Progress of Scale Effects in Land Use

The concepts of scale and scale effect in land use were introduced in this study,and the relationship between scale effect and land use was also discussed,which showed the deficiency in present studies and the trend of further studies.

Scale dependence of plant species richness and vegetation-environment relationship along a gradient of dune stabilization in Horqin Sandy Land, Northern China

Ecological patterns and processes in dune ecosystems have been a research focus in recent years, however the information on how dune stabilization influences the spatial scale dependence of plant diversity is still lacking. In this study, we measured the plant species richness, soil properties and altitude across four spatial scales （1, 10, 100 and 1,000 m2） at three different dune stabilization stages （mobile dune, semi-fixed dune and fixed dune） in Horqin Sandy Land, Northern China. We also examined the relationships between plant species richness, community composition and environmental factors along the gradient of dune stabilization. Our results showed that plant species richness increased with the increase of spatial scales in each dune stabilization stage, as well as with the increase of dune stabilization degrees. Canonical correspondence analysis （CCA） showed that plant distribu- tions in the processes of dune stabilization were determined by the combined environmental gradient in relation to soil organic carbon （SOC）, total nitrogen （TN）, carbon/nitrogen （C/N）, pH, electrical conductivity （EC）, soil water content （SWC）, fine sand （FS）, very fine sand （VFS）, silt and clay （SC）, and altitude. Plant species richness was significantly and positively correlated to SOC and TN in mobile dune, and significantly and positively correlated to SOC, TN, C/N, VFS and SC in semi-fixed dune. However, no significant correlation between plant species richness and environmental factors was observed in fixed dune. In addition, plant species richness in different dune stabili- zation stages was also determined by the combined gradient of soil properties and altitude. These results suggest that plant species richness has obvious scale dependence along the gradient of dune stabilization. Soil resources depending on dune habitats and environmental gradients caused by dune stabilization are important factors to de- termine the scale dependence of species diversity in sand dune ecosystems.

Response of CH_4 emission of paddy fields to land management practices at a microcosmic cultivation scale in China

The terrestrial ecosystem may be either a source or a sink of CH_4 in rice paddies, depending, to a great extent, on the change of ecosystem types and land use patterns. CH_4 emission fluxes from paddy fields under 4 cultivation patterns (conventional plain culture of rice(T1), no-tillage and ridge culture of rice(T2), no-tillage and ridge culture of rice and wheat (T3), and rice-wheat rotation(T4)) were measured with the closed chamber technique in 1996 and 1998 in Chongqing, China. The results showed that differences existed in CH_4 emission from paddy fields under these land management practices. In 1996 and 1998, CH_4 emission was 71 48% and 78 82%(T2), 65 93% and 57 18%(T3), and 61 53% and 34 22%(T4) of that in T1 during the rice growing season. During the non-rice growing season, CH_4 emission from rice fields was 76 23% in T2 and 38 69% in T1 The accumulated annual CH_4 emission in T2, T3 and T4 in 1996 decreased by 33 53%, 63 30% and 65 73%, respectively, as compared with that in T1 In 1998, the accumulated annual CH_4 emission in T1, T2, T3 and T4 was 116 96 g/m^2, 68 44 g/m^2, 19 70 g/m^2 and 11 80 g/m^2, respectively. Changes in soil physical and chemical properties, in thermal and moisture conditions in the soil and in rice plant growth induced by different land use patterns were the dominant causes for the difference in CH_4 emission observed. The relative contribution of various influencing factors to CH_4 emission from paddy fields differed significantly under different land use patterns. However, the general trend was that chlorophyll content in rice leaves, air temperature and temperature at the 5 cm soil layer play a major role in CH_4 emission from paddy fields and the effects of illumination, relative humidity and water layer depth in the paddy field and CH_4 concentration in the crop canopy were relatively non-significant. Such conservative land use patterns as no-tillage and ridge culture of rice with or without rotation with wheat are thought to be beneficial to reducing CH_4 emission from paddy fields and are, therefore, recommended as a significant solution to the problems of global(climatic) change.

Forecast of the Scale of Urban Construction Land in Chongqing Municipality during the Period 2010-2014

With the rapid development of China's modern cities,the scale of urban construction land has experienced dramatic changes.The forecast of urban construction land is the important content of urban construction development,and guarantee for healthy,rapid and intensive development of cities,therefore,we must reasonably determine the scale of urban construction land.Based on the status quo of construction land in Chongqing Municipality during the period 2000-2009,this article selects GM(1,1) model,linear model and non-linear model,to forecast the scale of construction land and each type of land subordinate to it in Chongqing Municipality during the period 2010-2014,respectively.The results show that the construction land in Chongqing Municipality will increase substantially during the period 2010-2014,and the area of each type of land subordinate to construction land will also increase to varying degrees,therefore the land contradictions will become more prominent.

Land Breeze and Thermals: A Scale Threshold to Distinguish Their Effects

Land breeze is a type of mesoscale circulation developed due to thermal forcing over a heterogeneous landscape. It can contribute to atmospheric dynamic and hydrologic processes through affecting heat and water fluxes on the land-atmosphere interface and generating shallow convective precipitation. If the scale of the landscape heterogeneity is smaller than a certain size, however, the resulting land breeze becomes weak and becomes mixed up with other thermal convections like thermals. This study seeks to identify a scale threshold to distinguish the effects between land breeze and thermals. Two-dimensional simulations were performed with the Regional Atmospheric Modeling System （RAMS） to simulate thermals and land breeze. Their horizontal scale features were analyzed using the wavelet transform. The thermals developed over a homogeneous landscape under dry or wet conditions have an initial scale of 2-5 km during their early stage of development. The scale jumps to 10-15 km when condensation occurs. The solution of an analytical model indicates that the reduced degree of atmospheric instability due to the release of condensation potential heat could be one of the contributing factors for the increase in scale. The land breeze, on the other hand, has a major scale identical to the size of the landscape heterogeneity throughout various stages of development. The results suggest that the effects of land breeze can be clearly distinguished from those of thermals only if the size of the landscape heterogeneity is larger than the scale threshold of about 5 km for dry atmospheric processes or about 15 km for moist ones.

County scale spatial differential characteristics of cultivated land use grade: A case of Binchuan County

Land resource is the material foundation of human survival and economic development, and the cultivated land is the essence of land resources. This paper takes the county scale, by using the method of GIS spatial analysis and statistical analysis unifies, to explore the quality of cultivated land in Binchuan County using level, and explain the utilization level of county cultivated land quality spatial differentiation characteristics. The results showed that:(1) in the quantity of cultivated land quality and utilization level, the average utilization of paddy land was greater than that of dry land, and the comprehensive utilization of cultivated land and so on. Among them, the paddy land ranged from grade 6 to 15, the average utilization was grade 11.6; dry land ranged from grade 2 to 11, the average utilization was grade 5.9; comprehensive range of cultivated land is grade 2 to 15, the average utilization was grade 8.1;(2) the quality of cultivated land utilization spatial differentiation. Paddy field, dry land and cultivated land and large value distribution in the central and southern, inverted V shape distribution; the smaller the value distribution in the East and West, a dumbbell shaped distribution. Among them, they don't use a larger value of paddy land distributed in the central, South and southwest, the maximum value is 14.3, the smaller the value distribution in the West and East, the minimum value is grade 7; the larger the value distribution by the dry land in the South and West, the maximum value is grade 10.2, the smaller the value distribution in the West and East. The minimum value is grade 2.3; the comprehensive utilization of cultivated land don't distributed larger value in the central, South and south-west, the maximum value is grade 12.7, the smaller the value distribution in the West and East, the minimum value is grade 3.5. This paper can provide scientific basis for the dynamic monitoring of cultivated land quality, the transformation of low yield farmland and the early warning of cultivated land pressure.

Study of Urban and Rural Construction Land Change Based on Small Scale in Dafang

This paper is to examine the urban and rural construction land data of Dafang between basic year and final year based on country scale and spatial econometrics,and analyze its spatial pattern and change feature. According to the results,the construction lands in all the villages of Dafang County showed strong spatial autocorrelation and significant spatial cluster. After the analysis of local Moran's I,the construction lands in 381 villages of 36 counties presented strong activity. The original small-scale villages were gradually enlarging,which will not only gradually benefit local development,but also be in accordance with the strategy of " one city,one district,eight parks".

Effects of Finer Scale Soil Survey and Land-Use Classification on SWAT Hydrological Modelling Accuracy in Data-Poor Study Areas

The limited availability of high-quality spatial data often limits the development of hydrological modelling in developing countries. Hydrological models with data at different scales may generate large uncertainties in modelling outputs. This study analysed the accuracy of four SWAT built models that combine soil and land use/land cover (LULC) data at the scale of 1:250,000 and 1:100,000 in a basin of Mexico. SWAT model allowed determining that large-scale maps produced better results than data from small-scale. Sensitivity analysis with different soil data was less than LULC data. However, the small-scale can be used for exploratory purposes when testing SWAT performance.

土地经营规模、农社交易关系与合作社增收效应

基于2020年中国乡村振兴综合调查数据,运用内生转换模型实证检验农户的土地经营规模对农社交易关系的影响以及不同类型交易关系下的合作社增收效应。结果表明:土地经营规模会显著促进农户选择松散型和紧密型交易,而对准一体化交易的影响并不显著,且其影响会因农户家庭人力资本、所在村庄集体行动能力和村庄地形而具有明显的异质性。合作社增收效应与农社交易关系之间并非简单的线性关系,在紧密型交易关系下合作社具有明显的增收效应,在松散型交易关系下增收效应并不明显,在准一体化交易关系下增收效应反而会受到抑制。不同农社交易关系的合作社增收效应在不同家庭人力资本农户中没有显著差异;对于村庄集体行动能力较弱的农户,松散型交易关系下的合作社增收效应会受到抑制;对于非平原地区的农户,紧密型交易关系下的合作社增收效应较明显。

西南地区河成湖与火山湖土地利用对水质的多时空尺度影响差异

为探究不同时空尺度下不同湖泊类型土地利用对水质的影响差异,以四川省自贡市富顺西湖(河成湖)和云南省腾冲市青海湖(火山湖)为研究对象,提取6个空间尺度(50、60、70、80、90、100 m湖岸带缓冲区)的景观格局指数,结合雨季(2022年7月)和旱季(2023年4月)湖泊水质参数,采用冗余分析法定量探究不同时空尺度下土地利用对两类湖泊水质影响的差异性。结果表明:(1)富顺西湖与腾冲青海湖水质参数季节性差异显著,雨季水质优于旱季,两个湖泊水环境质量存在显著差异,腾冲青海湖水环境质量优于富顺西湖,腾冲青海湖符合地表水环境Ⅱ类、Ⅲ类水质标准,富顺西湖达到Ⅳ类、Ⅴ类水质标准。(2)富顺西湖在旱季和50~60 m湖岸带缓冲区尺度下土地利用参数对水质变量的解释率最大,腾冲青海湖在雨季和60 m湖岸带缓冲区尺度下土地利用参数对水质变量的解释率最大。(3)土地利用指数对两类湖泊水质的影响各不相同。富顺西湖流域内斑块密度、景观形状指数和聚合度指数与多数水质指标呈正相关,“源”景观聚集程度和破碎化程度高会加剧对水质的威胁。腾冲青海湖流域内林地面积占比和聚合度指数对水质具有正效应,能够改善水环境质量;斑块指数和景观形状指数值的增加会加剧斑块破碎化,导致水质恶化。本研究基于不同时空尺度对土地利用与两类湖泊水质关系的差异性进行深入探讨,指导不同类型湖泊的区域规划与管理,为湖泊环境质量评价及保护和制定针对性的湖泊缓冲带设置、生态修复等策略提供科学依据,进而促进湖泊水质安全和水资源可持续利用。

博斯腾湖不同时空尺度下土地利用景观格局对水质的影响

定量分析不同尺度半径范围内博斯腾湖景观格局对水环境的影响,为有效保护流域水质与生态管理提供科学依据。基于2020—2021年博斯腾湖平、丰、枯水期23个采样点的实测水质数据和Google Earth遥感数据,结合冗余分析(RDA)和Spearman相关分析,揭示不同时空尺度下土地利用景观格局对水质的影响。结果表明:(1)博斯腾湖水体中COD_(Mn)、TN浓度异常偏高,分别有21.7%、55.1%的采样点超过地表水Ⅲ类水标准,表明TN和COD_(Mn)是其主要污染物;(2)5种不同缓冲区半径内土地利用与水质呈现显著相关性,丰、平、枯水期的1000、3000、500 m半径缓冲区对水质解释率最佳,分别为40.0%、35.6%和31.1%;(3)景观异质性特征与土地破碎化程度随空间尺度增大而增强;(4)土地利用类型中,耕地是水质恶化的主要污染输出源,其次为草地,尽管草地对净化水质起到积极作用,但其不恰当的管理方式使污染物进入水中,导致水质恶化;(5)景观格局指数中,LSI(景观形状)与NH3-N、TN呈现正相关性,SHDI(香农多样性指数)与NH3-N呈显著正相关性,表示随着景观破碎化程度增大,水质恶化程度加剧,LSI与水质的关联存在着很大的不确定性,仍需进一步探讨。

玉米完全成本保险对农户玉米种植面积的影响研究——基于内蒙古试点的准自然实验

随着中国农业农村现代化进程的加速,适度规模经营已成为关键的发展策略。土地流转作为实现规模化经营的重要手段,其效率直接影响到农业的集约化和现代化进程。近年来,土地流转价格不断攀升,从2011年的196.18元/亩上升到2022年的352.04元/亩,涨幅高达79%,且土地成本已占到玉米每亩种植成本的40%。玉米完全成本保险政策的实施,旨在确保种粮农户的收益稳定,并增强整体的粮食安全保障能力。为了切实保障农户的种植收益,关键在于激励农户增加对土地等关键生产要素的投入。购买该保险后,农户更有动力扩大玉米等主粮作物的种植面积,这对于提升粮食安全保障能力尤为重要。本文基于内蒙古玉米主产区通辽市和鄂尔多斯市400多户农户的调研数据,利用Heckman两阶段模型探讨了玉米完全成本保险对农户是否扩大种植规模及玉米种植面积的潜在影响。研究发现,该保险能够扩大农户的种植规模,并且与玉米种植面积的扩大存在正向关系。即使将核心解释变量“是否购买保险”替换为“上一年保险赔付金额”,这一结论也通过了稳健性检验。基于以上研究结论,本文建议政府和保险公司进一步推广和完善玉米完全成本农业保险,将其作为激励农户参与土地流转、促进农业规模化经营的有效工具,从而为农业现代化提供坚实的风险管理支持。

邻里推荐对农户有机肥施用行为的影响——来自四川省水稻主产区的实证分析

有机肥施用可以提高农产品品质和降低农业碳排放,邻里交流能以较快速度、较低成本为农户提供有机肥施用的相关信息,进而影响其有机肥施用行为。然而,关于邻里推荐对农户有机肥施用影响效果的经验证据仍然很少。本文基于四川省水稻主产区农户调查数据,分析邻里推荐对农户有机肥施用的影响及作用机制。结果表明,邻里推荐能显著提高农户有机肥施用的概率。这一结论经过稳健性检验仍然成立。邻里推荐会通过增强农户对农业绿色生产的价值认知和有机肥施用的经济效益认知,对其有机肥施用产生重要影响。不同农户会因对邻里的信任程度差异、与亲戚朋友的交往频率和家离集市距离的不同,导致其有机肥施用行为表现出明显差异。相较于低信任邻里农户、家离集市距离远和与亲戚朋友交往频率低的农户,邻里推荐对高信任邻里农户、家离集市距离近和与亲戚朋友交往频率高农户的有机肥施用影响更大。此外,邻里推荐和农技推广存在替代效应,邻里推荐会降低农技推广对农户有机肥施用的促进作用。

Influences of labor migration on rural household land transfer:A case study of Sichuan Province,China

The influence of labor migration on rural household land transfer has been hotly debated in academic circles, which focuses on whether part-time employment leads to land transfer. Using survey data on rural households in the Sichuan Province, and applying the theoretical framework of new economics of labor migration, this study explores the influences of labor migration on the direction and scale of land transfer from the perspective of rural household structure. The results indicate that: 1) the quantity of laborers has significant influence on the direction and scale of land transfer. The larger the on-farm labor variable(Labor), the lesser the possibility that land will be rented-out and the amount of land rented out will also be smaller. In addition, there is a greater probability that land will be rented-in and the amount of land rented-in will be greater. 2) The greater the ratio of off-farm laborers to rural household laborers(Off-farm) the greater the possibility that land will be rented-out. In addition the higher the ratio of on-farm laborers to the total household laborers(On-farm), the larger the possibility that land will be rented-in. Meanwhile, if the household has individuals at the age of 64 or older(Old) who are engaged in agriculture, there is a smaller possibility that land will be rentedout. 3) the ratio of part-time laborers to rural household laborers(Pluriactivity) have significant inverse U-shaped influences on the rent-in of land as well as the amount of land rented-in. The inflection points are 33.27% and 14.10%, respectively. Such findings confirm the significance of this study in better understanding the influence of labor migration on rural household land transfer.

Spatial heterogeneity of urban land-cover landscape in Guangzhou from 1990 to 2005

Urbanization has boon the most important process that changed land cover landscape in Guangzhou since reformation, especially since 1990. It is essential for monitoring and assessing ecological consequences of urbanization to understand landscape quantitative characteristics and its changes. Based on four land-cover type maps interpreted from remote sensing TM images of 1990, 1995, 2000 and 2005, combining gradient analysis with landscape metrics, the quantified spatial pattern and its dynamics of urbanization in Guangzhou was got. Three landscape metrics were computed within different regional areas including the whole study area, two transects along two highways （one N-S and the other W-E） and radiation zones with equal distance outwards the city center were set. Buffer zones for transects N-S and W-E were outlined along highways. The following questions should be answered in this paper： What responses were implied with changing spatial grain size or extent for landscape pattern analysis？ Could gradient progress of urbanization be characterized by landscape pattern analysis？ Did landscape metrics reveal urban expanding gradually？ Were there directional differences in land cover landscape pattern during urbanizing development？ The results gave some affirmative answers. Landscape pattern exhibited obviously scale-dependent to grain size and extent. The landscape metrics with gradient analysis could quantitatively approach spatial pattern of urbanization. A precise location for urbanized area, like city center and sub-center, could be identified by multiple landscape metrics. Multiple adjunctive centers occurred as indicated by analysis of radiation zones around the city center. Directional differences of landscape pattern along the two transects （N-S and W-E） came into being. For example, fragmentation of landscape in the transect W-E was obviously higher than that in the transect N-S. All in all, some interesting and important ecological implications were revealed under landscape patterns of two transects or radiation zones, and that was the important step to link pattern with processes in urban ecological studies and the basis to improve urban environment.

基于泛克里金插值法的Landsat8热红外数据的高空间分辨率地表温度反演

地表温度(land surface temperature, LST)地表物理状态过程中的一个重要参数,目前反演高精度地表温度是一个重要的研究目标。本文根据热辐射传输方程,利用空间分辨率30m Landsat8传感器的热红外数据反演地表温度,并利用泛克里金插值法对反演温度的结果进行尺度转换,获取2 m分辨率的地表温度数据。本文以广东省河源市东江林场为例,对2013年10月21日、2014年10月24日及2015年10月27日的Landsat8进行温度反演,对其反演结果进行泛克里金插值,最终获取2 m高空间分辨率的温度数据。本文以广州东江林场2013年10月21日、2014年10月24日和2015年10月27日获取的landsat8为例,为了检验地表温度数据的尺度转换的合理性,本文利用莫兰系数和夏皮洛-威尔逊检验法检验地表温度是否空间自相关性以及是否为正态分布。三帧温度结果的莫兰系数分别是0.96,0.96,0.97,表明该三帧温度数据空间自相关;由夏皮洛-威尔逊检验法获取的p值分别为0.1857,0.09968,0.08534,均大于0.05,温度数据服从正态分布。对2015年泛克里金插值前后的温度值与实测温度进行比较,平均误差系数减少了5.63%。由此可见,本文利用泛克里金法插值法对Landsat8反演的温度进行尺度转换后获得的结果更为合理。

Long-term oscillation of drought conditions in the western China： an analysis of PDSI on a decadal scale

Water resource availability is one of the primary limiting factors with regard to ecosystems in the western China. Having a clear understanding of multi-scale drought patterns in this region is a key step for adaption and mitigation to climate change. The Palmer drought severity index （PDSI） is a widely applied index to assess drought conditions. In this study, long-term monthly self-calibrated PDSI data from 1951 to 2012 were examined for drought spatiotemporal variations in the western China. The results clearly indicated that apparent spatial heterogeneities were evidenced between two sub-regions （arid land with annual precipitation less than 200 mm and semiarid land with annual precipitation between 200 to 500 mm） as well as in the entire region of the western China. Ensemble empirical mode decomposition （EEMD） analyses on monthly PDSI and other atmospheric variable time-series obtained from the Department of Civil and Environmental Engineering, Princeton University revealed that all monthly time-series of variables could be completely decomposed into eight intrinsic mode functions （IMFs） and a trend （residual）. This indicates that the monthly PDSI and atmospheric variables of the semiarid area in the western China contain eight quasi-period oscillations on various timescale spanning, seasonal to decadal cycles and a trend of a larger timescale from 1951-2012. The multi-scale drought patterns identified in this research could be powerful supports for decision-making regarding coping with droughts in this region.

高空间分辨率遥感影像填海造地识别方法研究

以空间分辨率为0.54 m的沿海地区卫星遥感影像为数据源,根据填海造地地块时序化监管的几何与光谱特征分析结果将其分类为围而未填、填而未用、已填已用(有建筑设施) 3种类型,构建与海岸线填海造地影像目标类型适配的谱系化深度学习特征样本库;再利用训练的多尺度粒度实例分割网络模型(MS-CNN)对该类地块进行识别,同时对比2012—2022年3个局部区域的变化影像图,以分析填海造地不同时期的识别效果。结果表明,MS-CNN能较好地识别填海造地,地块识别结果精确率为93.26%,召回率为91.73%,F1-score为92.5%,提高了填海地块全局和局部尺度粒度的特征表达能力,改善了光谱异质性高等因素导致的多尺度共生目标错漏检问题,为填海造地识别监测提供了一种准确可行的方法。

Land Surface Hydrology Parameterization over Heterogeneous Surface for the Study of Regional Mean Runoff Ratio with Its Simulations

An analytical expression for subgrid–scale inhomogeneous runoff ratios generated by heterogeneous soil moisture content and climatic precipitation forcing is presented based on physical mechanisms for land surface hydrology and theory of statistical probability distribution. Thereby the commonly used mosaic parameterization of subgrid runoff ratio was integrated into a statistical–dynamic scheme with the bulk heterogeneity of a grid area included. Furthermore, a series of numerical experiments evaluating the reliability of the parameterization were conducted using the data generated by the emulated simulation method. All the experimental results demonstrate that the proposed scheme is feasible and practical.

Suitability Analysis of Scale Management in Northeast China Based on Efficiency Evaluation

Under the resource constraint of low per capita possession of cultivated land and the strategic requirements for ensuring national food security,the intensive and efficient use of cultivated land is an important topic for long-term research in China's academic circles. It is an important prerequisite for exploring the moderate scale management of agricultural land. The calculation results of 147 county-level units in Northeast China by DEA method show that in the use efficiency evaluation results of cultivated land of county-level units,the mean values of comprehensive efficiency,pure technical efficiency and scale efficiency were 0. 674,0. 705 and 0. 96,respectively,and the DEA effective units account for about 11%. The effective areas of pure technical efficiency and scale efficiency do not have a high level of superposition. To a certain extent,this also limits the improvement of overall efficiency. In view of the scale of family farmland management,counties and cities with an average per household possession of cultivated land of 1. 71-2. 13 ha can achieve both scale and efficiency through efficiency improvement.