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41.
Johnson  Chris J.  Boyce  Mark S.  Mulders  Robert  Gunn  Anne  Gau  Rob J.  Cluff  H. Dean  Case  Ray L. 《Landscape Ecology》2004,19(8):869-882
Multiscale analyses are widely employed for wildlife-habitat studies. In most cases, however, each scale is considered discrete and little emphasis is placed on incorporating or measuring the responses of wildlife to resources across multiple scales. We modeled the responses of three Arctic wildlife species to vegetative resources distributed at two spatial scales: patches and collections of patches aggregated across a regional area. We defined a patch as a single or homogeneous collection of pixels representing 1 of 10 unique vegetation types. We employed a spatial pattern technique, three-term local quadrat variance, to quantify the distribution of patches at a larger regional scale. We used the distance at which the variance for each of 10 vegetation types peaked to define a moving window for calculating the density of patches. When measures of vegetation patch and density were applied to resource selection functions, the most parsimonious models for wolves and grizzly bears included covariates recorded at both scales. Seasonal resource selection by caribou was best described using a model consisting of only regional scale covariates. Our results suggest that for some species and environments simple patch-scale models may not capture the full range of spatial variation in resources to which wildlife may respond. For mobile animals that range across heterogeneous areas we recommend selection models that integrate resources occurring at a number of spatial scales. Patch density is a simple technique for representing such higher-order spatial patterns.  相似文献   
42.
Recovering native uniqueness has major importance for breeds with historic introgression. The aim of the study was to estimate population genetic parameters for two local red cattle breeds from Northern Germany and to study possibilities to reverse introgression. Genealogical information consisted of 90,783 individuals for German Angler and 187,255 individuals for Red Dual-Purpose cattle breed, with additional information on sex, born, breed, status, and conventional breeding values. It is concluded that the native genetic contribution could be included as an additional trait in the total merit index in order to recover a part of the native genetic background. Native contributions should be estimated in the long term from marker data in order to account for Mendelian sampling. The maintenance of a sufficient genetic diversity of native alleles can be achieved by an advanced OCS with appropriate constraints.  相似文献   
43.
1. In commercial layer breeding, extensive gene pools are tested and selected for market requirements which must be anticipated at least 5 years ahead. Field results confirm a continuous positive genetic trend in egg output and better feed efficiency which can be converted into land savings.

2. Animal welfare and cage-free housing dominate future needs of the market. Nesting behaviour and minimal tendency to develop feather-pecking or cannibalism without beak treatment are key trait complexes. Stronger shells for longer production cycles without moulting have to be combined with better bones.

3. No single big gene effect can be expected to control the multifactorial problem of feather-pecking. Adjusting the shape of the beak, with a heritability of .10–.25, can contribute to reducing the risk of severe cannibalism.

4. For better skeletal integrity, the assessment of bone quality in pedigree birds housed in enriched cages is done by keel bone palpation or ultrasound measurement of the humerus. Both traits show similar heritabilities in the range of .15–.30 and can be included in a balanced selection approach for performance, quality and welfare traits.

5. The combination of performance testing and genome-wide DNA marker analysis is a promising tool to generate more progress for a balanced performance and behaviour profile.  相似文献   

44.
浙北地区早熟松花菜品种比较试验   总被引:1,自引:0,他引:1  
在浙北松花菜秋季栽培区选择试点,对6个早熟松花菜新品种进行了比较试验。试验结果表明,浙农松花50天是浙北地区秋季抢早栽培的较为理想的品种,而农美50天产量潜力最大,但成熟期略迟,生产上可根据实际情况加以应用。  相似文献   
45.
邵晖  陈红枫 《安徽农业科学》2011,39(33):20763-20765,20828
阐述了区域发展循环经济的基础和契机,以安徽省为例分析了发展循环经济面临资源制约和环境压力加大、配套政策法制体系有待进一步完善和贯彻落实、循环经济指标尚未纳入政绩考核、循环经济技术支撑基础依然亟需加强等挑战,提出以任务和目标明确循环经济发展的方向、以重点领域作为循环经济发展的载体、以重点工程作为发展循环经济的手段、以制度建设作为循环经济发展的保障等路径。  相似文献   
46.
为有效解决生态停车场交付使用后一段时间就出现草皮空秃严重的问题,该研究系统地对生态停车场结构中的3类面层材料、5类结合层材料、5类基层材料作了对比。结果表明:当停车场结构的基础为素土夯实,基层采用150 mm厚三七灰土加100 mm厚C15素混凝土,结合层采用30 mm厚1∶3水泥砂浆时,面层采用200~300 mm厚自然石既能有效控制草皮空秃问题,停车场的结构稳定性也较好;当停车场结构的基础为素土夯实,第1基层采用150 mm厚三七灰土,第2基层材料改用200 mm厚级配砂石,结合层材料改用50mm厚1∶3泥砂混合时,面层材料采用60 mm厚嵌草砖或70 mm厚植草格的综合效果良好。  相似文献   
47.
在福建省华安县西陂国有林场,对降香黄檀53个家系6年生试验林的生长指标进行综合分析。结果表明:表现最为优良的前3个家系是BS29、BS28、DF35,其次为家系ZQ5、ZQ6、ZQ7、LZ8、BWL84、BWL90、FJ117,均在生长量上表现良好;表现最差的家系是FJ121、FJ120、LD43,其次为家系WC11、BS31、LD42、WZS55、WZS58、GZ106、HK15,均在生长量上表现差。初步筛选出适合于闽南沿海地区种植的10个优良家系:BS29、BS28、DF35、ZQ5、ZQ6、ZQ7、LZ8、BWL84、BWL90、FJ117。  相似文献   
48.
苏慧 《湖南农机》2011,38(1):64-65
CAD/CAM应用越来越广泛,但对于CAD/CAM应用软件的选型是一些设计人员及企业面临的问题,文章介绍了CAD/CAM软件系统的组成,CAD/CVM应用软件的选型要素,企业选型时应注意的事项.  相似文献   
49.
During 11 breeding seasons, 351 7- to 10-day-old horse embryos were nonsurgically transferred into recipients that ovulated between 3 and 10 days earlier. Pregnancy rates at 14 and 40 days and foaling rates were 77.8% (273/351), 69.2% (243/351), and 64.4% (226/351), respectively. Pregnancy loss between 14 and 40 days was 11% and between 40 days and delivery was 7%. The transfer of quality grade 3 to 4 embryos resulted in a significantly lower pregnancy rate at 14 days compared with the transfer of grade 1 to 2 embryos (46.2% vs. 79%; P < .05). Eight-day-old embryos resulted in significantly lower pregnancy losses than day 9 or 10 embryos, as occurred for embryos between 400 and 1200 μm compared with embryos <400 μm. Embryos recovered from mares >20 years resulted in a significantly higher pregnancy loss rate than those recovered from younger mares. The same happened for embryos coming from mares affected by reproductive pathologies compared with healthy mares performing sport activity. None of the evaluated parameters influenced recipients' foaling rate significantly.  相似文献   
50.
曹景林 《湖北农业科学》2011,(21):4321-4325,4349
提出了在烟草育种中应用轮回选择方法的必要性,综述了轮回选择改良群体的理论与方法和轮回选择在烟草育种中的应用效果,同时探讨了轮回选择在烟草群体改良中的应用特点和方法。  相似文献   
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