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961.
J. V. Savva E. A. Vaganov 《Mitigation and Adaptation Strategies for Global Change》2006,11(1):269-290
Scots pine provenance trials were established in 1964 in forest-steppe and in 1974 in southern taiga zones of Central Siberia
from seeds collected over whole Russia. Tree-ring characteristics (radial growth and density chronologies) from 12 and 16
provenances planted in those plantations were measured densitometrically. Tree-ring analysis revealed a retention of a genetically
fixed response to climatic factors proper to pines' origin. Trees from higher latitudes keep the orientation towards accelerated
growth at the beginning of a growing season, which is followed by a rapid transition to formation of latewood cells and deceleration
of growth earlier, than in medium-latitude trees. Main climatic factors controlling tree-rings formation differed slightly
between different provenances within plantations. Genetically fixed ability of the provenances are not great (less than 15%),
that proves high adaptability of pines to abrupt climatic change. Tree-ring formation of Scots pine provenances is mainly
determined by the environmental factors. 相似文献
962.
杨树是黄土高原的主要树种之一。本文根据阴山东段不同立地条件下25年生的四种杨树解析木生长量资料,与该地区同时期气候因素进行了关联分析,按关联度大小,选取了八个气候因素作为聚类因子,再将关联度归一化,求得各因子的权重,表示各气候因素对树木生长作用的大小。最后根据黄土高原西部68个气象站1951—1980年的气候资料,应用动态聚类分析法,把黄土高原西部地区划分成几个不同类型林业气候区,区划结果与实际考察基本相符合。 相似文献
963.
Lasco Rodel D. Pulhin Florencia B. 《Mitigation and Adaptation Strategies for Global Change》2000,5(1):81-97
Tropical forests in countries like thePhilippines are important sources and sinks of carbon(C). The paper analyzes the contribution of Philippineforests in climate change mitigation. Since the 1500s,deforestation of 20.9 M ha (106 ha) of Philippineforests contributed 3.7 Pg (1015 g) of C to theatmosphere of which 2.6 Pg were released this century. At present, forest land uses store 1091 Tg(1012 g) of C and sequester 30.5 Tg C/yr whilereleasing 11.4 Tg C/yr through deforestation andharvesting. In the year 2015, it is expected that thetotal C storage will decline by 8% (1005 Tg) andtotal rate of C sequestration will increase by 17%(35.5 Tg/yr). This trend is due to the decline innatural forest area accompanied by an increase intree plantation area. We have shown that uncertaintyin national C estimates still exists because they arereadily affected by the source of biomass and Cdensity data. Philippine forests can act as C sink by:conserving existing C sinks, expanding C stocks, andsubstituting wood products for fossil fuels. Here weanalyze the possible implications of the provisions ofthe Kyoto Protocol to Philippine forests. Finally, wepresent current research and development efforts ontropical forests and climate change in the Philippinesto improve assessments of their role in the nations Cbudgets. 相似文献
964.
城市大气总悬浮颗粒物与城市热岛 总被引:7,自引:3,他引:7
城市大气总悬浮颗粒物是造成全球大部分城市空气污染严重的原因之一,世界各国对之已进行过很多的研究。大量的研究显示,总悬浮颗粒物的污染非常严重,是影响城市空气质量的首要污染物。总悬浮颗粒物的源以人为来源为主,其汇则以湿沉降为主。总悬浮颗粒物对城市气候的影响主要通过2种方式:一种是通过散射或吸收太阳辐射直接影响气候;另一种是以云凝结核的形式改变云的光学特性和云的分布而间接影响气候。但是总悬浮颗粒物与城市热岛相互关系的研究目前还未受到应有的关注,总悬浮颗粒物与城市热岛的相互作用尚未有定论,总悬浮颗粒物既有促进城市热岛形成,也有促进城市冷岛形成的研究报道。文章认为可从如下3个方面探讨总悬浮颗粒物与城市热岛的相互关系:(1)总悬浮颗粒物在城市热岛中的贡献;(2)总悬浮颗粒物影响城市热岛的作用机理;(3)总悬浮颗粒物与城市植被和城市热岛的相互关系及植被对总悬浮颗粒物的净化、对城市热岛的缓解。研究总悬浮颗粒物与城市热岛的相互关系为制定科学合理的城市大气总悬浮颗粒物污染防治措施,有效缓解现代城市热岛难题提供理论依据。 相似文献
965.
Saulo R. Freitas Karla M. Longo Maria A. F. Silva Dias Pedro L. Silva Dias Robert Chatfield Elaine Prins Paulo Artaxo Georg A. Grell Fernando S. Recuero 《Environmental Fluid Mechanics》2005,5(1-2):135-167
The atmospheric transport of biomass burning emissions in the South American and African continents is being monitored annually using a numerical simulation of air mass motions; we use a tracer transport capability developed within RAMS (Regional Atmospheric Modeling System) coupled to an emission model. Mass conservation equations are solved for carbon monoxide (CO) and particulate material (PM2.5). Source emissions of trace gases and particles associated with biomass burning activities in tropical forest, savanna and pasture have been parameterized and introduced into the model. The sources are distributed spatially and temporally and assimilated daily using the biomass burning locations detected by remote sensing. Advection effects (at grid scale) and turbulent transport (at sub-grid scale) are provided by the RAMS parameterizations. A sub-grid transport parameterization associated with moist deep and shallow convection, not explicitly resolved by the model due to its low spatial resolution, has also been introduced. Sinks associated with the process of wet and dry removal of aerosol particles and chemical transformation of gases are parameterized and introduced in the mass conservation equation. An operational system has been implemented which produces daily 48-h numerical simulations (including 24-h forecasts) of CO and PM2.5, in addition to traditional meteorological fields. The good prediction skills of the model are demonstrated by comparisons with time series of PM2.5 measured at the surface. 相似文献
966.
The 2011 Durban Adaptation Charter for Local Governments calls on local governments, worldwide, to institutionalise climate response, with the aim of minimising the impacts of climate change on local livelihoods and vulnerable communities. This paper, through the use of case studies, in-depth interviews and document review, assesses how three non-metropolitan municipalities in KwaZulu-Natal, a district municipality, and two local municipalities under its jurisdiction, are responding to this call. The results suggest that while the municipalities have adopted measures to institutionalise climate responses, the responses are relatively new and implementation is slow, complex and fraught with limitations and competing demands. Furthermore, there appears to be a lack of co-ordination of responses between the two levels of government, which has the potential to lead to duplication. Given the multi-scalar nature of climate change, emphasis on co-ordination and the inclusion of all municipal departments in the development and implementation of responses is necessary. 相似文献
967.
Introduction: Studies thus far have focused on automobile accidents that involve driver distraction. However, it is hard to discern whether distraction played a role if fault designation is missing because an accident could be caused by an unexpected external event over which the driver has no control. This study seeks to determine the effect of distraction in driver-at-fault events. Method: Two generalized linear mixed models, one with at-fault safety critical events (SCE) and the other with all-cause SCEs as the outcomes, were developed to compare the odds associated with common distraction types using data from the SHRP2 naturalistic driving study. Results: Adjusting for environment and driver variation, 6 of 10 common distraction types significantly increased the risk of at-fault SCEs by 20-1330%. The three most hazardous sources of distraction were handling in-cabin objects (OR = 14.3), mobile device use (OR = 2.4), and external distraction (OR = 1.8). Mobile device use and external distraction were also among the most commonly occurring distraction types (10.1% and 11.0%, respectively). Conclusions: Focusing on at-fault events improves our understanding of the role of distraction in potentially avoidable automobile accidents. The in-cabin distraction that requires eye-hand coordination presents the most danger to drivers’ ability in maintaining fault-free, safe driving. Practical Applications: The high risk of at-fault SCEs associated with in-cabin distraction should motivate the smart design of the interior and in-vehicle information system that requires less visual attention and manual effort. 相似文献
968.
为更系统地归纳安全氛围与安全绩效的关系,探究安全氛围、安全绩效及安全结果间的影响机制,采用Meta分析方法,通过2000—2020年54篇文献的55个独立研究样本进行定量综合分析,并进一步探讨安全氛围与安全绩效各维度间的关系,同时运用Meta二元回归探究潜在调节变量对2者间关系的调节作用。结果表明:安全氛围显著正向影响安全绩效,在高危行业中安全氛围对安全绩效影响更大;安全氛围与安全参与、安全遵守均显著正相关,且安全氛围对安全参与的影响强于对安全遵守的影响;安全氛围和安全绩效均与安全结果显著负相关,且安全绩效对安全结果的影响强于安全氛围对安全结果的影响。 相似文献
969.
Yongliang SUN Xiaoyan LI Lianyou LIU Heye XU Dengshan ZHANG 《Frontiers of Environmental Science & Engineering in China》2008,2(3):340-348
The Qinghai Lake Watershed, containing the largest saline lake in northwest of China, has suffered from severe sandy land
development in recent years. This paper analyzes its daily precipitation, temperature, and wind from 1958 to 2001, and the
spatial and temporal distributions of sandy land through the interpretation of remote sensing images covering four years (1977,
1987, 2000, and 2004). Results showed that since the middle of the 1960s, the daily precipitation (P) of 0<P⩽5 mm decreased, while the P>20 mm increased significantly (S<0.05) in their annual total amounts and days. The maximum daily precipitation also increased significantly. Both the maximum
dry spell and the total dry spell of more than ten days had a significant upward trend. Since the beginning of the 1960s,
all the extremely high, extremely low and mean temperatures increased significantly (S<0.01), at a rate of 0.1°C/10a, 0.2°C/10a, and 0.2°C/10a, respectively. The days with extremely high temperature had a significant
upward trend, while the days with extremely low temperature had a significant downward trend. The Qinghai Lake was significantly
shrinking (S<0.01) and provided abundant sediments for Aeolian erosion. The NNW wind prevailed in the watershed, and the largest scale
wind was from the west and concentrated on the dry months. As a result, the sandy land was mainly born on the east bank of
Qinghai Lake. The total sandy land area in the watershed had grown from 587.4 km2, 660.7 km2, 697.6 km2 to 805.8 km2, accordingly, its area percentage growing from 2.0%, 2.2%, 2.4% to 2.7%, respectively. 相似文献
970.
全球气候变暖成因分析 总被引:18,自引:1,他引:17
论述了太阳辐射、大气环流和地表状况是形成气候的3个基本因素.此外,还有人类活动、太阳活动、火山活动等影响气候变化的第4类因子.影响全球气候变暖的因素既有自然因素,也有人为因素.但导致近百年全球气候持续变暖的主要因素是人为因素(人类活动),即自19世纪末工业革命后,世界各国工业化、城市化快速发展,使大气中CO2等“温室效应“气体持续增加,而森林植被遭到大量砍伐和破坏,全球森林植被覆盖率持续下降,平衡大气中CO2与O2的生态功能不断下降,结果导致全球“温室效应“持续增强,使近百年来全球气候持续变暖.自然因素太阳活动对全球气候变暖的影响是周期性而不是持续性的.太阳活动增强期(高峰期)有增温作用,减弱期(低谷期)有降温作用,对全球气候变暖有影响,但比起人类活动造成的CO2等气体“温室效应“持续增强对气候持续变暖的影响相对较小. 相似文献