Neonicotinoids, bees and opportunity costs for conservation

Restrictions on the use of neonicotinoid insecticides in the European Union are widely debated in relation to bee decline, but their potential consequences at the interface between sustainable crop production and conservation are less frequently discussed. This paper raises issues to be considered if we are to achieve a balanced consensus in this contentious area. The common legal framework governing testing and environmental impact for all chemical crop protection products is highlighted, leading to concerns that the current focus on impact of neonicotinoids is diverting attention from other drivers of bee decline to the detriment of a balanced conservation strategy. The evidence for the causal relationship between neonicotinoid use and bee decline is considered and information gaps requiring further work identified. How research into the parallel use of pesticides and beneficial invertebrates in integrated pest management (IPM) can inform the pollinator debate is highlighted. The importance of the neonicotinoids in major IPM systems is illustrated, leading to discussion of potential consequences for conservation of biodiversity and sustainable crop protection if they were lost and we revert to reliance on other pest management options. Increasing agricultural production and conservation are sometimes viewed as being contradictory and the paper concludes by calling for a broadening of the discussion to consider the complimentary objectives of bee conservation and sustainable crop production, so that advances in both fields can hasten consensus on the way forward, rather than perpetuating the current rather polarised debate

Termites mitigate the effects of drought in tropical rainforest

Acknowledgments: This work was supported by the South East Asia Rainforest Research Partnership (SEARRP) with permission from the Maliau Basin Management Committee. We thank G. Reynolds, U. Jami, and L. Kruitbos for coordinating fieldwork; S. Both and U. Kritzler for help in establishing the experimental plots; R. Walsh for providing rainfall data; and A. Zanne and A. Cheesman for discussions on experimental design. We thank J. Nash from Bayer Southeast Asia Pte-Ltd, Singapore, for donating Premise 200SC and Agenda 10SC. We thank J. Rees, A. Tagliabue, M. Begon, R. Williams, W. Cheng, C. Dahlsjö, R. Kitching, and J. Barlow for comments on the manuscript. Finally, we thank all our field assistants: R. Binti Manber, A. Jupri, F. John, Y. Binti Suffian, E. Bin Esing, D. Bin Paul, Z. Bin Angau, A. Allbanah Bin Anchun, N. Angau, D. Ku Shamirah Binti Pg Bakar, E. Binti Nahun, R. Rusili, A. Bin Rantau, R. Bin Sahamin, A. Mastor, M. Adzim Bin Rahili, M. Azuan, H. Nasir, and N. Fazzli. Funding: This publication is a contribution from the UK NERC-funded Biodiversity And Land-use Impacts on Tropical Ecosystem Function (BALI) consortium (NERC grant NE/L000016/1). Author contributions: C.L.P., H.M.G., L.A.A., P.E., and T.A.E. conceived and designed the experiment; C.L.P., P.E., and T.A.E. established the experimental plots; H.M.G., L.A.A., and P.E. collected the data; H.M.G., L.A.A., P.E., and R.K.D. analyzed the data; C.S.V., F.H., and H.S.T. carried out laboratory analysis; H.M.G. and L.A.A. led the writing of the manuscript with significant input from C.L.P., P.E., R.K.D., and Y.A.T. Competing interests: None declared. Data and materials availability: Data have been deposited in the NERC Environmental Information Data Centre (37).Peer reviewedPostprin

An Amazonian rainforest and its fragments as a laboratory of global change

We synthesize findings from one of the world’s largest and longest-running experimental investigations, the Biological Dynamics of Forest Fragments Project (BDFFP). Spanning an area of ~1,000 km2 in central Amazonia, the BDFFP was initially designed to evaluate the effects of fragment area on rainforest biodiversity and ecological processes. However, over its 38-year history to date the project has far transcended its original mission, and now focuses more broadly on landscape dynamics, forest regeneration, regional- and global-change phenomena, and their potential interactions and implications for Amazonian forest conservation. The project has yielded a wealth of insights into the ecological and environmental changes in fragmented forests. For instance, many rainforest species are naturally rare and hence are either missing entirely from many fragments or so sparsely represented as to have little chance of long-term survival. Additionally, edge effects are a prominent driver of fragment dynamics, strongly affecting forest microclimate, tree mortality, carbon storage and a diversity of fauna. Even within our controlled study area, the landscape has been highly dynamic: for example, the matrix of vegetation surrounding fragments has changed markedly over time, succeeding from large cattle pastures or forest clearcuts to secondary regrowth forest. This, in turn, has influenced the dynamics of plant and animal communities and their trajectories of change over time. In general, fauna and flora have responded differently to fragmentation: the most locally extinction-prone animal species are those that have both large area requirements and low tolerance of the modified habitats surrounding fragments, whereas the most vulnerable plants are those that respond poorly to edge effects or chronic forest disturbances, and that rely on vulnerable animals for seed dispersal or pollination. Relative to intact forests, most fragments are hyperdynamic, with unstable or fluctuating populations of species in response to a variety of external vicissitudes. Rare weather events such as droughts, windstorms and floods have had strong impacts on fragments and left lasting legacies of change. Both forest fragments and the intact forests in our study area appear to be influenced by larger-scale environmental drivers operating at regional or global scales. These drivers are apparently increasing forest productivity and have led to concerted, widespread increases in forest dynamics and plant growth, shifts in tree-community composition, and increases in liana (woody vine) abundance. Such large-scale drivers are likely to interact synergistically with habitat fragmentation, exacerbating its effects for some species and ecological phenomena. Hence, the impacts of fragmentation on Amazonian biodiversity and ecosystem processes appear to be a consequence not only of local site features but also of broader changes occurring at landscape, regional and even global scales

Late Quaternary reptile extinctions : size matters, insularity dominates

Aim: A major Late Quaternary vertebrate extinction event affected mostly large‐bodied ‘megafauna’. This is well documented in both mammals and birds, but evidence of a similar trend in reptiles is scant. We assess the relationship between body size and Late Quaternary extinction in reptiles at the global level. Location: Global. Methods: We compile a body size database for all 82 reptile species that are known to have gone extinct during the last 50,000 years and compare them with the sizes of 10,090 extant reptile species (97% of known extant diversity). We assess the body size distributions in the major reptile groups: crocodiles, lizards, snakes and turtles, while testing and correcting for a size bias in the fossil record. We examine geographical biases in extinction by contrasting mainland and insular reptile assemblages, and testing for biases within regions and then globally by using geographically weighted models. Results: Extinct reptiles were larger than extant ones, but there was considerable variation in extinction size biases among groups. Extinct lizards and turtles were large, extinct crocodiles were small and there was no trend in snakes. Lizard lineages vary in the way their extinction is related to size. Extinctions were particularly prevalent on islands, with 73 of the 82 extinct species being island endemics. Four others occurred in Australia. The fossil record is biased towards large‐bodied reptiles, but extinct lizards were larger than extant ones even after we account for this. Main conclusions: Body size played a complex role in the extinction of Late Quaternary reptiles. Larger lizard and turtle species were clearly more affected by extinction mechanisms such as over exploitation and invasive species, resulting in a prevalence of large‐bodied species among extinct taxa. Insularity was by far the strongest correlate of recent reptile extinctions, suggesting that size‐biased extinction mechanisms are amplified in insular environments

Habitat Fragmentation, Variable Edge Effects, and the Landscape-Divergence Hypothesis

Edge effects are major drivers of change in many fragmented landscapes, but are often highly variable in space and time. Here we assess variability in edge effects altering Amazon forest dynamics, plant community composition, invading species, and carbon storage, in the world's largest and longest-running experimental study of habitat fragmentation. Despite detailed knowledge of local landscape conditions, spatial variability in edge effects was only partially foreseeable: relatively predictable effects were caused by the differing proximity of plots to forest edge and varying matrix vegetation, but windstorms generated much random variability. Temporal variability in edge phenomena was also only partially predictable: forest dynamics varied somewhat with fragment age, but also fluctuated markedly over time, evidently because of sporadic droughts and windstorms. Given the acute sensitivity of habitat fragments to local landscape and weather dynamics, we predict that fragments within the same landscape will tend to converge in species composition, whereas those in different landscapes will diverge in composition. This ‘landscape-divergence hypothesis’, if generally valid, will have key implications for biodiversity-conservation strategies and for understanding the dynamics of fragmented ecosystems

Habitat fragmentation causes immediate and time-delayed biodiversity loss at different trophic levels

Intensification or abandonment of agricultural land use has led to a severe decline of semi-natural habitats across Europe. This can cause immediate loss of species but also time-delayed extinctions, known as the extinction debt. In a pan-European study of 147 fragmented grassland remnants, we found differences in the extinction debt of species from different trophic levels. Present-day species richness of long-lived vascular plant specialists was better explained by past than current landscape patterns, indicating an extinction debt. In contrast, short-lived butterfly specialists showed no evidence for an extinction debt at a time scale of c. 40 years. Our results indicate that management strategies maintaining the status quo of fragmented habitats are insufficient, as time-delayed extinctions and associated co-extinctions will lead to further biodiversity loss in the future

Local-scale attributes determine the suitability of woodland creation sites for Diptera

New native woodlands are typically created in a small and isolated configuration, potentially reducing their value as a resource for biodiversity. The use of ecological networks for habitat restoration and creation could be beneficial for woodland biodiversity. This approach is conceptualised as local and landscape-scale conservation actions to increase the area, quality, amount and connectivity of habitat types. However, there is limited evidence about the value of secondary woodlands and the relative or combined effects of network variables for woodland insects.  Seventy-eight woodland sites created in the last 160 years across England and Scotland were sampled for hoverflies (Diptera: Syrphidae) and craneflies (Diptera: Tipuloidea), using two Malaise net traps placed in the centre of each woodland. The diversity of insects supported by created woodland patches was analysed using measures of dissimilarity, and the relative direct and indirect effects of ecological network variables on their abundance and species richness were assessed using structural equation models.  We found 27% of British woodland hoverfly species and 43% of British woodland cranefly species in the study sites, indicating that woodland insects are colonising created native woodlands, despite their fragmented nature. However, these species communities were highly variable across woodland patches.  Landscape-scale variables had no effect on woodland-associated hoverflies or craneflies relative to local-scale variables. Local-scale variables relating to habitat 34 quality (i.e. structural heterogeneity of trees and understory cover) had the strongest influence on abundance and species richness.  Synthesis and applications – To benefit woodland-associated Diptera, woodland creation and restoration should maintain a focus on habitat quality. This should include active management to facilitate a diverse tree and understorey vegetation structure. Many woodlands in the UK are privately owned and landowners should be encouraged to plant and actively manage their woodlands to increase structural heterogeneity and resources for woodland insects

Arthropod distribution in a tropical rainforest: tackling a four dimensional puzzle

Quantifying the spatio-temporal distribution of arthropods in tropical rainforests represents a first step towards scrutinizing the global distribution of biodiversity on Earth. To date moststudies have focused on narrow taxonomic groups or lack a design that allows partitioning of the components of diversity. Here, we consider an exceptionally large dataset (113,952 individuals representing 5,858 species), obtained from the San Lorenzo forest in Panama, where the phylogenetic breadth of arthropod taxa was surveyed using 14 protocols targeting the soil, litter, understory, lower and upper canopy habitats, replicated across seasons in 2003 and 2004. This dataset is used to explore the relative influence of horizontal, vertical and seasonal drivers of arthropod distribution in this forest. We considered arthropod abundance, observed and estimated species richness, additive decomposition of species richness, multiplicative partitioning of species diversity, variation in species composition, species turnover and guild structure as components of diversity. At the scale of our study (2km of distance, 40m in height and 400 days), the effects related to the vertical and seasonal dimensions were most important. Most adult arthropods were collected from the soil/ litter or the upper canopy and species richness was highest in the canopy. We compared the distribution of arthropods and trees within our study system. Effects related to the seasonal dimension were stronger for arthropods than for trees. We conclude that: (1) models of beta diversity developed for tropical trees are unlikely to be applicable to tropical arthropods; (2) it is imperative that estimates of global biodiversity derived from mass collecting of arthropods in tropical rainforests embrace the strong vertical and seasonal partitioning observed here; and (3) given the high species turnover observed between seasons, global climate change may have severe consequences for rainforest arthropods