Devoto M.,University of Bristol |
Bailey S.,Forestry Commission |
Craze P.,University of Bristol |
Memmott J.,University of Bristol
Ecology Letters | Year: 2012
Theory developed from studying changes in the structure and function of communities during natural or managed succession can guide the restoration of particular communities. We constructed 30 quantitative plant-flower visitor networks along a managed successional gradient to identify the main drivers of change in network structure. We then applied two alternative restoration strategies in silico (restoring for functional complementarity or redundancy) to data from our early successional plots to examine whether different strategies affected the restoration trajectories. Changes in network structure were explained by a combination of age, tree density and variation in tree diameter, even when variance explained by undergrowth structure was accounted for first. A combination of field data, a network approach and numerical simulations helped to identify which species should be given restoration priority in the context of different restoration targets. This combined approach provides a powerful tool for directing management decisions, particularly when management seeks to restore or conserve ecosystem function. © 2012 Blackwell Publishing Ltd/CNRS.
Devoto M.,University of Bristol |
Devoto M.,University of Buenos Aires |
Bailey S.,University of Bristol |
Memmott J.,Forestry Commission
Oikos | Year: 2014
Bumble bees can forage on a large number of wild plants and crops. The survival of a colony depends on the availability of suitable food resources within foraging range and throughout their forage season. We studied the spatial and temporal use of floral resources by bumble bees in a set of 30 local plant communities and used these data to model colony survival under different combinations of patch size and bumble bee flight distance. Floral resources vary spatially and temporally at the landscape level, and bumble bees track these resources across the landscape during the season. The simulation model showed that different patterns of resources availability could affect the survival and distribution of bumble bee nests across the landscape. This model can be used to generate hypotheses explaining bumble bee richness and abundance that can be tested in real landscapes. Integrating the spatial and temporal dynamics of the flower resources used by bumble bees provides a new perspective that can be used to inform bumble bee conservation, particularly in the context of their widespread decline in recent decades. © 2013 Crown.
West D.,Forestry Commission
Ecos | Year: 2013
Different parts of the natural world may well have inherent value to society but they also need to pay their way in a meaningful sense to ensure their existence. The economic value of such places needs to be tangible and not based on contrived economic exercises.
Wojtas A.M.,Forestry Commission
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2010
This paper is a summary of a student internship with English Heritage's Photogrammetric Unit. During this placement affordable solutions for heritage close-range photogrammetric measurement were examined. Topcon's Image Surveying Station PI-3000 photogrammetric software was used on a project to record carvings found on one of the stones at Stonehenge. Analysis of this carving (and others) is essential in order to understand Stonehenge's history as well as to help to conserve its condition. An original survey of this carving was carried out in 1967 (Atkinson, 1968) providing context against which this survey using PI-3000 could be compared to in the future. In preparation for this work a comparison of camera calibration techniques (using PI-3000 and PhotoModeler) was carried out. Creating a 3D model using the photogrammetric method based on a bundle adjustment requires knowledge of camera calibration parameters. Photogrammetric camera calibration parameters allow for the recovery of the central perspective bundle. They can be determined during a self calibration process if using appropriate software. It was decided to assess the camera calibration provided by PI-3000. Therefore, to test the software, a Canon IXUS 900Ti was calibrated using PI-3000 and PhotoModeler. The paper presents the results of these calibrations and compares the two software packages. PI-3000 was then used to document a single carving found on inner face of the 53rd stone of Stonehenge. The outcome could be compared with the survey performed in 1967. Around ten images were collected with a calibrated Cannon A640 camera. Scale was introduced to the scene using a ruler laid against the stone. PI-3000 was then used to produce a meshed surface of the carving. Results will be presented. The paper concludes that off-the-shelf photogrammetric equipment and software could be utilized in commercial projects to provide heritage recording. However, principles of close range photogrammetry still needed to be understood in order to produce high quality results.
Wilkinson M.,Japan Forestry and Forest Products Research Institute |
Eaton E.L.,Japan Forestry and Forest Products Research Institute |
Broadmeadow M.S.J.,Forestry Commission |
Morison J.I.L.,Japan Forestry and Forest Products Research Institute
Biogeosciences | Year: 2012
The carbon balance of an 80-yr-old deciduous oak plantation in the temperate oceanic climate of the south-east of Great Britain was measured by eddy covariance over 12 yr (1999-2010). The mean annual net ecosystem productivity (NEP) was 486 g C m-2 yr-1 (95% CI of ±73 g C m-2 yr-1), and this was partitioned into a gross primary productivity (GPP) of 2034 ± 145 g C m-2 yr-1, over a 165 (±6) day growing season, and an annual loss of carbon through respiration and decomposition (ecosystem respiration, Reco) of 1548 ± 122 g C m-2 yr-1. Although the maximum variation of NEP between years was large (333 g C m-2 yr -1), the ratio of Ri eco/GPP remained relatively constant (0.76 ± 0.02 CI). Some anomalies in the annual patterns of the carbon balance could be linked to particular weather events, such as low summer solar radiation and low soil moisture content (values below 30% by volume). The European-wide heat wave and drought of 2003 did not reduce the NEP of this woodland because of good water supply from the surface-water gley soil. The inter-annual variation in estimated intercepted radiation only accounted for ∼ 47% of the variation in GPP, although a significant relationship (p< 0.001) was found between peak leaf area index and annual GPP, which modified the efficiency with which incident radiation was used in net CO2 uptake. Whilst the spring start and late autumn end of the net CO2 uptake period varied substantially (range of 24 and 27 days respectively), annual GPP was not related to growing season length. Severe outbreaks of defoliating moth caterpillars, mostly Tortrix viridana L. and Operophtera brumata L., caused considerable damage to the forest canopy in 2009 and 2010, resulting in reduced GPP in these two years. Inter-annual variation in the sensitivity of Reco to temperature was found to be strongly related to summer soil moisture content. The eddy covariance estimates of NEP closely matched mensuration-based estimates, demonstrating that this forest was a substantial sink of carbon over the 12-yr measurement period. © 2013 Author(s).