Illegal sand mining alters the species composition of ants, beetles, and spiders in a grassland: A case study in Eastern Cape, South Africa

Semi-natural habitats such as heathlands, are important for the conservation of biodiversity. Due to a significant decline in traditional management, e.g. burning and grazing, in combination with habitat loss, these ecosystems have become highly threatened. On the other hand, human activities create modern infrastructures, e.g. power-line corridors (PLCs), and they can function as an alternative habitat for species for which their semi-natural habitat has degraded. This study compared the species richness and species composition of carabid beetles and wolf spiders in PLCs, traditionally managed heathlands and former heathlands that are covered with coniferous forests. We also measured vegetation variables and used it to compare species richness of plant, abundances of species and Ellenberg indicator values in the different habitats. The results showed that species richness of carabid beetles in the traditionally managed heathland is significantly higher compared to the PLCs. The species composition of carabid beetles and wolf spiders were also significantly different in these two habitats, but there was no difference between the species composition of carabid beetles and wolf spiders in the PLCs and forests. This might be explained by the similar vegetation structure in the PLCs and the forests, such as the high abundance of trees and shrubs and low abundance of typical heathland plants. Our results showed that PLCs are not an alternative habitat for the carabid beetle and wolf spider heathland specialists. We discussed how the management could be changed in the PLCs in order to make them more valuable for these and other heathland species.

Loss of biodiversity in agroecosystems has negative implications for crop production and the functioning of the ecosystem. As such, agroecologists advocate minimum tillage practices in order to conserve biological diversity. To establish the influence of agricultural practices on biodiversity, we compared the species richness, abundance and composition of beetles, ants, spiders and small groups of ground dwelling arthropods in a veld and three agroecosystems (maize, sugarcane and multispecies pasture) under minimum tillage. Sampling was by pitfall trapping during the summer rainfall season in December 2019. Although ants were the most abundant (47%), followed by beetles (31%); beetles were the most speciose making up 40% of the morphospecies followed by spiders (31%). The veld had significantly greater relative proportion of species richness of spiders (54%) than the three agroecosystems, while significantly low relative proportion of species richness of ants was in the pasture (6%) compared to the veld (63%). Species richness and abundance of beetles were similar across habitat types. The four habitats supported different assemblages of ants, beetles and spiders. The differences in species composition among the habitats support the notion that agricultural practices with minimum soil disturbance enhance conservation of biological diversity, particularly, specialist species.

Illegal sand mining is carried out causing bad environmental problems. There needs to be a solution to solve the problem of illegal sand mining. The purpose of this study is to describe the impact of illegal sand mining in Merauke and the role of local wisdom to prevent illegal mining. This research is descriptive qualitative research. The place of research is Ndalir beach, the beach where sand mining occurs, and also Tomer village as one of the villages affected by illegal sand mining. Data was collected by direct observation and also in-depth interviews with several communities. The data obtained is that illegal sand mining provides benefits to the customary landowners of the sand village and also provides income to the sand miners. The negative impact of illegal mining is that it causes damage to mangrove forests resulting in abrasion, rising seawater to roads and homes, damage to roads and bridges. The solution is to adopt the local wisdom of the Kanum tribe, to prevent illegal sand mining.

Habitat fragmentation in an urban environment: large and small fragments support different arthropod assemblages

Summary Tropical biodiversity is seriously threatened by deforestation but few studies have quantified its impact. We aimed to measure the impact of forest clearance and different methods of establishing Terminalia ivorensis (Combretaceae) forest plantations on the abundance, richness and composition of ants, the most abundant group of arthropods in tropical forest canopies, in the Mblamayo Forest Reserve in Cameroon. For canopy ants, we quantified the effects of different methods of plantation establishment by sampling two sets of plots subjected to complete clearance, partial mechanical clearance and partial manual clearance relative to uncleared forest reference plots. For leaf‐litter ants, we quantified the impacts of different levels of forest disturbance along a gradient from near primary forest to complete forest clearance. A total of 97 ant species was recorded from the canopy (from approximately 48 500 individuals), at an average of 213 (±45) ants m−2. Jack‐knife estimates of species richness showed that at one site, Bilik, 87% more species occurred in the partial manual clearance plot than the complete clearance plot, with the partial mechanical clearance plot intermediate. At the other site, Ebogo, ant richness did not vary between treatments. Ants were 20 times more abundant in the partial manual clearance plot in Ebogo than the partial manual clearance plot in Bilik, largely due to a numerous Technomyrmex species that might have reduced ant richness on this plot. Cluster analysis of the similarities in ant species composition between plots, calculated by the Morisita index, showed that site and treatment affected species composition. Neither treatment nor site affected the relative number of species in different nesting categories. A total of 111 ant species (from 3650 individuals) was recorded from the leaf litter, at an average of 52 (±4·6) ants m−2. Species numbers were greatest in the two partial clearance plots in Ebogo (52–53 species), lowest in the two complete clearance plots (37), and intermediate and most variable in the three uncleared forest plots (40–52). Cluster analysis showed that species composition was not affected by treatment, while neither treatment nor site affected the relative number of ant species in different feeding categories. Despite some local effects by dominant species, our results support the view that deforestation can reduce arthropod species richness. This study is unique in showing that reforestation methods (using a single tree species) can have a marked effect on arthropod species richness and composition. Specifically, it reveals that ant species richness can be greater in plantations established after partial manual clearance than complete clearance.

Insect-resistant genetically modified (GM) plants have been cultivated in several countries on a large scale. These plants express the Cry toxins from the bacterium Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) (Bt), which confers target-pest resistance to plants. Studies on the effects of GM plants on nontarget organisms are important to assess the technology's impact on biodiversity. The objective of this study was to determine whether there are differences in the species richness and composition of ants and ground beetles in Bt maize (four different toxins: Cry1Ab, Cry1F, and Cry1A.105/Cry2Ab2) and conventional isoline (non-Bt) fields, in the first (summer) and second (winter) cropping seasons in 13 localities of Mato Grosso do Sul State, Brazil, over a 2-yr period (2009-2011). The assessment of Coleoptera and Formicidae species was performed using pitfall traps placed in fields throughout the period of vegetative growth and maturation of plants. Data were analyzed using faunistic indices of species richness, ordination by nonmetric multidimensional scaling, and multivariate analysis of variance. No statistically significant difference was found in the species richness of ant and ground beetle communities when comparing sites of Bt with those of non-Bt maize. Overall, Bt technology did not affect the composition of ant and ground beetles; however, municipality and cropping season exerted influence on the beetle composition. Some species were only observed in the first crop, whereas others were only observed in the second crop. This research suggests that Bt maize does not affect ant and ground beetle populations differently from its isoline.

Illegal sand mining has been identified as a significant cause of harm to riverbanks, as it leads to excessive removal of sand from rivers and negatively impacts river shorelines. This investigation aimed to identify instances of shoreline erosion and accretion at illegal sand mining sites along the Chambal River. These sites were selected based on a report submitted by the Director of the National Chambal Sanctuary (NCS) to the National Green Tribunal (NGT) of India. The digital shoreline analysis system (DSAS v5.1) was used during the elapsed period from 1990 to 2020. Three statistical parameters used in DSAS—the shoreline change envelope (SCE), endpoint rate (EPR), and net shoreline movement (NSM)—quantify the rates of shoreline changes in the form of erosion and accretion patterns. To carry out this study, Landsat imagery data (T.M., ETM+, and OLI) and Sentinel-2A/MSI from 1990 to 2020 were used to analyze river shoreline erosion and accretion. The normalized difference water index (NDWI) and modified normalized difference water index (MNDWI) were used to detect riverbanks in satellite images. The investigation results indicated that erosion was observed at all illegal mining sites, with the highest erosion rate of 1.26 m/year at the Sewarpali site. On the other hand, the highest accretion was identified at the Chandilpura site, with a rate of 0.63 m/year. We observed significant changes in river shorelines at illegal mining and unmined sites. Erosion and accretion at unmined sites are recorded at −0.18 m/year and 0.19 m/year, respectively, which are minor compared to mining sites. This study’s findings on the effects of illegal sand mining on river shorelines will be helpful in the sustainable management and conservation of river ecosystems. These results can also help to develop and implement river sand mining policies that protect river ecosystems from the long-term effects of illegal sand mining.

Abstract: Soil characteristics, disturbance histories, and species richness among distinct groups of plants and animals may be useful predictors of important conservation areas when data are limited. We used multivariate analysis of covariance to test the hypothesis that the species richness of plants, arthropods, herpetofauna, and breeding birds are correlated and increase with soil fertility (silt and clay content in sandy soils), soil variability, and hardwood midstory reduction in subxeric, nutrient‐poor longleaf pine sandhills at Eglin Air Force Base in northwest Florida. During 1994–1995 and 1998–1999, we sampled 30 81‐ha plots with varying fire‐exclusion histories and at two spatial scales of resolution (10 × 40 m and 81 ha). The relationship between the number of plant species and percent silt and clay and its coefficient of variation was significant and positive at the plot level (81 ha) but not at the subplot level (10 × 40 m). Herpetofaunal species richness was the only faunal variable that increased with silt and clay content, but the coefficient of variation did not. Multivariate effects of hardwood reduction were significant in 1998–1999 but not in 1994–1995, which suggests that the reintroduction of fire increased species richness across taxa. Univariate effects of hardwood reduction were marginally significant for plant species richness at the subplot level and not significant for herpetofaunal species richness at either scale. Plant and arthropod species richness were not correlated. Herpetofaunal species richness was not correlated with that of other taxa (plant and animal). The species richness of plants and arthropods were each significantly positively correlated with the richness of breeding bird species at the subplot level during 1994–1995, whereas only arthropod species richness was positively correlated with bird species richness at the plot level in either year. Our results suggest that the restoration of fire regime may be the most effective tool with which to increase diversity in pyrogenic areas considered for conservation protection.

Accurately assessing the natural variation in biodiversity is crucial as a baseline for monitoring trends and attributing them to natural or anthropogenic drivers. To assess this baseline, we estimated the species richness, composition and abundance of plants, beetles and ants in Evolution Canyon II (Israel), a protected reserve in the Eastern Mediterranean that is known both for its heterogeneity and for faster-than-average climate change. Consecutive sampling over 24 months in three divergent microhabitats of the canyon (south xeric- and north mesic-facing slopes and the valley bottom) during 2019–2021 was conducted using the same methods employed at the same site during 1998–2000, enabling us to also study seasonal and inter-annual variation. Altogether, 459 beetle species, 349 plant species and 47 ant species were found. These taxa exhibit substantial and persistent divergence between canyon slopes. Despite substantial species turnover rates between periods in all the taxa, almost no change was found regarding the biogeographical origins of plant and beetle species composition. In addition, species richness differences between microhabitats persisted between study periods, and year-round sampling revealed many dominant winter-peaking beetle species. These findings reflect the importance of thoroughly surveying diverse taxa, microhabitats, seasons and annual weather patterns when characterizing the natural baseline of a monitoring program.

Disturbance in dry coastal dunes in Denmark promotes diversity of plants and arthropods

Different response patterns of epigaeic spiders and carabid beetles to varying environmental conditions in fields and semi-natural habitats of an intensively cultivated agricultural landscape

Illegal sand mining in Cau River of Vietnam is common and indiscriminate due to the huge demand of river sand for industrial zone ground filling and the construction industry in the region. The number of illegal sand mining dredges as well as extracted sand volume has soared year after year and caused serious consequences. Although the local authorities have made efforts in controlling illegal sand mining in Cau River, this activity generally has continued to proliferate. The results of the study show that inadequate legal framework, unclear responsibilities among stakeholders, limited resources for management, and weak coordination among local authorities are the main constraints of illegal sand mining management. Improving the legal framework for sand mining, establishing surveillance teams at the commune level, enhancing coordination among local authorities, wider dissemination on the external effect of sand mining were drawn as feasible measures to improve sand mining management in Cau River.

Artisanal and Small-scale river sand mining is one of the upcoming activities associated with the environmental crisis concerning the water ecosystem. However, the determination of the duration in which illegal sand mining has occurred, and the future prediction on the extent of river sand mining is not well-established in most of the world. This study aimed to assess the extent of river sand mining activities across some of the catchments in Limpopo province, South Africa and understand the sustainable extraction of sand resources. This was followed by the determination of when sand mining activities commenced in each of the individual catchments. Thus, remote sensing was applied to predict the extent of river sand mining from the year 1992 to 2022, and statistical prediction models were utilised to predict the extent of sand mining for the next 10 years. The results of the study suggest that most of the catchments started to experience illegal sand mining activities from the year 1992, though the extraction was relatively low. Equally, a decrease in vegetation coverage across the river system has been evidenced, which also suggests that the extraction of sand and gravel has been elevated from the year 2010. In terms of the prediction model, the Turfloop River system was predicted to experience a large extraction ratio in the coming 10 years, with about 92.415 ha of land expected to be affected. Meanwhile, the Molototsi River system was denoted to be the least affected river system, with a reduced extraction ratio of about 6.57 ha expected in the next 10 years’ time.

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.

Cross-taxon congruence in insect responses to fragmentation of Brazilian Atlantic forest