灾区恢复重建后效评估研究进展

随着全球变化加剧,世界各地自然灾害的频发,国际社会为应对自然灾害进行了不懈努力,历届世界减灾大会不断强调对应急管理全流程的研究,恢复重建作为应急管理的重要环节而得到广泛重视。积极开展灾区恢复重建后效评估有利于保障灾区恢复重建实施与区域可持续发展。灾区恢复重建后效评估研究时间较短,首先比较分析了国内外恢复重建的内涵,明确了恢复重建后效评估的基本概念,并梳理了灾区恢复重建后效评估的在中国的发展演变。由于灾区恢复重建内容复杂多样,本文结合灾区恢复重建后效评估的发展历程、研究范围与关注时段,分别从项目、要素与可持续性三个关键视角对后效评估的理论方法等展开评述,结果表明:(1)项目后效评估在灾区恢复重建后效评估中起步较早,现有评估多集中于居民住房、基础设施、公共设施等工程质量的评估,但缺乏对项目设计过程中社会居民参与度、公众满意度以及社会经济效益等的评估。(2)要素后效评估在灾区恢复重建后效评估中涉及范围最广,具体包括社会、经济与环境等要素,这些要素的评估受政策绩效影响较大,后期需要构建综合的评估体系以开展科学评估。(3)可持续性后效评估以联合国可持续发展目标与地方国民经济与社会发展计划为基础构建评估框架,有利于促进灾区的可持续发展。通过综合分析《仙台减轻灾害风险框架》中"重建的更好"(BBB)理念,联合国可持续发展目标(SDGs)以及《巴黎协定》适应全球变化等诉求,结合当前灾区恢复重建后效评估现状进行展望,以期为灾区恢复重建与可持续发展提供一个更为系统、综合的技术参考。

全球历史LUCC数据集新疆地区耕地数据可靠性评估

全球历史土地利用/覆被变化数据是开展长时段气候与生态效应模拟研究的科学基础,然而,现有全球LUCC数据集在区域尺度上仍存在较大不确定性。结合区域土地垦殖史实评估全球数据集的可靠性,是改进数据集质量的基础和前提。文章以中国学者利用区域历史文献和土地资源调查数据重建的清中后期(1776—1909年)奇台-吉木萨尔地区、清末民国时期(1909—1944年)玛纳斯河流域和建国以来(1960—2000年)新疆地区耕地数据为基准,结合清康乾时期(1716—1778年)区域屯田点数据,采用趋势对比、数量对比和空间格局对比相结合的方法,对全球数据集中新疆地区耕地数据的可靠性进行了评估。结果表明,HYDE 3.2和SAGE数据集中清代以来新疆地区的耕地数据与区域重建结果相比,虽然耕地变化趋势均呈增加态势,但数量上差异较大。其中,HYDE3.2数据集在奇台-吉木萨尔地区的耕地数据存在明显低估,仅为区域数据的0.04—0.56;而在玛纳斯河流域地区,HYDE3.2和SAGE中的耕地数据又存在明显高估,分别为区域数据的3.08—8.95和4.80—5.12;与之相比,1960年以来全球数据集中新疆地区的耕地数据与区域数据差异有减小趋势,分别为陈氏数据的0.67—0.75和0.71—1.05。从耕地空间分布格局看,清康乾时期新疆地区屯田点扩散过程及区域垦殖史实均表明该区土地垦殖经历了“从南到北,由东向西”逐步推进的历史过程,且在清前期北疆地区仍以游牧为主,而该时期全球数据集中北疆地区已有较多耕地分布,且分别占到区域耕地总量的42.84%和61.26%。可见,全球数据集中新疆地区耕地数据未能客观反映该区域耕地变化的过程与格局特征,而数据来源和重建方法的差异是造成不同全球与区域性数据集结果差异的主要原因。

过去千年黄河中下游地区耕地覆被变化定量重建

Landscape in the middle and lower reaches of the Yellow River in China has un-dergone significant changes for thousands of years due to agricultural expansion.Lack of reliable long-term and high-resolution historical cropland data has limited our ability in un-derstanding and quantifying human impacts on regional climate change,carbon and water cycles.In this study,we used a data-driven modeling framework that combined multiple sources of data(historical provincial cropland area,historical coastlines,and satellite da-ta-based maximum cropland extent)with a new gridding allocation model for croplands dis-tribution to reconstruct a historical cropland dataset for the middle and lower reaches of the Yellow River at a 10-km resolution for 58 time points ranging from the period 1000 to 1999.The cropland area in the study area increased by 2.3 times from 21.87 million ha in 1000 to 50.64 million ha in 1999.Before 1393,the area of cropland increased slowly and was pri-marily concentrated in the Weihe and Fenhe plains.From 1393-1820,the area of cropland increased rapidly,particularly on the North China Plain.Since 1820,cropland cover has tended to become saturated.Our newly reconstructed results agreed well with remotely sensed data as well as historical document-based facts regarding cropland distribution.

Land use changes and their relations with carbon cycles over the past 300 a in China

Land use and land cover in China have changed greatly during the past 300 a, indicated by the rapid abrupt decrease of forest land area and the rapid increase of cropland area, which can affect terrestrial carbon cycle greatly. The first-hand materials are used to analyze main characteristics for land use and land cover changes in China during the study period. The following conclusions can be drawn from this study. The cropland area in China kept increasing from 60.78×106 hm2 in 1661 to 96.09×106 hm2 in 1998. Correspondingly, the forest land area decreased from 248.13×106 hm2 in 1700 to 109.01×106 hm2 in 1949. Affected by such changes, the terrestrial ecosystem carbon storage decreased in the mean time. Car-bon lost from land use and land cover changes mainly consist of the loss from vegetation biomass and soil. In the past 300 a, about 3.70 PgC was lost from vegetation biomass, and emissions from soil ranged from 0.80 to 5.84 PgC. The moderate evaluation of soil losses was 2.48 PgC. The total loss from vegetation and soil was between 4.50 and 9.54 PgC. The moderate and optimum evaluation was 6.18 PgC. Such carbon losses distribution varied spatially from region to region. Carbon lost more significantly in Northeast China and Southwest China than in other regions, because losses of forest land in these two regions were far greater than in the other regions during the past 300 a. And losses of carbon in the other regions were also definite, such as Inner Mongolia, the western part of South China, the Xinjiang Uygur Autonomous Region, and the Qinghai-Tibet Plateau. But the carbon lost very little from the traditional agricultural regions in China, such as North China and East China. Studies on the relationship between land use and land cover change and carbon cycle in China show that the land use activities, especially those related to agriculture and forest management, began to affect terrestrial carbon storage positively in recent years.

Comparisons of cropland area from multiple datasets over the past 300 years in the traditional cultivated region of China

Land use/cover change is an important parameter in the climate and ecological simulations. Although they had been widely used in the community, SAGE dataset and HYDE dataset, the two representative global historical land use datasets, were little assessed about their accuracies in regional scale. Here, we carried out some assessments for the traditional cultivated region of China （TCRC） over last 300 years, by comparing SAGE2010 and HYDE （v3.1） with Chinese Historical Cropland Dataset （CHCD）. The comparisons were performed at three spatial scales： entire study area, provincial area and 60 km by 60 km grid cell. The results show that （1） the cropland area from SAGE2010 was much more than that from CHCD moreover, the growth at a rate of 0.51% from 1700 to 1950 and -0.34% after 1950 were also inconsistent with that from CHCD. （2） HYDE dataset （v3.1） was closer to CHCD dataset than SAGE dataset on entire study area. However, the large biases could be detected at provincial scale and 60 km by 60 km grid cell scale. The percent of grid cells having biases greater than 70% （〈-70% or 〉70%） and 90% （〈-90% or 〉90%） accounted for 56%-63% and 40%-45% of the total grid cells respectively while those having biases range from -10% to 10% and from -30% to 30% account for only 5%-6% and 17% of the total grid cells respectively. （3） Using local historical archives to reconstruct historical dataset with high accuracy would be a valu- able way to improve the accuracy of climate and ecological simulation.

Reconstruction of cropland area and spatial distribution in the mid-Northern Song Dynasty （AD1004-1085）

To understand historical human-induced land cover change and its climatic effects, it is necessary to create historical land use datasets with explicit spatial information. Using the taxes-cropland area and number of families compiled from historical documents, we estimated the real cropland area and populations within each Lu （a province-level political region in the Northern Song Dynasty） in the mid-Northern Song Dynasty （AD1004-1085）. The estimations were accomplished through analyzing the contemporary policies of tax, population and agricultural development. Then, we converted the political region-based cropland area to geographically explicit grid cell-based fractional cropland at the cell size of 60 km by 60 km. The conversion was based on calculating cultivation suitability of each grid cell using the topographic slope, altitude and population density as the independent variables. As a result, the total area of cropland within the Northern Song territory in the 1070s was estimated to be about 720 million mu （Chinese area unit, 1 mu = 666.7 m2）, of which 40.1% and 59.9% oc- curred in the north and south respectively. The population was estimated to be about 87.2 million, of which 38.7% and 61.3% were in the north and south respectively, and per capita cropland area was about 8.2 mu. The national mean reclamation ratio （i.e. ratio of cropland area to total land area; RRA hereafter for short） was bout 16.6%. The plain areas, such as the North China Plain, the middle and lower reaches of the Yangtze River, Guanzhong Plain, plains surrounding the Dongting Lake and Poyang Lake and Sichuan Basin, had a higher RRA, being mostly over 40%; while the hilly and mountainous areas, such as south of Nanling Mountains, the southwest regions （excluding the Chengdu Plain）, Loess Plateau and south- east coastal regions, had a lower RRA, being less than 20%. Moreover, RRA varied with topographic slope and altitude. In the areas of low altitude （~〈250 m）, middle altitude （250-100 m） and high altitude （1000-3500 m）, there were 443 million, 215 million and 64 million mu of cropland respectively and their regional mean RRAs were 27.5%, 12.6% and 7.2% respectively. In the areas of flat slope, gentle slope, medium slope and steep slope, there were 116 million, 456 million, 144 million and 2 million mu of cropland respectively and their regional mean RRAs were 34.6%, 20.7%, 8.5% and 2.3% respectively.

Comparison of changes in land use and land cover in China and the USA over the past 300 years

Comparative studies of changes in land use and land cover between different countries over a long time-scale are helpful in understanding the processes and driving forces of these changes in different situations. We compared and analyzed the temporal and spatial characteristics of cropland, forest and grassland between China＇s mainland and the conterminous USA over the past 300 years. We found that, over the past 300 years, the area of cropland showed an overall increasing trend both in China and in the USA. In China, the area of cropland increased by about 79.46×104 km2 from 1661 to the 1980s, and the per capita cropland decreased from 0.37×104 m2 in 1685 to 0.10×104 m2 in 2000. For the USA, the area of cropland increased by 190.87×104 km2 between 1700 and 1950. The per capita cropland area of each time slice for the past 300 years was greater than 0.60×104 m2 and the maximum value was 2.01×104 m2 in 1890. As a result of the expansion in land reclamation, the forest and grassland areas of the USA have decreased by about 136.98×104 km2 and 136.98×104 km2, respectively, over the past 300 years; the corresponding values for China are about 89.73×104 km2 and 40.00×104 km2, respectively. In terms of the spatial patterns, the expansion in cropland in China mainly occurred in the border areas （including the northeast, southwest and Inner Mongolia） and in the hilly areas. Cropland expansion in the USA mainly occurred in the mid-west regions. In China, population growth is the most important driving factor in changes in land use and land cover, whereas in the USA, government policy plays the most significant role.

Evaluating the reliability of global historical land use scenarios for forest data in China

Global historical land use scenarios are widely used to simulate the climatic and ecological effects of changes in land cover;however,reliability evaluation of these scenarios for data on China’s forests is missing.By using a historical document-derived Chinese forest dataset(CHFD)for the years 1700–2000,we evaluated the reliability of data on forests in China over three global scenarios-SAGE(Center for Sustainability and the Global Environment),PJ(Pongratz Julia),and KK10(Kaplan and Krumhardt 2010)-through trend-related,quantitative,and spatial comparisons.The results show the following:(1)Although the area occupied by forests in China in the SAGE,PJ,KK10,and CHFD datasets decreased over the past 300 years,there were large differences between global scenarios and CHFD.The area occupied by forests in China in the SAGE scenario for 1700–1990 was 20%–40%more than that according to CHFD,and that occupied by forests in the KK10 from 1700 to 1850 was 32%–46%greater than that in CHFD.The difference between the PJ and CHFD was lower than 20%for most years.(2)Large differences were detected at the provincial and grid cell scales,where the PJ scenario was closer to CHFD in terms of total forested area.Provinces with large differences in terms of trend and quantity were 84%and 92%of all provinces,respectively.Grid cells with relative differences greater than 70%accounted for 60%–80%of all grids.(3)These global historical land use scenarios do not accurately reveal the spatiotemporal pattern of Chinese forests due to differences in the data sources,methods of reconstruction,and spatial scales.

An approach to spatially explicit reconstruction of historical forest in Northeast China

The spatially explicit reconstruction of historical land-cover datasets plays an important role in studying the climatic and ecological effects of land-use and land-cover change（LUCC）. Using potential natural vegetation（PNV） and satellite-based land use data, we determined the possible maximum distribution extent of forest cover in the absence of human disturbance. Subsequently, topography and climate factors were selected to assess the suitability of land for cultivation. Finally, a historical forest area allocation model was devised on the basis of the suitability of land for cultivation. As a case study, we used the historical forest area allocation model to reconstruct forest cover for 1780 and 1940 in Northeast China with a 10-km resolution. To validate the model, we compared satellite-based forest cover data with our reconstruction for 2000. A one-sample t-test of absolute bias showed that the two-tailed significance was 0.12, larger than the significant level 0.05, suggesting that the model has strong ability to capture the spatial distribution of forests. In addition, we calculated the relative difference of our reconstruction at the county scale for 1780 in Northeast China. The number of counties whose relative difference ranged from-30% to 30% is 99, accounting for 74.44% of all counties. These findings demonstrated that the provincial forest area could be transformed into forest cover maps well using the model.

过去2000年中国农耕区拓展与垦殖率变化基本特征

通过梳理和集成近年研究成果,综述了过去2000年中国主要农耕区拓展的阶段性及其间全国耕地面积和其中近千年垦殖率变化的主要特征。主要结论有:①中国主要农耕区第一次大规模拓展出现在西汉,从黄河中下游拓至整个长江以北地区;第二次在唐宋时期,主要是长江以南农耕区域从平原低地拓垦至丘陵山地;第三次在清中叶以后,主要是对东北、西北和西南等边疆地区的拓垦和山地的深度开发。②过去2000年中国耕地面积呈波动增加趋势,公元初突破5亿亩(1亩≈667 m2),8世纪前期突破6亿亩,11世纪后半叶达近8亿亩,16世纪后期突破10亿亩,19世纪前期突破12亿亩,1953年逾16亿亩,1980年逾20亿亩。③中国耕地空间分布的主体格局至11世纪前后就已基本奠定。1080年前后,黄淮海、关中平原等的垦殖率达30%以上,长江三角洲、鄱阳湖平原、两湖平原和四川盆地等达30%左右。1850年前后,华北平原、汾渭盆地和陇东地区、四川盆地、两湖平原、鄱阳湖平原及长三角地区等的垦殖率均超过30%。2000年前后,东北平原、黄淮海地区、汾渭盆地和陇东地区、四川盆地、长江中下游平原等农业区中有2/3以上垦殖率超过50%,辽西丘陵、坝上高原、黄土高原及南方各省的丘陵山地也多达15%以上;西北绿洲农业带及青藏高原河谷农业带的局部地区也达50%以上。

近70年来中国历史时期土地利用/覆被变化研究的主要进展

历史时期土地利用/覆被变化是当前全球变化研究的重要组成部分。中国拥有丰富的历史文献资料,在历史时期土地利用/覆被变化研究领域具有明显优势,并在近70年取得了丰硕的研究成果。本文从历史土地垦殖与林草地变迁过程、历史LUCC数量重建和历史LUCC空间重建等3个方面,简要回顾了中国历史时期土地利用/覆被变化研究所取得的主要进展,阐述了其由定性、半定量研究走向"三定"(定时、定量、定位)研究的时代背景及发展历程。并在此基础上,展望该领域未来研究的重点与方向。

元代前期省域耕地面积重建

基于历史文献资料重建区域历史时期土地利用／覆被变化，对深入研究区域生态环境效应、充实全球历史土地利用数据集等均具有重要意义。本文通过对元代（1271—1368年）屯田与屯户、垦田与户口等册载数据及相关史料的梳理与分析，提出了户均屯田数与户均垦田数的转换关系，构建了元代省域耕地面积估算方法，重建了至元二十七年（1290年）研究区省域耕地面积。结果表明：①元代户均屯田数和户均垦田数均具有明显北高南低的特征，这种区域差异性是南北方地区自然条件和种植制度等差异的客观反映，而地域一致性则是户均屯田数配拨以该地户均垦田数为参照的具体表征。②在省域尺度上，户均屯田数与户均垦田数存有一定偏差，其南北方地区的修订系数分别为1．23和0．65。③元代至元二十七年研究区耕地总量为535．4×106今亩，垦殖率为6．8％，人均耕地面积为6．7今亩；其中，境内北方地区耕地面积约占57．8％，垦殖率为6．6％，人均耕地面积为15．6今亩；南方地区约占42．2％，垦殖率为7．1％，人均耕地面积为4．1今亩。④黄河中下游的腹里地区、淮河流域的河南行省、长江中下游地区的江浙、江西及湖广行省和西南地区的云南行省是元代至元年间耕地的主要分布区。

全球历史森林数据中国区域的可靠性评估

全球历史土地利用数据集对于深入理解全球或区域环境变化具有重要意义。历史森林数据作为其重要组成部分,在区域尺度上的可靠性至今鲜有评估。以中国区域为研究对象,依据中国学者基于历史文献资料重建的中国历史森林数据(CHFD),采用趋势、数量和空间格局等对比法,对全球数据集(SAGE、PJ和KK10)中国森林数据的可靠性进行评估。结果表明:①虽然全球数据集中国森林数据与CHFD在近300年的变化趋势上均呈减少态势,但数量上差异较大。其中,SAGE数据集对中国1700年以来的森林面积估算较CHFD高出约20%～40%;KK10数据集重建的1700-1850年森林数量则高出约32%～46%;而PJ数据集由于吸纳了区域性研究成果,其总量与CHFD较为接近,多数时点的数量差异低于20%。②在省区尺度上,从总量与CHFD较为接近的PJ数据集来看,其与CHFD数据集森林变化趋势差异较大省区占到84%,而数量差异较大的省区占比高达92%。③在网格尺度上,PJ与CHFD数据集相对差异率> 70%的网格占比高达60%～80%,二者的时空动态格局差异明显。④全球数据集中国历史森林数据未能客观反映该区域森林变化的过程与格局特征,造成这一现象的原因在于全球与区域性数据集重建历史数据所依据的资料源不同,以及基于不同空间尺度构建的重建方法的差异等。

明代省域耕地数量重建及时空特征分析

基于明代册载田亩、屯田和人口数据,以及相关赋役制度和土地制度等史料,考察了明代册载田亩和屯田数据的合理性,辨识了导致明代册载数据失实的主要因素,重建了明代典型时点省域耕地面积。结果表明:①册籍讹误、官民田和卫所屯田的分类统计及山、塘、湖、荡等非耕地的登册起科,是导致洪武和万历年间册载数据失实的主要原因。②洪武年间河南和湖广册载田亩数据人均耕地面积畸高,其原因为"册籍讹误",订正后的数值分别为41万今亩和18万今亩;该时期研究区阙载的屯田总额约为5620万今亩。③非耕地的登册起科主要出现在南方地区,且洪武和万历年间浙江、南直隶、江西、湖广等省的册载田土数据中非耕地占比分别为24.7%、23.3%、4.4%、3.7%和28.9%、16.2%、19.2%、11.6%。④洪武二十六年(1393年)至万历十一年(1583年),研究区耕地总量由49 550万今亩增至75 430万今亩;省域土地垦殖变化呈现明显的区域差异,河南和山东两省垦殖率增量超过15个百分点,湖广和四川超过3个百分点,而其余各省增量低于1个百分点。区域历史时期土地利用/覆被变化数据重建,不仅是区域生态环境效应模拟的客观需求,也可为充实和完善全球数据集提供参考。

中国西部地区历史草地面积重建的方法——以甘宁青新区为例

历史草地面积重建作为历史土地利用与土地覆被变化研究的重要组成部分,可为区域乃至全球环境变化研究提供重要的基础数据。但受研究客体特性与重建资料多寡的制约,目前无论是数量估算上还是空间格局重建上均非常薄弱。本文试图在客观把握中国西部地区历史草地变化趋势与特征的基础上,利用现代遥感土地利用数据和潜在植被数据,确定土地垦殖前草地植被潜在分布范围;并结合历史耕地网格数据,构建以间接扣减为核心的草地面积重建方法;重建甘肃、宁夏、青海和新疆等省区过去300年的草地网格数据。结果表明:土地垦殖前,案例区草地覆被率高达40.87%。受土地垦殖的影响,在过去300年草地面积呈持续减少的态势。草地面积由1661年的1.11亿hm^2下降到1980年的1.03亿hm^2,并经历了1661—1724年的急剧减少、1724—1873年的缓慢减少和1873—1980年的快速减少三个时段,草地年均减少量分别为4.76万hm^2、0.75万hm^2和3.38万hm^2。在空间上,研究时段内草地垦殖区呈现出由甘肃、宁夏向青海、新疆转移的特点。以历史文献资料和1980年遥感草地网格数据为基础,对重建的草地数据开展了可靠性评估。评估显示,重建结果能够较好的再现草地变迁过程。本文构建的重建方法可被用于中国西部地区长时段的草地面积重建。

“潭蓬运河”的疏凿及地理位置考析

“潭蓬运河”又名“天威径”“仙人垅”等,是晚唐咸通年间由静海军节度使高骈疏凿的,位于广西壮族自治区防城港市以南的江山半岛附近海域,是中国海上丝绸之路的重要组成部分。但其地理位置问题,至今尚有诸多疑点。论文基于历史文献等资料,深入考析“天威径”疏凿的历史背景、具体经过及其地理位置,对进一步明晰“天威径”的历史文化价值和在海上丝绸之路的历史地位有着重要意义。通过对相关历史文献资料的梳理和历史地理背景的考察,重新论证了“天威径”开凿的历史背景、具体经过和地理位置,研究表明:①“潭蓬运河”的位置应当是位于江山半岛南端的白龙尾以外海域之中,所谓“潭蓬运河”的开凿过程就是对白龙尾以南海域中礁石的疏凿;②“潭蓬运河”疏凿的目的在于为驻安南唐军提供持续稳定的后勤补给,疏凿的时间是在懿宗咸通九年;③本着尊重史实的原则,高骈疏凿的礁石之处应当命名为“天威径”,而半岛上的潭蓬古运河处,则应改名为“天威径石刻遗迹”。

春季偏晚终雪记录隐示的南宋杭州1131-1270年气候变化

We collected and verified documentary records of the latest spring snowing dates(LSSD)in Hangzhou during Southern Song Dynasty.Furtherly,the statistical correlation between this proxy and February–April mean temperature in Hangzhou was examined,and samples later than the perennial mean of the LSSD during Southern Song Dynasty were transformed into the decadal mean of LSSD by means of Boltzmann function.General characteristics of this reconstructed LSSD series with a 10-year temporal resolution was analyzed,and it was also compared with other documentary evidences and reconstructed climate series in China for the period 1131–1270.The results and discussion suggested that:(1)Records of the LSSD in Hangzhou during Southern Song Dynasty did not refer to ice pellets and graupels,which had an explicit climate significance(–0.34℃/10 d,R2=0.37,p<0.001).However,when this proxy is used to reconstruct temperature changes,all dates should be converted into proleptic Gregorian style and meet the same criterion of"true Qi"as the Chinese traditional calendar after 1929.(2)The decadal mean of LSSD can be effectively estimated by using the forefront of LSSD in the decade on the basis of Boltzmann function,whose extrapolation has a lesser uncertainty than those on the basis of linear models or polynomial models.(3)The spring climate in Hangzhou during 1131–1270 was almost as warm as the period 1951–1980.At the centennial scale,this period can be divided into two phases:the cold 1131–1170 and the warm 1171–1270.In the latter,1181–1200 and 1221–1240 were two cold intervals at the multi-decadal scale.(4)The reconstructed LSSD series was consistent well with other documentary evidences and reconstructed climate series in China for 1131–1270,which may reflect the influence on the climate over most regions of China imposed by the Pacific Decadal Oscillation(PDO).