Spider Assemblages Research Articles

Spider Assemblages and Diversity in Rice–Crab Cocropping Production Fields1

Spider Assemblages and Diversity in Rice–Crab Cocropping Production Fields1

Composition and Diversity of Spiders in the Lian-huo Highway (Shangqiu Section) Shelter Forest and Campus Habitat of Henan Province, China

Background: Spider assemblages, which are easily sampled, are useful indicators that can be used to compare the biodiversity of various environments and assess the effects of disturbances on diversity. Because spiders are generally found in forests in high abundance, they form some good model taxa for biodiversity studies. Methods: The present study compares the composition and diversity of spiders in the Lian-Huo highway (Shangqiu section) shelter forest (HS) and campus habitat (CH) of Henan province, China. Sampling were collected from April to June 2018 and fourth time a month, a total of twenty-four samples were collected. Within each habitat type there were eight sites surveyed which represented a wide geographical spread of the habitats. Result: A total of 3725 individual spiders were collected from the two sites, representing 14 families and 23 species. Guild structure analysis of the collected spiders revealed 4 feeding guilds viz, web weavers, Sheet web weavers, Foliage hunter’s spider and Ambush hunters. The abundance of spiders in the campus habitat is significantly higher than that in Lian-Huo highway (Shangqiu section) shelter forestand the Shannon-Wiener index (H’) (HS=3.3827, CH=2.2007), Simpson index (D) (HS=0.8710, CH=0.7391), Evenness index (J) (HS=2.8391, CH=1.7088) and Richness index (E) (HS=0.7462, CH=0.6362) are significantly higher in the campus habitat than in the Lian-Huo highway (Shangqiu section) shelter forest. These results suggest that increasing the complexity of habitat structure and reducing anthropogenic disturbance is a meaningful way to conserve and restore Spiders diversity.

Ecologically sustainable retention forestry supports spider biodiversity in the Lower Morava UNESCO Biosphere Reserve

Abstract Floodplain forests are among the most endangered ecosystems worldwide, even though they are hotspots for numerous taxa. The abandonment of traditional management and large‐scale timber extraction, such as clear‐cutting, has led to a decline in floodplain forest biodiversity. Retention forestry has the potential to facilitate the implementation of an ecologically sustainable forest management approach. Despite the increasing popularity of this method, its potential for spider diversity conservation, especially its comparison with the widespread practice of clear‐cutting, is still poorly studied. We studied the short‐term effect of forestry treatments (dispersed retention with 60% retained trees and clear‐cutting) on the diversity of ground‐dwelling spiders in the floodplain forests along the Lower Morava (March) and Dyje (Thaya) rivers in the Czech Republic. Spiders were sampled using pitfall traps during 2021 (pre‐harvest year) and 2022 (post‐harvest year). A total of 10,005 specimens from 167 species were recorded. Both forestry treatments simplified habitat structure compared with pre‐harvest conditions, resulting in lower beta‐diversity within sites. However, dispersed retention had higher alpha‐ and beta‐diversity than clear‐cuts, indicating that retention provided a more complex‐structured habitat. Dispersed retention and clear‐cuts hosted distinct spider assemblages with characteristic indicator species. Species typical of open and significantly disturbed habitats preferred clear‐cuts, while species typical of forests and (semi‐) open habitats, including threatened species, showed a preference for dispersed retention. Our results demonstrated, for the first time, that dispersed retention forestry could serve as an effective management tool for conserving the ground‐dwelling assemblages of spiders in floodplain forests.

The influence of humidity gradient in a forest on ground spider assemblages: a preliminary study

A forest is a dynamic formation developed through evolutionary transformations that have progressed over a long time. Bioindication can help us understand changes occurring in a forest. Spiders play a significant role in biomonitoring. The presence of stenotopic spiders is affected by several factors, of which water availability is vital. According to the assumptions underlying water retention programs, water accumulated in retention reservoirs is expected to stimulate higher biodiversity of habitats. An analysis of the effect of a moisture gradient on the appearance of epigeic spiders in the Dąbrówka Forest Subdistrict has demonstrated the highest species diversity in the transect located closest to retention reservoirs (93 species). The species diversity of epigeic spiders decreased with the growing distance from these water reservoirs (transect B: 84 species; transect C: 70). Inverse relationships were determined with regard to the numbers of captured spiders (transect A: 927 specimens; B: 1134; C:1288). The spider species that dominated quantitatively was the forest species Pardosa lugubris, caught most abundantly in the area assigned to transect C (76.28%). A higher humidity gradient of a habitat (transects A and B) favors the occurrence of characteristic species with specific habitat and moisture requirements, which are ecologically valuable.

Spider assemblages (Arachnida: Araneae) in burned and intact mountain heathlands in the Northern Black Forest

Spider assemblages (Arachnida: Araneae) in burned and intact mountain heathlands in the Northern Black Forest

Salvage Logging and Secondary Succession Promote Spider Diversity in Post-disturbance Stands in Western Germany

Abstract Climate change and biodiversity loss strongly affect ecosystems. In recent years, forests have suffered substantially from climate-induced disturbances resulting in bark beetle outbreaks in coniferous forests. In forest plantations, such disturbances often cause large-scale diebacks, which are frequently salvage-logged. However, the consequences of natural disturbances and subsequent management for forest biodiversity and ecosystem services within plantations are largely unclear. Because they comprise good bioindicators for forest alterations, we here investigated epigeal spider diversity and community composition of three post-disturbance management approaches in former spruce plantations in western Germany. Taxonomic diversity of spiders was significantly enhanced on salvage-logged and secondary succession compared with standing deadwood sites. Nevertheless, the latter provided a refuge for forest specialists, moisture and shade-loving as well as smaller species, whereas the other two management categories were mostly inhabited by larger spiders associated with open habitats. Because all three post-disturbance management approaches harbored highly distinct spider communities and divergent functional guilds, we propose the application of a variety of management approaches for bark beetle-affected spruce plantations. The resulting habitat heterogeneity will likely enhance the biodiversity of spiders and other taxonomic groups. Study Implications: Bark beetle outbreaks became severe disturbances in spruce plantations. The management of affected stands usually aims at mitigating economic losses, but within the current biodiversity crisis, it is increasingly important to consider ecological consequences. This study shows that salvage logging or secondary succession can increase spider taxonomic diversity, although forest species preferred standing deadwood sites. All management categories harbored highly distinct spider assemblages characterized by different ecological and functional guilds. Our results indicated that spider communities were influenced by canopy openness, microclimate, and competition rather than post-disturbance management. Therefore, management practices should include diverse approaches to foster many different spider assemblages.

The spider fauna of Danish coastal dune habitats revisited after 25 years: evidence of faunistic impoverishment

Arthropod faunas have become impoverished in recent years in abundance as well as in diversity, but so far little evidence exists concerning spiders. In 2022, we repeated pitfall trap collections of spider assemblages completed 25 years previously in coastal dune habitats of the Hanstholm Reserve of National Park Thy, Denmark. Traps were placed approximately at the same spots, i.e. the habitats (white dune, grey dune, dry dune heathland, wet dune heathland, low pine plantation) were represented approximately as before. Contrary to most previous reports of insect decline, we found only weak evidence of reduction in abundance, but strong indications of reductions in faunistic value based on changes in ecological traits. Within the same period of spring and with the same number of traps, we collected 12% fewer spider individuals and 13% fewer species; rarefaction indicated that the lowered species richness was real. Species diversity had decreased and dominance increased. Changes in indices of ecological traits showed that the fauna had changed into decreased contribution of habitat specialists and species of restricted Danish distribution; the proportion of aeronauts had increased; the average body size had decreased. Indices of assemblage microclimatic niche positions and niche widths showed increased representation of shade and humidity loving species. Most of these changes were repeated in each of the habitats. Finally, we found evidence of a phenological shift towards activity earlier in spring in some species.Implications for insect conservationWe discuss possible management measures to counteract the observed trend towards reduced faunistic value.

Effects of mowing on body size patterns in spider assemblages of mesic meadows.

Habitat disturbance affects not only the abundance, species richness and species composition of the local fauna, but also the body size of specific individuals and body size patterns in animal assemblages. Particularly large disturbances occur in agroecosystems, where many agricultural treatments are carried out. One of them, which is most commonly applied to grasslands and which significantly damages the habitat structure, is mowing. We examined the effect of mowing on mean, skewness and kurtosis of the body size in epigeic spider assemblages. The research was conducted on mesic meadows in eastern Poland, in an agricultural landscape typical for this region, consisting of a mosaic of meadows, fields and forests. Spiders were collected using pitfall traps in two sampling periods: the first before mowing and the second when part of the meadows had been mown. Mowing had no significant effect on mean body size, skewness and kurtosis of the body size in epigeic spider assemblages. However, after the cut, mown plots showed, on average, significantly smaller spider species than unmown plots. Both the value of skewness and kurtosis significantly increased after mowing but to the same extent on both the control and mown plots. The decrease in mean body size and increase in skewness in spider assemblages were mainly due to an increase in the number of small species from the Linyphiidae family. It is likely that these species began to migrate (via ballooning) during the second sampling session, following the start of haying, and were thus caught in traps more frequently. Our study showed no clear, significant changes in the body size structure of epigeic spiders in mown meadows compared to unmown ones, which may suggest that the mowing, where extensive farming is practised, does not have a long-term significant negative impact on this group of invertebrates.

Spider assemblages (Arachnida, Araneae) in conventionally managed versus extensively used or restored grass- and farmland sites in Mecklenburg-Vorpommern

Spider assemblages (Arachnida, Araneae) in conventionally managed versus extensively used or restored grass- and farmland sites in Mecklenburg-Vorpommern

It is not a mere piece of the mainland: Fluvial islands contribute to regional spider diversity in a seasonally flooded Amazonian archipelago

Abstract Islands and analogous insular habitats are found in several ecological contexts. With the exception of oceanic islands, however, the contribution of these insular habitats to regional biodiversity remains poorly investigated, especially in tropical regions. We investigated the understory spider assemblages in an Amazonian river archipelago to evaluate the contribution of fluvial islands to regional spider diversity. We collected spiders on 30 islands ranging from 1 to 1527 ha and at 23 sites in mainland habitats represented by continuous igapó flooded forests and terra firme forests. Spiders were collected by shaking the vegetation over a white sheet during a standardised time of 30 min. From 1404 adult individuals, we identified 290 spider species or morphospecies, with 150 species being recorded on the fluvial islands, 122 in the igapó flooded forests and 103 in the terra firme forests. Spider assemblages of fluvial islands exhibit lower alpha diversity and equitability compared with mainland habitats. The species composition of fluvial islands was significantly distinct from that of mainland habitats, even when compared with neighbouring igapó flooded forests. Several families and species of spider were significantly associated with a particular habitat, including 8 families and 10 species identified as indicators of fluvial islands. Fluvial islands effectively contribute to regional diversity since their spider fauna is not a mere impoverished subset of species from mainland habitats. Events that alter the flood pulse in Amazonian rivers (e.g., construction of hydroelectric dams) could threaten the unique biological assemblages of the floodplain habitats, especially the fluvial islands.

Response of Spider and Epigaeic Beetle Assemblages to Overwinter Planting Regimes and Surrounding Landscape Compositions.

The rotation patterns of summer rice-winter oil seed rape and summer rice-winter fallow are the main planting regimes in the rice ecosystem in southern China. However, the impact of local rotation patterns and landscape factors on the overwintering conservation of predators in spider and epigaeic beetle assemblages remains poorly understood. Here, we investigate the diversity and density of spiders and beetles over two consecutive winters (2019/2020 and 2020/2021), focusing on the impact of two rotation patterns (rice-fallow and rice-oilseed rape) and surrounding landscape compositions on predator diversity. The main findings of our research were that spiders were more abundant and had a higher activity density in the fallow rice fields (FRs) compared to the oilseed rape fields (OSRs), whereas ground beetles exhibited the opposite pattern. Specifically, fallow rice fields supported small and ballooning spiders (e.g., dominant spider: Ummeliata insecticeps), while OSRs supported larger ground beetles (e.g., dominant beetles: Agonum chalcomus and Pterostichus liodactylus). Moreover, the composition of spider assemblages were impacted by semi-natural habitats (SNHs) during overwintering, while ground beetle assemblages were influenced by overwinter planting patterns. Overall, our results suggest that different planting regimes and preserving semi-natural habitats are a strategic way to enhance species diversity and functional diversity of ground predators. It is, therefore, recommended that to conserve and improve predator diversity during overwintering, land managers and farmers should aim to maintain diverse planting regimes and conserve local semi-natural habitats.

Characteristics of spider assemblages of subtropical rice paddy fields in the Yaeyama Islands, Japan

Spiders are important natural enemies of rice pests in paddy fields. To estimate their roles, it is essential to understand their functional diversity. However, little is known about the spider fauna of paddy fields in subtropical regions. Here, we investigated spider diversity and species composition in paddy fields in the Yaeyama Islands, in subtropical Japan. We collected 1489 individuals of at least 42 species in 13 families and 7 guilds from rice paddies on Ishigaki, Iriomote, and Yonaguni islands by net sweeping during the first and second crops from 2013 to 2015. The Tetragnathidae (39%), Araneidae (35%), and Thomisidae (18%) were the most abundant families, comprising > 90% of total abundance. Orb web weavers (73%) and ambush hunters (19%) were the most abundant guilds. The most common species were Neoscona theisi (Walckenaer, 1841) (Araneidae) (n = 352), Tetragnatha javana (Thorell, 1890) (Tetragnathidae) (n = 294), and Tetragnatha nitens (Audouin, 1826) (Tetragnathidae) (n = 94). The results show that the species composition of spiders in subtropical paddy fields is more similar to that in tropical paddy fields in Asia than to that in temperate paddy fields in mainland Japan. Ordination analysis showed that the composition of spiders on Ishigaki island varies greatly with season and year. This study makes a valuable contribution to knowledge of the comprehensive diversity of subtropical spiders associated with rice paddy fields in Japan.

Spatio‐temporal species aggregations do not rule out interspecific competition in tree hollow spider assemblages

Abstract A community's biological diversity reflects coexistence between species. This often depends, to some extent, on whether there is competition for resources and how it is dealt with. The nature of old‐growth tree hollows is confined and relatively isolated, which makes them ideal for investigating the competition phenomena between their inhabitants, such as Araneae. The existence of interspecific competition in the structuring of tree hollow spider assemblages in Mediterranean forests was inferred by spatial co‐occurrence pattern analyses with null models at both the community and pairwise levels. The analysis included 36 spider species collected monthly with emergence traps for 1 year. The distribution of four ecological traits, body size and phenology on the resulting pattern type was discussed. The analyses showed spatial segregation at the community level and spatial aggregations between species with different traits predominated at the pairwise level. Hunting strategy and body size were the main differential traits to facilitate these aggregations. In addition, only the aggregations led by Amaurobius scopolii–Scotophaeus scutulatus and Eratigena atrica–Liocranum majus also showed an overlap during their main activity period. Community segregation and spatio‐temporal aggregations of species with differential traits suggest that interspecific competition is a very likely structuring factor of tree hollow spider assemblages. Instead, segregations at the pairwise level seem to result from other factors, for example, habitat preferences.

Effects of a short-term temperature increase on arthropod communities associated with pastures.

The impact of climate change on islands is expected to cause dramatic consequences on native biodiversity. However, limited data are available for arthropod communities in island agroecosystems. In this study, we simulate a small-scale climatic change (average of +1.2°C), using Open Top Chambers (OTCs) in forage crops in the Azores Archipelago (Portugal) and test the responses of arthropod communities associated with intensively-managed pastures. At three sites, twenty 1 x 1 m plots were established: 10 treatment plots with OTCs and 10 control plots. Arthropods were sampled with pitfall traps on two sampling events (winter and summer of 2020). When considering all species collected, arthropods' abundance was lower in OTCs. Specific taxa, namely spiders and beetles, showed a fast response to the OTCs' presence. The assemblage of non-indigenous spiders well adapted to pastures showed a significant difference in diversity with a slightly greater richness, but lower abundance inside the warmer plots. However, the presence of OTCs resulted in a decrease in beetle richness and abundance. This decline may be attributed to the multiple effects of warming. Therefore, it is imperative to conduct further investigations to elucidate the ecological processes that underlie the observed patterns.

Impact of urbanisation on the taxonomic and functional diversity of spider assemblages in Guwahati City, Assam, India

Impact of urbanisation on the taxonomic and functional diversity of spider assemblages in Guwahati City, Assam, India

Effects of Natural Habitat and Season on Cursorial Spider Assemblages in Mediterranean Vineyards.

Natural habitats adjacent to vineyards are presumed to have a positive effect on the diversity of natural enemies within the vineyards. However, these habitats differ in vegetation structure and seasonal phenology and in turn could affect the species composition of natural enemies. Here, we compared the species richness and diversity and the composition of spider assemblages in several locations within three commercial vineyards and the nearby natural habitats in a Mediterranean landscape in northern Israel. We sampled spiders by means of pitfall traps in early and in late summer. Both the time in the season and the habitat (natural versus vineyard) affected spider species richness and diversity. More species were found in early summer (47) than in late summer (33), and more occurred in the natural habitat (34 species) than in the vineyards (27-31 species). Fifteen species were found exclusively in the natural habitat, and only 11 species were shared by the vineyards and natural habitat, four of which were the most abundant and geographically widely distributed species in the samples. In late summer, spider diversity in the natural habitat was higher than within the vineyards: the spider assemblages in the vineyards became dominated by a few species late in the crop season, while those of the natural habitat remained stable. Overall, the natural habitat differed in assemblage composition from all within-vineyard locations, while the three locations within the vineyard did not differ significantly in assemblage composition. Season (early vs. late summer), however, significantly affected the spider assemblage composition. This study documents the large diversity of spiders in a local Mediterranean vineyard agroecosystem. Over 60% of the known spider families in the region occurred in our samples, highlighting the importance of this agroecosystem for spider diversity and the potential for conservation biocontrol, where natural habitats may be a source of natural enemies for nearby vineyards.

Plantation clear‐fell patches benefit heathland arthropods

Abstract Plantation forests constitute a significant amount of the wooded area in many parts of the globe. However, the extent of biological provision conferred by plantation forest depends on regional conservation priorities and biogeographical context. Here, we evaluate the arthropod biodiversity in a chronosequence of pine plantation (clear‐felled, 1, 3, 5, 7, 9, 13, 21‐years) in the largest lowland conifer forest in the UK. We compare the assemblage within 37 plantation stands and eight important open habitat remnants in a formerly heathland dominated region. We also assess the configuration and potential isolation of ephemeral open early growth stage habitat across a 60‐year plantation rotation. Carabid and spider assemblages changed throughout the sampled chronosequence. In the early growth stages (1–7 years) before canopy closure, arthropod assemblages contained many individuals and species associated with dry‐open habitats, greater numbers of rare species than closed canopy plantation and had similar composition (non‐metric multidimensional scaling) to heathland samples. Early growth stages and heathlands primarily differed in the additional presence of generalist species in the plantation. Species associated with woodland increased in abundance as the plantation aged, but remained far less numerous than dry‐open or generalist species. The spatial distribution of young growth stages across the rotation cycle was significantly clustered in the early and late rotation phases. Plantation landscapes often support high species richness but we highlight their value for vulnerable heathland biodiversity early in the rotation cycle. To increase plantation value regional conservation priorities should be supported with appropriate consideration of growth stage configuration across the full rotation.

On epigeic spider assemblages (Arachnida: Aranei) of oak forests in the Leopard Land National Park and the Kedrovaya Pad’ Reserve, Maritime Territory, the Russian Far East

On epigeic spider assemblages (Arachnida: Aranei) of oak forests in the Leopard Land National Park and the Kedrovaya Pad’ Reserve, Maritime Territory, the Russian Far East

Opening the canopy to restore spider biodiversity in protected oakwoods

A mosaic of patches in various successional stages is key to maintaining high biodiversity in open temperate woodlands. The abandonment of traditional management, such as once widespread coppicing, has caused biodiversity loss and a shift to ecologically homogeneous communities. Invertebrates are one of the taxonomic groups that suffered the most from the lack of a regular disturbance regime. Despite the obvious importance of active management in maintaining high biodiversity in open temperate woodlands, our knowledge on its contribution to spider conservation is still poor. We investigated how the coppicing restoration affects the diversity of ground-dwelling spiders in the oakwoods of Podyjí National Park in the Czech Republic. We sampled the spider assemblages using pitfall traps within 10 plots in three successional stages: initial, advanced, and late successional stage (control). We collected a total of 9 919 individuals belonging to 143 spider species. The species richness was positively influenced by restoration and reached the highest values in the advanced successional stage. Each successional stage hosted distinct spider assemblages. The trait diversity (RaoQ) was very low in the late successional stage, primarily accommodating small spider species with a preference for shaded and humid habitats. On the other hand, canopy thinning supported high trait diversity of light-demanding and threatened species. Our results showed that the restoration of traditional coppicing could be an appropriate tool for maintaining biodiversity of ground-dwelling spiders in open oakwoods.

Impact of No-Tillage on Soil Invertebrate Communities in the Southern Forest Steppe of West Siberia: Preliminary Research

The aim of our study is to assess changes in soil macroinvertebrate biodiversity when conventional tillage (CT) is replaced by no-tillage (NT) in agroecosystems of the southern part of the West Siberian forest steppe. The research was conducted in the Novosibirsk region at the end of May 2017, May 2018, and in June 2018. The agricultural plots with CT and NT were located close to each other on identical soils, at a distance of about 200 m from the nearest forest shelterbelts. NT technology has been applied on the experimental plot since 2007. Sampling of invertebrates was conducted in two ways, namely soil sampling and pitfall trapping. The majority of basic physicochemical properties of soil were the same or similar between the CT and NT plots. However, depending on the type of tillage, different soil invertebrate communities had already developed in the control (CT) and experimental (NT) plots during this time. The community of the CT plot includes a large number of flying predatory Carabidae species typical of early successional stages (such as Bembidion properans and B. quadrimaculatum, Poecilus spp.) and phytophages, i.e., larvae of Elateridae. The NT plot has significantly higher density and species richness of earthworms (Eisenia nordenskioldi and synanthropic E. fetida in the NT plot versus one individual of E. nordenskioldi in the CT plot). The NT plot has a significantly richer and more abundant assemblage of spiders (especially in spring) and a poor assemblage of insect predators (except for the superdominant ground beetle Poecilus cupreus and the subdominant P. versicolor in summer 2018). Large numbers of larvae of some carabids (e.g., Amara consularis) were found in the NT soil, suggesting that they complete a full life cycle in this habitat.