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41.
We investigate the risk that supplemental feeding of white-tailed deer (Odocoileus virginianus) to improve trophy quality may degrade rangeland through overutilization of forage plants near the feeders. We divided a South Texas ranch into 6 areas (each 1100 ha). Supplemental feed was provided year-round in a centrally placed feeder in 3 areas, no supplement was provided in the 3 control areas. Radio-telemetry collars were fitted on 2 bucks and 2 does in each area. Spatial distribution of these deer was assessed using the CALHOME program. Feed supplementation did not alter home range size of does but did reduce their 50% core area. Bucks without supplemental feed showed 2 spatial strategies; sedentary bucks had home range distributions similar to supplemented bucks, while commuter bucks moved to supplemented areas during the breeding season. Browsing pressure near feeders and control sites was assessed by measuring consumption of seedlings set in arrays radiating from feeders and control points. Deer browsing was heavier near feeders than at the control sites, and the probability of a seedling being browsed increased with proximity to the feeder. We caution against long-term supplemental feeding in fixed locations because of the potential for localized range degradation around the feeders. 相似文献
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西安市冬季采暖气象条件分析和预报方法初探 总被引:6,自引:2,他引:6
对西安市冬季采暖气象条件和预报方法进行了研究。根据国家采暖规范结合西安冬季采暖的实际,首先对西安1951年7月到2003年6月历年的逐日气象资料进行了详尽的分析,比较了国家采暖日期相关规范和规定中的3种不同的统计方法,确定了符合西安特点的采暖初终日。充分利用T213数值预报产品,对2002年和2003年两个冬半年的逐日850hPa和500hPa各时次各类气象要素及与之对应的西安各时次实况的气温作了相关分析,建立了回归方程,提出了采暖期及其逐日气温预报。 相似文献
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黔东南地区短期气候预测方法研究 总被引:2,自引:0,他引:2
根据大气环流特征和小气候相关关系,找出预测黔东南地区春季倒春寒、3~6月降水量趋势、夏季及6~8月气温变化趋势和夏季旱涝趋势指标,用以制作黔东南地区长期天气趋势预测。 相似文献
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A generic network design in close range photogrammetry is one where optimal multi-ray intersection geometry is obtained with as few camera stations as practicable. Hyper redundancy is a concept whereby, once the generic network is in place, many additional images are recorded, with the beneficial impact upon object point precision being equivalent to the presence of multiple exposures at each camera position within the generic network. The effective number of images per station within a hyper redundant network might well be in the range of 10 to 20 or more. As is apparent when it is considered that a hyper redundant network may comprise hundreds of images, the concept is only applicable in practice to fully automatic vision metrology systems, where it proves to be a very effective means of enhancing measurement accuracy at the cost of minimal additional work in the image recording phase. This paper briefly reviews the network design and accuracy aspects of hyper redundancy and illustrates the technique by way of the photogrammetric measurement of surface deformation of a radio telescope of 26 m diameter. This project required an object point measurement accuracy of σ = 0·065 mm, or 1/400 000 of the diameter of the reflector. 相似文献
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山西运城市森林火险等级预报系统 总被引:1,自引:0,他引:1
利用有关气象及森林火灾资料,分析了林林火灾的发生与气象条件、火条件及森林含水率的关系,计算了森林火险综合预报指标,建立了以预报方程,经试用效果良好。 相似文献