Action of earthworms on flint burial – a return to Darwin’s estate

For thirty years, from the early 1840s, Charles Darwin documented the disappearance of flints in the grounds of Down House in Kent, at a location originally known as the “Stony Field”. This site (Great Pucklands Meadow - GPM) was visited in 2007 and an experiment set up in this ungrazed grassland. Locally-sourced flints (either large - 12 cm, or small – 5 cm dia.) were deposited at two densities within sixteen 1 m2 plots in a randomised factorial design. The area selected was distant from public access routes and remained unmown throughout the duration here reported. Fixed point photographs were taken at the outset to enable later photogrammetric analysis. After 6 years, the site was re-examined. The flints had generally been incorporated into the soil. Photographs were re-taken, proportion of buried flints recorded and measurements made of burial depth from a quarter of each plot. Results showed that large flints were more deeply incorporated than smaller (p=0.025), but more of the latter were below the soil surface. A controlled laboratory experiment was also conducted using Aporrectodea longa (the dominant earthworm species in GPM) to assess effects of casting in the absence of other biota. Results suggested that this species has a major influence on flint burial through surface casting. Combined with a long term, but small scale collection of A. longa casts from an area close to GPM, all results were consistent with those provided by Darwin and showed that rate of flint burial was within the range 0.21-0.96 cm y-1

Environmental impact assessments of the Three Gorges Project in China: issues and interventions

The paper takes China's authoritative Environmental Impact Statement for the Yangzi (Yangtze) Three Gorges Project (TGP) in 1992 as a benchmark against which to evaluate emerging major environmental outcomes since the initial impoundment of the Three Gorges reservoir in 2003. The paper particularly examines five crucial environmental aspects and associated causal factors. The five domains include human resettlement and the carrying capacity of local environments (especially land), water quality, reservoir sedimentation and downstream riverbed erosion, soil erosion, and seismic activity and geological hazards. Lessons from the environmental impact assessments of the TGP are: (1) hydro project planning needs to take place at a broader scale, and a strategic environmental assessment at a broader scale is necessary in advance of individual environmental impact assessments; (2) national policy and planning adjustments need to react quickly to the impact changes of large projects; (3) long-term environmental monitoring systems and joint operations with other large projects in the upstream areas of a river basin should be established, and the cross-impacts of climate change on projects and possible impacts of projects on regional or local climate considered. © 2013 Elsevier B.V.Xibao Xu, Yan Tan, Guishan Yan

Vehicular tracks and the influence of land use and habitat protection in the British uplands

Uplands cover around 25% of the Earth's land surface and comprise highly sensitive soils and habitats of global ecological importance that together provision a suite of valuable ecosystem services. Access to upland areas for land management and recreation is increasingly dependent on the use of motorised vehicles. However, despite the widely acknowledged detrimental consequences of vehicle track development and use, this activity is not currently quantified or monitored. In this study, surfaced and unsurfaced vehicular tracks, footpaths and land cover in an approximately 5% sample of mainland British uplands (1910 km2) were mapped using aerial imagery dating between 2007 and 2016. An information theory approach was used to identify models that best predicted the presence and extent of surfaced tracks as a function of land cover, protected status, extent of blanket peat, proximity to human population and altitude. A total of 2104 km of track were recorded, with 27% defined as being surfaced. This equates to a mean (±SE) track density of 1.10 ± 0.15 km km−2 in current use by vehicles across upland Britain. Areas of managed heather and grass-dominated habitat were the primary predictors of the presence and extent of surfaced tracks and we found no evidence that areas of conservation interest with protective designation were less susceptible to track construction. These data indicate that wide-ranging vehicular track networks exist in ecologically sensitive environments across the British uplands, with implications for the integrity of sensitive habitats and soils. Land use and management activities that are not facilitating ecological improvement or conservation appear to be driving the presence of surfaced tracks in 'protected' areas. The findings suggest that: a) urgent review and revision of upland track legislation is required in Great Britain; and b) wider assessment of upland tracks should be undertaken to inform global conservation strategies for these environments