Synanthropic spiders’ diversity (Arachnida, Araneae) in the urban zone of Morelia citiy, Michoacan, Mexico. How much does the time of construction of the houses influence?

Spiders have been used to evaluate changes in systems by anthropization effect, some species showing sensitivity to gradual and drastic changes such as urbanization, and other species have been documented as tolerant to this effect. The goal of this work was to describe the change in the spider community in relation to the age of buildings. at the west of Morelia, Michoacán, Mexico. Three categories of construction time and the neighboring vegetation as the pre-urbanization environment were used for comparison. Using direct capture, pit-fall traps and beating nets, 3,619 spiders were collected, and 3,219 (315 males, 630 females and 2,274 immatures) were used for the analysis after removal juveniles that was not possible to identify. A total of 28 families, 93 genera, 47 species and 55 morphospecies were identified. This represents the greatest richness and abundance recorded in urban environments of the country. It describes changes in alpha diversity from colonization in recent constructions to those built 17 years ago. I t was observed that abundance, richness, and diversity decrease with the age of a building, but with high equitability in every age of construction. The age of a building is an important factor for the process of succession in urban environments.

Beta Diversity along an Elevational Gradient at the Pico da Neblina (Brazil): Is Spider (Arachnida-Araneae) Community Composition Congruent with the Guayana Region Elevational Zonation?

Beta diversity is usually high along elevational gradients. We studied a spider community at the Pico da Neblina (Brazil), an Amazonian mountain which is one of the southern components of the Guayana region. We sampled six elevations and investigated if beta diversity patterns correspond to the elevational division proposed for the region, between lowlands (up to 500 m), uplands (500 m to 1500 m), and highlands (>1500 m). Patterns of dominance increased with elevation along the gradient, especially at the two highest elevations, indicating that changes in composition may be accompanied by changes in species abundance distribution. Beta diversity recorded was very high, but the pattern observed was not in accordance with the elevationaldivision proposed for the region. While the highlands indeed harbored different fauna, the three lowest elevationshad similar species compositions, indicating that the lowlands spider community extends into the uplands zone. Other measures of compositional change, such as similarity indices and species indicator analysis, also support this pattern. Our results, in addition to a revision of the literature, confirm the high diversity and endemism rates of montane spider communities, and we stress the importance of protecting those environments, especially considering the climate crisis.

Seasonal Dynamics on Spider Population in Pathiramanal Island, Kerala, India: A Case Study

Impact of temperature, rainfall, and humidity varied across different seasons, and the spiders responded differently in each season. Spider community reaches its peak in growing season (October to January). The growing season is recorded as the period with average temperature, rainfall, and relative humidity and which is found to be more suitable for spider population to increase, because highest proportion of spiders is trapped during this season. Ecological factors diminished the spider fauna from February to May (dry season) with high temperature and then gradually decreased through June to September (rainy season) because of heavy rainfall. Correlation analysis of variables with species richness and number of individuals is tested to check the statistical significance between them. Season-wise dendrogram is plotted to show the similarity between the seasons. For the estimation of spider diversity in three different seasons, indices such as Fisher alpha diversity index, Shannon diversity index and Simpson’s diversity index are evaluated.

Spider Community Variability and Response to Restoration in Arid Grasslands of the Pacific Northwest, USA

Grassland restoration in North America has intensified but its impact on major invertebrate groups, including spiders, is unclear. We studied three grassland locations in the Pacific Northwest, USA, to (1) describe variability in spider communities, (2) identify environmental variables that may underlie patterns in spider communities, and (3) determine whether spiders and environmental variables differ between actively (removal of disturbances, then plant with natives) vs. passively restored sites (removal of disturbance only). We found spider richness, diversity, and composition differed among the three locations but abundance did not. Sites with more litter and invasive grass cover had more spiders while sites at higher elevation and with more forb and biological soil crust cover had increased spider richness and diversity. Spider community composition was associated with elevation and litter cover. Surprisingly, no spider community or environmental variables differed between actively and passively restored sites, except that litter cover was higher in passively restored sites. This study demonstrates that even in superficially similar locations, invertebrate communities may differ greatly and these differences may prevent consistent responses to active vs. passive restoration. If increasing biodiversity or the abundance of invertebrate prey are goals, then environmental factors influencing spider communities should be taken into account in restoration planning.

Effect of bench terracing on ground dwelling arthropods

<p>Eucalypt trees are the most planted tree in the world, and in Portugal these plantations occupy 26% of the forested area. The area of Eucalypt monoculture is growing since the 50’s due to the importance of this tree for the pulp and paste industry. With short rotation cycles, it is important to facilitate the cut and transport of the logged trees. In this sense, many forested areas in mountainous regions are being terraced with bulldozers.</p><p>Terracing is a well know soil conservation practice, reducing runoff peak flows, increasing water infiltration and subsequent low soil erosion rates. Nevertheless, the impacts of terracing for eucalypt plantations are still unknown, especially in terms of biodiversity of soil fauna. Hence, to address this research gap, the present study aimed to assess the impacts of terracing on the ground dwelling arthropods in eucalypt plantations.</p><p>This study took place in a mountain slope with old eucalypt trees that were logged (May 2019) and then terraced (July) as ground preparation to receive a new eucalypt plantation. The community of ground dwelling arthropods were accessed using pitfall traps.  The arthropods were collected before the terracing process, in Spring 2019, and then seasonally after terracing until the Spring of 2020Total abundance and richness at order level, as well as, abundance, richness, Shannon-Wiener diversity and Pielou’s Evenness indexes, at Family level of Coleoptera, Araneae and Hymenoptera, were used to depict differences between pre- and post-terracing. The results showed that although terracing did not reduce the total abundance or richness, it changed the community structure. In particular, it was observed an increase in opportunist and generalist families after terracing such as Staphylinidae and Myrmicinae. The spider community also changed, with more hunter families captured after the terrace construction. In overall, the results of our study reveal that although the total abundance and richness of arthropods was not altered by the construction of terraces, their structure was modified.</p>