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1.
Land cover data for landscape ecological studies are frequently obtained by field survey. In the United Kingdom, temporally separated field surveys have been used to identify the locations and magnitudes of recent changes in land cover. However, such map data contain errors which may seriously hinder the identification of land cover change and the extent and locations of rare landscape features. This paper investigates the extent of the differences between two sets of maps derived from field surveys within the Northumberland National Park in 1991 and 1992. The method used in each survey was the Phase 1 approach of the Nature Conservancy Council of Great Britain. Differences between maps were greatest for the land cover types with the smallest areas. Overall spatial correspondence between maps was found to be only 44.4%. A maximum of 14.4% of the total area surveyed was found to have undergone genuine land cover change. The remaining discrepancies, equivalent to 41.2% of the total survey area, were attributed primarily to differences of land cover interpretation between surveyors (classification error). Differences in boundary locations (positional error) were also noted, but were found to be a relatively minor source of error. The implications for the detection of land cover change and habitat mapping are discussed. 相似文献
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The re-emergence of indigenous forest in an urban environment, Christchurch, New Zealand 总被引:4,自引:0,他引:4
Glenn H. Stewart Maria E. Ignatieva Colin D. Meurk Richard D. Earl 《Urban Forestry & Urban Greening》2004,2(3):149-158
Christchurch, the second largest city in New Zealand is a planned city on a coastal plain on the east coast of the South Island. The birth of the city and the subsequent century of development was characterised by colonial values and tree and garden planting with familiar European species along with those from Australia, North America, and eventually all other continents. The image of an “English garden city” with classical parks of oaks and willow-lined rivers became the accepted norm and the way in which the city has been promoted to potential tourists. Gardening is one of the top two recreational activities and exotic species greatly outnumber native species in the flora and in gardens. This has had serious consequences for the highly fragmented and degraded indigenous vegetation and its co-adapted wildlife. A few hardy indigenous species continued to regenerate through this period, but since the 1970s, there has been a progressive change of attitude and interest in reclaiming the natural heritage of the city, manifest in widespread private and public planting of indigenous species and active habitat restoration. In this article we examine the indigenous and exotic shrub and tree components of the Christchurch flora as planted street trees, in domestic gardens, and in parks. We also present data on shrub and tree regeneration in parks and domestic gardens in the city. Indications are that the more sensitive, less intrusive management of urban environments, combined with the greater density of indigenous seed sources, has allowed regeneration of a wide range of indigenous species across a broad spectrum of habitats – from neglected gardens to pavement cracks to exotic plantations. This is despite the competition from the prodigious seed banks and density of exotic trees, shrubs, and ground covers and albeit minimal impacts of introduced browsing and seed eating mammals. If the present trends continue through appropriate management and facilitation, these tentative signs of native forest regeneration should eventually proliferate into a sustainable mixed origin urban forest that resurrects and preserves the natural character of the region. 相似文献
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Natural grasslands deliver essential ecosystem services through plant production, which enhances water supply, nutrient cycling, soil retention and greenhouse gas mitigation. Although the condition of montane grasslands for provision of ecosystem services is maintained by regular annual or biennial burning, controversy exists over the impact of different frequencies and seasons of burning on grassland productivity. The objective of this study was to determine the long-term effects of different burning regimes on primary production and quality of the montane grasslands of the KwaZulu-Natal Drakensberg. There were no significant differences in the mean standing live mass between 30 years of annual winter and biennial spring burning. However, in unburnt areas productivity was 20% lower (118.2?g m?2) than in regularly burnt grassland (144.7–154.5?g m?2). Crude protein did not vary between the annual winter and biennial spring treatments (95–113?kg ha?1), but was significantly lower in unburned areas (45?kg ha?1). However, an infrequent fire in a protected area caused a temporary spike in crude protein (16%) compared with regular burning (5–10%), which can benefit wildlife. We conclude that montane grasslands can be burnt annually or biennially in the dormant season to promote long-term productivity. 相似文献
5.
Validation of the Accutrend Plus point‐of‐care triglyceride analyzer in horses,ponies, and donkeys
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Charlotte Marly-Voquer Colin C. Schwarzwald Regula Bettschart-Wolfensberger 《The Canadian veterinary journal. La revue veterinaire canadienne》2016,57(1):70-75
Five horses were presented for treatment of atrial fibrillation by transvenous electrical cardioversion (TVEC). A dexmedetomidine infusion was administered for sedation during positioning of the cardioversion catheters, and continued during general anesthesia. Shocks were applied until return to sinus rhythm. Dexmedetomidine infusion provided excellent conditions for TVEC catheter placement and procedure. 相似文献
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This article considers the experiences of a Samoan female geographer undertaking community‐based field research in her home country, and identifies some lessons for researchers working in similar circumstances. The paper suggests that ethical behaviour in research is ‘place‐specific’, and there is therefore a need to employ culturally sensitive and ‘location‐specific’ methodologies when undertaking community‐based research fieldwork. For the lead researcher, growing up in Samoa played a significant role in gaining an understanding of a set of robust and effective procedures to evaluate citizens' resilience to climatic and other environmental challenges. Fluency in everyday and more formal local languages, and awareness of local differences, each with multi‐layered connections to local communities, understanding cultural nuances and practising respect for va tapuia [sacred space or relationships] protocols, together facilitated the process of knowledge acquisition and helped to confirm the validity of the conclusions derived from the study. 相似文献
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This paper describes three experiments aimed at determining the proportion of dead birds at sea which come ashore and are found by members of the public, and discusses the results in relation to wind velocities. From 11% to 58% of the ringed (Larus spp.) corpses thrown into the Irish Sea between Liverpool and the Isle of Man on three occassions in 1973 and early 1974 were recovered. There were large differences between experiments in the timing of the recoveries, although half usually occurred within 11–14 days of dropping. The resultant wind velocities during the time the first bodies recovered from each experiment were at sea were calculated. Comparison of the observed and expected tracks of these bodies confirmed that the wind was the main factor influencing the direction of drift. Gull corpses drifted at a minimum of 2·55±0·93% of the wind speed, although there was much variation and some travelled at over 4% windspeed. With a few exceptions, the observed distribution of recoveries could be broadley predicted by wind vector analysis. The amount of onshore wind when the bodies had reached coastal waters was not related to the subsequent recovery rates. Further experiments are necessary if some of our findings are to be explained and examination of the effect of tidal cycles on the beaching of corpses would also be of value. 相似文献
10.
This paper is the sequel to an earlier publication (see Biological Conservation, Vol. 5, No. 4 pp. 243–250, October 1973) on the conservation status of deer and describes an IUCN programme for the conservation of world-threatened deer. Research requirements for conservation of deer that are currently threatened with extinction are discussed. The immediate conservation objective is to ensure the species' or subspecies' survival, and the long-term objective is to restore their productive status in the wild. A framework for research to provide data to guide conservation practices is outlined. It comprises a set of research questions, to aid the planning of studies, and statements of the conservation action potential of the results of these investigations. The proposed organization of the IUCN programme and its current status is described. University and other research institutions that would be interested in participating or co-operating in the programme are invited to write to IUCN. 相似文献