Richard F. Pywell

Restoration of ecosystem services and biodiversity: conflicts and opportunities

Ecological restoration is becoming regarded as a major strategy for increasing the provision of ecosystem services as well as reversing biodiversity losses. Here, we show that restoration projects can be effective in enhancing both, but that conflicts can arise, especially if single services are targeted in isolation. Furthermore, recovery of biodiversity and services can be slow and incomplete. Despite this uncertainty, new methods of ecosystem service valuation are suggesting that the economic benefits of restoration can outweigh costs. Payment for Ecosystem Service schemes could therefore provide incentives for restoration, but require development to ensure biodiversity and multiple services are enhanced and the needs of different stakeholders are met. Such approaches must be implemented widely if new global restoration targets are to be achieved.

The effect of arable field margin composition on invertebrate biodiversity

Abstract A replicated field experiment designed to compare five types of field margin in terms of their invertebrate biodiversity was established in North Yorkshire, UK. Four replicate margins on arable land each contained five treatment plots 72 m long by 6 m wide. The treatments were: (1) cropped to the edge; (2) sown ‘tussocky’ grass mix; (3) sown ‘grass and wildflower’ mix; (4) Split margin (3 m ‘tussocky’ grass adjacent to hedge and 3 m ‘grass and wildflower’ next to crop); and (5) natural regeneration. Invertebrates were sampled by pitfall trapping, sweep netting, and butterfly and bumblebee transects, and identified to species level. The use of different flower species by foraging bumblebees was also examined. Despite all treatments containing a flush of annual weeds early in the establishment year, the five margin types were distinct in their vegetation composition by their first mid-summer. Where statistically significant results were obtained for invertebrates, avoidance of the ‘cropped’ treatment was by far the commonest observed response. This tendency could be clearly demonstrated amongst the carabids, spiders, butterflies, bumblebees, millipedes and harvestmen, with margins often containing double or more the number of invertebrates of similar areas cropped to the edge. Having avoided the crop, preferences for other margin types were mixed, but there was a marked tendency by many nectar and/or pollen-feeding, flying insects towards greater abundance on those margins containing sown ‘wildflowers’ (e.g. butterflies Meadow Brown and Ringlet, Bumblebees, Pollen Beetle Meligethes sp.) or flowers either sown or unsown (Soldier Beetle Rhagonycha fulva ). There was a less strong tendency for predatory species occurring in the vegetation canopy and depending on small, especially flying insects for food, to also prefer the flowery treatments (e.g. total spiders caught by sweeping, seven-spot ladybird). Harvestmen in autumn reject natural regeneration in favour of any sown treatment. Only one species, the carabid Nebria brevicollis , was trapped in higher numbers in the cropped treatment than on any sown margin, and then only in autumn. Of the six common bumblebee species, the two longest-tongued species showed different patterns of flower visitation from the remaining four. These results clearly demonstrate that sown field margins can rapidly produce substantial biodiversity benefits on arable land, with the resulting fauna influenced by the type of field margin created.

Wildlife-friendly farming increases crop yield: evidence for ecological intensification.

Ecological intensification has been promoted as a means to achieve environmentally sustainable increases in crop yields by enhancing ecosystem functions that regulate and support production. There is, however, little direct evidence of yield benefits from ecological intensification on commercial farms growing globally important foodstuffs (grains, oilseeds and pulses). We replicated two treatments removing 3 or 8% of land at the field edge from production to create wildlife habitat in 50–60 ha patches over a 900 ha commercial arable farm in central England, and compared these to a business as usual control (no land removed). In the control fields, crop yields were reduced by as much as 38% at the field edge. Habitat creation in these lower yielding areas led to increased yield in the cropped areas of the fields, and this positive effect became more pronounced over 6 years. As a consequence, yields at the field scale were maintained—and, indeed, enhanced for some crops—despite the loss of cropland for habitat creation. These results suggested that over a 5-year crop rotation, there would be no adverse impact on overall yield in terms of monetary value or nutritional energy. This study provides a clear demonstration that wildlife-friendly management which supports ecosystem services is compatible with, and can even increase, crop yields.

Country-specific effects of neonicotinoid pesticides on honey bees and wild bees

Damage confirmed Early studies of the impacts of neonicotinoid insecticides on insect pollinators indicated considerable harm. However, lingering criticism was that the studies did not represent field-realistic levels of the chemicals or prevailing environmental conditions. Two studies, conducted on different crops and on two continents, now substantiate that neonicotinoids diminish bee health (see the Perspective by Kerr). Tsvetkov et al. find that bees near corn crops are exposed to neonicotinoids for 3 to 4 months via nontarget pollen, resulting in decreased survival and immune responses, especially when coexposed to a commonly used agrochemical fungicide. Woodcock et al., in a multicounty experiment on rapeseed in Europe, find that neonicotinoid exposure from several nontarget sources reduces overwintering success and colony reproduction in both honeybees and wild bees. These field results confirm that neonicotinoids negatively affect pollinator health under realistic agricultural conditions. Science, this issue p. 1395, p. 1393; see also p. 1331 Bee health is affected by neonicotinoids under field-realistic conditions across crops conditions. Neonicotinoid seed dressings have caused concern world-wide. We use large field experiments to assess the effects of neonicotinoid-treated crops on three bee species across three countries (Hungary, Germany, and the United Kingdom). Winter-sown oilseed rape was grown commercially with either seed coatings containing neonicotinoids (clothianidin or thiamethoxam) or no seed treatment (control). For honey bees, we found both negative (Hungary and United Kingdom) and positive (Germany) effects during crop flowering. In Hungary, negative effects on honey bees (associated with clothianidin) persisted over winter and resulted in smaller colonies in the following spring (24% declines). In wild bees (Bombus terrestris and Osmia bicornis), reproduction was negatively correlated with neonicotinoid residues. These findings point to neonicotinoids causing a reduced capacity of bee species to establish new populations in the year following exposure.

A Comparison of Techniques for Restoring Heathland on Abandoned Farmland

1. Recent changes in agricultural policies have reduced the extent of cultivated farmland. This has provided opportunities to restore heathland vegetation on lowland sites where it once occurred. 2. Between December 1988 and April 1990 large-scale replicated experiments were established on abandoned farmland in southern Britain to compare the effectiveness of four treatments for heathland restoration : (i) the application of herbicide ; (ii) the addition of harvested heather shoots ; (iii) the addition of heathland topsoil ; and (iv) the translocation of heathland turves. 3. The number of seedlings of heathland plant species on each treatment was counted in December 1990 and 1991, and the shoot frequency of these species was recorded in January 1993. 4. The grassland soil had a significantly higher pH and contained greater concentrations of extractable phosphorus and exchangeable calcium than that of the adjacent heathland. Despite this, the controls showed that there was some natural regeneration of heathers within the grassland. 5. Herbicide treatment inhibited the regeneration of heathland plants. Cultivation followed by the application of harvested heather shoots increased the number of seedlings of heathland plant species, but some key species were missing. All the components of the heathland plant community occurred in greater numbers on the plots where heathland topsoil had been applied, and on the parts of transferred heathland turves which had died from drought. 6. The large-scale translocation of heathland turf appeared to be feasible and instantly recreated the mature heathland plant community. However, some changes in the plant community occurred which probably resulted from differences in soil drainage characteristics between the donor and recipient sites. Of the different sources of heathland plant propagules, harvested heather shoots were a renewable resource, whereas the collection of heathland topsoil and turves involved the destruction of existing heathland.

Impacts of neonicotinoid use on long-term population changes in wild bees in England

Wild bee declines have been ascribed in part to neonicotinoid insecticides. While short-term laboratory studies on commercially bred species (principally honeybees and bumblebees) have identified sub-lethal effects, there is no strong evidence linking these insecticides to losses of the majority of wild bee species. We relate 18 years of UK national wild bee distribution data for 62 species to amounts of neonicotinoid use in oilseed rape. Using a multi-species dynamic Bayesian occupancy analysis, we find evidence of increased population extinction rates in response to neonicotinoid seed treatment use on oilseed rape. Species foraging on oilseed rape benefit from the cover of this crop, but were on average three times more negatively affected by exposure to neonicotinoids than non-crop foragers. Our results suggest that sub-lethal effects of neonicotinoids could scale up to cause losses of bee biodiversity. Restrictions on neonicotinoid use may reduce population declines.

Wildlife-friendly farming benefits rare birds, bees and plants

Agricultural intensification is a leading cause of global biodiversity loss, especially for threatened and near-threatened species. One widely implemented response is ‘wildlife-friendly farming’, involving the close integration of conservation and extensive farming practices within agricultural landscapes. However, the putative benefits from this controversial policy are currently either unknown or thought unlikely to extend to rare and declining species. Here, we show that new, evidence-based approaches to habitat creation on intensively managed farmland in England can achieve large increases in plant, bee and bird species. In particular, we found that habitat enhancement methods designed to provide the requirements of sensitive target biota consistently increased the richness and abundance of both rare and common species, with 10-fold to greater than 100-fold more rare species per sample area than generalized conventional conservation measures. Furthermore, targeting landscapes of high species richness amplified beneficial effects on the least mobile taxa: plants and bees. Our results provide the first unequivocal support for a national wildlife-friendly farming policy and suggest that this approach should be implemented much more extensively to address global biodiversity loss. However, to be effective, these conservation measures must be evidence-based, and developed using sound knowledge of the ecological requirements of key species.

Soil fertility and its implications for the restoration of heathland on farmland in Southern Britain

Abstract The distribution and concentration of extractable soil nutrients were compared between undisturbed heathland soil profiles and those of adjacent farmland which was formerly heathland. Heathland soils are of low fertility and pH. The conversion of heathland to farmland was found to have had profound long-term effects on both soil structure and chemistry. The well-defined mineral and organic soil horizons were mixed by ploughing, and the concentrations of extractable nitrogen, phosphorus, calcium and pH were significantly increased by the addition of fertilizers and lime. Following the cessation of farming, concentrations of phosphorus and nitrogen declined significantly so that after five to 13 years there were few differences compared with heathland soils. However, the effects of liming were persistent and this was thought to increase indirectly the fertility of the soil. It may be necessary to reduce the nutrient concentrations and pH of these soils as part of the management to restore heathland vegetation under conservation set-aside schemes.

Rhinanthus: a tool for restoring diverse grassland?

The restoration of species-rich grasslands is often hindered by high residual soil fertility as a result of, e.g., intensive farming. The establishment of a diverse range of target species on such sites requires the reduction of soil fertility or of the vigour of competitive plants. Current methods to achieve these aims are often unsuccessful or complicated and expensive. It has been suggested thatRhinanthus species could be used to decrease the growth of competitive plants and enhance species diversity. We review evidence for this potential and suggest five key attributes that makeRhinanthus species a practical restoration tool.Rhinanthus species are natural components of species-rich grasslands (attribute 1), and seed of some species is relatively low cost and easily obtainable (2). Recent work has shown that certainRhinanthus species reduce the vigour of competitive species, especially agricultural grasses, and allow establishment and persistence of target species (3). We analyze demographic data and show that certainRhinanthus species have the ability for rapid population growth and spread, even in fertile grasslands (4). We also show that it is relatively easy for land managers to limit the population size ofRhinanthus species and prevent damage (e.g. excessive loss in production or invasion by weeds) to grasslands by excessive densities (5). We give suggestions for further research, including: the range of species-poor grasslands into whichRhinanthus can be introduced successfully and whichRhinanthus species should be used; the mechanisms by whichRhinanthus enhances diversity in restored grasslands; whether the ecotype or subspecies ofRhinanthus used affects restoration success; how management methods affect population growth and spread ofRhinanthus; and whether other parasitic plants could be used in habitat restoration.

Effects of vegetation structure and floristic diversity on detritivore, herbivore and predatory invertebrates within calcareous grasslands

Calcareous grasslands in Europe have shown wide scale declines in their extent and quality as a result of modern agricultural practices, increased atmospheric eutrophication and lack of management. In addition to being a key habitat for specialist plants, calcareous grasslands are also important for many threatened invertebrates. In this UK based study, we investigated the impact of military vehicle activity, floral species richness and vegetation structure on assemblages of detritivore, herbivore and predatory invertebrates. We also consider the impact that disturbance by military vehicle activity on the proportion of invertebrate species capable of flight, a surrogate for dispersal ability. Sward height was negatively correlated with detritivore, herbivore and predator species richness. Herbivores species richness was positively correlated with both forb and grass species richness. Spatial variation in the number of plant species was negatively correlated with herbivore species richness. Those sites most heavily disturbed by military vehicle activity supported the lowest proportions of flightless invertebrates. Successful management for calcareous grassland invertebrates should aim to maintain short swards with high floristic diversity, in terms of both the forbs and grasses. It should be noted, however, that these findings refer to principally surface rather than sward active invertebrates. While disturbance associated with military vehicle activity was not found to affect invertebrate species richness, it has negative consequences for the structure of invertebrate assemblages by selecting against invertebrates with low dispersal ability. To support invertebrate diversity in calcareous grasslands we emphasise the need for variety in the timing and type of management applied to promote heterogeneity in sward structure.