Estimation of Land Production and Its Response to Cultivated Land Conversion in North China Plain

Food safety and its related influencing factors in China are the hot research topics currently,and cultivated land conversion is one of the significant factors influencing food safety in China.Taking the North China Plain as the study area,this paper examines the changes of cultivated land area using satellite images,estimates land productivity from 1985 to 2005 using the model of Estimation System for Land Productivity(ESLP),and analyzes the impact of cultivated land conversion on the land production.Compared with the grain yield data from statistical yearbooks,the results indicate that ESLP model is an effective tool for estimating land productivity.Land productivity in the North China Plain showed a slight decreasing trend from 1985 to 2005,spatially,increased from the north to the south gradu-ally,and the net changes varied in different areas.Cultivated land area recorded a marginal decrease of 8.0 × 105 ha,mainly converted to other land uses.Cultivated land conversion had more significant negative impacts on land produc-tion than land productivity did.Land production decreased by about 6.48 × 106 t caused by cultivated land conversion between 1985 and 2005,accounting for 91.9% of the total land production reduction.Although the land productivity increased in Anhui and Jiangsu provinces,it can not offset the overall adverse effects caused by cultivated land con-version.Therefore,there are significant meanings to control the cultivated land conversion and improve the land pro-ductivity for ensuring the land production in the North China Plain.

Analysis on the Influencing Factors and Control Measures of "Non-Grain Conversion" of Cultivated Land in Agricultural Land Transfer

Through the method of literature analysis,this paper analyzes the present situation of the"non-grain conversion"of cultivated land in the transfer of agricultural land in China,summarizes the influencing factors and consequences of the phenomenon of"non-grain conversion"of cultivated land in the transfer of agricultural land,and finally puts forward some measures.The study found that costs and benefits are the fundamental factors affecting the"non-grain conversion"of cultivated land in agricultural land transfer,and other main factors include government and policy guidance,industrial and commercial capital to the countryside,labor transfer and so on.The"non-grain conversion"of cultivated land in the transfer of agricultural land is a serious threat to China s food security,leading to the decline of the quality of agricultural land and the destruction of the ecological environment,as well as the risk of breach of contract in"industrial and commercial capital to the countryside".Based on the understanding of the influencing factors of non-grain conversion,this paper puts forward the following measures:strengthening the control of the use of cultivated land in agricultural land transfer;implementing accurate subsidies for grain cultivation and ensuring the benefit of grain growers;adopting grain planting incentive mechanism to increase grain enthusiasm;strengthening media publicity and education to enhance food security awareness.The improvement of the current situation of the"non-grain conversion"of cultivated land in the transfer of agricultural land will be of great significance to the protection of agricultural land and food security in China.

ANALYSIS AND MODELING ON CULTIVATED LAND CONVERSION——Case Study of Hebei Province

With the acceleration of the urbanization and industrialization of China, it is inevitable that cultivated land converts to built-up land for industrial, commercial and residential uses, which would impose pressure both on food security and on the sustainability of urbanization itself for such a country with large population and few cultivated land. Based on the three-time Landsat Thematic Mapper (TM) digital images and statistic data of Hebei Province, the general facts of cultivated land conversion and its driving forces were analyzed by establishing econometric model in this paper. Some conclusions were drawn as the following: during 1985-2000, the rate of cultivated land converting to built-up area in Hebei was 4.01% or 0.27% per year. Of all the converted cultivated land, 20.96% was converted to built-up area and of all the new built-up areas, 83.4% was converted from cultivated land; meanwhile the conversion is uneven not only in time but also in space; factors such as edge length shared by cultivated land and built-up land, agricultural value per hectare, non-agriculture value per hectare, GDP, total population, farmer’s net income per capita and time had significant effects on this conversion.

Research on Converting Cultivated Land into Forests and Regional Sustainable Development

The capability of sustainable development of Wuchuan County is evaluated comprehensively with theories and methods of regional sustainable development capability evaluation, which are extensively applied at home and abroad. The results indicate that the developing speed and patterns of Wuchuan County cannot satisfy the demand of the regional sustainable development. Moreover, the patterns, distributions, tree species, growing patterns, and other aspects must consider the restriction of ecological water utilization. It is put forward that the standards for selecting the converting lands are slope, desertification degree, and rainfall.In addition, the control of soil erosion and the prevention of land desertification are selected as the dualpurpose of the converting project.

Mutual Conversion of Land Use between Urban and Rural Area in the Process of Urbanization: A Case Study of Shandong Province

Urbanization is one of the driving forces for the land use change in type and structure, and its prominent effect is to convert rural land to urban land. This paper takes Shan-dong Province as an example to analyze the current situation of the mutual conversion between the urban and rural areas from the aspects of the structure of land use, the decreasing tendency of the cultivated land, the changes of land use in urban and rural residential areas. It points out that cultivated land is converted to residential area land, industrial and/or mining area land. The relationship between the urban area land and the cultivated land is more direct; meanwhile, the changes of rural residential area lag behind obviously. The decrease of the cultivated land and the decline of soil quality will be the two difficult problems in the process of urbanization.

Conversion of Andean montane forest to exotic forest plantation modifies soil physicochemical properties in the buffer zone of Ecuador's Podocarpus National Park

Background:Andean montane forests(AMF)are biodiversity hotspots that provide fundamental hydrological services as well as carbon storage and sequestration.In recent decades,southern Ecuador AMFs have been seriously threatened by increased logging and conversion to forest plantations with exotic species.In this context,our main objective was to evaluate the effects of AMF conversion to forest plantations on soil physicochemical properties in the buffer zone(Bz)of the Podocarpus National Park(PNP),in southern Ecuador.For this purpose,random samples were taken at a depth of 0-10 cm in four plots in each contrast zone and analyzed for bulk density,porosity,textural class,leaf litter depth,soil pH,as well as the contents of organic matter(SOM),soil organic carbon(SOC),total nitrogen,and available phosphorus and potassium.Results:The results indicate that the conversion of AMFs produces an increase in bulk density and a decrease in SOM,SOC,and total nitrogen contents,thus modifying soil properties,which could result in a decrease in water regulation capacity and produce an increased risk of soil erosion.This accelerates degradation processes,as well as threatens shortages of the drinking water supply.Conclusions:This study can help decision-makers to implement soil management plans in the Bz of the PNP,based on the implementation of new regulations,where the conservation of AMF is promoted.In addition,it is recommended to apply environmental restoration strategies in the anthropized areas of the AMF,as well as in the areas with exotic eucalyptus and pine plantations.

Land Consolidation with Seedling Cultivation Could Decrease Soil Microbial PLFA Diversity

The impact of land consolidation on the soil microbial PLFA diversity is of great importance for understanding the effective arable land usage,improving agricultural ecological conditions and environment.In this study,we collected the soil samples(0–20 cm)in experimental plots with 0(Z0),1(Z1a)and 4(Z4a)years of land consolidation in the forest station of Ningbo City,Zhejiang Province,southeastern China.The results were analyzed using ANOVA for randomized block design.Compared with control(Z0),the soil pH value under Z1a treatment increased by 14.6%,soil organic carbon(SOC)content decreased by 65.4%,so did the PLFA contents and relative abundance of all the microbial PLFA diversity(P<0.05),respectively.Meanwhile,for the Z1a treatment,the ratio of fungi to bacteria(F/B)significantly decreased by 35.9%(P<0.05),while the ratio of Gram-positive bacteria to Gram-negative bacteria(G+/G−)signific antly increased by 56.1%.This was strongly related to the increased soil pH values and the decrease of SOC.The Shannon index(H)and evenness index(E)of soil microbial PLFA diversity were significantly decreased after land consolidation(P<0.05).Compared to the Z1 treatment,the microbial PLFA diversity was improved slightly.Therefore,the land consolidation could significantly affect the composition of soil microbial PLFA diversity,and decrease the soil ecosystem stability.

基于Sentinel-2和Landsat卫星时序数据的耕地撂荒识别

充足的粮食供应是当下经济发展和社会稳定的重要保障之一,撂荒作为耕地边际化的极端表现,对其开展监测对保障耕地数量和质量至关重要。本文以四川省南充市营山县为研究区域,通过GEE平台,使用Sentinel-2和Landsat 7、8数据构建时序数据集,计算NDVI、EVI、NDWI、BSI、MSI等指数,分别利用支持向量机和随机森林法提取耕地撂荒,总分类精度为73.76%,Kappa系数为0.68,针对耕地撂荒最佳提取效果,F_(1)得分为0.6911。本文方法对山地丘陵地区耕地撂荒监测有较大的借鉴意义。

Impacts of Cultivated Land Conversion on Environmental Sustainability and Grain Self-sufficiency in China

Using provincial data, the present paper examines the impact of cultivated land conversion on agriculture and the environment. It is found that the grain production center is gradually moving towards more fragile and water scarce areas, putting more pressure on the environment. Land conversion caused large losses in ecosystem service values in the 1990s, but large scale ecological restoration programs have been implemented since 2000 to compensate for such losses. The ecological restoration programs are concentrated in regions with relatively low land productivity, whereas cultivated land conversion usually takes place in areas with relatively high land productivity. Newly-cultivated land, especially that in areas marginally suit for agricultural production, is likely to have much lower productivity levels than the original cultivated land. Because the stock of potentially cultivable land is almost exhausted, China＇s grain self-suffiency policy can only be maintained by preserving the available stock of arable land and increasing its productivity in a sustainable way.

西藏自治区和青海省耕地质量评价及影响因素研究

以西藏自治区和青海省为研究区,从土壤性状和技术条件评价耕地质量,识别其主导限制因子,探索其宏观影响因素,以期为提升耕地生产力、保障高原地区粮食安全提供支撑.基于主观和客观综合赋权确定指标权重,引入随机森林(RF)方法探索区域宏观自然-经济-社会因素影响.结果显示:西藏自治区和青海省耕地主要以中等地为主,面积占比为44.6%,中等地多为青海省的湟水谷地地区的坡耕地,较高的田面坡度制约了耕地高效利用.海拔和距城镇距离对于高原地区整体耕地质量具有重要影响.在多数地区,海拔与耕地质量呈现出负相关关系;距城镇距离对于耕地质量的影响存在空间差异;在藏中南和边疆带区,受到技术条件影响,高质量耕地往往布局在城市周边;在高原东北部河谷地区,邻近城市周边的耕地土壤质量更低,土壤退化更易发生.

土地资源管理中县级国土空间总体规划编制问题及对策

针对南华县国土空间总体规划中耕地“非农化”“非粮化”、用地布局缺乏科学性等问题,通过采取工程措施与调出补划相结合的方式,调整规划分区规则以及分类型、分区域布局新增建设用地等措施,使永久基本农田中的“非耕地”面积减少了149.02 hm^(2),农田保护区面积增加了9 607.35 hm^(2),城镇开发边界和村庄建设边界外的新增建设用地规模由6 044.02 hm^(2)下降到417.83 hm^(2)。

Estimation of soil organic carbon stock and its controlling factors in cropland of Yunnan Province,China

Soil organic carbon(SOC)is the most important indicators of soil quality and health.Identifying the spatial distribution of SOC and its influencing factors in cropland is crucial to understand the terrestrial carbon cycle and optimize agronomic management.Yunnan Province,characterized by mountainous topography and varied elevation,is one of the highest SOC regions in China.Yet its SOC stock of cropland and influencing factors has not been fully studied due to the lack of adequate soil investigation.In this study,the digital mapping of SOC at 1 km resolution and the estimation of total SOC stock in cropland of Yunnan Province was undertaken using 8637 topsoil(0-20 cm)samples and a series of spatial data through Random Forest(RF)model.It was showed that across the cropland of Yunnan Province,the mean SOC density and total stock were 4.84 kg m^(-2) and 337.5 Mt,respectively.The spatial distribution indicated that relatively high SOC density regions resided in the northwest and northeast parts of Yunnan Province.Elevation(19.5%),temperature(17.3%),rainfall(14.5%),and Topographic wetness index(9.9%)were the most important factors which controlled spatial variability of SOC density.Agronomic practices(e.g.,crop straw treatments,fertilizer management)should be optimized for the sustainable development of crop production with high SOC sequestration capacity in Yunnan Province.

综合“同质等效—流补平衡”的耕地“进出平衡”管制:方法与实证

研究目的:明确耕地“进出平衡”的管制体系,构建综合“同质等效—流补平衡”的管制框架,为科学制定农用地用途管制规则、合理确定耕地“进出平衡”管制要求提供参考。研究方法:逻辑推理法和案例分析法。研究结果:(1)耕地“进出平衡”应以一般耕地和可恢复非耕农用地为对象,综合“同质等效”与“流补平衡”的管制要求,实现耕地长期稳定利用的目标;(2)以“同质等效”和“流补平衡”为管制评价依据和分区划定原则,可为落实区域耕地“进出平衡”提供方法支撑;(3)宜兴市永久基本农田外的农用地可划分为备选补入区(2848.07 hm^(2))、备选流出区(2847.70 hm^(2))、重点保护区(3063.06 hm^(2))和特色发展区(16286.94 hm^(2))4种类型,落实耕地“进出平衡”管制后宜兴市耕地耕作适宜性均值可由0.60提升至0.64。研究结论:明确耕地“进出平衡”管制规则有助于落实耕地保有量和明确耕地利用优先序,并且实现耕地的量质并提、格局优化和功效改善。

基于面向对象结合随机森林模型的Sentinel-2A影像耕地信息提取

为了更快、更准确地提取耕地信息,以山东省青岛市莱西市夏格庄镇为研究区,利用Sen⁃tinel-2A影像融合光谱特征、遥感指数特征、纹理特征和形状特征等31个特征变量,设计4种耕地信息提取方案,采用结合面向对象的随机森林(Random Forest,RF)分类模型提取耕地信息,并基于相同分类条件,与传统机器学习分类方法对比,评价模型的优适性。结果表明:结合所有分类特征变量的方案4耕地提取效果最佳,其中旱地提取精度高达99.6%,大棚提取精度达88.4%;5种分类方法中,结合面向对象的RF模型耕地提取精度最高,减弱了分类结果的“椒盐”现象,优化了分类结果。

耕地“非农化”的时空格局演变及其驱动因素研究——基于影响分析与组态分析的双重视角

研究目的:探究中国耕地“非农化”时空演变特征及其压力、状态与响应因素的多重并发影响和因果组态复杂机制。研究方法:基于多元线性回归模型、时空地理加权回归(GTWR)模型的影响分析和基于模糊集定性比较法(fsQCA)的组态分析。研究结果:(1)2004—2020年中国耕地“非农化”面积总体呈增长态势,不同地区、不同类型城市和不同单元分别表现出“东多西少”“阶梯递增”“中西扩散”特征。(2)社会经济驱动因素对耕地“非农化”的影响体现出明显时空异质效应,其中人口城镇化、土地城镇化和产业结构是普遍性的因素。(3)压力、状态与响应中单因素并不构成影响耕地“非农化”的必要条件,不同地区耕地“非农化”的实现是诸多因素构成的不同组态构型并发协同作用的结果,但在不同组态构型的核心因素和辅助因素会发生角色和地位的转换。研究结论:耕地“非农化”受经济、社会和资源配置等多重因素影响,地方政府在制定调控管理政策时需着眼于不同组态路径中压力、状态及响应多重条件的适配关系,加强城市建设占用耕地的空间规划管控。

长江中下游地区耕地土壤有机碳密度变化率驱动因素

为探究长江中下游地区耕地土壤固碳增汇措施,该研究收集与整理长江中下游地区59处长期定位试验观测数据,量化不同类型耕地土壤有机碳密度变化率的差异特征,运用随机森林模型与线性规划探究土壤有机碳密度变化率的驱动因素与提升途径。结果表明:水田和旱地土壤有机碳密度变化率范围分别为−1548.15~3577.10 kg/(hm^(2)·a)和−261.89~3245.01 kg/(hm^(2)·a),差异不显著(P=0.85)。有机肥氮量、土壤pH值、化肥氮量、秸秆氮量对水田土壤有机碳密度变化率的影响较大;有机肥氮量和化肥氮量对旱地影响较大。因此,建议长江中下游地区可通过有机无机肥科学配施,合理调控水田土壤pH值和秸秆还田量。该研究可为长江中下游地区耕地固碳增汇的技术推广提供参考。

白桦育苗及栽培技术

为服务和满足陇东地区白桦工程造林和园林绿化对优质苗木的需求,在实践基础上,总结了陇东地区白桦育苗与栽植技术,包括种子采集与处理,苗圃整地、催芽、播种、幼苗期管理等幼苗育苗技术,营养钵壮苗、间苗培育技术,栽植地选择与整地,栽植后幼林地管理等林地管理技术。

基于随机森林下的云南省耕地利用效率测算及基尼系数分析

以2011—2020年云南省16个地州市为研究对象,对地均农业机械动力、地均劳动力等10个指标进行数据收集,在R语言中的随机森林算法下得到指标权重进而得出16个地州市的耕地利用效率;并根据基尼系数平均差公式计算得到6组不同区域之间的耕地利用效率基尼系数。结果表明,迪庆藏族自治州、德宏傣族景颇族自治州、怒江傈僳族自治州、大理白族自治州在2011—2020年平均耕地利用效率较高,普洱市、临沧市平均耕地利用效率相对偏低;滇中和滇西相比其他5组不同区域的耕地利用效率基尼系数整体在减小,而滇中和滇南以及滇南和滇北的平均基尼系数是6组不同区域平均基尼系数中最小的2组。

耕地“非粮化”现状及其原因分析——以思南县杜家寨村为例

随着我国乡村振兴战略的深入实施,城市化、工业化快速扩张,耕地被大量占有、挤压,耕地“非粮化”速度也越来越快。耕地“非粮化”作为影响粮食安全的重要因素,已成为亟待解决的社会热点问题。本文通过问卷调查深入了解思南县杜家寨村耕地利用现状,并使用二元Logistic回归分析耕地“非粮化”产生的原因。结果显示,杜家寨村耕地“非粮化”率为43.80%,所有驱动因子中影响最大的是土地流转,其次是家庭类型,然后是经济作物价格,最后是种粮补贴。基于此,本文提出以下对策建议:(1)降低耕地破碎化,开展规模经营;(2)增加种粮补贴,提高农民种粮积极性;(3)积极推进土地合理流转,加大流转用途监管;(4)强化村集体组织监督,引导农民合理利用耕地。

安徽省耕地非农化的时空演变特征及迁移路径

研究目的:为有效应对安徽省耕地非农化问题,探究县域耕地非农化的时空演变特征及迁移路径。研究方法:以1990-2020年共7年的安徽省LUCC数据为基础,借助ArcGIS软件,引入重心模型、标准差椭圆模型,探究耕地非农化的时空演变及迁移路径。研究结果:1990-2020年期间,安徽省县域耕地非农化重心空间路径表现为“y”型形态,呈现出先远离后靠近的态势。研究结论:揭示了安徽省县域耕地非农化近30年来的时空演变及迁移趋势,以期为政府部门掌握耕地非农化趋势提供一定参考,从而更好保护耕地。