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1.
中国南方地区水稻生产的变化对国家粮食安全具有重要影响。本文利用Landsat数据提取1990-2015年南方地区水稻种植制度分布及变化,并分析其对粮食产能的影响。结果表明:① 1990-2015年,水稻复种指数从148.3%下降到129.3%,双季稻改种单季稻(“双改单”)损失的播种面积为253.16万hm2,区域上以长江中下游地区变化最为突出。南方地区水稻种植制度整体呈现由北向南“双退单进”的变化格局;② 1990-2015年,“双改单”导致全国水稻产量减少6.1%,粮食产量减少2.6%。水稻主产区湖南省和江西省以及经济发展较好的浙江省因“双改单”水稻减产幅度较大,均超过13%;③ 充分利用“双改单”稻田的粮食产能相当于新增耕地223.3万hm2,为2001-2015年通过土地整治项目新增耕地总量的54%,是2016-2020年全国新增耕地规划目标的1.7倍,可节省约1674.4亿元新增耕地开垦费用。因此,与其追求低质量的“新”耕地,不如充分利用已有的高质量“旧”耕地,政府应转变耕地占补平衡的考核方式,将因提高复种指数增加的播种面积纳入补充指标。  相似文献   

2.
Glaciers and snow are major constituents of solid water bodies in mountains; they can regulate the stability of local water sources. However, they are strongly affected by climate change. This study focused on the Tianshan Mountains, using glacier and snow datasets to analyse variations in glaciers, snow, water storage, and runoff. Three typical river basins(Aksu, Kaidou, and Urumqi Rivers) were selected to interpret the impacts of glacier and snow changes on regional water resources in the Tianshan Mountains. The results exhibited a nonlinear functional relationship between glacial retreat rate and area, demonstrating that small glacial retreat is more sensitive under climate change. Further, the glacial retreat rate at the low-middle elevation zone was seen to be faster than that at the high elevation zone. The regional average terrestrial water storage(TWS) decrease rate in the Tianshan Mountains was –0.7±1.53 cm/a during 2003–2015. The highest TWS deficit region was located in the central part of the Tianshan Mountains, which was closely related to sharp glacial retreats. The increases in glacier and snow meltwater led to an increase in runoff in the three typical river basins, especially that of the Aksu River(0.4×10~8 m~3/a). The decreasing and thinning of areas, and increasing equilibrium line altitude(ELV) of glaciers have been the major causes for the decrease in runoff in the three river basins since the mid-1990 s. Therefore, the results reveal the mechanisms causing the impacts of glaciers and snow reduction in mountains on regional water resources under climate change, and provide a reference for water resources management in the mountainous river basins.  相似文献   

3.
The cultivation of mountainous land results in water loss and soil erosion. With rapid urbanization and industrialization in China, labor emigration relieves the cultivation of mountainous areas in regions with high poverty and leads to a significant land use transition. This research built an analysis framework for "land use transition – driving mechanism – effects –responses" for mountainous areas of China undergoing land use transition and then proposed the direction of mountainous land consolidation. The results showed that the turning point of land use morphology was the core of rural land use transition in mountainous areas. The expansion of cropland and the contraction of forestland have transitioned to the abandonment of cropland and the expansion of forestland; this transition was the main characteristic of the dominant land use change. Land marginalization and land ecological functional recovery were the main characteristics of the recessive land use transition in mountainous areas. Socioeconomic factors were the primary driving forces during land use transition in mountainous areas, with labor emigration being the most direct force. The rising costs of farming and the challenging living conditions causing labor emigration were fundamental driving forces. Rural land use transition in mountainous areas reduced the vulnerability of the ecological function of land ecosystems. The advantages and disadvantages of the socioeconomic effects should focus on rural development of mountainous areas as well as the livelihood of farmers; this should be further supported by empirical and quantitative research. Rural land use transition of mountainous areas improves natural restoration and is related to socioeconomic development. Rural land consolidation of mountainous areas should conform to land use transition,with the goal of shifting from the increase of cultivated land to the synergies of ecological and environmental protection.  相似文献   

4.
The spatio-temporal pattern of the global water resource has significantly changed with climate change and intensified human activities. The regional economy and ecological environment are highly affected by terrestrial water storage(TWS), especially in arid areas. To investigate the response relationships between TWS and changing environments(climate change and human activities) in Central Asia, we used the Gravity Recovery and Climate Experiment(GRACE) data, Climatic Research Unit(CRU) climate data and Moderate Resolution Imaging Spectroradiometer(MODIS) remote sensing data products(MOD16A2, MOD13A3 and MCD12Q1) from 2003 to 2013, as well as the slope and Pearson correlation analysis methods. Results indicate that:(1) TWS in about 77% of the study area decreased from 2003 to 2013. The total change volume of TWS is about 2915.6 × 108 m~3. The areas of decreased TWS are mainly distributed in the middle of Central Asia, while the areas of increased TWS are concentrated in the middle-altitude regions of the Kazakhstan hills and Tarim Basin.(2) TWS in about 5.91% of areas, mainly distributed in the mountain and piedmont zones, is significantly positively correlated with precipitation, while only 3.78% of areas show significant correlation between TWS and temperature. If the response time was delayed by three months, there would be a very good correlation between temperature and TWS.(3) There is a significantly positive relationship between TWS and Normalized Difference Vegetation Index(NDVI) in 13.35% of the study area.(4) The area of significantly positive correlation between TWS and evapotranspiration is about 31.87%, mainly situated in mountainous areas and northwestern Kazakhstan. The reduction of regional TWS is related to precipitation more than evaporation. Increasing farmland area may explain why some areas show increasing precipitation and decreasing evapotranspiration.(5) The influences of land use on TWS are still not very clear. This study could provide scientific data useful for the estimation of changes in TWS with climate change and human activities.  相似文献   

5.
Based on panel data from 1991, 2000 and 2010 at the county level in China, this study analyzed the coupling characteristics and spatio-temporal patterns of agricultural labor changes and economic development under rapid urbanization using quantitative and GIS spatial analysis methods. Three primary conclusions were obtained.(1) During 1991–2010, China's agricultural labor at the county level showed a decreasing trend, down 4.91% from 1991 to 2000 and 15.50% from 2000 to 2010. In spatial distribution, agricultural labor force has evolved by decreasing eastward and increasing westward.(2) During 1991–2010, China's agricultural economy at the county level showed a sustained growth trend, with a total increase of 140.13%, but with clear regional differences. The proportion of agricultural output in national GDP gradually decreased, characterized by decreases in eastern China and increases in western China.(3) The coupling types of economic-labor elasticity coefficient are mainly growth in northwest China, for both the agricultural economy and labor, and are intensive in southeast China, with growth of the agricultural economy and reduction of agricultural labor. Regions with lagged, fading, and declining coupling types are generally coincident with the high incidence of poverty in China. However, different coupling types had a positive developing trend for 1991–2010. Finally, based on the coupling types and spatial distribution characteristics of economic-labor elasticity coefficients, some policy suggestions are proposed to promote the integration of the primary, secondary, and tertiary industries and the vitalization of rural economies.  相似文献   

6.
粮食生产格局是国家粮食安全的基础。自从1978年改革开放以来,中国社会经济的快速发展推动城市化进程不断加快,城乡居民的膳食结构亦发生了显著变化。在这样的背景下,粮食生产格局也发生了较大变化。一是传统的粮食生产南北格局发生变化,"北移"特征明显。1980年南方省区粮食产量占比60%,北方省区占比40%,到2015年北方省区占比56%,南方省区下降为44%;二是东中西部粮食生产呈现"东缩中扩"特征,东部沿海省区粮食生产明显萎缩,中部粮食生产呈扩大态势。1980年东中西部粮食占比分别为38%、36%和26%,到2015年则为27%、46%和27%;三是粮食生产空间集中度增大。1980年全国13个粮食主产省区的总产量占比为69.27%,到2015年达到76.18%,粮食主产区对国家粮食安全的影响力增强。城市化快速发展对粮食播种面积的影响具有显著的区域差异。随着城市化水平提高,东中部和南北方粮食播种面积此消彼长,增减幅度在7%–8%之间。膳食结构变化对粮食生产格局的影响表现在两个方面,一方面粮食消费总量减少,粮食播种面积占农作物播种面积比重从1980年的82%下降为2015年的68%;另一方面,粮食消费结构发生变化,人口直接消费的粮食减少,动物消费的饲料粮扩大。表现为稻谷和小麦种植面积占比下降,饲料粮(主要是玉米)种植面积占比从1980年代的20%增大到36%。未来随着国家粮食生产功能区的建立,粮食生产的空间格局将合理回归,饲料粮需求持续增加但生产扩大的空间有限。  相似文献   

7.
Geographically explicit historical land use and land cover datasets are increasingly required in studies of climatic and ecological effects of human activities. In this study, using historical population data as a proxy, the provincial cropland areas of Qinghai province and the Tibet Autonomous Region(TAR) for 1900, 1930, and 1950 were estimated. The cropland areas of Qinghai and the TAR for 1980 and 2000 were obtained from published statistical data with revisions. Using a land suitability for cultivation model, the provincial cropland areas for the 20 th century were converted into crop cover datasets with a resolution of 1 × 1 km. Finally, changes of sediment retention due to crop cover change were assessed using the sediment delivery ratio module of the Integrated Valuation of Ecosystem Services and Trade-offs(InVEST) model(version 3.3.1). There were two main results.(1) For 1950–1980 the fractional cropland area increased from 0.32% to 0.48% and land use clearly intensified in the Tibetan Plateau(TP), especially in the Yellow River–Huangshui River Valley(YHRV) and the midstream of the Yarlung Zangbo River and its two tributaries valley(YRTT). For other periods of the 20 th century, stability was the main trend.(2) For 1950–1980, sediment export increased rapidly in the Minhe autonomous county of the YHRV, and in the Nianchu River and Lhasa River basins of the YRTT, which means that sediment retention clearly decreased in these regions over this period. The results of this assessment provide scientific support for conservation planning, development planning, or restoration activities.  相似文献   

8.
基于VIC水文模型输出的水文要素数据,采用小波分析法及Mann–Kendall非参数检验,分析了东亚夏季风及海河流域各水文要素的周期性变化情况以及两者之间的潜在关系。结果表明:东亚夏季风和海河流域各水文要素在40年周期尺度上具有一致性;此外,近60年来各水文要素均呈下降趋势,其中环太行山–燕山山脉山前区域趋势最明显,并且均与东亚夏季风关系密切,1970年以来东亚夏季风的持续减弱导致流域内持续干旱及水资源短缺。研究还发现东亚夏季风具有显著80年周期变化,并且可能在2040 s为海河流域带来大量降水。因此,对东亚夏季风的研究可以为预测海河流域水资源变化及管理提供重要的科学参考。  相似文献   

9.
气候变化和人类活动对植被生产力的相对贡献尚未有足够的认识。本研究基于过程模型模拟了2000–2015年气候因子主导的青藏高原高寒草地的总初级生产力(GPPp),并将MODIS的总初级生产力作为人类活动和气候变化共同作用下的总初级生产力(GPPa)。人类活动消耗的总初级生产力(GPPh)等于GPPp减去GPPa。约75.63%和24.37%面积的GPPa分别表现为增加和减少趋势。气候变化和人类活动分别主导了约42.90%和32.72%面积的GPPa的增加。相反,气候变化和人类活动分别主导了约16.88%和7.49%面积的GPPa的减少。草甸的GPPp和GPPh的变化趋势的绝对值分别大于草原的GPPp和GPPh的变化趋势的绝对值。所有海拔的GPPp的变化都大于GPPh的变化,当海拔≥5000m(草甸)、4600m(草原)或4800m(草甸+草原)时,GPPp和GPPh都表现为降低趋势,这表明气候变化主导着海拔5000 m(草甸)、4600 m(草原)、4800 m(草甸+草原)以下的GPPa,而人类活动的减少主导着海拔5000 m(草甸),4600 m(草原)、4800 m(草甸+草原)及其以上海拔的GPPa。因此,GPPa变化的原因随着海拔、区域和草地类型的变化而变化,草地应该采用分类管理。  相似文献   

10.
对农户水稻熟制决策行为差异及其空间特征的研究是理解水稻熟制动态变化、保障区域粮食安全的关键和提出应对策略的前提。利用野外调研与室内统计分析等方法,以鄱阳湖区为研究区,对研究区402例农户问卷调查数据进行实证研究分析。结果表明:(1)湖区水稻种植呈现南北差异,东南部(进贤县等)双季稻种植处于绝对优势,而西北部(德安县等)以单季稻为主;(2)不同县域的水稻熟制选择差异较大,以双季稻农户为主,占受访农户的63.57%,然而复种指数仍然偏低,仅1.55,且有近三成的农户发生了水稻熟制变更。基于以上研究结果,通过种在哪、谁来种、种什么、怎么种等角度出发,鄱阳湖区应该从提高水稻生产比较效益、促进土地流转及适度规模经营和优化水稻种植环境等方面引导、规范农户水稻种植,提高区域水稻复种指数和粮食供给功能,务实农业供给侧改革,进而实现耕地资源高效、可持续利用。  相似文献   

11.
本文在采用经济学分析方法,在理论上解析了农业劳动力非农就业对农地利用的影响。作为理性经济人的农民对劳动力在两个部门的配置和不同质量土地的利用方式上遵循收益最大化原则和"均衡原理"。非农收益较高、劳动力之间存在比较优势,其结果是农地经营的劳动力投入数量和质量降低。劳动力成为农户土地利用决策的主要约束条件,一方面,由于质量较好的土地仍然有较高的经营收益,所以农户不会放弃这些土地的经营,甚至采取集约化利用的方式;另一方面,质量较差的土地容易被粗放化利用,收益极低的土地容易被边际化。本文的分析为农业政策和生态建设政策提供了学术基础。农业劳动力非农就业且务农机会成本上升,将导致质量差的土地退出农业生产,这需要政府决策者应给予高度重视。  相似文献   

12.
China's economy has undergone rapid transition and industrial restructuring. The term "urban industry" describes a particular type of industry within Chinese cities experiencing restructuring. Given the high percentage of industrial firms that have either closed or relocated from city centres to the urban fringe and beyond, emergent global cities such as Shanghai, are implementing strategies for local economic and urban development, which involve urban industrial upgrading numerous firms in the city centre and urban fringe. This study aims to analyze the location patterns of seven urban industrial sectors within the Shanghai urban region using 2008 micro-geography data. To avoid Modifiable Areal Unit Problem(MAUP) issue, four distance-based measures including nearest neighbourhood analysis, Kernel density estimation, K-function and co-location quotient have been extensively applied to analyze and compare the concentration and co-location between the seven sectors. The results reveal disparate patterns varying with distance and interesting co-location as well. The results are as follows: the city centre and the urban fringe have the highest intensity of urban industrial firms, but the zones with 20–30 km from the city centre is a watershed for most categories; the degree of concentration varies with distance, weaker at shorter distance, increasing up to the maximum distance of 30 km and then decreasing until 50 km; for all urban industries, there are three types of patterns, mixture of clustered, random and dispersed distribution at a varied range of distances. Consequently, this paper argues that the location pattern of urban industry reflects the stage-specific industrial restructuring and spatial transformation, conditioned by sustainability objectives.  相似文献   

13.
生境质量变化监测与评价对于生物多样性保护意义重大。为探明云南省拉市海流域的生境变化情况,本文基于SPOT卫星影像提取云南拉市海流域2000年与2015年两期土地利用数据,运用InVEST模型对流域生态退化度、生境质量和生境稀缺性进行评价,采用空间统计方法定量分析了2000–2015年的空间动态变化。结果表明:在研究的15年间,拉市海地区生境退化区总体较少,数量上明显减少,生态退化度呈阶梯式下降;总体上生境质量保持良好并有所提升,少部区域生境质量降低;耕地生境稀缺性增加,人地矛盾突出。拉市海生境质量提升的原因可归结为三个方面:1)当地自2000年起实行的退耕还林政策得到了很好的落实并取得了显著成效,伐木毁林等森林破坏基本杜绝,生态环境得到了恢复;2)较高的林地占比,赋予当地较高生境适宜性本底;3)当地旅游经济的发展,使生态优势转化为经济优势,大幅提高了居民经济收入水平和生活水平;同时生态资源红利的持续发挥,增加了居民生态保护的积极性,保障了森林、湿地及珍贵动植物资源保护,使生态退化减弱,生境质量提升。同时,必须注意到当地人地矛盾的加剧。为持续减轻生态退化,促进生境质量的提升,还需推动生态经济发展,进一步提高居民收入水平,减少生产生活对第一产业的依赖,缓解人地矛盾,从而使流域经济和生态协同发展,保障可持续发展目标。  相似文献   

14.
城市绿地系统作为城市生态系统的一个非常重要的组成部分,在维护城市生态系统稳定、提供生态系统服务以及提高城市环境质量等方面起着积极的作用。本研究以北京市城市区域为例,基于城市绿地空间分布数据和遥感数据,分析了2000-2020年城市绿地景观格局的变化,以及城市绿地生态系统服务及其空间分布的变化,并研究了它们之间的相互作用关系。结果表明:(1)2000-2020年北京城市绿地建设成效较为显著,绿地面积增加了77.41%,主要由耕地和建设用地转变而来。(2)2000-2020年北京城市绿地滞尘量、吸收SO2量、吸收NO2量、降温增湿量、固碳释氧量和暴雨缓排量总体上均呈持续增加的趋势。(3)城市绿地景观变化与绿地生态系统服务之间关系密切,斑块总面积与生态系统服务的相关性最高,除暴雨缓排外,斑块总面积与各项生态系统服务之间的相关系数均高于0.85。研究结果可以为优化北京绿地、更大程度发挥绿地对生态环境的改善作用提供理论指导,为北京市的生态环境建设提供科学依据。  相似文献   

15.
Land use and land cover change(LULCC) strongly influence regional and global climate by combining both biochemical and biophysical processes. However, the biophysical process was often ignored, which may offset the biogeochemical effects, so measures to address climate change could not reach the target. Thus, the biophysical influence of LULCC is critical for understanding observed climate changes in the past and potential scenarios in the future. Therefore, it is necessary to identify the mechanisms and effects of large-scale LULCC on climate change through changing the underlying surface, and thus the energy balance. The key scientific issues on understanding the impacts of human activities on global climate that must be addressed including:(1) what are the basic scientific facts of spatial and temporal variations of LULCC in China and comparative countries?(2) How to understand the coupling driving mechanisms of human activities and climate change on the LULCC and then to forecasting the future scenarios?(3) What are the scientific mechanisms of LULCC impacts on biophysical processes of land surface, and then the climate?(4) How to estimate the contributions of LULCC to climate change by affecting biophysical processes of land surface? By international comparison, the impacts of LULCC on climate change at the local, regional and global scales were revealed and evaluated. It can provide theoretical basis for the global change, and have great significance to mitigate and adapt to global climate changes.  相似文献   

16.
The North China Plain is one of the most water-stressed areas in China. Irrigation of winter wheat mainly utilizes groundwater resources, which has resulted in severe environmental problems. Accurate estimation of crop water consumption and net irrigation water consumption is crucial to guarantee the management of agricultural water resources. An actual crop evapotranspiration(ET) estimation model was proposed, by combining FAO Penman-Monteith method with remote sensing data. The planting area of winter wheat has a significant impact on water consumption; therefore, the planting area was also retrieved. The estimated ET showed good agreement with field-observed ET at four stations. The average relative bias and root mean square error(RMSE) for ET estimation were –2.2% and 25.5 mm, respectively. The results showed the planting area and water consumption of winter wheat had a decreasing trend in the Northern Hebei Plain(N-HBP) and Southern Hebei Plain(S-HBP). Moreover, in these two regions, there was a significant negative correlation between accumulated net irrigation water consumption and groundwater table. The total net irrigation water consumption in the N-HBP and S-HBP accounted for 12.9×10~9 m~3 and 31.9×10~9 m~3 during 2001–2016, respectively. Before and after 2001, the decline rate of groundwater table had a decreasing trend, as did the planting area of winter wheat in the N-HBP and S-HBP. The decrease of winter wheat planting area alleviated the decline of groundwater table in these two regions while the total net irrigation water consumption was both up to 28.5×10~9 m~3 during 2001–2016 in the Northwestern Shandong Plain(NW-SDP) and Northern Henan Plain(N-HNP). In these two regions, there was no significant correlation between accumulated net irrigation water consumption and groundwater table. The Yellow River was able to supply irrigation and the groundwater table had no significant declining trend.  相似文献   

17.
Rice(Oryza sativa L.) is the most important staple crop of China, and its production is related to both natural condition and human activities. It is fundamental to comprehensively assess the influence of terrain conditions on rice production to ensure a steady increase in rice production. Although many studies have focused on the impact of one or several specific factors on crop production, few studies have investigated the direct influence of terrain conditions on rice production. Therefore, we selected Hunan Province, one of the major rice-producing areas in China, which exhibits complex terrain conditions, as our study area. Based on remote sensing data and statistical data, we applied spatial statistical analysis to explore the effects of terrain factors on rice production in terms of the following three aspects: the spatial patterns of paddy fields, the rice production process and the final yield. We found that 1) terrain has a significant impact on the spatial distribution of paddy fields at both the regional scale and the county scale; 2) terrain controls the distribution of temperature, sunlight and soil, and these three environmental factors consequently directly impact rice growth; 3) compared with the patterns of paddy fields and the rice production process, the influences of terrain factors on the rice yield are not as evident, with the exception of elevation; and 4) the spatial distribution of paddy fields mismatched that of production resources due to terrain factors. Our results strongly suggest that managers should scientifically guide farmers to choose suitable varieties and planting systems and allocate rice production resources in the northern plain regions to ensure food security.  相似文献   

18.
目前,关于里海的两个主要问题是水位变化及其生态条件。历史上,里海的海水入侵和衰退对该区域的生活和生产有很大影响。应用地质数据、历史数据和考古数据,以及观测数据,本文对地质历史时期里海水位的变化、年度和季度变化以及短期的波动进行了研究。文章对解释里海水位波动的两种不同的方法进行了论述,并认为里海水位变化是受地质、水文气候和水量平衡以及人类活动等因素的影响的多级过程,其中主要影响因素为水文气候的变化。  相似文献   

19.
本文运用文献计量方法对1992-2019年在Web of Science数据库中发表的耕地撂荒领域的910篇文献进行总量和关键词分析,并根据关键词领域从耕地撂荒监测与制图、驱动力与影响因素、效应评估与权衡三个方面进行主题综述。研究发现:(1)目前撂荒耕地的提取与制图渠道以农户调研与遥感技术为主,结合空间信息的NDVI时间序列撂荒地提取方法具有较高精度;(2)从作用程度、来源、属性三个维度对耕地撂荒的驱动力和影响因素进行归纳,发现耕地边际化是耕地撂荒的根本驱动力,劳动力析出是耕地撂荒的直接驱动力,社会经济因素是主要驱动力;(3)耕地撂荒的环境效应具有空间异质性,时空差异、景观环境、气候、耕种、地形特征均会对耕地撂荒的环境效应起决定作用;耕地撂荒效应权衡主要集中在生态系统服务功能和价值领域,但相关空间背景的作用往往被忽略。在系统梳理现有文献的基础上,本文从开展全国层面的撂荒耕地调查、开展多尺度的撂荒驱动力研究、结合国情开展撂荒效应权衡研究等方面对未来耕地撂荒研究进行展望。  相似文献   

20.
The lake hydrological and meteorological data of the Tibetan Plateau are not rich. This research reports the observed climatic data and measured water levels of saline lakes from the local meteorological stations in the Zabuye salt lake, the Dangqiong Co salt lake and the Bankog Co salt lake in recent two decades. Combining with satellite remote sensing maps, we have analyzed the changes of the water level of these three lakes in recent years and discussed the origins of the changes induced by the meteorological factors. The results show that the annual mean temperature and the water level reflect a general ascending trend in these three lakes during the observation period. The rising rates of the annual mean temperature were 0.08℃/yr during 1991–2014 and 0.07℃/yr during 2004–2014, and of the water level, were 0.032 m/yr and 0.24 m/yr, respectively. Analysis of changes of the meteorological factors shows the main cause for the increase of lake water quantity are the reduced lake evaporation and the increased precipitation in the lake basins by the rise of average temperature. Seasonal variation of lake water level is powered largely by the supply of lake water types and the seasonal change of regional climate.  相似文献   

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