The Stonehenge landscape habitat restoration project: conservation opportunities for rare butterflies?

Landscape restoration has the potential to mitigate habitat loss and fragmentation. However, restoration can take decades to reach the ecological conditions of the target habitats. The National Trust’s Stonehenge Landscape Restoration Project provides an opportunity to evaluate the ecological benefits against the economic and temporal costs. A field survey between June and September 2010 using Lepidoptera as bio-indicators showed that restored grasslands can approach the ecological conditions of the target chalk grassland habitat within 10 years. However, specialist species like Lysandra bellargus (Adonis blue) were absent from restored grasslands and may require additional management to assist their colonisation. Analysis of the Lepidoptera communities showed that both small-scale habitat heterogeneity and age of the habitat were important for explaining Lepidoptera occurrence. These results demonstrate that habitat restoration at the landscape scale combined with appropriate site-scale management can be a relatively rapid and effective method to restore ecological networks and buffer against future climate change.

Winter floods in Britain are connected to atmospheric rivers

Damage from flooding in the winter and fall seasons has been widespread in the United Kingdom (UK) and Western Europe over recent decades. Here we show that winter flood events in the UK are connected to Atmospheric Rivers (ARs), narrow ribbons along which a large flux of moisture is transported from the subtropics to the mid-latitudes. Combining river flow records with rainfall measurements, satellite data and model simulations, we demonstrate that ARs occur simultaneously with the 10 largest winter flood events since 1970 in a range of British river basins, suggesting that ARs are persistently critical in explaining extreme winter flooding in the UK. Understanding the physical processes that determine the persistence of AR events will be of importance in assessing the risk of future flooding over north-western Europe and other mid-latitude regions.

Enhancing habitat to help the plight of the bumblebee

Modern farming has caused considerable declines in UK bumblebee populations, and, while options exist for farmers to increase the quantity of bee-friendly habitat, uptake has been low. Robin Blake explains how existing habitats on farms could be enhanced for the benefit of bumblebees

Plant and invertebrate resources for farmland birds in pastoral landscapes

On 16 UK livestock holdings within pastoral landscapes, we investigated the provision of plant and invertebrate resources for farmland birds in spring barley and winter wheat cereal-based whole crop silages as alternatives to maize and grass silages. The benefits of low input barley systems were also investigated; barley fields were subjected to two separate herbicide sub-treatments on a split-field design (high input broad-spectrum or low input narrow spectrum herbicides). The abundance of plant resources and invertebrates was assessed for three growing seasons during summer and winter for each crop type. The study clearly demonstrated the value of spring barley for the provision of plant resources when compared to the other silage cropping systems, whilst invertebrate responses were variable. No differences in plant and invertebrate resources were found between the barley treatments. Throughout the year, forage maize afforded the lowest provision of resources for farmland birds, and because it is likely that maize will continue to be grown in pastoral areas, the value of this habitat needs to be improved if farmland birds are to benefit. To provide plant and invertebrate resources for farmland birds in pastoral landscapes we strongly advocate the growing of spring sown barley whole-crop silage followed by over-wintering stubbles. © 2011 Elsevier B.V. All rights reserved.

New tools to boost butterfly habitat quality in existing grass buffer strips

There are approximately 29,000 ha of grass buffer strips in the UK under Agri-Environment Schemes; however, typically they are floristically poor and as such are of limited biodiversity value. Introducing a sown wildflower component has the potential to increase dramatically the value of these buffer strips for a suite of native species, including butterflies. This study investigates management practices aiming to promote the establishment and maintenance of wildflowers in existing buffer strips. The effectiveness of two methods used to increase the establishment of wildflowers for the benefit of native butterfly species were tested, both individually and in combination. The management practices were: (1) the application of a selective graminicide (fluazifop-P-butyl) which reduces the dominance of competitive grasses; and (2) scarification of the soil which creates germination niches for sown wildflower seeds. A wildflower seed mix consisting of nine species was sown in conjunction with the scarification treatment. Responses of wildflowers and butterflies were monitored for two years after establishment. Results indicate that the combined scarification and graminicide treatment produced the greatest cover and species richness of sown wildflowers. Butterfly abundance, species richness and diversity were positively correlated with sown wildflower species richness, with the highest values in the combined scarification and graminicide treatment. These findings have confirmed the importance of both scarification as a means of introducing wildflower seed into existing buffer strips, and subsequent management using graminicides, for the benefit of butterflies. Application of this approach could provide tools to help butterfly conservation on farmland in the future.

Assessing bee species richness in two Mediterranean communities: importance of habitat type and sampling techniques

The decline of bees has raised concerns regarding their conservation and the maintenance of ecosystem services they provide to bee-pollinated wild flowers and crops. Although the Mediterranean region is a hotspot for bee species richness, their status remains poorly studied. There is an urgent need for cost-effective, reliable, and unbiased sampling methods that give good bee species richness estimates. This study aims: (a) to assess bee species richness in two common Mediterranean habitat types: semi-natural scrub (phrygana) and managed olive groves; (b) to compare species richness in those systems to that of other biogeographic regions, and (c) to assess whether six different sampling methods (pan traps, variable and standardized transect walks, observation plots and trap nests), previously tested in other European biogeographic regions, are suitable in Mediterranean communities. Eight study sites, four per habitat type, were selected on the island of Lesvos, Greece. The species richness observed was high compared to other habitat types worldwide for which comparable data exist. Pan traps collected the highest proportion of the total bee species richness across all methods at the scale of a study site. Variable and standardized transect walks detected the highest total richness over all eight study sites. Trap nests and observation plots detected only a limited fraction of the bee species richness. To assess the total bee species richness in bee diversity hotspots, such as the studied habitats, we suggest a combination of transect walks conducted by trained bee collectors and pan trap sampling

Population estimates and habitat use by the critically endangered Taita Apalis Apalis fuscigularis in south-eastern Kenya

The Taita Apalis Apalis fuscigularis (IUCN category: Critically Endangered) is a species endemic to south-eastern Kenya. We assessed population size and habitat use in the three forest sites in which it is known to occur (Ngangao, Chawia and Vuria, totalling 257 ha). The estimate of total population size, derived from distance sampling at 412 sample points, ranged from 310 to 654 individuals, with the northern section of Ngangao fragment having 10-fold higher densities than Chawia (2.47-4.93 versus 0.22-0.41 birds ha(-1)). Ngangao north alone hosted 50% of the global population of the species. The highly degraded Vuria fragment also had moderately high densities (1.63-3.72 birds ha(-1)) suggesting that the species tolerates some human disturbance. Taita Apalis prefers vegetation with abundant climbers, but the predictive power of habitat use models was low, suggesting that habitat structure is not a primary cause for the low density of the species in Chawia. Protecting the subpopulation in the northern section of Ngangao is a priority, as is identifying factors responsible of the low abundance in Chawia, because ameliorating conditions in this large fragment could substantially increase the population of Taita Apalis.

Cryopreservation of winter-dormant apple buds: 1 - variation in recovery with cultivar and winter conditions

The widely-adopted protocol for the cryopreservation of winter buds of fruit trees, such as Malus and Pyrus, was developed in a region with a continental climate, that provides relatively hard winters with a consequent effect on adaptive plant hardiness. In this study the protocol was evaluated in a typical maritime climate (eastern Denmark) where milder winters can be expected. The survival over two winters was evaluated, looking at variation between seasons and cultivars together with the progressive reduction in survival due to individual steps in the protocol. The study confirms that under such conditions significant variation in survival can be expected and that an extended period of imposed dehydration at -4oC is critical for bud survival. The occurrence of freezing events during this treatment suggests that cryodehydration may be involved, as well as evaporative water loss. To optimize the protocol for maritime environments, further investigation into the water status of the explants during cryopreservation is proposed. Keywords: Malus x domestica, cryopreservation, dormant bud, survival, grafting

Is a native rodent competitively dominant over an invasive rodent in lowland agro-forest habitat of the Philippines?

In the lowland agro-forest of the Sierra Madre Biodiversity Corridor (SMBC), it is considered that a native rodent species, Rattus everetti is competitively dominant over an invasive pest species, Rattus tanezumi. The main aim of this study was to assess the response of R. tanezumi following short term removal of R. everetti. We tested this experimentally by trapping and removing R. everetti from two treatment sites in agro-forest habitat on three occasions over three consecutive months. This was followed by three months of non-removal trapping. Two non-treatment sites were trapped for comparison. Following R. everetti removal, R. everetti individuals rapidly immigrated into the treatment sites and a significantly higher proportion of R. tanezumi females were in breeding condition in the treatment sites than in the non-treatment sites. The results from this study provide evidence of competition between native and invasive rodent species in complex agro-ecosystems. We were also able to demonstrate that R. everetti populations are able to recover rapidly from the non-target effects of short-term lethal control in and around agro-forest.

Model studies of the interannual variability of the northern-hemisphere stratospheric winter circulation: the role of the quasi-biennial oscillation

A series of experiments are described that examine the sensitivity of the northern-hemisphere winter evolution to the equatorial quasi-biennial oscillation (QBO). The prime tool for the experiments is a stratosphere-mesosphere model. The model is integrated over many years with the modelled equatorial winds relaxed towards observed values in order to simulate a realistic QBO. In experiment A the equatorial winds are relaxed towards Singapore radiosonde observations in the height region 16-32 km. In contrast to previous modelling studies, the Holton-Tan relationship (warm/cold winters associated with easterly/westerly QBO winds in the lower stratosphere) is absent. However, in a second experiment (run B) in which the equatorial winds are relaxed towards rocketsonde data over the extended height range 16-58 km, a realistic Holton-Tan relationship is reproduced. A series of further studies are described that explore in more detail the sensitivity to various equatorial height regions and to the bottom-boundary forcing. The experiments suggest that the evolution of the northern-hemisphere winter circulation is sensitive to equatorial winds throughout the whole depth of the stratosphere and not just to the lower-stratospheric wind direction as previously assumed.