumseed input and seed bank density, and in shifting species composition from a community dominated byB. tectorumto one composed of a suite of species, withB. tectorumas a component rather than a dominant. This study provides a meso-scale precursor for landscape-scale adaptive management using grazing and burning methodologies.

Regional factors rather than forest type drive the community structure of soil living oribatid mites (Acari, Oribatida)

Most European forests are managed by humans. However, the manner and intensity of management vary. While the effect of forest management on above-ground communities has been investigated in detail, effects on the below-ground fauna remain poorly understood. Oribatid mites are abundant microarthropods in forest soil and important decomposers in terrestrial ecosystems. Here, we investigated the effect of four forest types (i.e., managed coniferous forests; 30 and 70 years old managed beech forests; natural beech forests) on the density, diversity and community structure of oribatid mites (Acari). The study was replicated at three regions in Germany: the Swabian Alb, the Hainich and the Schorfheide. To relate changes in oribatid mite community structure to environmental factors, litter mass, pH, C and N content of litter, fine roots and C content of soil were measured. Density of oribatid mites was highest in the coniferous forests and decreased in the order 30 years old, 70 years old, and natural beech forests. Mass of the litter layer and density of oribatid mites were strongly correlated indicating that the litter layer is an important factor regulating oribatid mite densities. Diversity of oribatid mites was little affected by forest type indicating that they harbor similar numbers of niches. Species composition differed between the forest types, suggesting different types of niches. The community structure of oribatid mites differed more strongly between the three regions than between the forest types indicating that regional factors are more important than effects associated with forest type.