Assessing the effect of the time since transition to organic farming on plants and butterflies

1.Environmental changes may not always result in rapid changes in species distributions, abundances or diversity. In order to estimate the effects of, for example, land-use changes caused by agri-environment schemes (AES) on biodiversity and ecosystem services, information on the time-lag between the application of the scheme and the responses of organisms is essential

Early changes in Orthopteran assemblages after grassland restoration : a comparison of space-for-time substitution versus repeated-measures monitoring

Grasslands harbour significant biodiversity and their restoration is a common intervention in biodiversity conservation. However, we know very little on how grassland restoration influences arthropod groups. Here we compared orthopteran assemblages in croplands, natural grasslands and one to four-year-old grasslands restored in a large-scale restoration on former croplands in Hortobágy National Park (E-Hungary). Sampling was done by standardized sweep-netting both in a repeated measures design and space-for-time substitution (chronosequence) design. General linear models with repeated measures from five years showed that species richness, abundance and Shannon diversity of orthopterans decreased in the year following restoration but increased afterwards. By the fourth year, species richness almost doubled and abundance increased almost ten-fold in restored grasslands compared to croplands. Multivariate analyses showed that species composition in the first two years did not progress much but by the third and fourth year there was partial overlap with natural grasslands. Local restoration conditions (last crop, seed mixture) and landscape configuration (proportion of natural grasslands < 1 km away) did not influence the above patterns in either the repeated measures or the chronosequence design, whereas time since restoration affected almost all community variables. Our results suggest that generalist ubiquitous species appeared in restored grasslands first and the more sensitive species colonized the restored fields gradually in later years. The qualitative and quantitative properties of the orthopteran assemblages in restored fields did not yet reach those of natural grasslands, therefore, our study suggests that the full regeneration of the orthopteran assemblages takes more than four years

Decreased Functional Diversity and Biological Pest Control in Conventional Compared to Organic Crop Fields

Organic farming is one of the most successful agri-environmental schemes, as humans benefit from high quality food, farmers from higher prices for their products and it often successfully protects biodiversity. However there is little knowledge if organic farming also increases ecosystem services like pest control. We assessed 30 triticale fields (15 organic vs. 15 conventional) and recorded vascular plants, pollinators, aphids and their predators. Further, five conventional fields which were treated with insecticides were compared with 10 non-treated conventional fields. Organic fields had five times higher plant species richness and about twenty times higher pollinator species richness compared to conventional fields. Abundance of pollinators was even more than one-hundred times higher on organic fields. In contrast, the abundance of cereal aphids was five times lower in organic fields, while predator abundances were three times higher and predator-prey ratios twenty times higher in organic fields, indicating a significantly higher potential for biological pest control in organic fields. Insecticide treatment in conventional fields had only a short-term effect on aphid densities while later in the season aphid abundances were even higher and predator abundances lower in treated compared to untreated conventional fields. Our data indicate that insecticide treatment kept aphid predators at low abundances throughout the season, thereby significantly reducing top-down control of aphid populations. Plant and pollinator species richness as well as predator abundances and predator-prey ratios were higher at field edges compared to field centres, highlighting the importance of field edges for ecosystem services. In conclusion organic farming increases biodiversity, including important functional groups like plants, pollinators and predators which enhance natural pest control. Preventative insecticide application in conventional fields has only short-term effects on aphid densities but long-term negative effects on biological pest control. Therefore conventional farmers should restrict insecticide applications to situations where thresholds for pest densities are reached

Effects of plant diversity, habitat and agricultural landscape structure on the functional diversity of carabid assemblages in the North China Plain

1. This study investigated the effects of plant diversity, habitat type and landscape structure on the functional diversity of the carabid assemblages in the agro-landscape of the North China Plain. We hypothesize (i) small, herbivorous and omnivorous carabids are more strongly affected by local plant diversity, while large and predatory carabids are strongly affected by landscape structure, and (ii) habitat type influences the diversity across functional groups. 2. In 2010, carabid beetles were sampled by pitfall traps in 6 typical habitats of the agro-landscape: wheat/maize fields, peanut fields, orchards, field margins, windbreaks and woodland. 3. Our results showed that (i) habitat type played a predominant role in driving the changes in the diversity of carabid assemblages, followed by local plant diversity while the landscape structure had little effect; (ii) small and omnivorous carabid were strongly affected by local plant diversity, while the composition of large and predatory carabid was strongly associated with the landscape structure; and (iii) habitats dominated by woody species harbored different assemblages to habitats dominated by herbaceous plants for overall carabids and three functional groups excluding omnivorous beetles. 4. Informed by our results, we suggest the differentiated responses between functional groups should be appreciated in conservation management. In the intensively managed agro-landscape, maintenance of diverse habitats and creating a more complex vegetation structure would be the most efficient measures to enhance the diversity of carabid assemblages. Particularly, the maintenance of extensively managed habitats coupled with a targeted increase in the local plant diversity is crucial to optimize the biological pest-control by carabid assemblages

Forty years of carabid beetle research in Europe - from taxonomy, biology, ecology and population studies to bioindication, habitat assessment and conservation

Volume: 100Start Page: 55End Page: 14

Species traits explaining sensitivity of snakes to human land use estimated from citizen science data

Understanding how traits affect species responses to threats like habitat loss may help prevent extinctions. This may be especially true for understudied taxa for which we have little data to identify declines before it is too late to intervene. We used a metric derived from citizen science data on snake occurrences to determine which traits were most correlated with species' sensitivity to human land use. We found that snake species that feed primarily on vertebrates, that use a high proportion of aquatic habitats, and that have small geographic ranges occurred in more natural and less human-dominated landscapes. In contrast, body size, clutch (or litter) size, the degree of exposure to human-dominated landscapes, reproductive mode, habitat specialization, and whether a species was venomous or not had less effect on their sensitivity to human land use. Our results extend previous findings that higher trophic position is correlated with extinction risk in many vertebrates by showing that snake species that feed primarily on vertebrates are more sensitive to human land use – a primary driver of extinction. It is likely that conversion of natural landscapes for human land use alters biotic communities, causing losses of important trophic groups, especially in aquatic and riparian communities. Practitioners should therefore prioritize preserving aquatic habitat and natural landscapes with intact biotic communities that can support species at higher trophic levels, as well as focus monitoring on populations of range-restricted species

Managing aflatoxin in smallholder groundnut production in Southern Africa: Paired comparison of the windrow and Mandela cock techniques

Timely drying of groundnuts is important after harvest. In most parts of sub-Saharan Africa, moisture content reduction is practically achieved by solar drying. In particular, the groundnuts are traditionally cured in the field using the inverted windrow drying technique. Recently, the Mandela cock technique, a ventilated stack of groundnut plants with a chimney at the center, has been introduced in the southern Africa region with the aim of reducing moisture content and the risk of aflatoxin contamination. An on-farm study was conducted in Malawi to compare the effectiveness of the Mandela cock and Windrow drying techniques with respect to aflatoxin control. For two consecutive years, farmers (2016, n = 29; 2017; n = 26) were recruited to test each of the two drying techniques. A mixed-design ANOVA showed that the Mandela cock groundnut drying technique led to sig- nificantly (p < 0.001) higher aflatoxin levels in groundnut seed compared to the traditional inverted windrow drying (5.7 μg/kg, geometric mean vs 2.5 μg/kg in 2016 and 37.6 μg/kg vs 8.4 μg/kg in 2017). The present findings clearly demonstrate the need for regulation and technology validation if farmers and consumers are to benefit