Arthropod Species Richness Research Articles

Latitudinal gradients of biodiversity and ecosystem services in protected and non-protected oak forest areas can inform climate smart conservation

Adaptive governance of areas set aside for future protection of biodiversity, sustainable production, and recreation requires knowledge about whether and how effects of area protection are modulated by climate change and redistribution of species. To investigate this, we compare biodiversity of plants (assessed using vegetation plots) and arthropods (collected with Malaise traps, analyzed using metabarcoding) and productivity (tree growth, determined using dendrochronology) in protected and non-protected oak (Quercus spp.) forests along a latitudinal gradient (55.6 °N – 60.8 °N) in Sweden. We also compare historical, recent and projected future climate in the region. In contrast to established global latitudinal diversity gradients, species richness of plants and arthropods increased northwards, possibly reflecting recent climate-induced community redistributions, but neither was higher in protected than in non-protected areas, nor associated with contemporary ground temperature. Species composition of arthropods also did not differ between protected and non-protected areas. Arthropod biomass increased with latitude, suggesting that the magnitude of cascading effects mediated via their roles as pollinators, herbivores, and prey for other trophic levels, varies geographically and will change with a moving climate. Annual growth rate of oaks (an ecosystem service in the form of biomass increase and carbon sequestration) was independent of latitude and did not differ between protected and non-protected areas. Our findings question the efficacy of contemporary designation and management of protected oak forests, and emphasize that development and implementation of modified climate smart conservation strategies is needed to safeguard ecosystem functioning, biodiversity, and recreational values of protected forest areas against future challenges.

Manipulating the community structure of arthropods in rice fields with floral resources plants

Abstract Conservation biological control encourages natural enemies to suppress target pests through manipulation of environmental factors that influence natural enemy survival and effectiveness, including microclimates, availability of food for adults and alternative prey, and shelter from adverse environmental conditions. This study aimed to identify selective flowering plants that could be used to manipulate the arthropod community structure in rice fields. Three rice fields (a field without resources of flowering plants, a field with vegetable crop, and a field with ornamental plant) were used in this experiment. The flowering plants included Helianthus sp., Catharanthus roseus, and Cosmos sulphureus while the vegetable plants included eggplant, cucumber, and long beans. Arthropod recording was carried out by direct observation and yellow pan traps from 14 to 98 days after planting. We recorded 33,728 arthropods representing 153 species in 68 families, 13 orders, and 2 classes. The presence of flowering plant significantly affects abundance, species richness, diversity index, and evenness of arthropods both in dry and wet seasons. The rice field surrounded with ornamental plants or vegetables showed the lowest abundance of phytophagous arthropods, the highest abundance of parasitoid and predatory arthropods. Therefore, vegetable crops such as cucumber, long beans and eggplant have great opportunities as refugia in rice fields.

Landscape context affects patch habitat contributions to biodiversity in agroecosystems

AbstractEffective conservation schemes are needed to advance the dual objectives of biodiversity conservation and agronomic production in agricultural landscapes. Understanding how plant and arthropod taxa respond to both local habitat patch characteristics and landscape complexity is crucial for planning effective agri‐environment schemes. This study investigated the relative effects of local variables (plant and insect diversity ≤100 m from patch habitat center) and landscape variables (landscape composition and configuration metrics ≤5 km from patch habitat center) on the diversity of plants and arthropods within noncrop habitat patches (1) at different spatial extents ranging from 0.1 to 5 km, while (2) quantifying differential effects of local and landscape variables on particular components of diversity (i.e., species richness and abundance), and accounting for (3) particular components of landscape extent (0.1‐, 0.5‐, 1‐, 2‐, and 5‐km radii) and complexity (i.e., landscape composition and configuration). Landscape variables were significantly correlated with local plant and arthropod species richness and abundance at all spatial extents. Biodiversity responses to landscape variables were largely scale‐dependent, as pairwise comparisons were significantly different between all spatial extents except between 1‐ and 2‐km extents, and correlations were lowest at the 5‐km extent. Partial R2 values for predicting local biodiversity were highest when both local and landscape variables were included as predictors of species richness and abundance, increasing from 0.163 to 0.469 when landscape variables were included, underscoring the importance of considering both local and landscape effects on local diversity. Landscape configuration variables accounted for more variation in plant and arthropod species richness than composition variables. However, models performed best when composition and configuration were considered together rather than alone, suggesting that both components of landscape complexity should be considered for identifying and managing conservation areas in crop fields. Existing conservation schemes that incentivize farmers to create or conserve seminatural patch habitat within crop fields may be more effective when combined with landscape‐scale designs that enhance landscape complexity across the Northern Great Plains. Local conservation efforts should be coordinated with landscape‐level efforts to ultimately enhance biodiversity and desired ecosystem service outcomes across agricultural landscapes.

Habitat loss and simplification lower arthropod richness but not diversity

AbstractHabitat loss is rarely truly random and often occurs selectively with respect to the plant species comprising the habitat. Such selective habitat removal that decreases plant species diversity, that is, habitat simplification or homogenization, may have two negative effects on other species. First, the reduction in plant community size (number of individuals) represents habitat loss for species at higher trophic levels who use plants as habitat. Second, when plants are removed selectively, the resulting habitat simplification decreases the diversity of resources available to species at higher trophic levels. It follows that habitat loss combined with simplification will reduce biodiversity more than habitat loss without simplification. To test this, we experimentally implemented two types of habitat loss at the plant community level and compared biodiversity of resident arthropods between habitat loss types. In the first type of habitat loss, we reduced habitats by 50% nonselectively, maintaining original relative abundance and diversity of plant species and therefore habitat and resource diversity for arthropods. In the second type of habitat loss, we reduced habitats by 50% selectively, removing all but one common plant species, dramatically simplifying habitat and resources for arthropods. We replicated this experiment across three common plant species: Asclepias tuberosa, Solidago altissima, and Baptisia alba. While habitat loss with simplification reduced arthropod species richness compared with habitat loss without simplification, neither type of habitat loss affected diversity, measured as effective number of species (ENS), or species evenness as compared with controls. Instead, differences in ENS and evenness were explained by the identity of the common plant species. Our results indicate that the quality of remaining habitat, in our case plant species identity, may be more important for multi‐trophic diversity than habitat diversity per se.

Soil Moisture and Litter Coverage Drive the Altitude Gradient Pattern of Soil Arthropods in a Low-Elevation Mountain

This study sought to investigate the vertical distribution pattern of the soil faunal community in a low-altitude mountain area. On 8 July 2022, a low hill was selected as the study area, and soil arthropods were collected through traps. The leaf litter, vegetation type, and distribution quantity of each sampling site were investigated while the soil faunae were collected. In addition, the soil’s physical and chemical parameters were measured. The results of a one-way ANOVA showed that there were significant differences (p < 0.05) in the soil properties, leaf litter, and plant quantities at different altitudes within the research area. A total of 1086 soil arthropods, belonging to five classes and ten orders, were collected during the study period. The dominant species of soil arthropods at different altitudes were significantly different. The dominant species in low-altitude areas were Armadillidium sp. and Aethus nigritus. However, Eupolyphaga sinensis and Philodromidae were the dominant species in high-altitude areas. The results of a non-metric multidimensional scaling (NMDS) analysis showed that the soil faunae at different altitudes were clustered into two communities: a high-altitude community and a low-altitude community. With the increase in altitude, the species richness of the soil arthropods gradually decreased, and their abundance showed a decreasing trend. A redundancy analysis (RDA) of the soil arthropods and environmental factors showed that soil moisture (p < 0.01), pH (p < 0.01) and defoliation (p < 0.05) had significant effects on the distribution of the soil fauna. The results of a Pearson correlation analysis indicated that different environmental factors had interactive effects on the distribution of the soil arthropods. The quantity and species richness of the soil arthropods in different sample lines were tested using a variance analysis. The results showed that there were significantly smaller quantities of soil arthropods in the sampling line closer to the trekking ladder. This indicates that human tourism, namely mountaineering activities, had a direct impact on the soil fauna. This study can provide a reference for and data support in the development of biodiversity conservation measures for forest parks in low mountain areas.

Genetic variation within a stick insect species associated with community-level traits.

Phenotypic variation within species can affect the ecological dynamics of populations and communities. Characterizing the genetic variation underlying such effects can help parse the roles of genetic evolution and plasticity in 'eco-evolutionary dynamics' and inform how genetic variation may shape patterns of evolution. Here we employ genome-wide association (GWA) methods in Timema cristinae stick insects and their co-occurring arthropod communities to identify genetic variation associated with community-level traits. Previous studies have shown that maladaptation (i.e., imperfect crypsis) of T. cristinae can reduce the abundance and species richness of other arthropods due to an increase in bird predation. Whether genetic variation that is independent from crypsis has similar effects is unknown and was tested here using genome-wide genotyping-by-sequencing data of stick insects, arthropod community information, and GWA mapping with Bayesian sparse linear mixed models. We find associations between genetic variation in stick insects and arthropod community traits. However, these associations disappeared when host-plant traits are accounted for. We thus use path analysis to disentangle interrelationships among stick-insect genetic variation, host-plant traits and community traits. This revealed that host-plant size has large effects on arthropod communities, while genetic variation in stick insects has a smaller, but still significant effect. Our findings demonstrate that: (1) genetic variation in a species can be associated with community-level traits, but that (2) interrelationships among multiple factors may need to be analyzed to disentangle whether such associations represent causal relationships. This work helps to build a framework for genomic studies of eco-evolutionary dynamics.

Quantifying potential trade-offs and win-wins between arthropod diversity and yield on cropland under agri-environment schemes–A meta-analysis

In Europe, agri-environment schemes (AES) are a key instrument to combat the ongoing decline of farmland biodiversity. AES aim is to support biodiversity and maintain ecosystem services, such as pollination or pest control. To what extent AES affect crop yield is still poorly understood. We performed a systematic review, including hierarchical meta-analyses, to investigate potential trade-offs and win-wins between the effectiveness of AES for arthropod diversity and agricultural yield on European croplands. Altogether, we found 26 studies with a total of 125 data points that fulfilled our study inclusion criteria. From each study, we extracted data on biodiversity (arthropod species richness and abundance) and yield for fields with AES management and control fields without AES. The majority of the studies reported significantly higher species richness and abundance of arthropods (especially wild pollinators) in fields with AES (31 % increase), but yields were at the same time significantly lower on fields with AES compared to control fields (21 % decrease). Aside from the opportunity costs, AES that promote out-of-production elements (e.g. wildflower strips), supported biodiversity (29–32 % increase) without significantly compromising yield (2–5 % increase). Farmers can get an even higher yield in these situations than in current conventional agricultural production systems without AES. Thus, our study is useful to identify AES demonstrating benefits for arthropod biodiversity with negligible or relatively low costs regarding yield losses. Further optimization of the design and management of AES is needed to improve their effectiveness in promoting both biodiversity and minimizing crop yield losses.

Pengaruh Aplikasi Pupuk Organik Plus Pada Bawang Merah (Allium ascalonicum) terhadap Keanekaragaman Arthropoda di Lahan Gambut

Shallots (Allium ascalonicum L.) from the Lilyceae family are annual horticultural plants. The aim of this research is to determine the effect of the application of organic fertilizer plus on the diversity of arthropods in shallot plants in peatlands. The method used in this research was a one-factor Completely Randomized Design (CRD) consisting of 4 treatments and 5 replications. Data from arthropod identification results are grouped based on order and family which are presented in tabular form. Then an analysis was carried out using diversity indices, species richness and species evenness. The results of the research show that the most dominant arthropods are the predator group. The results also show that the level of arthropod species diversity is moderate, the level of arthropod species richness is low, the level of evenness of arthropod species shows an unstable distribution. The most dominant group of arthropods is the predator group and the results of the LSD analysis test at the 5% level showed a real influence on the diversity of arthropods in shallot plants in peatlands where organic fertilizer plus 125 g/hole was applied with an average of 48.40 individuals.

Assessing whether peri-urban agricultural land or plantation forest is a better green infrastructure for ground arthropods at local and landscape scales

City agencies across multiple continents have invested millions of funds in ambitious afforestation projects in urban and peri-urban areas to enhance the city green infrastructure. One example is the Beijing One Million Mu Plain Afforestation Project, which has established 146,000 ha of plantation forests, mainly on arable lands. This contradicts the national arable land conserving policies and has dramatically changed local habitat types and landscape context. However, the impact of these processes on biodiversity is not well understood. To investigate this impact at local and landscape scales, we explored a space-for-time approach. We selected 12 plantation forests and their nearby arable lands along a gradient of plantation forest cover in the surrounding landscapes. We surveyed ground spiders and carabids and analyzed their responses to local habitat type, landscape context, and their interaction. In the sampled landscapes, plantation forest cover increased (12.0%–35.9%), while arable land cover decreased (58.3%–31.8%). 96.3% of the new plantation forests were established on arable lands. Intensive afforestation on arable lands did not increase local ground arthropod diversity. In fact, ground arthropod abundance and species richness in plantation forests were significantly lower than in arable lands when the surrounding arable land cover was relatively high. With surrounding arable land cover decreasing, ground arthropod abundance and species richness in plantation forests increased but did not exceed those in nearby arable lands. Hence, the overall ground arthropod diversity at landscape scale was not improved. These findings suggest that, from a biodiversity conservation perspective, plantation forests did not surpass peri-urban agricultural lands as a better green infrastructure . However, ground arthropods benefit from rich local non-crop herb communities. Conserving peri-urban agricultural lands and implementing extensive management regimes for agricultural lands and existing plantation forests are more effective tools than ambitious afforestation of agricultural land in peri-urban areas of Beijing and other metropolises.

The influence of distance from crushed stone mining on surface-active arthropods and soil properties

ABSTRACT Background: Mining of crushed stone for use in construction is among the various anthropogenic activities in the Eastern Cape province in South Africa that alter natural landscapes. However, little is known about the impact of these activities on arthropods and soil chemical properties. Objectives: We investigated the effect of distance (5, 30, 50 and 70 metres) from the mining sites on species richness, abundance and composition of surface-active arthropods, as well as composition and concentration of soil chemical properties (soil pH, calcium, magnesium, phosphorus and zinc). Methods: The study was conducted at two mining sites in Nyandeni Local Municipality within the O.R. Tambo District Municipality that were commissioned in 2014. Arthropods were sampled using pitfall traps and thereafter sorted into morphospecies, while an auger was used to collect soil samples. Permutational multivariate analysis was used to compare the composition of the arthropods and soil chemical properties among distances from the mining activities, while arthropod species richness and abundance, as well as concentrations of soil chemical properties, were analysed using the one-way analysis of variance or Kruskal-Wallis test. Results: Arthropod species richness, abundance and composition were not influenced by distance from mining activities. Although among soil chemical properties, mining activities altered the concentration of zinc only, we found dissimilarities in soil composition between the sampling point at the edge of the mining activities and sampling points that were away from the mining sites. Conclusion: We found no evidence of the impact of crushed stone mining on surface-active arthropods; however, our study revealed a negative impact of crushed stone mining on soil chemical properties.

Organic orchard floor management in peach: effects on arthropods and associated fruit injury in the Intermountain West.

Understanding orchard floor management is critical to organic tree-fruit production systems given its impact on weeds, soil fertility, tree health, and crop yield. Several viable options are available to producers for weed management and promotion of organic fertility, including use of turf and broadleaf alleyway covers and living and nonliving tree-row mulches. While these measures can be effective, little is known about how these strategies influence arthropod pests, which cause fruit injury. Here, we assessed 6 organic orchard floor management strategies for their impact on arthropod abundance and diversity in an organic peach production system in northern Utah from 2010 to 2014, using sweep netting and pitfall collections along with observed peach fruit damage. Generally, we found that alleyway and tree-row treatments had no impact on total arthropod diversity, species richness, or community diversity. However, earwig (Forficula auricularia) abundance was significantly impacted by alleyway and tree-row treatments that resulted in increased fruit injury. Trefoil alleyway treatments consistently increased earwig abundance across life-history stages, while mulch or Alyssum (straw) tree-row treatments harbored more earwigs and, as a result, increased earwig fruit injury. Since earwigs are especially prone to damaging young, developing fruits, it is imperative that more work is done to assess earwig abundances and life-history traits. Our results demonstrate that detrimental arthropods are sensitive to orchard floor management and can further inform integrated pest management approaches that complement sustainability goals.

Persisting roadblocks in arthropod monitoring using non-destructive metabarcoding from collection media of passive traps.

Broad-scale monitoring of arthropods is often carried out with passive traps (e.g., Malaise traps) that can collect thousands of specimens per sample. The identification of individual specimens requires time and taxonomic expertise, limiting the geographical and temporal scale of research and monitoring studies. DNA metabarcoding of bulk-sample homogenates has been found to be faster, efficient and reliable, but the destruction of samples prevents a posteriori validation of species occurrences and relative abundances. Non-destructive metabarcoding of DNA extracted from collection medium has been applied in a limited number of studies, but further tests of efficiency are required with different trap types and collection media to assess the consistency of the method. We quantified the detection rate of arthropod species when applying non-destructive DNA metabarcoding with a short (127-bp) fragment of mitochondrial COI on two combinations of passive traps and collection media: (1) water with monopropylene glycol (H2O-MPG) used in window-flight traps (WFT, 53 in total); (2) ethanol with monopropylene glycol (EtOH-MPG) used in Malaise traps (MT, 27 in total). We then compared our results with those obtained for the same samples using morphological identification (for WFTs) or destructive metabarcoding of bulk homogenate (for MTs). This comparison was applied as part of a larger study of arthropod species richness in silver fir (Abies alba Mill., 1759) stands across a range of climate-induced tree dieback levels and forest management strategies. Of the 53 H2O-MPG samples from WFTs, 16 produced no metabarcoding results, while the remaining 37 samples yielded 77 arthropod MOTUs in total, of which none matched any of the 343 beetle species morphologically identified from the same traps. Metabarcoding of 26 EtOH-MPG samples from MTs detected more arthropod MOTUs (233) than destructive metabarcoding of homogenate (146 MOTUs, 8 orders), of which 71 were shared MOTUs, though MOTU richness per trap was similar between treatments. While we acknowledge the failure of metabarcoding from WFT-derived collection medium (H2O-MPG), the treatment of EtOH-based Malaise trapping medium remains promising. We conclude however that DNA metabarcoding from collection medium still requires further methodological developments and cannot replace homogenate metabarcoding as an approach for arthropod monitoring. It can be used nonetheless as a complementary treatment when enhancing the detection of soft-bodied arthropods like spiders and Diptera.

Ecosystem engineering and leaf quality together affect arthropod community structure and diversity on white oak (Quercus alba L.)

Shelter building caterpillars act as ecosystem engineers by creating and maintaining leaf shelters, which are then colonized by other arthropods. Foliage quality has been shown to influence initial colonization by shelter-building caterpillars. However, the effects of plant quality on the interactions between ecosystem engineers and their communities have yet to be studied at the whole plant level. We examined how leaf tying caterpillars, as ecosystem engineers, impact arthropod communities on Quercus alba (white oak), and the modifying effect of foliage quality on these interactions. We removed all leaf tying caterpillars and leaf ties on 35 Q. alba saplings during the season when leaf tying caterpillars were active (June–September), and compared these leaf tie removal trees to 35 control trees whose leaf ties were left intact. Removal of these ecosystem engineers had no impact on overall arthropod species richness, but reduced species diversity, and overall arthropod abundance and that of most guilds, and changed the structure of the arthropod community as the season progressed. There was an increase in plant-level species richness with increasing number of leaf ties, consistent with Habitat Diversity Hypothesis. In turn, total arthropod density, and that of both leaf tying caterpillars and free-feeding caterpillars were affected by foliar tannin and nitrogen concentrations, and leaf water content. The engineering effect was greatest on low quality plants, consistent with the Stress-Gradient Hypothesis. Our results demonstrate that interactions between ecosystem engineering and plant quality together determine community structure of arthropods on Q. alba in Missouri.

Long-term mammal herbivory on arthropod assemblages at Kruger National Park, South Africa.

Protected savannas are essential reserves for biological diversity, including endangered arthropod species, however, extreme grazing by mammals has cascading impacts on the communities and disrupts the functioning of these ecosystems globally. The current study assessed the abundance, species richness and composition of arthropods at the long-term grazing exclosures of Kruger National Park, South Africa. Pitfall traps and active searches were used to sample arthropods at the ungrazed, moderately, and heavily grazed exclosures. We found that Hymenoptera, Coleoptera, Diptera and Araneae were the most abundant orders of arthropods sampled. The abundance of multi-taxon, Diptera and Hymenoptera was significantly different between exclosures. In contrast, Coleoptera had high numbers of morphospecies compared to Hymenoptera, Araneae and Diptera. Species richness for multi-taxon, Diptera and Hymenoptera was significantly high at the heavily grazed compared to moderately grazed and ungrazed exclosures. Up to 22.2%, 41.2%, and 44.4% of the morphospecies were unique to the ungrazed, moderately and heavily grazed exclosures, respectively. A high proportion of morphospecies shared between exclosures were Coleoptera (41.0%) and Hymenoptera (38.5%) compared to Diptera and Araneae with less than 5% recorded across exclosures. Thus, morphospecies within the least abundant orders, namely Diptera and Araneae, were represented by singletons that were unique to particular exclosures compared to the most abundant arthropod orders (e.g., Coleoptera and Hymenoptera). We conclude that long-term mammal grazing enhances species richness and niche composition together with sparse and unique arthropods in the protected savannas. Therefore, managed grazing regimes can serve as a tool for maintaining the integrity of the protected savannas.

Commercial banana and macadamia plantations in a savanna matrix support high levels of arthropod diversity

Expansion and intensification of agroecosystems is one of the major causes of habitat loss in the savanna biome in South Africa. As such, this study sought to determine the influence of commercial subtropical fruit plantations (banana and macadamia) on species richness, abundance, and composition of surface-active arthropods compared to the savanna biome. Given that pesticides and herbicides are applied from spring to early autumn in banana and macadamia plantations, we sampled in winter to reduce the potential impact of pesticides and herbicides. Surface-active arthropods were sampled using pitfall traps. Habitat type did not affect species richness and abundance of ants and spiders, as well as species richness of beetles. However, significantly greater abundance of beetles was recorded in the macadamia plantation compared to the banana and savanna. This could have been due to greater abundance of herbivorous beetles and other insects, which would have increased the diversity of predatory beetles. Furthermore, unlike the banana plantation, the macadamia plantation was characterised by a deep leaf litter layer and the presence of weeds and grasses, which probably increased abundance of beetles. Species composition indicated that the studied arthropod taxa associate with specific habitats, as demonstrated by the three habitats supporting different species composition. Despite savanna habitat not supporting high species richness or abundance of surface-active arthropods, we recorded the highest number of unique species of ants and spiders in the savanna rather than in the plantations. These results highlight the importance of natural landscapes in conservation of surface-active arthropods.

Effects of field-level strip and mixed cropping on aerial arthropod and arable flora communities

Loss of arthropod biodiversity can impair the provision of ecosystem services in agricultural landscapes. Crop diversification strategies offer the possibility to support arthropod communities without putting aside agricultural land as conservation areas. Within-field crop diversification measures, such as strip cropping and crop mixtures, may provide arthropods with continuity and diversity in food, shelter and habitat at fine spatial and temporal resolutions. However, it is unclear how strip cropping and plant species diversity within strips influences aerial arthropod and weed communities in commercially sized arable fields. In this 2-year study we tested the effects of crop heterogeneity on aerial arthropod and plant communities in organically managed strip fields. We tested effects of configurational crop heterogeneity by comparing sole cropping (MONO) with strip cropping (STRIP), and compositional crop heterogeneity by comparing STRIP with flower-legume-grain crop mixtures grown in strips (STRIPMIX). Aerial arthropod communities were assessed in 138 sweep net transects and plant communities in 124 vegetation plots in cabbage, wheat, sugar beet and barley. Higher configurational crop heterogeneity by strip cropping reduced herbivore abundances and increased natural enemy species richness in organic cabbage strips. Cabbage in MONO had a significantly higher herbivore abundance (+11%) and a lower natural enemy species richness (−57%) than cabbage in STRIP. Higher compositional crop heterogeneity by sowing additional plant species in strips (STRIPMIX) significantly increased plant abundance (+33%), plant species richness (+21%), total aerial arthropod abundance (+45%), and total aerial arthropod species richness (+21%) compared to STRIP. Our work shows that both configuration of crop areas (MONO vs. STRIP) and plant species diversity within strips (STRIP vs. STRIPMIX) can support arthropod biodiversity and natural pest suppression, but that arthropod responses differ between diversification strategies and crop combinations. Further optimization of design and management of within-field crop diversification strategies holds potential to attain biodiversity-based cropping systems which deliver multiple ecosystem services and have a reduced dependency on pesticides.

Assisted migration experiments along a distance/elevation gradient show limits to supporting home site communities

We addressed the hypothesis that intraspecific genetic variation in plant traits from different sites along a distance/elevation gradient would influence the communities they support when grown at a new site. Answers to this hypothesis are important when considering the community consequences of assisted migration under climate change; i.e., if you build it will they come?. We surveyed arthropod communities occurring on the foundation riparian tree speciesPopulusangustifolia along a distance/elevation gradient and in a common garden where trees from along the gradient were planted 20–22 years earlier. Three major patterns were found: 1) In the wild, arthropod community composition changed significantly. Trees at the lower elevation site supported up to 58% greater arthropod abundance and 26% greater species richness than more distant, high elevation trees. 2) Trees grown in a common garden sourced from the same locations along the gradient, supported arthropod communities more similar to their corresponding wild trees, but the similarity declined with transfer distance and elevation. 3) Of five functional traits examined, leaf area, a trait under genetic control that decreases at higher elevations, is correlated with differences in arthropod species richness and abundance. Our results suggest that genetic differences in functional traits are stronger drivers of arthropod community composition than phenotypic plasticity of plant traits due to environmental factors. We also show that variation in leaf area is maintained and has similar effects at the community level while controlling for environment. These results demonstrate how genetically based traits vary across natural gradients and have community-level effects that are maintained, in part, when they are used in assisted migration. Furthermore, optimal transfer distances for plants suffering from climate change may not be the same as optimal transfer distances for their dependent communities.

Multitrophic arthropod diversity mediates tree diversity effects on primary productivity.

Forests sustain 80% of terrestrial biodiversity and provide essential ecosystem services. Biodiversity experiments have demonstrated that plant diversity correlates with both primary productivity and higher trophic diversity. However, whether higher trophic diversity can mediate the effects of plant diversity on productivity remains unclear. Here, using 5 years of data on aboveground herbivorous, predatory and parasitoid arthropods along with tree growth data within a large-scale forest biodiversity experiment in southeast China, we provide evidence of multidirectional enhancement among the diversity of trees and higher trophic groups and tree productivity. We show that the effects of experimentally increased tree species richness were consistently positive for species richness and abundance of herbivores, predators and parasitoids. Richness effects decreased as trophic levels increased for species richness and abundance of all trophic groups. Multitrophic species richness and abundance of arthropods were important mediators of plant diversity effects on tree productivity, suggesting that optimizing forest management for increased carbon capture can be more effective when the diversity of higher trophic groups is promoted in concert with that of trees.

High species turnover of arthropod communities associated with distinct vegetation patches (“heuweltjies”) in an arid shrubland

Dryland ecosystems are often characterized by their vegetation patchiness. The Succulent Karoo, a semi-arid region in South Africa is characterised by distinct vegetation patches surrounded by a homogenous vegetation matrix. These patches, locally known as heuweltjies, are naturally developed earthen mounds found throughout the region that contribute significantly to landscape heterogeneity. Arthropods are key for ecological functioning in semi-arid ecosystems. However, few studies have assessed the role that heuweltjies play in maintaining arthropod diversity in the landscape. This study investigates how arthropod abundance, species richness, beta-diversity and composition respond to heuweltjies at multiple spatial scales (biotope and site). Two sampling techniques (pitfall and vacuum sampling) were used to collect epigaeic (ground) and foliage-dwelling arthropods on heuweltjies and in the surrounding matrix, at three different sites in the Succulent Karoo during drought conditions. Heuweltjies had greater epigaeic and foliage alpha-diversity and abundance than the matrix. Additionally, epigaeic and foliage arthropod community composition were dissimilar at both the biotope and site scales. Beta diversity across the three sites was high and driven by species turnover. At the biotope scale, heuweltjie and matrix plots both showed high beta-diversity. This study took place during a prolonged drought with high plant mortality and relatively few foliage arthropods, but patterns in arthropod diversity between heuweltjies and the surrounding matrix were nevertheless still apparent. These results suggest that heuweltjies promote arthropod diversity and heterogeneity in the landscape, playing a vital role as refuges, providing food and nesting resources for various arthropod species.

Soil arthropods promote litter enzyme activity by regulating microbial carbon limitation and ecoenzymatic stoichiometry in a subalpine forest

Soil arthropods are crucial decomposers of litter at both global and local scales, yet their functional roles in mediating microbial activity during litter decomposition remain poorly understood. Here, we conducted a two-year field experiment using litterbags to assess the effects of soil arthropods on the extracellular enzyme activities (EEAs) in two litter substrates (Abies faxoniana and Betula albosinensis) in a subalpine forest. A biocide (naphthalene) was used to permit (nonnaphthalene) or exclude (naphthalene application) the presence of soil arthropods in litterbags during decomposition. Our results showed that biocide application was effective in reducing the abundance of soil arthropods in litterbags, with the density and species richness of soil arthropods decreasing by 64.18–75.45 % and 39.19–63.30 %, respectively. Litter with soil arthropods had a greater activity of C-degrading (β-glucosidase, cellobiohydrolase, polyphenol oxidase, peroxidase), N-degrading (N-acetyl-β-D-glucosaminidase, leucine arylamidase) and P-degrading (phosphatase) enzymes than litter from which soil arthropods were excluded. The contributions of soil arthropods to C-, N- and P-degrading EEAs in the fir litter were 38.09 %, 15.62 % and 61.69 %, and those for the birch litter were 27.97 %, 29.18 % and 30.40 %, respectively. Furthermore, the stoichiometric analyses of enzyme activity indicated that there was potential C and P colimitation in both the soil arthropod inclusion and exclusion litterbags, and the presence of soil arthropods decreased C limitation in the two litter species. Our structural equation models suggested that soil arthropods indirectly promoted C-, N- and P-degrading EEAs by regulating the litter C content and litter stoichiometry (e.g., N/P, LN/N and C/P) during litter decomposition. These results demonstrate that soil arthropods play an important functional role in modulating EEAs during litter decomposition.