Litter Arthropods Research Articles

Time-lapse camera trapping as an alternative to pitfall trapping for estimating activity of leaf litter arthropods.

Pitfall trapping is the standard technique to estimate activity and relative abundance of leaf litter arthropods. Pitfall trapping is not ideal for long‐term sampling because it is lethal, labor‐intensive, and may have taxonomic sampling biases. We test an alternative sampling method that can be left in place for several months at a time: verticallyplaced time‐lapse camera traps that have a short focal distance, enabling identification of small arthropods. We tested the effectiveness of these time‐lapse cameras, and quantified escape and avoidance behavior of arthropod orders encountering pitfall traps by placing cameras programed with a range of sampling intervals above pitfalls, to assess numerical, taxonomic, and body size differences in samples collected by the two methods. Cameras programed with 1‐ or 15‐min intervals recorded around twice as many arthropod taxa per day and a third more individuals per day than pitfall traps. Hymenoptera (ants), Embioptera (webspinners), and Blattodea (cockroaches) frequently escaped from pitfalls so were particularly under‐sampled by them. The time‐lapse camera method effectively samples litter arthropods to collect long‐term data. It is standardized, non‐lethal, and does not alter the substrate or require frequent visits.

Eastern Red-backed Salamanders Regulate Top-Down Effects in a Temperate Forest-Floor Community

Abstract Understanding the role of species interactions as regulatory mechanisms for ecosystem processes presents a challenge to ecologists working in systems with high species diversity and habitat complexity. Recent studies suggest that interactions among intraguild predators, such as terrestrial salamanders and large arthropods, might be important for the regulation of detritivores, fungivores, and perhaps detritus within terrestrial webs. A key prediction is that interactions among predators weaken trophic cascades. Our research examined this prediction by removing predators for 4 yr from unfenced field plots to investigate the effects on litter arthropods, the microbial community, and rates of leaf litter decomposition. We manipulated predator abundance in three treatments (salamander removal, centipede removal, and multiple predator removal) compared to a control in which no predators were removed. Despite difficulties in suppressing centipede numbers, we observed increases in salamanders, millipede...

Hunting for Wasps In-between: the Use of the Winkler Extractor to Sample Leaf Litter Hymenoptera.

Soil ecosystems are considered biodiversity hotspots. Most of terrestrial organisms depend almost exclusively on soils at least during some part of their life cycle. Although there is an intensive effort to understand the dynamics involving communities of soil animals, most groups are unappreciated in faunal inventories, such as some parasitic Hymenoptera with soil or litter hosts (SLH Hymenoptera), which are considered one of the largest and most diverse groups of soil- or litter-dwelling animals. Contrasting with flight interception traps, techniques that sample soil and litter specimens normally present low costs and easy transportation, being easily replicated within a site. Among them, the Winkler extractor is a useful technique to sample cryptic species associated with leaf litter. The aim of the present work was to describe the SLH Hymenoptera fauna collected in a pool of samples, using a technique to sample leaf litter arthropods. In this work, we report a total of 600 specimens belonging to Hymenoptera (excluding ants), belonging to 15 families distributed within 24 subfamilies, in samples of leaf litter obtained using the Winkler extractor. We observed that this technique is promising for sampling SLH Hymenoptera and should be considered as a complement for inventories of the Hymenoptera fauna.

Warming magnifies predation and reduces prey coexistence in a model litter arthropod system.

Climate warming can destabilize interactions between competitors as smaller organisms gain advantages in warmer environments. Whether and how warming-induced effects on competitive interactions are modified by predation remains unknown. We hypothesized that predation will offset the competitive advantage of smaller prey species in warmer environments because of their greater vulnerability to predation. To test this, we assembled a litter arthropod community with two Collembola species (Folsomia candida and Proisotoma minuta) of different body sizes across a temperature gradient (three thermal environments) and in the presence and absence of predatory mites. Predatory mites reduced Collembola coexistence with increasing temperatures. Contradicting our hypothesis, the larger prey species always outperformed the smaller prey species in warmer environments with predators. Larger prey probably benefited as they expressed a greater trait (body length) plasticity to warming. Warming can thus magnify predation effects and reduce the probability of prey coexistence.

Do fire and seasonality affect the establishment and colonisation of litter arthropods?

In tropical ecosystems, the influence of fire can have dramatic effects on the arthropod community and some taxa may take a long period to recover after such disturbance. Here we investigated the effects of an accidental fire on the reestablishment of litter arthropods and compared it with a control/unburned area. Seasonal data were also included in the analysis, as the rupestrian fields (transition between Brazilian savanna and Atlantic forest) have two well-defined seasons and arthropod populations tend to fluctuate accordingly. Our study commenced 4 months after fire and during the 2 years afterwards, we found 19 arthropod groups in the litter, of which flies, springtails, spiders, beetles, true-bugs, harvestmen, grasshoppers, hymenopterans (except ants), mites and roaches were the most representative. The unburned area hosted over 60 % of the total arthropod abundance and only true-bugs were significantly more abundant in the burned site, the other arthropods remained, in general, more abundant in the control/unburned area throughout the study. Arthropod abundance was threefold-higher in the rainy season. Arthropods were able to recolonise the burned area soon after the fire event, but their abundance was low during the 2 years of study, revealing that fire effects can extend for long periods. We conclude that, despite rapid plant resprouting and arthropod colonisation after fire, 2 years were not enough for the full reestablishment of litter arthropods.

Leaf litter arthropod responses to tropical forest restoration.

Soil and litter arthropods represent a large proportion of tropical biodiversity and perform important ecosystem functions, but little is known about the efficacy of different tropical forest restoration strategies in facilitating their recovery in degraded habitats. We sampled arthropods in four 7‐ to 8‐year‐old restoration treatments and in nearby reference forests. Sampling was conducted during the wet and dry seasons using extractions from litter and pitfall samples. Restoration treatments were replicated in 50 × 50‐m plots in four former pasture sites in southern Costa Rica: plantation – trees planted throughout the plot; applied nucleation/islands – trees planted in patches of different sizes; and natural regeneration – no tree planting. Arthropod abundance, measures of richness and diversity, and a number of functional groups were greater in the island treatment than in natural regeneration or plantation treatments and, in many cases, were similar to reference forest. Litter and pitfall morphospecies and functional group composition in all three restoration treatments were significantly different than reference sites, but island and plantation treatments showed more recovery than natural regeneration. Abundance and functional group diversity showed a much greater degree of recovery than community composition. Synthesis and applications: The less resource‐intensive restoration strategy of planting tree islands was more effective than tree plantations in restoring arthropod abundance, richness, and functional diversity. None of the restoration strategies, however, resulted in similar community composition as reference forest after 8 years of recovery, highlighting the slow rate of recovery of arthropod communities after disturbance, and underscoring the importance of conservation of remnant forests in fragmented landscapes.

The utility of DNA metabarcoding for studying the response of arthropod diversity and composition to land-use change in the tropics.

Metabarcoding potentially offers a rapid and cheap method of monitoring biodiversity, but real-world applications are few. We investigated its utility in studying patterns of litter arthropod diversity and composition in the tropics. We collected litter arthropods from 35 matched forest-plantation sites across Xishuangbanna, southwestern China. A new primer combination and the MiSeq platform were used to amplify and sequence a wide variety of litter arthropods using simulated and real-world communities. Quality filtered reads were clustered into 3,624 MOTUs at ≥97% similarity and the taxonomy of each MOTU was predicted. We compared diversity and compositional differences between forests and plantations (rubber and tea) for all MOTUs and for eight arthropod groups. We obtained ~100% detection rate after in silico sequencing six mock communities with known arthropod composition. Ordination showed that rubber, tea and forest communities formed distinct clusters. α-diversity declined significantly between forests and adjacent plantations for more arthropod groups in rubber than tea, and diversity of order Orthoptera increased significantly in tea. Turnover was higher in forests than plantations, but patterns differed among groups. Metabarcoding is useful for quantifying diversity patterns of arthropods under different land-uses and the MiSeq platform is effective for arthropod metabarcoding in the tropics.

“Berlese vs. Winkler”: Comparison of Two Forest Litter Coleoptera Extraction Methods and the Ecoli (Extraction of Coleoptera in Litter) Protocol

Abstract We present results of a comparison between the Winkler (Moczarski) eclector and the Berlese-Tullgren funnel methods for extracting forest litter-dwelling Coleoptera from sifted substrates, with a focus on relevance for taxonomic studies. A review of the history and methodologies of leaf litter arthropod extraction is provided. Repeated, timed trials were performed to compare the relative effectiveness of the two methods using litter samples from various sites across the southern United States. Extraction rates for Winkler and Berlese funnels were evaluated based on temporal and taxonomic criteria by comparing accumulations of Coleoptera specimens and species at timed intervals. In addition, Curculionidae, Staphylinidae, and “rare” species were targeted and evaluated separately. No clear differences in extraction efficiency, either temporally or taxonomically, between Winklers and Berleses were detected. But contrary to current extraction practices, extraction patterns for both Winklers and Berles...

Beetles (Coleoptera) of Peru: A Survey of the Families. Phengodidae LeConte, 1861

Diversity in Peru: 2 subfamilies, 7 genera, 12 species. Recognition: Phengodidae are commonly called glow-worms because the larviform females and larvae have bioluminescent organs in transverse bands along the body. They glow yellow-green using eleven paired photic organs of 2 thoracic through 9th abdominal segments; some genera have head organs that glow red. Some adult males are also bioluminescent, and at least one species has bioluminescent eggs. The adult male body length is 3.3–25 mm; larviform females are generally larger than males. The antenna has 10–12 antennomeres in adult males, and may be filiform, serrate, bipectinate or plumose. Adult males have truncate or dehiscent elytra. Phengodid larvae are slender, mostly well-sclerotized, and rounded in crosssection (compared to the flattened larvae of Lampyridae and Lycidae), resembling those of click beetles. Habitat: These may be nocturnal, active at nights. Winged males may be attracted at light traps. Females may be collected from loose bark while larvae are usually found under leaf litter or rotting logs. The larviform females and larvae are specialist predators of millipedes and other litter arthropods. Notes: The American family Phengodidae is now considered as separate from Asiatic Rhagophthalmidae, although sister group relationships of the families were supported by both morphological evidence (Lawrence et al., 1995), and comprehensive molecular phylogenies (Bocakova et al., 2007; Kundrata et al., 2014). Previous studies suggested rhagophthalmids as a clade of fireflies (Crowson, 1955; Suzuki, 1997). The following checklist is derived from Pic in Titschack (1954; as Drilidae), Zaragoza-Caballero (1984), and specimens housed in SEMC. The family was monographed by Wittmer (1976), but a number of new genera have been added since. Lawrence et al. (2000) reported the minute Penicillophorus (2–4 mm) as occurring in Colombia and Peru. The “railroad worm”, Phrixothrix, occurs in Peru but it is unclear if it is a pest (see Costa et al., 1999). An interactive key to the world fauna is available online (Lawrence et al., 2000); see Zaragoza-Caballero (2010) for an updated key to the genera of the large subfamily Mastinocerinae. Taximastinocerus is reported as new genus record for Peru based on 19 specimens (probably multiple species) collected by Chaboo in 2010–2011 with flight intercept traps and Malaise traps at the CICRA Biological Field Station, Madre de Dios, Peru.

Two new species of the genus Batropetes (Tetrapoda, Lepospondyli) from the Central European Rotliegend (basal Permian) in Germany

ABSTRACTTwo new species of Batropetes are described from the Lower Rotliegend of the Saar-Nahe Basin in western Germany. Batropetes palatinus, sp. nov., is characterized by a narrow, anteriorly elongated prefrontal, a slender postfrontal without an anterolateral process, a trapezoid postorbital, and a large quadrate in exterior view. Batropetes appelensis, sp. nov., is characterized by a high angular, ‘Z’-shaped angular-dentary suture, no indentation between stem and plate of interclavicle, and scapulocoracoid without ossified coracoid. The genus Batropetes is characterized by an average length of almost 8 cm, a short trunk with 17 or 19 presacrals depending on the species, large orbit with a raised rim, a large pineal foramen, three pits on the frontal, tricuspid teeth, a toothless palate, four short robust limbs, and completely ossified pectoral and pelvic girdles (except for the coracoids of B. appelensis and B. fritschi). Batropetes belongs to the Brachystelechidae, together with Carrolla and Quasicaecilia. Cladistic analysis reveals for the monophyletic genus Batropetes that B. appelensis forms a sister group to the remaining three species in the genus, and B. niederkirchensis is the sister group to B. palatinus and B. fritschi. The functional interpretation of the appendicular skeleton and the skull morphology suggest that all Batropetes species were terrestrial, living near the lakes in which they were preserved. They appear to have fed on small arthropods in the leaf litter or in the upper zone of the soil.http://zoobank.org/urn:lsid:zoobank.org:pub:6ACCFE1A-1404-4DEB-93D9-2F7962D205BESUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

Effects of Nesting Cormorants (Phalacrocorax carbo) on Soil Chemistry, Microbial Communities and Soil Fauna

Seabirds act as vectors transporting marine nutrients to land by feeding on fish while nesting and roosting on islands. By depositing large amounts of nutrient-rich guano on their nesting islands they strongly affect island soils, vegetation and consumers. However, few studies have investigated how nesting seabirds affect soil communities. In this study, we investigated how cormorant nesting colonies affect soil chemistry, soil microbes and soil and litter fauna on their nesting islands in the Stockholm archipelago, Sweden. We found that cormorant colonies strongly increase organic soil N and P concentrations, and the effect is stronger close to cormorant nests. Microbial communities were studied by extracting phospholipid fatty acids (PLFA) from the soil. The total amounts of PLFA and the amount of PLFA indicating bacterial biomass were lower on active cormorant islands than on reference islands. Furthermore, PLFA structure and thus microbial community structure differed between cormorant and reference islands. Among ten investigated soil and litter arthropod groups three groups (Thysanoptera, Araneae and Oribatida) showed lower densities and one group (Astigmata) showed higher densities in soils on active cormorant than on reference islands. Some arthropod groups showed strong spatial variation on the cormorant islands. Astigmata, Mesostigmata and Diptera showed higher densities in soil samples close to cormorant nests, whereas Oribatida, Collembola and Hemiptera showed lower densities in litter samples close to cormorant nests than in samples taken 3-20 m away from nests. Overall, the cormorant colonies strongly affected soil ecosystems of their nesting islands, but causal correlations between arthropod densities and soil factors were difficult to reveal. One likely reason may be that nesting cormorant islands are very heterogeneous habitats showing large spatial variation in both soil properties as well as fauna densities.

Responses to canopy loss and debris deposition in a tropical forest ecosystem: Synthesis from an experimental manipulation simulating effects of hurricane disturbance

Hurricanes, cyclones, or typhoons are intense and broad-scale disturbances that affect many island and coastal ecosystems throughout the world. We summarize the findings of the articles that compose this special issue of Forest Ecology and Management, which focuses on a manipulative experiment (the Canopy Trimming Experiment, CTE) that simulates two key aspects of hurricane effects in a wet tropical forest. Although previous studies of tropical and subtropical forests have documented changes resulting from hurricanes, it is not clear which of the two simultaneously occurring direct effects of hurricanes—canopy openness or debris deposition—most influence responses. In the Luquillo Experimental Forest (LEF) of Puerto Rico, a multi-disciplinary team of scientists used replicated factorial manipulations to determine the independent and interactive effects of canopy openness and debris deposition on structural and functional characteristics of the forest. The majority of responses were primarily driven by canopy openness rather than by debris deposition. Canopy openness resulted in significant increases in densities of and compositional changes in woody plants, ferns, and some litter arthropods, and significant decreases in coqui frog abundances, leaf decomposition, and litterfall. Debris deposition significantly increased tree basal area and microbial diversity on leaf litter, but these increases were relatively small and ephemeral. Several interactive effects of canopy openness and debris addition emerged, including those involving understory herbivory, canopy arthropod structure, terrestrial gastropod abundances and composition, and soil solution chemistry. Arguably, hurricanes are the most important natural disturbance that affect the LEF, and most characteristics that were measured in the CTE showed evidence of resistance or resilience. By identifying the causal factors affecting secondary successional trajectories of diverse taxa ranging from microbes to vertebrates, biogeochemical attributes, microclimatic characteristics, and measures of ecosystem processes following hurricane disturbance, we better understand tropical forest dynamics resulting from past hurricanes and are better able to predict mechanisms of change related to future hurricanes.

Impact of invasive earthworms on Ixodes scapularis and other litter-dwelling arthropods in hardwood forests, central New York state, USA

Invasive earthworms alter the structure of soils in northern hardwood forests, but the quantitative impacts on litter-dwelling invertebrates are unclear. Litter loss should reduce the habitat space, but nutrient-rich earthworm burrows might provide food resources. We investigated the impact of invasive earthworms on populations of Ixodes scapularis (black-legged ticks) and other litter-dwelling arthropods to determine the impact of a reduced litter environment. We used five pairs of one-hectare sites (earthworm invaded versus reference) within four separate contiguous forests in New York state. The presence of earthworms decreased the density of nymphal I. scapularis by 46.1% and larval I. scapularis by 29.3%. We also observed a dramatic decline in the total abundance of litter-dwelling arthropods with 69.9% of the arthropod population disappearing in the presence of earthworms. Additionally, litter arthropod populations declined disproportionately to leaf litter mass reduction indicating that the quality of the remaining litter material in the earthworm sites was poor. The impact of earthworm invasion on the litter environment and implications for the position of an important disease vector (I. scapularis) within the litter ecosystem are explored.

A canopy trimming experiment in Puerto Rico: The response of litter decomposition and nutrient release to canopy opening and debris deposition in a subtropical wet forest

In this study, we used a replicated factorial design to separate the individual and interacting effects of two main components of a severe hurricane – canopy opening and green debris deposition on leaf litter decay in the tabonuco forest in the Luquillo Mountains of Puerto Rico. We quantify changes in percent mass remaining (PMR), the concentration and absolute amounts of various chemical elements using fresh (green) and senesced leaf litter contained in litterbags of two different mesh sizes. Mass loss was significantly slowed by canopy trimming. There was no significant effect of debris treatment on the PMR of the litter. Canopy trimming increased the percent of initial N, Al, Ca, Fe, and Mg remaining and decreased the percent of initial Mn remaining compared with not trimmed plots. Debris addition increased the percent of initial N and P remaining and decreased the percent of initial Al, and Fe remaining in the decomposing litter compared to no debris added plots. Of the elements studied, only Al and Fe accumulated above 100% of initial. Accumulation of Al and Fe in the canopy trimmed and no debris plotsis most likely dominated by the adsorption of these ions onto the surfaces of the decaying litter. Overall, P showed a rapid initial loss during the first 0.2yr followed by steady loss. Nitrogen was lost steadily from leaf litter. The PMR of fresh and senesced litter was significantly affected by mesh size, with a higher mass remaining in small mesh bags. Fresh litter decayed faster than senesced litter; following patterns of initial N and P concentrations (higher in the former litter type). We found a significantly negative correlation between the Margalef index of diversity for the litter arthropods contained in the litterbags and the PMR, suggesting functional complexity is an important determinant of decay in this forest. Our results imply hurricanes can differentially impact litter decomposition and associated nutrient release via canopy opening and litter inputs.

Effects of Fire Intensity on Litter Arthropod Communities in Ozark Oak Forests, Arkansas, U.S.A

Fires are a significant source of landscape scale disturbance in forested ecosystems, but fire effects also vary on small spatial scales due to differences in fuel loads and local environmental conditions. We tested the hypothesis that such variation influences post fire arthropod communities and faunal recovery rates on a 1 m2 scale. We measured the abundance and species richness of selected arthropod taxa pre- and post-fire in patches of leaf litter experimentally burned at different intensities. Arthropod abundance declined sharply immediately after a burn and decreased with increasing fire intensity. Consistent with other studies of this system, the effects of fire on arthropod communities were still apparent >4 w post burn. The abundance of epigeic beetles recovered more quickly than the abundance of ants or springtails in some treatments. Recovery rates also differed among treatments but did not consistently support the prediction that recovery would be faster in plots subject to low intensity burns. We conclude that small scale differences in intensity within prescribed fires have measurable effects on litter arthropod communities in Ozark forests; however, these differences appear to be overshadowed by the more general effects of fire on arthropods.

Temporal effects on biodiversity and composition of arthropod communities along an urban–rural gradient

Global urbanization is rapidly increasing, yet the prevalence of single order and time point studies likely miss important temporal effects of urbanization on entire communities. We studied three sites along a rural–urban gradient in the Seattle metropolitan area with three sampling periods from 2009–2011 to examine how arthropod communities respond to increasing levels of urbanization in a similar habitat type through time. Consistent with previous studies, urban areas contained altered environmental conditions relevant for litter arthropods, and arthropod biodiversity decreased with urbanization. However, urban arthropod biodiversity was not influenced by environmental measures, supporting the idea of an “urban-filter”. Urbanization was not a factor influencing how communities responded to the effect of time, suggesting that other factors (e.g. disturbance) may ultimately be more important for determining patterns of biodiversity through time in urban areas. Finally, our study illustrates urbanization forces can structuring entire arthropod communities similarly through time, having important consequences for our understanding of urbanization’s temporal effects and indirect influence on community interactions and ecosystem processes. As the effects of urbanization will inevitably vary through time, we suggest that multiple time point studies are required to increase our ability to accurately describe arthropod community responses to increasing urbanization.

Effect of brushwood transposition on the leaf litter arthropod fauna in a cerrado area

The results of ecological restoration techniques can be monitored through biological indicators of soil quality such as the leaf litter arthropod fauna. This study aimed to determine the immediate effect of brushwood transposition transferred from an area of native vegetation to a disturbed area, on the leaf litter arthropod fauna in a degraded cerrado area. The arthropod fauna of four areas was compared: a degraded area with signal grass, two experimental brushwood transposition areas, with and without castor oil plants, and an area of native cerrado. In total, 7,660 individuals belonging to 23 taxa were sampled. Acari and Collembola were the most abundant taxa in all studied areas, followed by Coleoptera, Diptera, Hemiptera, Hymenoptera, and Symphyla. The brushwood transposition area without castor oil plants had the lowest abundance and dominance and the highest diversity of all areas, providing evidence of changes in the soil community. Conversely, the results showed that the presence of castor oil plants hampered early succession, negatively affecting ecological restoration in this area.

Litter manipulation and the soil arthropod community in a lowland tropical rainforest

Tropical soil arthropod communities are highly diverse and provide a number of important ecosystem services, including the maintenance of soil structure, regulation of hydrological processes, nutrient cycling and decomposition. Experiments in temperate regions suggest that litter dynamics are important in determining the abundance, richness and community composition of soil fauna, but there is little information for lowland tropical forests. We used a long-term litter manipulation experiment (removing, doubling and control) in a neotropical forest to investigate the consequences of changing litter dynamics on the soil arthropod community. The abundance and biomass of arthropods were reduced significantly by the removal of litter, but not affected by litter addition. Litter manipulation had no effect on simple measures of taxonomic richness or diversity, but multivariate ordination techniques revealed a significant shift in arthropod community composition with the removal, but not addition, of litter. This suggests the overall importance of top-down controls on the arthropod community in this ecosystem, with bottom-up influences only important following the removal of large quantities of litter. Of the parameters measured, the faunal composition of experimental plots was best predicted by litter depth and the concentrations of total carbon and readily-exchangeable phosphorus (in order of importance), highlighting the influential role of soil chemical properties, in addition to the physical properties of litter, in shaping soil arthropod communities. Comparison with the results of a previous study of litter-dwelling fauna in the same litter manipulation experiment suggested that the soil and litter arthropod communities are influenced by different parameters: total carbon and litter depth for the soil community, but sodium and calcium for the litter community, although phosphorus was important in both environments. We conclude that arthropod community composition is controlled by different factors in the soil than in the litter and is affected by decreasing, but not increasing, depth of litter.

Trees as templates for trophic structure of tropical litter arthropod fauna

Litter arthropod abundance in tropical forests is patchily distributed in space and time. This patchiness can be described by three general hypotheses relating plant-based effects to litter arthropod distribution. The tree hypothesis (H1) posits that environments maintained underneath tree canopies are different from those between canopies in ways that shape arthropod abundance. The species hypothesis (H2) refines this scenario, positing that different plant species might maintain distinct litter environments to which arthropod abundances respond. Without regard to specific plant effects, seasonal changes in litter profiles (H3) can account for temporal patchiness in arthropod abundance. The ecosystem size hypothesis provides a mechanism for tree, species and seasonal effects. It links increasing food chain length with habitat availability and its heterogeneity.In a Panamanian rainforest we sampled litter arthropods in quadrats located near (1 m) and far away (30 m) from the parent trunk of 93 tree individuals (to test the tree hypothesis) from 10 tree species (to test the species hypothesis) in the early wet season, when litter is deepest. To test for effects of seasonal changes of litter profiles, we then resampled 25 trees (i.e., five individuals from each of five species) in the late wet season, when climatic conditions are similar, but litter is shallowest.We found weak support for all tree, species and seasonality hypotheses. With few exceptions, trees and species did not sustain different arthropod abundances, neither early nor late in the wet season. Collembola abundance increased late in the wet season, when litter is shallowest. Supporting the ecosystem size hypothesis, accumulated litter either due to trees, species and seasonality sustained higher predator abundance and higher predator to prey ratios.Our results suggest that plants may account for detrital, brown, food web structure; but these effects are mostly through plant-based provision of structural support. This study adds to growing evidence relating the ecosystem size hypothesis to litter environments and suggest a framework to understand plant-based bottom-up forces in structuring litter communities.

Management intensity interacts with litter chemistry and climate to drive temporal patterns in arthropod communities during decomposition

a b s t r a c t Shifts in the density and composition of arthropod communities can alter soil carbon and nitrogen cycling dynamics. However, it is uncertain how factors such as land use intensity, litter chemical composition, and climate structure arthropod communities during decomposition. During a 730-day study, we characterized temporal changes in litter-colonizing arthropod communities in two litter types (corn, Zea mays, and grass, predominantly Bromus inermis) decomposing in three ecosystems representing an agricultural management intensity gradient (conventionally tilled, no-till, and old field). Further, to assess the relationships between litter chemistry and arthropod communities, we also correlated changes in arthropod densities and community composition with shifts in litter molecular chemical characteristics. Arthropod densities were greater in decomposing grass litter than in corn litter for seven out of thirteen taxa collected and all but two taxa increased in litter with management intensity (spiders – negative, Entomobryidae – no response). In contrast, total arthropod densities in soil decreased with management intensity. Temporal variation in arthropod density and community composition in litter corresponded with precipitation events and changes in litter chemistry during decomposition. For example, collembolan, oribatid, and mesostigmatid mite densities were negatively correlated with the relative abundance of lignin and positively correlated with nitrogen containing compounds. Our study demonstrates that the influence of agricultural management intensity on arthropods in litter is strikingly different from that in bulk soil, and suggests that management intensity interacts with litter chemistry and climate over the course of decomposition to determine both the density and composition of arthropod communities inhabiting litter at the soil surface.