Contrasting diversity patterns of epigeic arthropods between grasslands of high and low agronomic potential

Local and landscape environmental heterogeneity drive ant community structure in temperate seminatural upland grasslands

Environmental heterogeneity is an important driver of ecological communities. Here, we assessed the effects of local and landscape spatial environmental heterogeneity on ant community structure in temperate seminatural upland grasslands of Central Germany. We surveyed 33 grassland sites representing a gradient in elevation and landscape composition. Local environmental heterogeneity was measured in terms of variability of temperature and moisture within and between grasslands sites. Grassland management type (pasture vs. meadows) was additionally included as a local environmental heterogeneity measure. The complexity of habitat types in the surroundings of grassland sites was used as a measure of landscape environmental heterogeneity. As descriptors of ant community structure, we considered species composition in terms of nest density, community evenness, and functional response traits. We found that extensively grazed pastures and within-site heterogeneity in soil moisture at local scale, and a high diversity of land cover types at the landscape scale affected ant species composition by promoting higher nest densities of some species. Ant community evenness was high in wetter grasslands with low within-site variability in soil moisture and surrounded by a less diverse landscape. Fourth-corner models revealed that ant community structure response to environmental heterogeneity was mediated mainly by worker size, colony size, and life history traits related with colony reproduction and foundation. We discuss how within-site local variability in soil moisture and low-intensity grazing promote ant species densities and highlight the role of habitat temperature and humidity affecting community evenness. We hypothesize that a higher diversity of land cover types in a forest-dominated landscape buffers less favorable environmental conditions for ant species establishment and dispersal between grasslands. We conclude that spatial environmental heterogeneity at local and landscape scale plays an important role as deterministic force in filtering ant species and, along with neutral processes (e.g., stochastic colonization), in shaping ant community structure in temperate seminatural upland grasslands.

Agricultural Land Use Determines the Trait Composition of Ground Beetle Communities

In order to improve biological control of agricultural pests, it is fundamental to understand which factors influence the composition of natural enemies in agricultural landscapes. In this study, we aimed to understand how agricultural land use affects a number of different traits in ground beetle communities to better predict potential consequences of land-use change for ecosystem functioning. We studied ground beetles in fields with different agricultural land use ranging from frequently managed sugar beet fields, winter wheat fields to less intensively managed grasslands. The ground beetles were collected in emergence tents that catch individuals overwintering locally in different life stages and with pitfall traps that catch individuals that could have a local origin or may have dispersed into the field. Community weighted mean values for ground beetle traits such as body size, flight ability and feeding preference were estimated for each land-use type and sampling method. In fields with high land-use intensity the average body length of emerging ground beetle communities was lower than in the grasslands while the average body length of actively moving communities did not differ between the land-use types. The proportion of ground beetles with good flight ability or a carnivorous diet was higher in the crop fields as compared to the grasslands. Our study highlights that increasing management intensity reduces the average body size of emerging ground beetles and the proportion of mixed feeders. Our results also suggest that the dispersal ability of ground beetles enables them to compensate for local management intensities.

The role of network bridging organisations in compensation payments for agri-environmental services under the EU Common Agricultural Policy

Compensation payments to farmers for the provision of agri-environmental services are a well-established policy scheme under the EU Common Agricultural Policy. However, in spite of the success in most EU countries in the uptake of the programme by farmers, the impact of the scheme on the long term commitment of farmers to change their practices remains poorly documented. To explore this issue, this paper presents the results of structured field interviews and a quantitative survey in the Walloon Region of Belgium. The main finding of this study is that farmers who have periodic contacts with network bridging organisations that foster cooperation and social learning in the agri-environmental landscapes show a higher commitment to change. This effect is observed both for farmers with high and low concern for biodiversity depletion. Support for network bridging organisations is foreseen under the EU Leader programme and the EU regulation 1306/2013, which could open-up interesting opportunities for enhancing the effectiveness of the current payment scheme for agri-environmental services.

Intensive agriculture reduces soil biodiversity across Europe

Soil biodiversity plays a key role in regulating the processes that underpin the delivery of ecosystem goods and services in terrestrial ecosystems. Agricultural intensification is known to change the diversity of individual groups of soil biota, but less is known about how intensification affects biodiversity of the soil food web as a whole, and whether or not these effects may be generalized across regions. We examined biodiversity in soil food webs from grasslands, extensive, and intensive rotations in four agricultural regions across Europe: in Sweden, the UK, the Czech Republic and Greece. Effects of land-use intensity were quantified based on structure and diversity among functional groups in the soil food web, as well as on community-weighted mean body mass of soil fauna. We also elucidate land-use intensity effects on diversity of taxonomic units within taxonomic groups of soil fauna. We found that between regions soil food web diversity measures were variable, but that increasing land-use intensity caused highly consistent responses. In particular, land-use intensification reduced the complexity in the soil food webs, as well as the community-weighted mean body mass of soil fauna. In all regions across Europe, species richness of earthworms, Collembolans, and oribatid mites was negatively affected by increased land-use intensity. The taxonomic distinctness, which is a measure of taxonomic relatedness of species in a community that is independent of species richness, was also reduced by land-use intensification. We conclude that intensive agriculture reduces soil biodiversity, making soil food webs less diverse and composed of smaller bodied organisms. Land-use intensification results in fewer functional groups of soil biota with fewer and taxonomically more closely related species. We discuss how these changes in soil biodiversity due to land-use intensification may threaten the functioning of soil in agricultural production systems.

Effects of persistent insecticides on beneficial soil arthropod in conventional fields compared to organic fields, puducherry

The usage of synthetic fertilizers/insecticides in conventional farming has dramatically increased over the past decades. The aim of the study was to compare the effects of bio-pesticides and insecticides/pesticides on selected beneficial non targeted arthropods. Orders Collembola, Arachinida/Opiliones, Oribatida and Coleoptera were the main groups of arthropods found in the organic fields and Coleoptera, Oribatida, Gamasida and Collembola in conventional fields. Pesticides/insecticides had a significant effect on non-targeted arthropods order- Collembola, Arachinida/Opiliones, Hymenoptera and Thysonoptera were suppressed after pesticides/insecticides spraying. Bio-insecticides in organic fields had a non-significant effect on non targeted species and they started to increase in abundance after 7 days of spraying, whereas insecticide treatment in conventional fields had a significant long-term effect on non targeted arthropods and short term effect on pests/insects, it started to increase after 21 days of the spraying. These results indicate that insecticide treatment kept non targeted arthropods at low abundance. In conclusion, organic farming does not significantly affected the beneficial-non targeted arthropods biodiversity, whereas preventive insecticide application in conventional fields had significant negative effects on beneficial non targeted arthropods. Therefore, conventional farmers should restrict insecticide applications, unless pest densities reach the thresholds and more desirably can switch to organic farming practices.

Studies on agri-environmental measures: a survey of the literature

Agri-environmental measures (AEM) are incentive-based instruments in the European Union (EU) that provide payments to farmers for voluntary environmental commitments related to preserving and enhancing the environment and maintaining the cultural landscape. We review the AEM literature and provide an overview of important research topics, major research results and future challenges as discussed in the available literature concerning these measures. This review contributes to the existing literature by attempting to equally consider ecological and economic perspectives. The reviewed articles are analyzed regarding their regional focus, topics and methods. The analytical section of the article seeks to discuss commonly asked questions about AEM on the basis of results from reviewed studies. The vast amount of available literature provides valuable insights into specific cases and reveals a complex picture with few general conclusions. The existing research is usually either biased toward ecological or economic perspectives and fails to provide a holistic picture of the problems and challenges within agri-environmental programming (e.g., multiple measures, multiple target areas, legal aspects, financial constraints, transaction costs). Most empirical studies provide detailed insights into selected individual measures but are incapable of providing results at a level relevant to decision-making, as they neglect the role of farmers and the available AEM budget. Predominantly economic approaches often only consider rough assumptions of ecological and economic processes and are also not suitable for decision-making. Decision-support tools that build on these disciplinary results and simultaneously consider scheme factors and environmental conditions at high spatial resolution for application by the responsible authorities are rare and require further research.