共查询到20条相似文献，搜索用时 15 毫秒
1.
北极资源的开发与利用 总被引：1，自引：0，他引：1
随着全球气候加速变暖,北极冰雪融化,使得北极地区蕴藏的丰富的石油矿产资源的开发日益成为可能,不少国家都开始注意这块“香饽饽”,北极地区也随之展开了激烈的争夺战. 相似文献
2.
3.
Responses of crop yield and water use efficiency to climate change in the North China Plain 总被引：5，自引：0，他引：5
Based on future climate change projections offered by IPCC, the responses of yields and water use efficiencies of wheat and maize to climate change scenarios are explored over the North China Plain. The climate change projections of 21st century under A2A, B2A and A1B are from HadCM3 global climate model.A climate generator (CLIGEN) is applied to generate daily weather data of selected stations and then the data is used to drive CERES-Wheat and Maize models. The impacts of increased temperature and CO2 on wheat and maize yields are inconsistent. Under the same scenario, wheat yield ascended due to climatic warming, but the maize yield descended. As a more probable scenario, climate change under B2A is moderate relative to A2A and A1B. Under B2A in 2090s, average wheat yield and maize yield will respectively increase 9.8% and 3.2% without CO2 fertilization in this region. High temperature not only affects crop yields, but also has positive effect on water use efficiencies, mainly ascribing to the evapotranspiration intensification. There is a positive effect of CO2 enrichment on yield and water use efficiency. If atmospheric CO2 concentration reaches nearly 600 ppm, wheat and maize yields will increase 38% and 12% and water use efficiencies will improve 40% and 25% respectively, in comparison to those without CO2 fertilization. However, the uncertainty of crop yield is considerable under future climate change scenarios and whether the CO2 fertilization may be realized is still needed further research. 相似文献
4.
《灌溉排水学报》2019,(12)
【目的】评价2000—2018年黄河源植被变化趋势及其影响因素。【方法】基于MOD12A5数据,土地利用数据以及同德、玛多、泽库、达日、若尔盖、河南、玛沁、久治和红原9个气象站点的气象数据等,采用趋势分析和相关分析等方法,研究了2000―2018年黄河源植被叶面积指数(LAI)时空变化特征及与气候因子的关系。【结果】①2000―2018年黄河源植被LAI呈上升趋势,其绝对变化率和相对变化率分别为0.09/10 a和0.4%。②2000年时土地利用类型为裸地的区域植被状况正逐渐改善,但局部草地、林地和沼泽仍处于退化趋势。③黄河源年LAI值与气温、降水均呈正相关关系,其中温度有显著影响,气候因子的协调关系和年内时空分配也会极大地影响植被生长,而气候长期趋暖将会给源区植被带来更为复杂的问题和挑战。④生态治理工程实施较好的自然保护区(如鄂陵湖-扎陵湖自然保护区)植被呈明显改善趋势。【结论】气候暖湿化和生态治理工程可能是黄河源植被恢复的主要原因。 相似文献
5.
根河流域1980-2017年气候和径流的变化特征分析 总被引：2，自引：0，他引：2
根河流域处于我国寒温带地区,气候和自然环境较为特殊,分布着大面积冻土,对于气候变化非常敏感。【目的】通过分析根河流域气象要素和径流的变化,探讨气候和水文之间的相互关系,为该流域的水资源科学管理提供理论依据。【方法】以额尔古纳水系根河流域为研究对象,利用M-K检验和Hurst指数等方法,分析根河流域1980-2017年气象要素和径流的变化趋势及相互作用关系。【结果】①根河流域年平均气温在1980―2017年,共上升了1.10℃,在α=0.01的水平上呈上升趋势,且上升趋势有较强的持续性(H=0.75)。其中,生长季的气温变化最为强烈(Z=4.63)。②根河流域生长季降水量占年降水量的85%,趋于下降趋势,下降幅度为1.68 mm/a。③根河流域始冻期和完全冻结期的空气相对湿度分别α=0.001和α=0.01的水平上显著下降,且下降趋势有很强的持续性(H=1.0),变化幅度为0.05%/a。④根河流域径流量趋于下降趋势,在1997年和1999年发生突变,不年降水量发生突变的时间基本吻合,且降雨不径流的变化趋势一致,相关性分析表明,降雨不径流的相关系数为0.91。⑤根河流域径流量不年均气温相关系数为0.50,气温主要以增加流域各因子的蒸散发以及土壤和河流冻结、融化的时间或面积来影响流域径流量。【结论】根河流域降水量和径流在1980―2017年没有很大的变化趋势,气温呈猛烈的上升趋势,流域气候整体上趋于夏季越来越干冷,冬季干热的趋势。 相似文献
6.
特色林果业是新疆南部地区农业农村经济发展的支柱产业。质量安全是林果产业赖以发展的基础，也是新疆特色林果产业转型升级的重要保障。自21世纪初以来，新疆特色林果产业经历了由“扩大面积、提高产量”向“稳定面积、提质增效”的转变。然而，新疆特色果品仍然面临质量安全标准体系不健全，危害隐患不清晰、风险分析与控制技术手段相对落后，高效实时监测、追溯与预警手段缺乏等问题，造成目前“从果园到餐桌”全链条危害因子全程控制等理论与技术严重不足，特色林果产品以质论价、优质优价的实现机制尚未建立。建议:①尽快健全果品质量安全标准体系、检验检测体系与风险评估体系；②构建果品追溯管理大数据平台，建立健全质量安全全程追溯体系；③扎实推进果品全产业链执法监管体系建设；④加快果品质量安全信用与诚信体系和培训体系建设。 相似文献
7.
《Agricultural Systems》2005,85(3):306-323
This study is about changes in land use and interactions of land use change and livelihoods in the Chagga farming system on the slopes of Mt. Kilimanjaro, Tanzania. An aerial photo interpretation and fragmentation analysis of the years 1961, 1982 and 2000 was conducted covering approximately the Kirua Vunjo Division, a transect of 152 km2 from the forest reserve edge to the plains. Earlier changes were traced from literature review. The results show the expansion of cultivation to more marginal land down the slope, the disappearance and extreme fragmentation of bush land and appearance and expansion of settlements. The home garden area has experienced some specific internal change, but has not expanded down the slope. In the 1960s there were small open fields and patches of grazing lands amongst home gardens. In the 1980s the area was more uniformly covered by homegardens. Since then it has become patchy again as new homesteads have been built on subdivided farms and more food is produced on the higher slopes. Population pressure and the ensuing expansion of agriculture to more marginal land, intensification of the homegarden system, together with climate changes affecting the water supplies, have caused changes in farmers’ livelihoods. As land scarcity now hinders expansion of agriculture, farm size has seriously decreased, common resources have become scarce, and prices of coffee in the world market remain low, farmers are trying to intensify and diversify their farm production. Local initiative is leading to change, but the locally conceived alternatives are too few and lack integrated approaches of technical agricultural research, economic analysis, and policy studies and reforms. Non-agricultural activities and paid employment are becoming increasingly important. However, due to considerable entry barriers to remunerable off-farm jobs, not all households enjoy equal access to attractive non-farm opportunities. The future welfare of the area will depend on increasing the marketable knowledge and skills of the population that will enable it to become integrated in the economy of the region and the country. 相似文献
8.
《Agricultural Systems》2006,89(2-3):332-359
What is causing the increasing densities of native shrubs, or so-called ‘woody weeds’, in some semi-arid pastoral lands and how might they be most effectively managed? This question has been on the rangeland policy agenda in Australia for more than one hundred years. This paper describes a fresh examination of this question using a systems approach. A key component of the approach involved ‘mapping the problem’. Using a systems-based approach, landholders developed four system diagrams broadly describing the ecology of woody weed re-occurrence, control options, property economics and management constraints with diagrams identifying how different factors related to, or influenced, each other. Agency personnel also constructed a system diagram describing institutional and regulatory constraints, and their interactions. Later, all these system diagrams formed the basis for an adaptive management model with capabilities for developing and quantitatively evaluating alternative management strategies relating to woody weeds. This model is called the Woody Weed Planner.The Woody Weed Planner contains mathematical relationships developed through field experimentation over the last 25–50 years covering the ecology of woody weeds, control options and control economics. These relationships enable the user to generate mathematical responses as a result of changing model parameters. A key component of the model is the ability to simulate the effects of alternative management responses given different rainfall scenarios. To enable this to occur, the Planner allows the user to replay historical rainfall patterns and ask the question “what impact will these have on woody weeds, stocking rates and economic performance on my property?” 相似文献
9.
半干旱黄土区典型林地土壤水分消耗与补给动态研究 总被引：2，自引：2，他引：0
通过对半干旱黄土丘陵沟壑区几种典型林地生长季土壤水分进行动态监测,研究不同林种对土壤水分消耗和补给的影响。结果显示,土壤总含水率大小依次为草地、沙棘、河北杨、油松、山杏,并且这一次序主要来源于120 cm深度(相对稳定层)以下的差异;不同林地及草地土壤含水率季节变化表现基本一致,3—8月波动下降,8—10月持续上升;各林地及草地土壤水分在0~60 cm内变化活跃,60~120 cm内由上至下逐渐趋于稳定,120~200 cm内保持相对稳定;林种、土壤深度、月份3种因素单独作用和交互作用均造成土壤水分差异显著;水分补给期后各林地土壤水分仍处于一定亏缺状态。 相似文献
10.
【目的】明晰全球气候变化和退耕还林还草工程实施背景下的毛乌素沙地的地表温度的演变规律及其影响因素。【方法】基于地理空间数据云提供的2000—2015年MOSLT1M中国1 km地表温度和在NASA下载的2016—2019年MODIS/TERRA卫星的MOD11A2地表温度数据集,利用线性回归斜率法对2000—2019年毛乌素沙地的地表温度时空特征进行分析,并探究了地表温度与气候、土地利用类型和植被指数的相关性。【结果】毛乌素沙地的地表温度在空间分布上存在明显差异,从西北到东南逐渐降低,西部高于东部的总体变化趋势,在时间序列上,总体呈下降趋势,下降速率为0.59℃/(10a);毛乌素沙地年均地表温度与气温波动趋势大体一致,二者在2000—2005、2005—2009、2009—2013年时间段均出现先降低后升高的规律,且2003、2012年同为极小值点;地表温度受土地利用类型变化影响较大,不同土地利用类型的地表温度差异明显,建设用地和未利用地的地表温度最高,其次是草地和林地,最后是耕地和水域;地表温度与NDVI的变化趋势呈负相关,决定系数为0.5131;毛乌素沙地的地表温度的时空变化趋势... 相似文献
11.
《Agricultural Water Management》2006,82(3):297-317
Changes in water and nitrogen management for spring barley and potato, arising from possible climate change in Ireland, were assessed using simulation models. The locations in Ireland with the highest proportion (by area) of barley and potato production were identified and 1961–1990 and 2041–2070 monthly climate data were used to drive mechanistic crop models. Nitrogen and water response curves were created using current recommended management guidelines as a starting point. A series of step-wise manual irrigation simulations were then undertaken to estimate the minimum future irrigation demand for specific areas. It was concluded that there will be little impact on spring barley production, but in some areas (towards the centre and western half of Ireland) it might be possible to reduce nitrogen application rates by half. The impact of climate change on potato production will be more pronounced: without irrigation yield will only remain viable in areas where rainfall remains high, elsewhere between 150 and 300 mm of irrigation will be required each year, but this might be offset by the possibility of reducing nitrogen inputs by up to half. It was also concluded that potato production on less suitable (heavier) soils would be less desirable if irrigation is required because of possible run-off losses that may occur. 相似文献
12.
O. Marinoni J. Navarro GarciaS. Marvanek D. PrestwidgeD. Clifford L.A. Laredo 《Agricultural Systems》2012,105(1):33-45
Policy makers in the agricultural sector are confronted with challenges which might drive land use change and ultimately agricultural profitability to a substantial degree. The challenges include questions around climate variability, demographic changes, use of land for bio-fuel production and ensuring an increase in food production. As profitability triggers many agri-business decisions, knowledge about the existing socio-economic landscape and the economic profile of a region as well as potential impacts on profits provides useful contextual information when agricultural policies are designed. Given the upcoming challenges and their associated uncertainties, it is important to ensure that a map of agricultural profit can be reproduced in a scenario and simulation setting which will allow exploring uncertainties around the impacts on agricultural profits as well. There is however currently no flexible system in operation which allows for a consistent update of a map of agricultural profits in Australia or elsewhere. This paper describes a process that has been developed to produce a map of agricultural profit for Australia for the year 2005/2006. The process involves a complex data architecture that accounts for heterogeneous information that is collected by a variety of institutions across different scales. All information can be comfortably queried and query results can be forwarded for immediate processing and subsequent visualisation in a geographic information system (GIS). To facilitate the production of profit maps in the future, the system provides flexibility regarding an update of new economic information but it can also be linked to maps that show an updated distribution of land use. A map of agricultural profit on a large scale and regular updates thereof will help understand profit trends in time and across space. It will help identifying regions that have a lower economic profile and will inform decisions regarding the design of regulatory policies. As these maps are developed using national scale data, we do not recommend using the results at the farm level but we suggest using separate catchment scale profit assessments to calibrate the national scale profit map. The proposed system is well suited to be used in various land use management and economic scenarios and will represent a step forward regarding a scenario impact assessment on agricultural profits. It will also help understand the economic benefit of land use on a large scale. 相似文献
13.
Adapting to climate change: Agricultural system and household impacts in East Africa 总被引：4，自引：0，他引：4
The East African region exhibits considerable climatic and topographic variability. Much spatial and temporal variation in the response of different crops to climate change can thus be anticipated. In previous work we showed that a large part of this variation can be explained in terms of temperature and, to a lesser extent, water effects. Here, we summarise simulated yield response in two crops that are widely grown in the region, maize and beans, and investigate how the impacts of climate change might be addressed at two levels: the agricultural system and the household. Regionally, there are substantial between-country and within-system differences in maize and bean production responses projected to 2050. The arid-semiarid mixed crop-livestock systems are projected to see reductions in maize and bean production throughout most of the region to 2050. Yields of these crops in the tropical highland mixed systems are projected to increase, sometimes substantially. The humid-subhumid mixed systems show more varied yield responses through time and across space. Some within-country shifts in cropping away from the arid-semiarid systems to cooler, higher-elevation locations may be possible, but increased regional trade should be able to overcome the country-level production deficits in maize and beans caused by climate change to 2050, all other things being equal. For some places in the tropical highlands, maize and bean yield increases could have beneficial effects on household food security and income levels. In the other mixed systems, moderate yield losses can be expected to be offset by crop breeding and agronomic approaches in the coming decades, while more severe yield losses may necessitate changes in crop types, movement to more livestock-orientated production, or abandonment of cropping altogether. These production responses are indicative only, and their effects will be under-estimated because the methods used here have not accounted for increasing weather variability in the future or changes in the distribution and impacts of biotic and other abiotic stresses. These system-level shifts will take place in a context characterised by high population growth rates; the demand for food is projected to nearly triple by the middle of this century. Systems will have to intensify substantially in response, particularly in the better-endowed mixed systems in the region. For the more marginal areas, the variability in yield response, and the variability in households’ ability to adapt, suggest that, even given the limitations of this analysis, adaptation options need to be assessed at the level of the household and the local community, if research for development is to meet its poverty alleviation and food security targets in the face of global change. 相似文献
14.
Daniel H. Phillips Yvonne Reinink Timothy E. Skarupa Charles. E. Ester III Jon A. Skindlov 《Irrigation and Drainage Systems》2009,23(2-3):109-124
The Salt River Project (SRP) was created in the early 1900s to assure an adequate water supply for its shareholders in the Salt River Valley, Arizona, USA. The straight forward job of storing inflows and meeting demand from a single reservoir system soon became more complex. As the population of the Salt River Valley swelled, additional reservoirs were added to the system, alternative supplies of water were developed, and hydro-power generation became a financial consideration in reservoir operations. Nevertheless, the primary operational objective continues to be the conjunctive management of multiple sources of water to ensure an adequate carry-over supply of water for SRP’s shareholders in the Salt River Valley. This objective has traditionally been accomplished by managing the reservoir system as if each time the reservoirs fill to capacity is the beginning of an extended drought comparable to the worst historical drought in recorded history. Over the past 20 years, several subtle yet significant events have taken place which raise concerns regarding SRP’s traditional method of water planning and management. Changes in demand patterns as land is converted from mainly agricultural use to urban use, an ongoing drought rivaling the historical drought of record, tree-ring studies suggesting even more severe droughts having occurred in pre-historic times and, the specter of a changing climate due to global warming all suggest that a business as usual approach to water management and planning may no longer be appropriate. 相似文献
15.
Impacts of population growth, economic development, and technical change on global food production and consumption 总被引：3，自引：0，他引：3
Uwe A. Schneider Petr HavlíkErwin Schmid Hugo ValinAline Mosnier Michael ObersteinerHannes Böttcher Rastislav SkalskýJuraj Balkovi? Timm SauerSteffen Fritz 《Agricultural Systems》2011,104(2):204-215
Over the next decades mankind will demand more food from fewer land and water resources. This study quantifies the food production impacts of four alternative development scenarios from the Millennium Ecosystem Assessment and the Special Report on Emission Scenarios. Partially and jointly considered are land and water supply impacts from population growth, and technical change, as well as forest and agricultural commodity demand shifts from population growth and economic development. The income impacts on food demand are computed with dynamic elasticities. Simulations with a global, partial equilibrium model of the agricultural and forest sectors show that per capita food levels increase in all examined development scenarios with minor impacts on food prices. Global agricultural land increases by up to 14% between 2010 and 2030. Deforestation restrictions strongly impact the price of land and water resources but have little consequences for the global level of food production and food prices. While projected income changes have the highest partial impact on per capita food consumption levels, population growth leads to the highest increase in total food production. The impact of technical change is amplified or mitigated by adaptations of land management intensities. 相似文献
16.
为了解林窗特征及其空间分布对森林结构优化和功能恢复的重要驱动作用,以湖南省亚热带阔叶林为研究对象,根据长期监测数据,综合利用描述性统计方法、Ripley’s K函数和空间点模式分析方法,量化分析自然干扰林窗和人为干扰林窗的结构特征、空间分布模式以及影响林窗分布的空间变量。结果表明,林窗平均面积为78.9 m^2,林窗平均密度为12.8个/hm^2,与人工林相比,次生林呈现出林窗面积较小、密度较大、形状较复杂等特点;不同干扰类型的林窗在面积、形状和林下植被高度等特征上存在较大差异;林窗在空间分布模式上也有差异,但在大尺度上都呈现出聚集分布模式;次生林林窗分布的主要影响因素是坡度和坡位,而人工林林窗分布的主要影响因素是坡度、林分密度和可达度(与最近道路距离)。研究结果可为适应气候变化的森林经营提供方法借鉴和技术支撑。 相似文献
17.
R.L. McCown 《Agricultural Systems》1981,6(4):303-317
This is the first of a series of papers dealing with a survey of the agricultural climate as it pertains to the beef cattle industry in northern Australia. Beef cattle production here, as in most of the tropics, is characterised by an annual periodicity of weight gain and loss in train with seasonal water supply and temperatures. Trends in a weekly growth index derived from a simulated water budget and mean daily temperatures were found to correlate with trends in liveweight changes. Criteria for estimating the start and cessation of a ‘green season’ and a ‘dry season’, corresponding to the main liveweight gain and loss periods respectively, are derived and validated using cattle liveweight data from seven locations and both native and improved pastures. Linkage between cattle liveweight change and climate was close on native grass pastures but not on legume-improved pastures. 相似文献
18.
《京都议定书》框架下的碳减排机制,主要有太阳能、风能、水能及地热能等的利用,碳捕获与碳封存技术（CCS）,工业减排和碳汇林的种植等。事实证明,上述机制没有改变也不能遏制大气中CO2急剧上升的态势。为此,笔者首次提出碳汇草的碳汇机制和界定方法。碳汇草通过多次刈割封存,可实现生物质的飞跃大增产。经中国质量认证中心核算,碳汇草每年的净碳汇量为210 thm2,碳汇量巨大。目前,全球森林面积在不断减少,碳储总量不断下降,开发新的碳汇机制迫在眉睫。由于森林不能刈割封存,碳汇草50年的“碳汇增量”,是相同面积森林“碳汇增量”的约650倍,可实现大气CO2负增长。据测算,大气中CO2总量约3.11万亿t,封存6 661亿t植物碳产品可捕碳9 725亿t,CO2浓度即可从当前的0.04%降低到工业革命前的0.027 5%;仅需边际性土地、污染需治理土地、湿地与水面等约1亿hm2种植面积。项目的实施,可降低和提前CO2峰值,调节温室效应,消除雾霾,减缓全球气候变暖,创造巨大的生态效益、社会效益和经济效益,实现经济社会发展、环境保护与应对气候变化的共赢。 相似文献
19.
【目的】揭示内陆河流域集水区土地利用/覆被变化对水文过程的影响及其成因。【方法】基于能够逐年调用土地利用/覆被数据的LU-SWAT模型,并结合控制变量法研究了黑河流域集水区黑河上游1990—2009年土地利用/覆被变化对地表径流、侧向流、蒸散发量、地下径流以及总产水量的影响。【结果】LU-SWAT模型对于黑河上游月、年出山径流模拟结果较好,其月径流模拟的纳什系数为0.93,相关性系数为0.94;其年径流模拟的纳什系数为0.83,相关性系数为0.86。此外,其对各个水文要素的模拟结果符合西北干旱区内陆河流域集水区的水文特征;1990—2001年黑河上游土地利用变化主要表现在林地的减少,而2002—2009年土地利用的变化除了林地和草地的增加之外,还表现在裸地的大面积减少;1990—2001年黑河上游地表径流、侧向流、蒸散发量以及总产水量都呈现增加趋势,而地下径流呈减少趋势,2002—2009年流域地表径流、侧向流、蒸散发量以及总产水量减少,而地下径流量增加。在黑河上游,干旱条件下各水文要素对于土地利用覆被变化的响应更明显。【结论】1990—2001年林地的减少可能是流域地表径流、侧向流、蒸散发量以及总产水量都呈现增加趋势而地下径流呈减少趋势的主要原因。2002—2009年裸地的大面积减少可能是流域地表径流、侧向流、蒸散发量以及总产水量减少而地下径流量增加的主要原因。 相似文献
20.
Comparison of soil water content and corn yield in furrow and conventional ridge sown systems in a semiarid region of China 总被引：2，自引：0，他引：2
Water deficits and unusually warm soil temperatures can adversely affect conventional ridge sown systems. Increasingly serious water and temperature issues associated with global climate change may be problematic in the future, particularly in semiarid regions. This study explored the soil water and crop yield benefits of switching the sowing location of corn from ridges to furrows. Experiments were conducted over three years. Corn was grown in shallow furrow (SF) and deep furrow (DF) sown treatments until the V8 stage (eight visible leaf collars). New ridges were then built over the existing furrows. Grain yield was found to be higher in the SF and DF sown treatments than in a conventional ridge sown treatment (CR), especially in drought years. Switching sowing position from ridge to furrow could increase corn yield, directly, by improving soil moisture early in the growing season and, indirectly, by stimulating the growth of resource-capturing organs (e.g., leaves and roots). This simple and efficient approach to crop production in semiarid climates may be practical for the management of numerous agricultural systems, particularly those that are resource-limited, with greater vulnerability to the effects of global climate change. 相似文献