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71.
大兴安岭新林林业局森林资源可持续发展的技术体系 总被引:1,自引:0,他引:1
以大兴安岭林区具有典型代表性的新林林业局为研究对象,在对其自然资源、经济和社会调查后,建立了森林资源可持续发展的配套技术体系。包括种苗培育、资源调查与监测、资源采伐、资源更新、资源抚育技术体系以及资源效益评价体系等。 相似文献
72.
水资源是秦王川灌区发展的重要支撑 ,水资源能够保证未来的可持续利用 ,可为整个秦王川灌区实现可持续发展的基本目标创造良好的条件、打下坚实的基础。本文基于对水资源四种变化率指标的计算 ,评判了未来较长一段时间内秦王川灌区水资源可持续利用的潜力大小 ,即 2 0 1 0年灌区主要供给水资源能否满足各方面的用水需求 ,从而为该区域水资源利用宏观决策提供依据 相似文献
73.
荔枝霜疫霉(Peronophythora litchii)隶属于茸鞭生物界卵菌门疫霉属,由其引起的荔枝霜疫病是目前荔枝生产上一种最重要的病害,严重影响荔枝产量和鲜果品质。双组分信号途径在微生物中参与多种生命活动,但是在卵菌中尚未有相关研究。本研究通过生物信息学分析在荔枝霜疫霉中鉴定到2个杂合型组氨酸激酶(PlHK1、PlHK2)和1个响应调控蛋白(PlRR1)。其在卵菌中是保守存在的,并且与真菌在进化上相对独立。功能域分析表明,PlHK1和PlHK2的C端额外的融合了1个磷酸转移功能域(Hpt),这与真菌和植物的存在显著差异。转录分析表明3个基因在荔枝霜疫霉侵染阶段上调表达,并且响应渗透胁迫和氧化胁迫。以上结果揭示了双组分信号系统可能在疫霉致病过程中发挥重要作用。 相似文献
74.
In semi-arid Mediterranean areas, small grain aftermath stubble represents an important summer source of food for grazing flocks of small ruminants. Wheat stubble is a mediocre source of forage and flocks are grazed in summer under harsh conditions of temperature and air dustiness. However, stubble grazing procedures are changing, water and shading are more frequently available between grazing sessions (“improved management”), and the biological soundness of this ancestral practice needs to be re-visited. The present study was aimed at evaluating the cost in energy of “improved” wheat stubble grazing, compared with feeding a similar diet indoors. The intake of stubble was first quantitatively and qualitatively evaluated in Awassi sheep. Ewes consumed daily 980 ± 100 g day− 1 of wheat stubble. Ewes were then housed and fed diets consisting of wheat hay, straw and grain formulated to be iso-energetic and iso-nitrogenous to diets consumed from wheat stubble. The average intake of ME was similar during the confinement and the pasture periods (6.4 ± 0.5 and 7.6 ± 0.8 MJ day− 1of ME, respectively). During 2 days of each period, animals were fitted with external electrodes and data loggers of heart rate and skin temperature. Energy expenditure (EE) was calculated from oxygen consumption estimated as the product of heart beats rate measured for the two days by the amount of oxygen delivered to body tissues at each heart beat (O2 pulse). The O2 pulse was determined by simultaneously measurement of oxygen consumption and HR twice daily on two occasions, while grazing stubble and indoors. Energy expenditure and energy balance were not different in sheep while grazing wheat stubble (11.1 and − 3.5 MJ day− 1) or fed indoors (11.1 and − 4.8 MJ day− 1). Our data show that stubble did not cover nitrogen and energy requirements for maintenance, and that the cost of summer stubble grazing carried out under conditions described here is less than thought before. 相似文献
75.
城市的发展建设是建设文明社会、和谐社会的重要组成部分。在人文精神的引导下,城市建设应朝着人与自然的和谐方向发展。然而现代城市中出现的各种视觉上的污染及其所造成的危害,却与我们所提倡发展城市人文精神,建立人文城市的内涵相违背。本文在分析了城市的硬环境和软环境存在的几个重要的视觉污染的基础上,提出了发展人文城市,杜绝城市污染源的几点建议。 相似文献
76.
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78.
While several studies have demonstrated that roads can act as barriers to small mammal movement, the relationship between
road density and small mammal abundance has not yet been investigated. In southeastern Ontario, Peromyscus leucopus (white-footed mice) suffer high over-winter mortality rates, resulting in small springtime populations and frequent local
extinctions. Peromyscus leucopus movement is known to be inhibited by roads, which should result in lower rates of immigration into and recolonization of
habitats in landscapes with high road density. We tested two predictions: (1) Forest sites situated in landscapes with high
road densities have a higher chance of P. leucopus being absent during the early spring than forest sites situated in landscapes with low road densities and (2) P. leucopus populations during the summer are smaller in forest sites situated in landscapes with high road densities than in landscapes
with low road densities. We sampled P. leucopus in focal patches within nineteen landscapes (7 rural, low-road-density landscapes; 7 rural, high-road-density landscapes;
5 urban landscapes). There was no significant relationship between road density and the presence/absence of P. leucopus during the early spring. We found a significant positive effect of road density on P. leucopus relative abundance during the summer, even when we excluded the urban landscapes and based the analysis on only the 14 rural
landscapes. Our results suggest that any negative effect of roads on P. leucopus populations, created by their inhibition to moving across roads, is far outweighed by some positive effect of roads on P. leucopus abundance. We suggest that the two most likely explanations are that roads are positively correlated with an important as-yet-undetermined
component of habitat quality, or that roads positively affect P. leucopus by negatively affecting their predators. 相似文献
79.
以滇中城市群为研究对象,选取滇中城市群2000—2019年3期Landsat遥感数据,通过面向对象分类技术提取3期绿色空间信息,通过GIS空间分析法、转移矩阵模型和景观格局指数法,从总体动态特征、空间转移过程和景观格局指数变化3个方面对滇中城市群2000—2019年绿色空间格局进行城市群、州市和区县的多尺度研究。结果表明:城市群尺度总体上呈现绿色空间缩减,非绿色空间扩张的趋势,绿色空间转移主要发生在林地空间、耕地空间和灌草空间之间,绿色空间景观破碎化程度降低,景观多样性下降;州市尺度上,昆明市、曲靖市和红河州7县市绿色空间缩减程度最为严重,绿色空间景观格局指数也存在不同变化趋势和差异;区县尺度上,林地空间增加幅度较大和耕地空间、灌草空间下降幅度最大的区县均集中在滇中外围,非绿色空间增加幅度最大的区县集中于滇中中部和南部,滇中外围区县绿色空间斑块形状越来越规则,滇中西部区县景观多样性降低。多尺度研究不仅有助于对不同尺度上各个地区绿色空间的总体水平和动态特征进行全面分析,还有助于各级政府从不同尺度上制定相应的绿色空间保护和经济发展措施,对促进建设滇中高原生态宜居城市群具有重要意义。 相似文献
80.