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Woodpigeons Columba palumbus cause significant damage to oilseed rape Brassica napus. (Cruciferae) in Britain, especially between January and March. The potential of cinnamamide, a non-lethal chemical repellent, to protect growing oilseed rape from woodpigeon damage was assessed in 20×20 m plots laid out in a 9-ha field frequented by >500 woodpigeons. Despite a low initial loading of cinnamamide and low persistence of the compound after spraying, the inner leaves of treated plants received less damage than the inner leaves of untreated plants (P<0·05). This was reflected later in the trial in a decline in damage to the outer leaves of treated plants (P<0·05). No signs of phytotoxicity were seen on treated leaves during the trial. Cinnamamide did not completely protect the rape, and some plants in treated plots received considerable damage. This was probably due to the compound's poor persistence on the leaf and because it was applied late in the growing season (late February) when birds had already made inroads into the crop. © 1998 SCI.  相似文献   
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Natural disturbances such as wind are known to cause threats to ecosystem services as well as sustainable forest ecosystem management. The objective of this research was to better understand and quantify drivers of predisposition to wind disturbance, and to model and map the probability of wind-induced forest disturbances (PDIS) in order to support forest management planning. To accomplish this, we used open-access airborne light detection and ranging (LiDAR) data as well as multi-source National Forest Inventory (NFI) data to model PDIS in southern Finland. A strong winter storm occurred in the study area in December 2011. High spatial resolution aerial images, acquired after the disturbance event, were used as reference data. Potential drivers associated with PDIS were examined using a multivariate logistic regression model. The model based on LiDAR provided good agreement with detected areas susceptible to wind disturbance (73%); however, when LiDAR was combined with multi-source NFI data, the results were more promising: prediction accuracy increased to 81%. The strongest predictors in the model were mean canopy height, mean elevation, and stem volume of the main tree species (Norway spruce and Scots pine). Our results indicate that open-access LiDAR data can be used to model and map the probability of predisposition to wind disturbance, providing spatially detailed, valuable information for planning and mitigation purposes.  相似文献   
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Since 1999, the mountain pine beetle (Dendroctonus ponderosae Hopk. [Coleoptera: Scolytidae]) has impacted over 13 million hectares of pine forests in western Canada. Successful mitigation of the beetle depends on the accurate and timely identification of currently infested trees and on sustained control activities over several successive years. We monitored the success of mitigation activities in reducing damage caused by mountain pine beetle at two sites (A and B) on the leading edge of the current beetle epidemic in western Canada. Using three years of digital high spatial resolution aerial imagery (2006–2008) and one season of field measurements (2008), we estimated retrospective ratios of trees attacked by beetle in the current year (green attack) to trees attacked in the previous year (red attack), hereafter referred to as G:R. Our results indicate that mitigation activities slowed the rate of population growth, with G:R found to be decreasing or stable over sites A and B while mitigation was ongoing in 2005 and 2006 (site A 1.06:1; site B 0.32:1). When mitigation was discontinued over site A in 2007, the G:R increased markedly (1.94:1), while continued mitigation at site B in 2007 further reduced the G:R (0.22:1). Despite the cost associated with mitigation, its efficacy is rarely assessed and even more rarely documented. The approach presented herein enables a sample-based appraisal of mitigation efforts.  相似文献   
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Anthropogenic climate change has significant consequences for the sustainability and productivity of agroforestry ecosystems upon which millions of smallholders in the tropics depend and that provide valuable global services. We here consider the current state of knowledge of the impacts of climate change on tree genetic resources and implications for action in a smallholder setting. Required measures to respond to change include: (1) the facilitated translocation of environmentally-matched germplasm across appropriate geographic scales, (2) the elevation of effective population sizes of tree stands through the promotion of pollinators and other farm management interventions; and (3) the use of a wider range of ??plastic?? species and populations for planting. Key bottlenecks to response that are discussed here include limitations in the international exchange of tree seed and seedlings, and the absence of well-functioning delivery systems to provide smallholders with better-adapted planting material. Greater research on population-level environmental responses in indigenous tree species is important, and more studies of animal pollinators in farm landscapes are required. The development of well-functioning markets for new products that farmers can grow in order to mitigate and adapt to anthropogenic climate change must also consider genetic resource issues, as we describe.  相似文献   
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This preliminary study identified the fungal endophytes of Sitka spruce (Picea sitchensis) in four Scottish plantations, analysed their recruitment possibilities and community structure across the sites, and identified the possible origins of the endophytes in this non‐native host. Although Sitka spruce is native to north‐western North America, it comprises a huge portion of Scottish forestry and is an economically vital timber tree. Needles from two age classes were collected and cultured for emerging endophyte isolates. Using a combination of morphological features and genetic sequencing of the nuclear ribosomal ITS regions of representative morphological types, 57 morphotypes were recorded which represented at least 15 different species, including a hypothesized sister species to the pathogen of Pseudotsuga menziesii in North America and Europe, Nothophaeocryptopus gaeumannii (previously P. gaeumannii) that was present at all sites tested. Diversity, recruitment, site, needle age and needle part effects are discussed. The phylogeny of Nothophaeocryptopus based on analysis of combined ITS and Tub2 sequence data is given in order to assess the relationship of the unknown endophyte to the Douglas fir pathogen N. gaeumannii.  相似文献   
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Spatial and temporal aspects of flight activity of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), were investigated in a grain-growing district in southern New South Wales, Australia. This species is now considered an important economic pest in Australia due to the development of a high level of resistance to phosphine. Flight activity was monitored at 4-weekly intervals near and away from grain silos. We present data for the first time from trapping with a commercial aggregation pheromone lure (active trapping phase), as well as data on C. ferrugineus by-catch from trapping using an aggregation pheromone lure for another species (passive trapping phase). There was a strong seasonal pattern to flight activity, with no flight detected during the winter months of June, July, or August. This appears to be primarily related to ambient temperature, with maximum temperatures above 20 °C initiating flight. Beetles were trapped both near and away from grain storages, demonstrating flight dispersal in the farm environment. The results of this study in southern New South Wales also show that C. ferrugineus beetles of both sexes are flying in the farm environment. During the passive trapping phase, the sex ratio of trapped beetles did not deviate from 1:1, but during active trapping, the sex ratio was biased to females (3:1). While more work is required, information garnered from this study provides a basis for management strategies for the control of C. ferrugineus in south-eastern Australia.  相似文献   
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