The response of carabids to landscape simplification differs between trophic groups

We studied the response of carabid species richness and density to landscape simplification (measured as percentage cover of non-crop habitat surrounding each study site) in 36 wheat fields using pitfall traps. Carabids were divided to trophic groups following the literature. The number of species from different trophic groups declined with increasing landscape simplification in the order: carnivores > phytophages > omnivores. Density compensation of both carnivores and phytophages suggests that species decline is caused by the loss of specific resources rather than by an overall reduction in food availability. Increasing evenness indicates that a greater share of phytophagous species contributes to density compensation at poorer sites. A comparison with data from complementing studies shows that marked differences in species numbers (carnivores > omnivores > phytophages) are due to a different sensitivity of trophic groups to agricultural management. Since our findings seem to be partly due to increasing sensitivity to landscape changes with trophic rank, and partly to decreasing sensitivity of depauperate communities to local environmental stress, species loss can best be explained by the co-action of factors at local and regional scales. Species richness decline might significantly alter the role of carabids as biocontrol agents.     

Ground beetle species (Carabidae,Coleoptera) activity and richness in relation to crop type,fertility management and crop protection in a farm management comparison trial

Ground beetle activity and species richness was monitored using pitfall traps in a plot trial system on a farm in northern England where the effects of organic and conventional fertility and crop protection management were separated within different crop types between 2005 and 2008. As well as analyses on species activity the beetles were split into small, medium‐sized and large groups, and into groups of herbivores and specific Collembola feeders. Crop type had significant effects on the activity of the 20 most abundant species and all groups, generally with most in beans and winter barley and least in vegetables and spring barley. Most significant reactions to crop protection and fertility management were in cereals and grass/clover. Activity of small species was highest in conventionally crop‐protected cereals but not in vegetables, with more medium‐sized and herbivorous species in organic plots, but there was little influence of crop protection management on large and Collembola feeding species. However, large species were significantly more active in organically fertilised cereals and grass/clover, but not in vegetables, and there were more Collembola feeders in conventional cereals but not in grass/clover. Small species were more abundant in conventionally fertilised grass/clover but there were more in organic cereals and vegetables. These inconsistent activity reactions to management were also observed with individual species but most preferred organically managed plots. There were few significant crop protection : fertility management interactions. Species richness was also significantly affected by crop type and where management had an influence, more species were found in organically managed plots. Constrained ordination emphasised that ground beetle activity was influenced more by crops than by management. Given the diverse nature of organic crop rotations, crop type should be considered a major influence in any environmental manipulation aimed at increasing ground beetle activity for provision of ecosystem services.     

The ground beetle fauna (Coleoptera:Carabidae) of abandoned fields, as related to plant cover, previous management and succession stage

This study describes differences in species richness, diversity and composition of Carabidae in gradients from recently abandoned, non-grazed fields over stages of overgrowth into forest on formerly agricultural land in a large, sandy outwash plain, south Sweden. Totally 80 pitfall traps, (4 succession stages, each represented by 4 sites; 5 traps per site) installed on 29 March 2006 were emptied continuously until 1 November. Succession stages were: 7–10 y old fallows after cereals with thin and low vegetation of small perennial and annual herbs (Ia), 7–10 y old fallows abandoned as lay with a rich plant cover of broad-leaved grasses and herbs (Ib), 20–25 y old fallows with a shrub layer of colonising pine and narrow-leaved grasses (II), and ca 80 y old pine stands planted on originally cultivated ground with a rich shrub layer but lacking herbaceous plants (III). A total of 14,068 individuals of 71 carabid species were captured. Species richness was highest in stage Ib, whereas Shannon species diversity was highest in Ia. Both species richness and diversity were lowest in III, sites II being intermediate. Total number of individuals captured site⁻¹ was low in III, being highest in Ib. Mean body weight and total dry mass of species, however, increased with succession stage. Amara and Harpalus species were most common in Ia but important also in Ib, with large differences in species composition between the two stages. These genera were almost lacking in III, where Carabus spp. and Pterostichus niger dominated. The share of Calathus was highest in II, where C. fuscipes played a dominating role. P. versicolor dominated in Ib, whereas P. lepidus was quite common in all non-forest stages. Duration and intensity of capturing activity necessary to find most species of the sites are discussed. Many scarce or rare species in south Scandinavia were captured, mainly in Ib. Abandoned non-grazed fields are important hibernating and breeding refuges for many carabids. Using extensive and non-expensive management this ought to be considered as an additional alternative in environment conservation policy, which now usually recommends economically subsidised grazing on set-aside land.     

The measurement of marine species diversity, with an application to the benthic fauna of the Norwegian continental shelf

Species diversity includes two aspects, the number of species (species richness) and the proportional abundances of the species (heterogeneity diversity). Species richness and heterogeneity diversity can be measured over different scales; a single point, samples, large scales, biogeographical provinces and in assemblages and habitats. In the literature, the terminology of these scales is confused. Here, scales are given a uniform notation. Scales of species richness and heterogeneity diversity are distinguished from turnover (beta) diversity, which is the degree of change in species composition along a gradient. Methods of measurement of the scales of species richness, heterogeneity diversity, turnover diversity and for estimating total species richness are reviewed. Two methods for measuring heterogeneity diversity are recommended Exp H′ (where H′ is the Shannon-Wiener index) and 1/Simpson’s index, together with an equitability index J′. The reviewed methods are then applied to a data set from the Norwegian continental shelf to illustrate the advantages of the recommended methods. Finally, the application of the methods to assessment of effects of disturbance, to studies of gradients of species richness and to conservation issues are discussed.     

Response of wild bee diversity,abundance, and functional traits to vineyard inter‐row management intensity and landscape diversity across Europe

Agricultural intensification is a major driver of wild bee decline. Vineyards may be inhabited by plant and animal species, especially when the inter‐row space is vegetated with spontaneous vegetation or cover crops. Wild bees depend on floral resources and suitable nesting sites which may be found in vineyard inter‐rows or in viticultural landscapes. Inter‐row vegetation is managed by mulching, tillage, and/or herbicide application and results in habitat degradation when applied intensively. Here, we hypothesize that lower vegetation management intensities, higher floral resources, and landscape diversity affect wild bee diversity and abundance dependent on their functional traits. We sampled wild bees semi‐quantitatively in 63 vineyards representing different vegetation management intensities across Europe in 2016. A proxy for floral resource availability was based on visual flower cover estimations. Management intensity was assessed by vegetation cover (%) twice a year per vineyard. The Shannon Landscape Diversity Index was used as a proxy for landscape diversity within a 750 m radius around each vineyard center point. Wild bee communities were clustered by country. At the country level, between 20 and 64 wild bee species were identified. Increased floral resource availability and extensive vegetation management both affected wild bee diversity and abundance in vineyards strongly positively. Increased landscape diversity had a small positive effect on wild bee diversity but compensated for the negative effect of low floral resource availability by increasing eusocial bee abundance. We conclude that wild bee diversity and abundance in vineyards is efficiently promoted by increasing floral resources and reducing vegetation management frequency. High landscape diversity further compensates for low floral resources in vineyards and increases pollinating insect abundance in viticulture landscapes.