Temperature and Precipitation Suitability Evaluation for the Winter Wheat and Summer Maize Cropping System in the Huang-Huai-Hai Plain of China

The Huang-Huai-Hai Plain is the most important winter wheat and maize production region in China.In response to the increasing population pressure,the Chinese authorities strongly invested in improving the irrigation systems and increasing ground and surface water exploitation within the plain to increase the crop productivity.This resulted in a reduction of water resource availability and in turn indirectly affected the suitability of various agricultural ecosystems in the plain.The main purpose of this study was to review the suitability of temperature and precipitation for the winter wheat and summer maize cropping system in the Huang-Huai-Hai Plain,in order to provide a preliminary irrigation scheme.This analysis provides a first attempt to enhance the water resource management as well as to increase the water use efficiency.For this aim,a GIS-based multicriteria analysis procedure has been developed consisting of（1） definition of objectives（evaluated entities） and database building;（2） definition of evaluation criteria;（3） standardization of the criteria;（4） combination of the criteria;（5） classification of the objectives;and（6） integration of the objectives.The land suitability classification maps were transformed into maps of required irrigation amounts for each growing stage of the winter wheat and summer maize cropping system.The study also exemplified the limitations and proposed future research activities that will improve the detail and accuracy of the evaluation results.

The impacts of climate change on wheat yield in the Huang-Huai-Hai Plain of China using DSSAT-CERES-Wheat model under different climate scenarios

Climate change has been documented as a major threat to current agricultural strategies.Progress in understanding the impact of climate change on crop yield is essential for agricultural climate adaptation,especially for the Huang-Huai-Hai Plain(3H Plain)of China which is an area known to be vulnerable to global warming.In this study,the impacts of climate change on winter wheat(Triticum aestivum L.)yield between the baseline period(1981–2010)and two Representative Concentration Pathways(RCP8.5 and RCP4.5)were simulated for the short-term(2010–2039),the medium-term(2040–2069)and the long-term(2070–2099)in the 3H Plain,by considering the relative contributions of changes in temperature,solar radiation and precipitation using the DSSAT-CERES-Wheat model.Results indicated that the maximum and minimum temperatures(TMAX and TMIN),solar radiation(SRAD),and precipitation(PREP)during the winter wheat season increased under these two RCPs.Yield analysis found that wheat yield increased with the increase in SRAD,PREP and CO2 concentration,but decreased with an increase in temperature.Increasing precipitation contributes the most to the total impact,increasing wheat yield by 9.53,6.62 and 23.73%for the three terms of future climate under RCP4.5 scenario,and 11.74,16.38 and 27.78%for the three terms of future climate under RCP8.5 scenario.However,as increases in temperature bring higher evapotranspiration,which further aggravated water deficits,the supposed negative effect of increasing thermal resources decreased wheat yield by 1.92,4.08 and 5.24%for the three terms of future climate under RCP4.5 scenario,and 3.64,5.87 and 5.81%for the three terms of future climate under RCP8.5 scenario with clearly larger decreases in RCP8.5.Counterintuitively,the impacts in southern sub-regions were positive,but they were all negative in the remaining sub-regions.Our analysis demonstrated that in the 3H Plain,which is a part of the mid-high latitude region,the effects of increasing thermal resources were counteracted by the aggravated water deficits caused by the increase in temperature.

Water consumption in summer maize and winter wheat cropping system based on SEBAL model in Huang-Huai-Hai Plain, China

Crop consumptive water use is recognized as a key element to understand regional water management performance. This study documents an attempt to apply a regional evapotranspiration model（SEBAL） and crop information for assessment of regional crop（summer maize and winter wheat） actual evapotranspiration（ET a） in Huang-Huai-Hai（3H） Plain, China. The average seasonal ET a of summer maize and winter wheat were 354.8 and 521.5 mm respectively in 3H Plain. A high-ET a belt of summer maize occurs in piedmont plain, while a low ET a area was found in the hill-irrigable land and dry land area. For winter wheat, a high-ET a area was located in the middle part of 3H Plain, including low plain-hydropenia irrigable land and dry land, hill-irrigable land and dry land, and basin-irrigable land and dry land. Spatial analysis demonstrated a linear relationship between crop ET a, normalized difference vegetation index（NDVI）, and the land surface temperature（LST）. A stronger relationship between ET a and NDVI was found in the metaphase and last phase than other crop growing phase, as indicated by higher correlation coefficient values. Additionally, higher correlation coefficients were detected between ET a and LST than that between ET a and NDVI, and this significant relationship ran through the entire crop growing season. ET a in the summer maize growing season showed a significant relationship with longitude, while ET a in the winter wheat growing season showed a significant relationship with latitude. The results of this study will serve as baseline information for water resources management of 3H Plain.

Proton accumulation accelerated by heavy chemical nitrogen fertilization and its long-term impact on acidifying rate in a typical arable soil in the Huang-Huai-Hai Plain

Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultivation and heavy chemical N input in the Huang-Huai-Hai Plain, the impact extent of induced proton input on soil pH in the long term was not yet clear. In this study, acidification rates of different soil layers in the soil profile （0-120 cm） were calculated by pH buffer capacity （pHBC） and net input of protons due to chemical N incorporation. Topsoil （0-20 cm） pH changes of a long-term fertilization field （from 1989） were determined to validate the predicted values. The results showed that the acid and alkali buffer capacities varied significantly in the soil profile, averaged 692 and 39.8 mmolc kg-1 pH-1, respectively. A significant （P〈0.05） correlation was found between pHRC and the content of calcium carbonate. Based on the commonly used application rate of urea （500 kg N ha-1 yr-1）, the induced proton input in this region was predicted to be 16.1 kmol ha-1 yr-1, and nitrification and plant uptake of nitrate were the most important mechanisms for proton producing and consuming, respectively. The acidification rate of topsoil （0-20 cm） was estimated to be 0.01 unit pH yr-1 at the assumed N fertilization level. From 1989 to 2009, topsoil pH （0-20 cm） of the long-term fertilization field decreased from 8.65 to 8.50 for the PK （phosphorus, 150 kg P205 ha-1 yr-1; potassium, 300 kg K20 ha-1 yr-1; without N fertilization）, and 8.30 for NPK （nitrogen, 300 kg N ha-1 yr-1; phosphorus, 150 kg P2Os ha-1 yr-1; potassium, 300 kg K20 ha -1 yr-1）, respectively. Therefore, the apparent soil acidification rate induced by N fertilization equaled to 0.01 unit pH yr-1, which can be a reference to the estimated result, considering the effect of atmospheric N deposition, crop biomass, field management and plant uptake of other nutrients and cations. As protons could be consumed by some field practices, such as stubble return and coupled water and nutrient management, soil pH would maintain relatively stable if proper management practices can be adopted in this region.

Spatiotemporal variation of drought characteristics in the Huang- Huai-Hai Plain, China under the climate change scenario

Understanding the potential drought characteristics under climate change is essential to reduce vulnerability and establish adaptation strategies, especially in the Huang-Huai-Hai Plain （3H Plain）, which is a major grain production area in China. In this paper, we investigated the variations in drought characteristics （drought event frequency, duration, severity, and intensity） for the past 50 years （1961-2010） and under future scenarios （2010-2099）, based on the observed meteorological data and the Representative Concentration Pathway （RCP） 8.5 scenario, respectively. First, we compared the applicability of three climatic drought indices： the standardized precipitation index （SPI）, the standardized precipitation evapotranspiration index based on the Penman-Monteith equation （SPEI-PM） and the same index based on the Thornthwaite equation （SPEI-TH） to correlate the recorded agricultural drought areas. Then, we analyzed the drought characteristics using ＇run theory＇ for both historical and the future RCP 8.5 scenario based on the best performing index. Correlation analyses between drought indices and agricultural drought areas showed that SPEI-PM performed better than SPI and SPEI-TH in the 3H Plain. Based on the results of SPEI-PM, drought risks including duration, severity and intensity during 1961-2010 showed an decreasing trend. However, under the RCP 8.5 scenario, drought is expected to rise in frequency, duration, severity, and intensity from 2010-2099, although drought components during the 2010-2039 are predicted to be milder compared with historical conditions. This study highlights that the estimations for atmospheric evaporative demand would create differences in the prediction of long-term drought trends by different drought indices. The results of this study can help inform researchers and local policy makers to establish drought management strategies.

Acid and Alkali Buffer Capacity of Typical Fluvor-Aquic Soil in Huang-Huai-Hai Plain

Soil acid and alkali buffer capacity, as a major indicator for evaluating its vulnerability and resistibility to acidification and alkalization, is an important factor affecting the sustainable agriculture, through knowledge on which soil acidification process can be predicted and modified. In this study, titration curve method was adopted to investigate the pH buffer capacity （pHBC） of fluvor-aquic soil, and separate titration curves were established by adding incremental amounts of either standardized hydrochloric acid （HC1） （0.12 mol L^-1） or sodium hydroxide （NaOH） （0.10 mol L^-1） to soil suspended in deionized water （soil：solution = 1：5）. Soil pH was measured after 7 d resuspension and isothermal equilibrium （T = 25℃）. Linear regressions were fitted to the linear portion of each titration curve and the slopes of these lines were derived as the soil pHBC. The results showed that significant correlations between the amounts of adding acid or alkali and each pH change were presented, and titration curve method was feasible for measurement of pHBC on typical fluvor-aquic soil in Huang-Huai-Hai Plain, and the coefficients of determination were higher than the similar researches on acid soil （R^2 = 0.96）. The slope-derived pHBC of acid and alkali were 158.71 and 25.02 mmol kg^-1, respectively. According to the classification of soil buffer systems, the soil tested belongs to the calcium carbonate buffer system, carbonates contribute the most to pHBC, and the contribution of soil organic matter relatively less than it.

A Study on the Driving Factors of Food Production in Huang-Huai-Hai Plain Based on Path Analysis

The effects of 14 factors on food production in Huang-Huai-Hai Plain are analyzed by path analysis in this paper,and then the linear regression models of them are established by SPSS software. The results show that electricity consumption for agriculture,growing area of crops,the affected area,annual average temperature and arable land area at the end of the year have great effects on food production. Finally some recommendations are put forward to improve the food production in Huang-Huai-Hai Plain such as improving the level of agricultural mechanization,stabilizing food production,preventing natural disasters and increasing the effective irrigation area.

Effect of water fluctuation on agricultural production in the Huang-Huai-Hai Plain, China

The biggest load of water resources for agricultural economy in the Huang-Huai Plainwill only arcount for 67.1 % of the forecasted irrigated area in 2010. The irrigated area and thequantity of water diverting from the Huanghe River was 2.2 million hm2 and 10.8 billion m3respectively in the lowe reaches of the river in the 1990s. The annual amount of yield increase forgrain is 6.3 billion kg calculated by converting and the annual benefit of yield-increase is 4.4 billionRMB yuan in the irrigated area of the region. The daily economic losses of industry and agricultureby absence of flow in the area in the 1990s is 44. 1 million RMB yuan. The annual water quantity willbe increased by 9.9 billion m3 after diverting water from the Huanghe River and 12.6 billion m3 afterdiverting water from the Changjiang River respectively in the plain in 2010.

Evaluation on the Influencing Factors of Agricultural Land Productivity in Huang-Huai Plain,China

Taking Huang-Huai Plain as an example,evaluation index system is established from four aspects,including the resources condition,the social and economic condition,the agricultural science and technology condition,and the disaster resistant and sustainable production condition.Correlation coefficient method and expert consultation method are used to determine the weight of evaluation index.After the standardization of extreme value,weighted sum method and multiple regression method are adopted to evaluate the influencing factors of agricultural land productivity in Huang-Huai Plain,China.Evaluation result shows that agricultural science and technology condition has a lower contribution rate to the productivity of Huang-Huai Plain than that to Henan Province.Resources condition has a higher contribution rate to the productivity of Huang-Huai Plain than that to Henan Province.Both the social and economic condition and the disaster control and sustainable production condition show relatively small contribution rate to the productivity of Huang-Huai Plain.It can be concluded that the main factors affecting the productivity of Huang-Huai Plain are the backward agricultural science and technology level,the poor farmland quality and the farmland infrastructure.Based on this,relevant suggestions are put forward to improve the farmland productivity of Huang-Huai Plain.

封丘县典型农田土壤质量与时空变化特征

黄淮海平原作为我国重要的粮食产区,系统全面地评价该区域典型潮土的质量变化,对指导农业生产具有重要意义。以典型潮土分布的封丘县作为研究区,选取1984、2003和2011年的17项土壤指标,基于土壤参与生态过程中作物生产、碳固存、持水净化和养分运移等功能,构建土壤综合质量评价系统,采用主成分分析结合逼近理想点排序法(TOPSIS)计算各功能得分及土壤质量综合指数,通过GIS空间插值描述封丘县27年内潮土耕作区土壤质量和功能的时空变化特征。结果表明:(1)封丘县土壤全氮、全磷、碱解氮、有效磷、速效钾和有机质含量及阳离子交换量、饱和导水率和孔隙度均呈现不同程度的提升趋势;全钾含量、pH、容重、田间持水量和有效含水量则呈逐年降低趋势;(2)封丘县土壤作物生产、碳固存和养分运移功能得分均有所提升,增长率分别为9.29%、9.68%和7.36%,持水净化功能得分则降低4.17%;(3)封丘县土壤质量综合指数提升较为明显,1984年全县耕地土壤质量综合指数均≤2.0,2003年综合指数>2.0的耕地面积占全县总面积的8.44%,2011年提升至24.05%。整体而言,封丘县该时期的耕地保护和利用模式基本是有效的,封丘县耕地整体质量不断向好的方向发展,相关结果可以为黄淮海地区耕地资源可持续利用提供参考。

黄淮海平原地下水化学演化特征、形成机制及其开发利用建议

【研究目的】地下水是保障黄淮海平原生产、生活所需的主要水资源之一。在人类活动的影响下,地下水环境恶化已成为制约社会经济发展和生态平衡的重要因素。深入探究地下水化学演化特征及其形成机制,可为地下水资源的合理开发利用提供重要参考依据。【研究方法】本文将黄淮海平原分为山前平原、中部平原、滨海平原三个水文地质单元,综合运用Piper三线图、Gibbs图、主成分分析等方法,研究了中国黄淮海平原的地下水化学特征及其形成机制。【研究结果】结果显示,从山前平原到中部平原再到滨海平原地下水中TDS含量逐渐升高,由淡水逐渐演化为微咸水、咸水、盐水、卤水;研究区地下水化学类型从山前平原的44种增至中部平原的74种,而后下降至滨海平原的22种;其中,山前平原地下水化学类型以HCO_(3)-Ca·Mg、HCO_(3)-Ca为主,主要受控于一个4因素模式,相比之下,中部平原和滨海平原地下水化学则分别受控于3因素模式。【结论】黄淮海平原地下水化学特征呈明显分带性,从山前平原到中部平原到滨海平原地下水化学类型由HCO_(3)型逐渐演化为HCO_(3)·SO_(4)型、HCO_(3)·Cl型、SO_(4)型、SO_(4)·Cl型,最终演化为Cl型水。研究区地下水化学在空间尺度上主要受控于多种自然因素(岩石风化、蒸发浓缩和阳离子交替吸附、海水入侵),其在时间尺度上明显受多种人类活动(地下水超采、土地利用变化、生活污水、化肥、动物粪便)的影响。针对山前平原至滨海平原各区不同的地下水化学特征及其人类活动影响,有针对性地提出了黄淮海平原地下水资源开发利用方面的管控建议。

黄淮海平原灌区节水高效耕作制度构建

黄淮海地区是我国重要的粮食产区,平均复种指数为150%,小麦-玉米一年两熟加春播作物组成的两年三熟制为该区域的主要种植制度。受水资源限制,部分地区复种指数呈现下降趋势,严重影响了区域粮食安全。发展节水高效耕作制度成为解决区域粮食安全和生态安全的重大科技问题。介绍了山东农业大学在小麦-玉米周年节水高效耕作制度和春播作物覆盖节水耕作制度两个方面的最新进展:前者重点介绍秸秆还田与高效耕作、高杆喷灌水肥一体化、肥水耦合、测墒补灌等生物节水与农艺节水的技术创新与集成;后者重点介绍多功能生物降解地膜的研制与花生、马铃薯等覆盖节水增产技术体系。在此基础上,提出黄淮海地区耕作制度的发展方向与技术需求(采取深松与秸秆还田技术相结合、深松与高杆喷灌结合、废弃物还田、合理灌水与施用氮肥相结合、地膜覆盖技术等),以期为黄淮海平原灌区粮食安全和生态安全提供战略支撑与技术支持。

2023年春末黄淮海麦区“烂场雨”极端性特征及大尺度大气环流场

基于中国气象局逐日降水和日照资料及NCEP/NCAR再分析数据集,分析了2023年5月下旬黄淮海麦区高影响“烂场雨”事件的极端性特征及其大气环流配置型,发现:就旬平均而言,黄淮海麦区寡照的极端性要强于降水;但各省份间差异明显,其中河南省最为严重。为和历史事件对比,首次提出了河南“烂场雨”事件的客观定义指标,并由此筛选出1981年以来全省18次最为典型的“烂场雨”事件。此次“烂场雨”事件在所有事件中,雨量为第六多,日照为第二少。因此,对河南省而言,寡照时长的极端性亦更为明显。对1981—2022年所有事件合成结果显示,造成“烂场雨”的大尺度大气环流形势为西太平洋副热带高压偏西偏强且西段脊线偏北,欧亚中高纬地区为“西低东高”环流型。对比发现,2023年5月下旬“烂场雨”事件的大气环流型在中高纬度和历史事件相似,但热带地区受超强台风玛娃的影响,副热带高压西段发生挤压形变,西北侧的西南风水汽输送明显偏强。同时因“玛娃”长时间稳定维持在菲律宾以东附近,台风东北侧引导的东南风气流较副热带高压西北侧的西南风距平更为强盛。两支水汽在黄淮海地区汇合叠加,造成小麦产区的持续降水和寡照。

基于双时相卫星遥感光谱指数估算土壤有机质含量

以黄淮海平原典型县——封丘县为研究区,探讨了在一年两熟、裸土时间窗口较短的区域中,基于两景影像波段组合构建的双时相光谱指数在有机质含量预测中的表现。研究共计采集117个代表性土样,以分析筛选出的裸土期(10月)内双时相(获取时间:2014年10月6日和2017年10月30日)高质量Landsat 8卫星影像作为数据源,构建了4种类型的光谱指数:比值光谱指数、差值光谱指数、归一化光谱指数以及优化光谱指数,并结合最小绝对收缩和选择算子变量筛选方法和支持向量机算法建立了有机质预测模型。留一交叉验证结果表明,与直接使用影像波段反射率或者基于单景影像构建的光谱指数(单时相光谱指数)相比,利用双时相光谱指数可以更好地利用时相信息优势,其有机质预测精度更高(R^(2)=0.53,RMSE=2.01 g/kg)。而且,基于双时相光谱指数所构建的预测模型得到的有机质空间分布格局与真实值较为吻合。可见,本文提出的在黄淮海平原典型县域利用双时相光谱指数预测土壤有机质的方法,可以促进具有短裸土期特点区域的高分辨率土壤属性遥感预测与制图研究。

黄淮海平原北部不同熟性夏玉米品种抗倒伏能力研究

在玉米全程机械化栽培趋势下,针对黄淮海平原区夏玉米倒伏严重问题,以7个不同生育期夏玉米品种(中晚熟2个,中熟3个,中早熟2个)为材料,探讨不同熟性夏玉米品种灌浆期的抗倒伏能力。结果表明,黄淮海平原北部夏玉米植株株高、穗位高、穗高系数、基部第3节间长及基部节间K含量与品种熟性无关;中熟、中早熟品种水溶性碳水化合物含量明显大于中晚熟品种;中熟、中晚熟品种基部第3节间粗、近地面两层节根数、单株总根条数、植株抗拉力、基部第3节间穿刺强度及植株根拔力显著大于早熟品种。相关性分析表明,夏玉米植株抗拉力与穗高系数呈显著负相关,与单株总根数呈显著正相关;基部第3节间穿刺强度与节间K含量呈正相关。因此,黄淮海平原北部选育机收粒夏玉米品种时,除关注灌浆、脱水速率快之外,还应兼顾株高适宜、穗位低、基部节间粗壮等抗倒性状,同时,采用适宜栽培措施,抑制基部节间伸长、促进节间增粗及充实、加强根系发育,提高植株抗倒伏能力。研究结果为黄淮海平原北部高产、抗倒、机收粒夏玉米品种选育提供理论依据。

黄淮海平原气象干旱的演化特征与时空规律

干旱事件广泛地影响着作物的生长和发育,黄淮海平原是中国主要的粮食产区之一,全面了解该地区干旱变化特征对保障中国粮食安全至关重要。该研究基于标准化降水指数(standardized precipitation index,SPI)、标准化降水蒸散指数(standardized precipitation evapotranspiration index,SPEI)、自校正帕默尔干旱指数(self-calibrating palmer drought index,scPDSI)、干燥度指数(aridity index,AI)4种干旱指数,对黄淮海平原干旱强度、干旱频率、干旱面积占比、干旱持续时间进行对比分析。结果表明,4种干旱指数均指示出1970—2020年黄淮海平原干旱强度逐渐减弱,干旱面积占比先增加后减少、再增加再减少、再增加的波动变化趋势,且在空间上均呈现出平原中部变湿、东西部变干的趋势。但不同指数在表征干旱空间特征上还存在一定的空间分异。对于干旱频率,SPI和AI指数显示出北部地区干旱频率高达60%,而南部地区低于20%;SPEI和scPDSI指数则显示出的南北差异较小,分别介于25%~40%和30%~50%。对于干旱持续时间,SPI指数监测的南北差异最为明显,而SPEI和scPDSI指数监测的区域差异较小。SPI和SPEI两种干旱指数监测的干旱持续时间较短,scPDSI指数监测的干旱持续时间较长。综合来看,北部区域干旱强度更为严重,且干旱发生频率高、持续时间长,而南部地区则相反。研究可为制定应对干旱的农业政策提供科学的参考依据。

黄淮海平原农村产业结构与用地结构关系研究——以曲周县为例

基于信息熵、结构变化率偏差系数和向量自回归模型,以曲周县为典型案例,研究黄淮海平原农村产业结构和用地结构的动态变化特征及其互动关系。结果表明,近年来,曲周县产业结构演变经历第一产业主导、一二产业均衡和第二产业主导的过程;第一产业用地占比极大,导致用地结构极不均衡,但目前正在向均衡状态发展。产业结构调整与用地结构调整之间不协调,用地结构调整具有滞后性,但二者之间存在长期稳定的相互关系。2009年之前,产业结构调整促进了用地结构变化,之后因果关系相反,且后期阶段的用地结构调整对后续用地结构优化及产业结构升级的带动作用更加持久和显著。未来一段时期内,通过提升第一产业用地效率、挖掘第二产业用地潜力以及拓宽第三产业用地范围等方式优化三次产业用地结构,是促进黄淮海平原农村地区产业结构不断升级的有效途径。

基于径流-蒸散发-蓄水量协同率定的平原区水文模拟研究

平原区无统一流域出口断面,相关模型参数率定与水文模拟是水文学研究的薄弱环节和难点问题。以黄淮海平原为研究对象,基于实测数据、遥感反演结果及同化的区域水循环通量和储量等多源要素数据集,利用可变下渗容量(VIC)模型,构建了基于径流、蒸散发和蓄水量协同率定的模型参数率定方法,评估了其在黄淮海平原水文模拟中的适用性,并利用机器学习、广义似然不确定性估计等方法分析了该模型对水文模拟精度、模型参数异参同效性和径流模拟不确定性等方面的改进效果。得到的主要结论为:①VIC模型在黄淮海平原具有较好的适用性,与实测值相比,模拟径流和蒸散发量在率定期的相关系数大于0.9,蓄水量的相关系数大于0.6;②对于VIC模型的6个参数,第2层土壤厚度d 2最敏感,其次是可变下渗曲线指数B,其余参数敏感性较弱;③与传统的单一径流率定方法相比,参数协同率定方法提高了蒸散发量和蓄水量的模拟精度,减小了模型参数的优选空间与不确定性置信区间,模拟径流的90%置信区间约缩小26%,降低了水文模拟的不确定性。研究成果对水文模拟技术进步具有重要的支撑作用。

Land use transitions and their dynamic mechanism: The case of the Huang-Huai-Hai Plain

Land use transition refers to changes in land use morphology, including dominant morphology and recessive morphology, of a particular region over a period of time driven by various factors. Recently, issues related to land use transition in China have attracted interest among a wide variety of researchers as well as government officials. This paper examines the patterns of land use transition and their dynamic mechanism in the Huang-Huai-Hai Plain during 2000-2010. First, the spatio-temporal patterns of land use transition, their character- istics and the laws governing them were analyzed. Second, based on the established con- ceptual framework for analyzing the dynamic mechanism of land use transition, a spatial econometric regression analysis method was used to analyze the dynamic mechanism of the five types of major land use transition in the Huang-Huai-Hai Plain at the county level. Land use pattern changes in the study area were characterized by an increase in construction land, water body and forested land, along with a decrease in farmland, unused land and grassland. The changes during 2000-2005 were much more significant than those during 2005-2010. In terms of factors affecting land use transitions, natural factors form the basis, and they have long-term effects. Socio-economic factors such as population and GDP, however, tend to determine the direction, structure, size and layout of land use transition over shorter time periods. Land law and policy factors play a mandatory guiding and restraining role in land use transitions, so as to improve the overall efficiency of land use. Land engineering is also an important tool to control land use transitions. In general, the five types of major land use transition were the result of the combined action of various physical, social and economic factors, of which traffic condition and location condition had the most significant effects, i.e. they were the common factors in all land use transitions. Understanding the spatio-temporal process of land use transitions and their dynamic mechanisms is an important foundation for utilizing land resources, protecting regional ecological environment and promoting sustain- able regional socio-economic development.

Exploring the urban-rural development differences and influencing factors in the Huang-Huai-Hai Plain of China

Uneven urban and rural development is one of the main reasons for the decline of the countryside.This imbalance could be measured by the urban-rural difference index(URDI).Existing studies on urban-rural differences have focused on single dimension between urban and rural areas,and lack a systematic multi-dimensional measurement.Based on the construction of an index system and model for measuring urban-rural differences,this study took the Huang-Huai-Hai Plain(HHHP)as the study area,explores the spatial pattern of urban-rural differences in the area,and used geographical weighted regression models to identify the factors affecting urban-rural development differences.Results show that the mean value of URDI in the HHHP was 0.295,and the URDI in its western region was higher than that in the east.The average URDI was relatively high in the western counties along the Beijing–Guangzhou Railway.The low level of urban-rural'population-land-industry'development in the HHHP is an important reason for the small differences between urban and rural areas.Improvements in road transportation infrastructure have led to an increase in the urban-rural development gap.However,the driving force of the road network on urban development is greater than that on rural areas.The role of county economic agglomeration is gaining strength.In the process of rapid economic development,more attention should be paid to the development of the rural economy and the overall revitalization of the countryside.The equivalent allocation of social service facilities is an effective way to solve the problem of urban-rural imbalance.Further analysis demonstrated that terrain factors have relatively little influence on the URDI.This study provides a new perspective and measurement method for understanding the integration of urban and rural development,and provides a useful reference for guiding the urban-rural integration development and the rural revitalization.