Litter Microarthropod Research Articles

Urbanization and plant invasion alter the structure of litter microarthropod communities.

Anthropogenic activity underpins the creation of urban ecosystems, often with introduced or invasive species playing a large role in structuring ecological communities. While the effects of urbanization on charismatic taxa such as birds, bees or butterflies have received much attention, the impacts on small and inconspicuous organisms remain poorly understood. Here, we assess how the community structure of leaf litter-inhabiting microarthropods in city parks varies along an urbanization gradient in Toronto, Canada. At each park, we established paired forest understorey plots which were either dominated by native vegetation or dog-strangling vine Vincetoxicum rossicum, an invasive species that is spreading throughout northeastern North America and abundant in urban areas. We compared microarthropod richness, abundance and diversity in ecological traits between invaded and non-invaded plots as well as compositional dissimilarities among plots across the urbanization gradient. We recorded 123 genera and found (a) there was a negative effect of urbanization on microarthropod richness and abundance but only in invaded plots; (b) richness and abundance increased continuously with urbanization in non-invaded plots, but peaked at intermediate urbanization levels in invaded plots and (c) there was significant turnover with increasing urbanization, with distinct communities represented in highly urbanized areas compared to less urbanized areas, regardless of whether invaded. We also found litter microarthropod richness and abundance increased with soil ammonium and decreased with nitrate. These trends were especially strong for fungivorous microarthropods; however, there was no relationship between soil nutrients and urbanization or invasion. Urbanization and biological invasion drive biodiversity change, and there is a need to disentangle these effects on ecological communities and related ecosystem processes. We show microarthropod communities change with urbanization, with the effects of invasion most prominent in non-urban areas. Here, there is high richness and abundance but low ecological trait diversity, possibly because certain feeding traits are excluded and others overrepresented. Understanding of urban ecological systems must include knowledge of the microarthropods that interact widely across food webs, form distinct communities in highly urban areas and drive many of the important ecological functions upon which people in cities depend.

Tест-система визначення вмісту мангану у ґрунтах долини ріки Cамари дніпровської

Наведено характеристику фізико-хімічного тест-методу, який дає можливістьпросто та недорого виконати якісний, напівкількісний та кількісний аналіз ґрунтівна вміст мангану.

The effect of microarthropods on litter decomposition depends on litter quality

Many studies have investigated whether microbiota has been adapted to decompose a given litter type but we have limited information about the specific role of microarthropods in litter decaying processes. This experiment studied functional redundancy of microarthropods in a litter decomposition system by interchanging mesofauna among three different litter types. The study hypothesized that total microarthropod densities would be lower in foreign litter type than in original (‘home’) litter; and litter with foreign mesofauna would decompose slower than with native one. Scotch pine (Pinus sylvestris), Turkey oak (Quercus cerris) and black locust (Robinia pseudoacacia) litter were stored in microcosms with original microbiota. Microarthropods from the same (‘home’) or different (‘foreign’) type of litter were inoculated to microcosms. Litter mass loss and total density of collembolans, oribatid and other mites were recorded at the end of incubation (3 and 12 months). Litter quality determined total density of microarthropods irrespective of the origin of animals. Litter mass loss values differed in the three litter types. For pine litter, the origin of microarthropods had significant effects on litter mass loss. In oak litter, mainly microarthropod density influenced decomposition. Neither the origin nor the density of animals influenced the decomposition rate of black locust litter. Litter quality may have determined the different patterns of decaying. Mesofauna may enhance litter decomposition stronger in recalcitrant litter than in high-quality litter.

Genetic variation within a dominant shrub structures green and brown community assemblages

Two rising challenges in ecology are understanding the linkages between above- and belowground components of terrestrial ecosystems and connecting genes to their ecological consequences. Here, we blend these emerging perspectives using a long-term common-garden experiment in a coastal dune ecosystem, whose dominant shrub species, Baccharis pilularis, exists as erect or prostrate architectural morphotypes. We explored variation in green (foliage-based) and brown (detritus-based) community assemblages, local ecosystem processes, and understory microclimate between the two morphs. Prostrate morphs supported more individuals, species, and different compositions of foliage arthropods, litter microarthropods, and soil bacteria than erect morphs. The magnitude of community compositional differences was maintained from crown to litter to soil. Despite showing strikingly similar responses, green and brown assemblages were associated with different underlying mechanisms. Differences in estimated shrub biomass best explained variation in the green assemblage, while understory abiotic conditions accounted for variation in the brown assemblage. Prostrate morphs produced more biomass and litter, which corresponded with their strong lateral growth in a windy environment. Compared to erect morphs, the denser canopy and thicker litter layer of prostrate morphs helped create more humid understory conditions. As a result, decomposition rates were higher under prostrate shrubs, despite prostrate litter being of poorer quality. Together, our results support the hypothesis that intraspecific genetic variation in primary producers is a key mediator of above- and belowground linkages, and that integrating the two perspectives can lead to new insights into how terrestrial communities are linked with ecosystem pools and processes.

Microstegium vimineumInvasion Changes Soil Chemistry and Microarthropod Communities in Cumberland Plateau Forests

Abstract Microstegium vimineum (Japanese Stiltgrass) is an exotic shade-tolerant C4 grass that invades open and forested habitats throughout the southeastern United States. Studies suggest that invasive plants can alter ecosystem biogeochemistry by changing soil chemistry and biota. The objective of our study was to determine if M. vimineum invasion induces soil chemical changes that alter litter microarthropod communities in acidic, nutrient-poor upland forests of the Cumberland Plateau. In a greenhouse experiment comparing forest soil in tubs seeded with M. vimineum to those left unseeded over 1 year, we found that after 6 months, soil pH under M. vimineum was significantly higher than that in the unseeded tubs. We compared A-horizon chemistry, litter nutrients, and microarthropod community diversity in 3 forested sites with and without M. vimineum. We found higher pH, phosphorus (P), and base cations, and lower aluminum (Al) in soil under dense M. vimineum growth compared to soil under surrounding unin...

Season mediates herbivore effects on litter and soil microbial abundance and activity in a semi-arid woodland

Herbivores can directly impact ecosystem function by altering litter quality of an ecosystem or indirectly by shifting the composition of microbial communities that mediate nutrient processes. We examined the effects of tree susceptibility and resis- tance to herbivory on litter microarthropod and soil microbial communities to test the general hypothesis that herbivore driven changes in litter inputs and soil microclimate will feedback to the microbial commu- nity. Our study population consisted of individual pinon pine trees that were either susceptible or resistant to the stem-boring moth (Dioryctria albovit- tella) and susceptible pinon pine trees from which the moth herbivores have been manually removed since 1982. Moth herbivory increased pinon litter nitrogen concentrations (16%) and decreased canopy precipi- tation interception (28%), both potentially significant factors influencing litter and soil microbial commu- nities. Our research resulted in three major findings: (1) In spite of an apparent increase in litter quality, herbivory did not change litter microarthropod abun- dance or species richness. (2) However, susceptibility to herbivores strongly influenced bulk soil microbial communities (i.e., 52% greater abundance beneath herbivore-resistant and herbivore-removal trees than susceptible trees) and alkaline phosphatase activity (i.e., 412% increase beneath susceptible trees relative to other groups). (3) Season had a strong influence on microbial communities (i.e., microbial biomass and alkaline phosphatase activity increased after the summer rains), and their response to herbivore inputs, in this semi-arid ecosystem. Thus, during the dry season plant resistance and susceptibility to a common insect herbivore had little or no observable effects on the belowground organisms and processes we studied, but after the rains, some pronounced effects emerged.

From forest to fen: Microarthropod abundance and litter decomposition in a southern Appalachian floodplain/fen complex

Summary Our study compared decomposition and litter microarthropod abundance among five plant communities in a mountain floodplain/fen complex located in the southern Appalachian Mountains, USA. We found that the least disturbed plant communities, red maple in particular, have the quickest decomposition, the greatest number of litter microarthropods, the highest soil organic carbon, and the lowest soil pH. Positive correlations were shown between soil organic carbon and total microarthropods; negative correlations were found between soil pH and total microarthropods. No correlations were found between soil moisture and decomposition or total microarthropod numbers. We conclude that soil characteristics related to disturbance, rather than to the presence of a closed canopy, are the main influences on decomposition and litter microarthropods.

Impacts of herbivorous insects on decomposer communities during the early stages of primary succession in a semi-arid woodland

Changes in nutrient inputs due to aboveground herbivory may influence the litter and soil microbial community responsible for processes such as decomposition. The mesophyll-feeding scale insect ( Matsucoccus acalyptus) found near Sunset Crater National Monument in northern Arizona, USA significantly increases piñon ( Pinus edulis) needle litter nitrogen (N) and phosphorus (P) concentrations by 50%, as well as litter inputs to soil by 21%. Because increases in needle litter quality and quantity of this magnitude should affect the microbial communities responsible for decomposition, we tested the hypothesis that insect herbivory causes a shift in soil microbial and litter microarthropod function. Four major findings result from this research: (1) Despite increases in needle inputs due to herbivory, soil carbon (C) was 56% lower beneath scale-susceptible trees than beneath resistant trees; however, soil moisture, N, and pH were similar among treatments. (2) Microbial biomass was 80% lower in soils beneath scale-susceptible trees when compared to resistant trees in the dry season, while microbial enzyme activities were lower beneath susceptible trees in the wet season. (3) Bacterial community-level physiological profiles differed significantly between susceptible and resistant trees during the dry season but not during the wet season. (4) There was a 40% increase in Oribatida and 23% increase in Prostigmata in susceptible needle litter relative to resistant litter. Despite these changes, the magnitude of microbial biomass, activity, and community structure response to herbivory was lower than expected and appears to take a long time to develop. These results suggest that herbivores impact soils in subtle, but important ways; we suggest that while litter chemistry may strongly mediate soil fertility and microbial communities in mesic ecosystems, the influence is lower than expected in this primary succession xeric ecosystem where season mediates differences in microbial populations. Understanding how insect herbivores alter the distribution of susceptible and resistant trees and their associated decomposer communities in arid environments may lead to better prediction of how these ecosystems respond to climatic change.

Environmental Effects and Economics of Mechanized Logging for Fuel Reduction in Northeastern Oregon Mixed-Conifer Stands

Abstract Fuel reduction by mechanical thinning and removal was studied in mixed-conifer stands in northeastern Oregon between 1995 and 1997. A single-grip harvester was coupled with either a forwarder or a skyline yarding system, and operational economics, fuel reduction, stand damage, soil disturbance, effects on soil biota and down-woody material were measured in three replicates of paired stands. After logging with the harvester, the two log-extraction systems achieved nearly equivalent fuel reduction with 45.7 and 46.8% mass reduction by the forwarder and skyline system, respectively. Fine-woody fuel increased slightly in all units, but mass of heavy fuels decreased. Most mass reduction in the forest floor occurred in the duff layer with 56 and 49% reduction in forwarder and skyline units, respectively. Reduction in stem density and basal area were similar for the two extraction systems; in forwarder units stem density was reduced by 61.6% and basal area by 55.4%, while in skyline units stem density was reduced by 66.5% and basal area by 51.1%. Of seedlings and trees examined, 32% had noticeable damage after harvest. Damage included bole wounding (38.9% of damaged stems), bark scraping (35.0%), wrenched stems (28.9%), broken branches (26.5%), broken terminal leaders (15.4%), and crushed foliage (4.1%). More damage occurred to residual large trees than to seedlings. Both log-extraction systems met the silvicultural prescription of reducing fuel and protecting residual large-diameter western larch, Engelmann spruce, Douglas-fir, and lodgepole pine. While fuel, stem, and basal area reduction lowered fire risk from a model 10 to a model 8 in all stands, large-woody material for wildlife also changed. Mean log length was lower in harvested units relative to unharvested controls, but this did not decrease occupation of logs by ants or the activities of woodpeckers feeding on them. Of 37 logged hectares, 1.4% (0.5 ha) of the soil area was compacted, mostly in forwarder units, within landings, and within trails close to landings. The percent area with displaced soil varied from 5 to 43% among units and was located within trails or in intertrail areas between the trails. Light displacement of soil resulted in a short-term increase in the abundance of soil microarthropods. The effects of compaction on litter microarthropods was more persistent, with lower numbers in compacted litter a year after harvest. While revenue was similar for forwarder and skyline units ($68 vs. $70/metric ton, respectively), total operational costs were $81/metric ton in the skyline units, compared to $46/metric ton in the forwarder units. These results are discussed in the context of options available to managers for balancing fuel reduction needs with both environmental and economic constraints. West. J. Appl. For. 18(4):238–249.

Earthworms, arthropods and plant litter decomposition in aspen (Populus tremuloides) and lodgepole pine (Pinus contorta) forests in Colorado, USA : The 7th international symposium on earthworm ecology · Cardiff · Wales · 2002

We compared the abundance and community composition of earthworms, soil macroarthropods, and litter microarthropods to test faunal effects on plant litter decomposition rates in two forests in the subalpine in Colorado, USA. Litterbags containing recently senesced litter of Populus tremuloides (aspen) and Pinus contorta (lodgepole pine) were placed in aspen and pine forests to monitor their decay rates and quantify litter microarthropod abundance. Earthworms and macroarthropods were collected by hand from the soil. Three species of earthworms were found in the aspen forest: Octolasion cyaneum, an anecic worm; Dendrobaena octaedra, an epigeic worm and Aporrectodea trapezoides, an endogeic worm. We found a higher density and fresh biomass of earthworms in the aspen (40 worms m–2 and 4.4 g m–2) than in the pine forest (0.8 worms m–2 and 0.6 g m–2). The lodgepole pine contained only earthworm species, D. octaedra. Macroarthropod density did not differ between the forests. Total density of microarthropods in the aspen and lodgepole pine forests was 6.40 and 5.24 individuals g–1 of dry litter, respectively and did not significantly differ between forests. The percent of mass remaining was different between litter species (r2 = 0.73, P < 0.01). Aspen litter decayed significantly faster than pine regardless of location. The percent of mass remaining of aspen and lodgepole pine were significantly correlated with the density of earthworms in both forests (P < 0.01). In the pine forests, the percent mass remaining of aspen and lodgepole pine litter was also significantly correlated with the density of mites (Acarina) (P = 0.03), prostigmatid mites (P = 0.02) and the total abundance of litter fauna (P = 0.02). Our results suggest that introduced earthworms play an important role on litter decomposition in the aspen forest, and that litter decomposition in these subalpine sites might be influenced differentially by various groups of soil and litter fauna.

Earthworms, arthropods and plant litter decomposition in aspen (Populus tremuloides) and lodgepole pine (Pinus contorta) forests in Colorado, USAThe 7th international symposium on earthworm ecology · Cardiff · Wales · 2002

Summary We compared the abundance and community composition of earthworms, soil macroarthropods, and litter microarthropods to test faunal effects on plant litter decomposition rates in two forests in the subalpine in Colorado, USA. Litterbags containing recently senesced litter of Populus tremuloides (aspen) and Pinus contorta (lodgepole pine) were placed in aspen and pine forests to monitor their decay rates and quantify litter microarthropod abundance. Earthworms and macroarthropods were collected by hand from the soil. Three species of earthworms were found in the aspen forest: Octolasion cyaneum , an anecic worm; Dendrobaena octaedra , an epigeic worm and Aporrectodea trapezoides , an endogeic worm. We found a higher density and fresh biomass of earthworms in the aspen (40 worms m –2 and 4.4 g m –2 ) than in the pine forest (0.8 worms m –2 and 0.6 g m –2 ). The lodgepole pine contained only earthworm species, D. octaedra . Macroarthropod density did not differ between the forests. Total density of microarthropods in the aspen and lodgepole pine forests was 6.40 and 5.24 individuals g –1 of dry litter, respectively and did not significantly differ between forests. The percent of mass remaining was different between litter species (r 2 = 0.73, P

Soil and litter organisms in Pacific northwest forests under different management practices

Soil and litter organisms are important indicators of stress and disturbance to forest ecosystems. In this study, soil and litter organisms were monitored for their response to different forest management practices. Litter and soil cores (0–10, 10–20 cm) were collected at approximately 8 week intervals over a 19 month period from a low elevation 110–140-year-old Douglas-fir forest and adjacent 8-year-old clearcut and from a high elevation 200–250-year-old Douglas-fir forest and adjacent 5-year-old clearcut. The low elevation clearcut had been broadcast burned and replanted with Douglas-fir trees and a grass–legume mixture whereas the high elevation clearcut was not burned, large woody debris was left, and it was replanted with Douglas-fir, Noble-fir, Grand-fir, and western white pine. The litter and soil cores were analyzed for types of microarthropods and numbers of nematodes, fungi, culturable, aerobic bacteria, spore-forming bacteria, and chitin-degrading bacteria. Microbial community metabolic profiles, using the Biolog™ method, were also generated for the 0–10 cm soil samples. Populations of Pseudomonas spp. were analyzed in the litter and soil samples using 16S rDNA fingerprints. Plant surveys were conducted to identify potential relationships of soil organisms to plant community composition. At both elevational field sites, there were significantly ( P<0.05) higher levels of nematodes and microarthropods in litter and soil in forest plots than in clearcut plots. Bacterial and fungal populations were also significantly higher in litter in forest plots than in clearcut plots at the high elevation site. In the litter and soil at the low elevation site and the soil at the high elevation site, however, microbial levels were higher in clearcut plots than in forest plots. The Pseudomonas spp. populations and the microbial community metabolic profiles in the 0–10 cm soil differed significantly between the forest and clearcut plots at the low elevation site but not at the high elevation site. At both elevational field sites, the plant cover (%) and plant density were significantly higher in clearcut plots than in forest plots. These observed differences in the population size and composition of organisms between mature forests and both low management and high management clearcuts demonstrated the impacts forest management practices may have on the soil ecosystem.

Non-litter effects of elevated CO2 on forest floor microarthropod abundances

The arthropod assemblages of the litter and soil play significant roles in decomposition and nutrient cycling. At the FACE (Free-Air CO2 Enrichment) site at the Duke Forest, we assessed the responses of the litter microarthropod assemblage to elevated CO2 (200 ppm above ambient) in a loblolly pine plantation. Following the initiation of the elevated CO2 treatment, a trend toward lower microarthropod abundance under elevated CO2 emerged. After 18 months, the mean microarthropod abundance was 33% lower in the elevated treatment (P=0.04). The decline was evident in all microarthropod groups, but was significant only in the oribatid mites (P=0.04). Because these responses precede any changes in litter quality resulting from the CO2 treatment, they may reflect plant-derived changes in the soil that are being conveyed into the litter layer.

Response of soil and leaf litter microarthropods to forest application of diflubenzuron

The objective of this study was to assess the effects of forest application of diflubenzuron (Dimilin®), a gypsy moth suppressant, on nontarget invertebrates in litter and soil on the forest floor. Four experimental watersheds (two treatment and two reference) in the Fernow Experimental Forest, West Virginia, were sampled for two years before and one year after application of diflubenzuron (70 g ha−1, AI). Soil and leaf litter arthropods were monitored before and after application using soil cores and litter bag colonization samplers. Frequency analysis, BACIP, and ANOVA were used to analyse the data for diflubenzuron treatment effects. During the 36 month study, soil core samples were dominated by mites (49%) and springtails (28%). A total of 19 taxonomic groups were suitable for statistical analysis. We detected no significant treatment effects based on total organism counts or counts by trophic categories (p < 0.05). There were no significant treatment effects for populations of major taxonomic groups, except for Araneae (spiders). Analysis of leaf litter bags also showed no significant differences in total numbers of invertebrates or in trophic categories between treated and reference watersheds during the 12 month post-treatment study. Density of one species of springtail (Sminthurus purpurescens) and springtails as a group were significantly lower in treated watersheds. High variation was associated with both soil core and leaf bag samples; because of this variation, a significance level of 0.05 should be considered very conservative. Long-term trends in soil biota were evident, demonstrating the need for well-established pre-treatment baseline data for pesticide impacts on soil organisms

Decomposition of leaf litter in an Appalachian forest: effects of leaf species, aspect, slope position and time

Leaf decomposition was studied using leaves of three species (yellow-poplar, red maple, and chestnut oak). Litterbags containing 10 g of leaves were placed on a northeast-facing slope and a southwest-facing slope and at three slope positions (upper, middle, and lower) on each aspect. Bags were initially placed in January and samples were removed to determine mass loss beginning in April, then at 2 month intervals until December. The main effects (aspect, species, slope position and time of removal) were all statistically significant. Yellow-poplar and red maple litter decomposed much faster than did chestnut oak, and leaves placed on north-facing slopes decomposed faster than those on south-facing slopes. Generally, leaves placed at the middle slope position decomposed slower than at those at either the upper or lower positions. We examined the microarthropods in leaf litter during the growing season and found that Oribatei and Collembola dominated the populations present. They were generally more abundant in leaves on north-facing slopes, and numbers of microarthropods generally increased throughout the year. Chemical analysis of decomposing leaf litter revealed that nitrogen and phosphorus contents of leaves were relatively stable over time. Sodium dropped quickly at first, then stabilized. Potassium and magnesium decreased with the time whereas calcium increased in the leaves of some species and decreased in others.

Litter microarthropod responses to canopy herbivory, season and decomposition in litterbags in a regenerating conifer ecosystem in Western Oregon

The microarthropod community response to season, change in foliage litter quality during decomposition, and manipulated canopy herbivory by insects was measured in litterbags under 10-year-old Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, in western Oregon. Collembola accounted for 35% of the total fauna, oribatid mites for 29%, and fungivorous actinedids for 22%. The community structure was affected by responses to canopy defoliation, season, and changes in litter quality. Of 33 taxa, three were significantly more abundant under trees subject to lepidopteran defoliation (≤20% foliage removal), compared to other treatments, indicating responses to defoliator-induced changes in litter environment. Most taxa (23) showed seasonal fluctuations in abundance related to the seasonal pattern of temperature and precipitation and to the pattern of N and Ca mobilization from litterbags. Five taxa showed significant longterm trends in abundance, indicating responses to changes in litter quality, perhaps a loss of P and K. These data indicate that microarthropod communities respond qualitatively to environmental changes, including canopy defoliation. The qualitative changes can affeet decomposition processes.

Water effect onRebudia pinatadecomposition and microarthropod population in Negev desert

Abstract The effects of supplemental water and natural rainfall on the density of microarthropods in soil and litter and on the rates of decomposition of Rebudia pinata were studied in three habitats (loess plain, hill slope, and hill top) of the Negev Desert. There were significant differences in decomposition rates in mass losses between the watered and control plots at loess plain and hill slope location during the treatment period. No significant differences in mass loss were obtained during the dry period. Microarthropods exhibited numerical response in density to supplemental rainfall. These results suggest that a linkage exists between rain events, decomposition, and microarthropod activity.

Errata: Litter Decomposition, Nitrogen Dynamics and Litter Microarthropods in a Southern Appalachian Forest 8 Years Following Clearcutting

Errata: Litter Decomposition, Nitrogen Dynamics and Litter Microarthropods in a Southern Appalachian Forest 8 Years Following Clearcutting

Litter Decomposition, Nitrogen Dynamics and Litter Microarthropods in a Southern Appalachian Hardwood Forest 8 Years Following Clearcutting

.' SUMMARY (1) Litter decomposition rates, nitrogen dynamics and litter microarthropods on the xeric slopes of a watershed 8 years after clearcutting (WS 7) and on an adjacent reference watershed (WS 2) at the Coweeta Hydrologic Laboratory were measured using litterbags. Litter of Comusflorida L., Acer rubrum L. and Quercusprinus L. was used as experimental substrates in three plots on adjacent areas of both watersheds. Results from this study were compared with those obtained before and after cutting to assess the longer-term changes induced by canopy removal. (2) Reduced litter decomposition rates were associated with clearcutting. Litter nitrogen dynamics were also affected. Net immobilization of nitrogen in litter substrates was lower on WS 7. Lower net nitrogen immobilization was related to slower increases in nitrogen concentration per unit mass lost in litter on WS 7. (3) Mean annual densities of total litter microarthropods remained 28% lower on WS 7 than on WS 2, 8 years after cutting. Previous studies indicated clearcutting initially reduced mean annual densities of litter microarthropods by>50%. Mesostigmata and Oribatei densities averaged 50 and 54% lower, respectively, than on WS 2. Prostigmata and Collembola densities averaged 20 and 24% lower, respectively, than on WS 2. This differential response changed the relative abundances of major groups. Changes in litter decomposition rates and nitrogen dynamics were consistent with effects associated with lower microarthropod densities and suggest that reduced microarthropod densities may be important. (4) Results of this study differ from those at northern hardwood forest sites where clearcutting caused increased decomposition rates. This suggests that generalizations from northern hardwood forests may not apply to other regions. Instead the effects of canopy

Influence of elevated ecosystems levels on litter decomposition and mineralization

Litter decomposition was studied at two forested watersheds in east Tennessee which differed primarily in their past history of atmospheric S input. Cross Creek Watershed, located near a large coal-fired power plant, has received greater S inputs than the more remote Camp Branch Watershed. Decomposition was estimated through the measurement of forest floor respiration, litter microflora populations, litter and soil microarthropod populations, and litter nutrient status. Average forest floor respiration rates were very similar, 6.78 g CO2 m−2 day−1 or 2472 g m−2 yr−1 at Camp Branch and 6.86 g CO2 m−2 day−1 or 2505 g M−2 yr−1 at Cross Creek. Fractional loss rates provided estimates of annual decay rates (k) of 0.35 and 0.39 for Camp Branch and Cross Creek, respectively. Litter decomposition was estimated to contribute 23% of the total CO2 output at Camp Branch and 26% at Cross Creek, while root respiration accounts for about 43 to 46%. Bacterial and fungal populations were about equal in size at both watersheds, with bacteria averaging 100 × 106 g−1 of litter and fungi 23 × 106 g−1 of litter. Total numbers of arthropods averaged 34% greater at Camp Branch. Acarina populations averaged 59% higher at Camp Branch, while Collembola numbers were about equal at the two watersheds. Nutrient mobility in the litter and soil was similar at both watersheds. The order of decreasing mobility was K, Mg, Ca, S, N, and P. Litterfall nutrient concentrations were slightly higher for all elements at Cross Creek, resulting in greater litter concentrations of Ca and Mg. Litter concentrations of S and N, however, were significantly greater at Camp Branch, indicating watershed differences in the loss rates and cycling processes of these elements. There were no differences between the loss rates or litter concentrations of P, K, and Na at either site. Overall, decomposition was similar at the two watersheds. Historic S inputs do not appear to have had a major effect on decomposition rate or decomposer organisms with the possible exception of lowered arthropod populations at Cross Creek.