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81.
Tropical savannas are an important reservoir of global biodiversity. Australia’s extensive savannas, although still largely intact, are experiencing substantial declines in terrestrial biodiversity due to a variety of interrelated effects of altered fire regimes, grazing and increases in invasive species. These disturbance processes are spatially variable, combine to increase landscape to local-scale landscape heterogeneity, but rarely result in well-defined patch boundaries. We quantified the importance of this heterogeneity for native reptile and small mammal species in a tropical savanna landscape of Queensland, Australia. We used high resolution remote sensing imagery (IKONOS) to map habitat pattern at a 4 m spatial resolution and at variable extents. We found that landscapes dominated by grass or bare ground had low reptile and small mammal diversity, while landscapes with a heterogeneous mix of grass, bare ground and trees had high species diversity and relative abundance of most species. Landscape heterogeneity may increase reptile and small mammal species richness by: (i) increasing the variety and abundance of foraging resources such as seeds and invertebrates; (ii) providing cover from predators and high summer temperatures; and (iii) increasing functional connectivity and dispersal success. The importance of these resources and processes varies among individual species and at different spatial scales, reiterating the need to consider habitat requirements of multiple species in landscape management and conservation planning.  相似文献   
82.
当前农民对农业技术培训的新要求   总被引:1,自引:0,他引:1  
新形势下的基层农业技术培训与以往的培训相比,无论在培训时间、培训地点、培训方式和培训内容上均有不同的要求。为了搞好基层农业技术培训,要根据农民提出的问题和要求,准备不同的培训内容,因时因地制宜地采用多种方式,灵活安排培训时间,采用室内和室外相结合的方式进行培训,与时俱进,才能真正取得良好的效果。  相似文献   
83.
Radiation use by oil seed crops — a comparison of winter rape, linseed and sunflower For the production of grain crops rich in oil, winter rape, linseed and sunflower are similarly suitable at many arable locations. We wanted to compare the extent to which radiation (PAR) is intercepted and utilized by the individual species for dry matter and yield production. For this purpose, a 2‐year field experiment comprising the factors genotype, N fertilization and soil tillage was conducted. For five phases of crop development, growth rates (CGR, RGR and NAR) and PAR utilization were calculated. At full ripeness, total dry matter, grain, oil and energy yields, the crop‐ and year‐specific PAR supply, its interception and utilization for dry matter production and the resulting energy binding were determined. Due to the different individual vegetation periods, the PAR supply of the crops differed. The crop assimilation areas also differed, with values for winter rape and sunflower higher than those for linseed. The yield productivity of winter rape and sunflower was also higher than that of linseed. N fertilization increased yield to different extents for the different crops. On average, winter rape and sunflower produced the same amounts of dry matter and energy yield. Due to a higher harvest index, sunflower had the highest grain yield, and because the oil concentration in grain was comparatively high sunflower produced the highest oil yield, too. Under cool and wet climate conditions, however, the productivity of sunflower is offset by a relatively high yield risk because of uncertain ripening. The highest PAR utilization by linseed did not compensate for its very short vegetation period in combination with the lowest PAR interception.  相似文献   
84.
Research demonstrating the biophysical benefits of urban trees are often used to justify investments in urban forestry. Far less emphasis, however, is placed on the non-bio-physical benefits such as improvements in public health. Indeed, the public-health benefits of trees may be significantly larger than the biophysical benefits, and, therefore, failure to account for the public-health benefits of trees may lead to underinvestment in urban forestry. In addition, the distribution of trees that maximizes bio-physical benefits may not maximize public-health benefits.  相似文献   
85.
设计依猪只个体日龄、体重等参数而异的饲料配方是实现猪精细饲养的关键,目前已有很多具备此功能的饲料配方软件,但它们大多数基于PC平台。结合智能手机便于携带、可移动性好等优点开发的基于智能手机平台的猪饲料配方软件,便于携带且操作简单,使用NRC1998模型精确预测了猪营养需要量,配方结果更准确科学,饲料原料营养成分数据用XML文件贮存,数据读取方便,有效地降低了系统开发成本。  相似文献   
86.
孙军 《林产工业》2003,30(1):15-18
介绍了减少锅炉SO2排放的基本途径与主要方法,重点分析了这些方法在人造板企业的适用性.  相似文献   
87.
Seedling crops of gazania, geranium, marigold, mimulus, pansy, verbena and vinca were grown to 60% anthesis in three greenhouse temperature regimes: (a) 26 °C day/6 ± 3 °C night (LT), with a 16.5 °C mean daily temperature (MDT), (b) 26 °C day/17 ± 4 °C night, with a 21 °C MDT, and (c) variable day/night temperatures in response to heating and cooling by a phase change material energy storage module (PCM) with an 8 ± 2 °C night and a 16 °C MDT. Crops bloomed from 2 to 17 days earlier in the 26 °C/17 °C greenhouse. The morphological characteristics of all cultivars of gazania, mimulus, pansy and verbena, geranium and vinca were similar regardless of greenhouse temperature regime. Marigold diploid and triploid cultivars and mimulus were morphologically more variable than the other bedding plant species. Crops grown in the PCM and LT greenhouses had virtually identical morphological characteristics and bloomed in about the same number of days. Plant height was not affected by DIF environments in the greenhouses. The PCM and LT greenhouses had a similar MDT, but the distribution of numbers of hours of mean daily temperatures was different.  相似文献   
88.
小尾寒羊泌乳期母羊能量需要量及代谢规律研究   总被引:4,自引:0,他引:4  
选择有代表性的小尾寒羊泌乳母羊6只,分成哺育单羔和双羔两组,每组3只,分泌乳前期(1~30天),泌乳中期(31~60天)和泌乳后期(61~90天)3个阶段进行饲养试验、消化代谢试验、呼吸测热试验及屠宰试验等研究。两组试羊均按NRC(1978)推荐的绵羊泌乳期哺育双羔母羊能量需要量供给代谢能和其它养分。结果表明,在本研究条件下,小尾寒羊泌乳母羊(包括哺育单、双羔者)在整个泌乳期内的平均日干物质(DM)、有机物质(OM)、代谢能(ME)和泌乳量分别为1689g,1571g,19.893MJ和653g。DM、OM和总能(GE)表观消化率分别为70.71%,72.58%和70.34%,代谢率(MEI/DEI)为84.89%。甲烷能占GEI的9.18%。每日畜体产热量(HP)为625.5KJ/kgW0.75。研究还表明:小尾寒羊泌乳母羊的每日维持代谢能和净能需要量分别为582.6和460KJ/kgW0.75,每户1kg原乳需要10802KJ的代谢能。维持效率为0.790泌乳效率为0.479,HI占GEI的18.10%。分析结果证明,试羊的泌乳量、采食量、畜体产热量和能量转化效率在单、双羔之间均无显著差异(P>0.05)。小尾寒羊泌乳母羊的代谢能总需要量(MER)可用下式估计:羊羔:MER=576.9W0.75+10810M;双羔:MER=588.2W0.75+10794M;平均:MER=582.6W0.75+1  相似文献   
89.
营养水平对肉鸡肌肉组织学的影响   总被引:14,自引:0,他引:14  
试验设计了 9种能量或蛋白质水平不同的饲粮 ,研究了不同营养水平对肉鸡胸肌组织学的影响。结果表明 :饲粮能量或蛋白质水平增加 ,肉鸡胸肌纤维密度减小、直径增大 (P <0 0 1 )。所有处理中 ,高能中蛋白组试鸡胸肌纤维密度最小、直径最大 ,低能低蛋白组试鸡胸肌纤维密度最大 ,高能低蛋白组试鸡胸肌纤维直径最小。  相似文献   
90.
集成材的技术要求和试验方法   总被引:1,自引:0,他引:1  
我国非结构用集成材尚无统一标准,不同厂家的产品质量要求高低不一,造成珍贵木材资源的浪费和经济效益不佳。以日本集成材标准为基础,结合我国生产实践经验提出的集成材技术要求,有助于克服这一困难。据测算,采用该技术要求可使集成材出材率达到25%左右。  相似文献   
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