Changes of local agricultural landscape patterns induced by land consolidation in hilly and mountainous Southwestern China

Land consolidation (LC), as a type of human disturbance, improves land production efficiency and changes landscape distribution through land parcel reallocation. The objective of this study was to comparatively analyze the changes of landscape patches before and after a land consolidation project (LCP) and the effects of land levelling, irrigation and drainage work and road engineering on the landscape structure. FRAGSTAT3.3 and buffer zone analysis were used to investigate those changes. The results suggest that the heterogeneity of landscape depressed, and tended to simplification after LC. Dry land was the most highly variable land use pattern, and the change of forestland was least due to its locations at a gradient larger than 25°. LC resulted in a more rational use of land, and could be an important step in promoting rural development in depressed and fragmented agricultural areas through unused land exploitation, small-patch combination, irrigation and water conservancy, and road construction. Land levelling leveled off the gradient field surface and decreased the slope. The fragmentized patches were much more incorporated with increasing slope. On the other hand, the ridge of a field became longer so that the length of field surface and area of patch were increased. Land levelling regulated, simplified and combined patches, so that the complexity degree was reduced. It is found that the buffer distance of 35 m was a turning point of human disturbance by irrigation and drainage systems, and patches presented flaky distribution when the buffer distance was smaller than 35 m. Meanwhile, the distance range between 25 m to 50 m was an impressible area for road engineering, which was sensitive to human actions, and the changes of all landscape metrics were larger than those in other buffer zones. In general, LC not only reallocated fragmented parcels, but also improved agricultural conditions.

Modern pollen-vegetation relationships along altitudinal vegetation belts in the Leigong Mountain of southwestern China

Understanding the distribution,dispersal,and correlation of modern pollen with vegetation in mountainous regions is essential for establishing accurate modern analogs for fossil pollen records.This study,conducted in Leigong Mountain on the YunnanGuizhou Plateau of southwestern China,involved the collection of 35 surface soil samples from diverse vegetation communities along an elevational gradient ranging from 1210 to 1875 meters.The results reveal a close correspondence between modern pollen assemblages and vegetation zones.Principal Component Analysis(PCA)results indicate that pollen assemblages can effectively distinguish between subtropical montane evergreen broad-leaved forest(SEBF)and subtropical montane deciduous broadleaved forest(SDBF).However,both SEBF and SDBF show significant overlap with subtropical montane evergreen-deciduous broad-leaved mixed forest(SEMF).Detrended Correspondence Analysis(DCA)results clearly distinguish the three vegetation zones,and the first axis of DCA shows a significant positive correlation with elevation(p<0.01,R=0.48).Discriminant Analysis(DA)successfully assigns 94.4%of the modern pollen samples to their respective vegetation zones.Pollen taxa such as Impatiens,Astertype,and Rosaceae exhibit significant indicative capabilities for the SEBF zone,effectively distinguishing this vegetation zone from others.Pinus and Alnus display overrepresentation in the Leigong Mountain region,while Quercus(D,deciduous-type)and Poaceae exhibit high representation in the SEBF zone.In the SEBF zone,both pollen diversity and richness are the lowest.Our study reveals the complex relationship between the richness and diversity of pollen and vegetation.The diversity and richness of tree and shrub pollen are found to be lower than those of the corresponding plants.The pollen-vegetation relationship elucidated in this study serves as a critical reference for reconstructing ancient environments from fossil pollen retrieved in this region.

Effects of Land Management Practices on Soil Water in Southwestern Mountainous Area, China

The effects of selected land management practices （cross-sloping tillage, ridge culture, organic manure, and straw mulch） on soil water conservation in a southwestern mountainous area, China, were studied during November 2002 to November 2004. The experimental field is divided into three parts based on soil layer depths, 0-60 cm （part Ⅰ）, 0-40 cm （part Ⅱ）, and 0- 20 cm （part Ⅲ）, and they all had the same slope azimuth （SE）, slope （10°）, and slope type （linear）. The experimental plots were subjected to the following treatments： cross-sloping tillage （CST）; cross-sloping tillage with organic manure （CST/ OM）; cross-sloping tillage with straw mulch （CST/SM）; contour ridge culture （CRC）; contour ridge culture with organic manure （CRC/OM）; and contour ridge culture with straw mulch （CRC/SM）, to identify the effects of management practices on soil water. Water contents were determined for soil samples collected, using a 2.2 cm diameter manual probe. Soil water was monitored once every five days from Nov. 20, 2002 to Nov. 20, 2004. The results indicated that, in the study stages, an integration of rainfall, evaporative losses, and crop transcription controlled the basic tendencies of profile （mean） soil water, while land management practices, to a certain extent, only modified its amount, distribution, and routing. Moreover, these modifications also mainly focused on the first 20 cm depth of topsoil layer. When each management practice was compared with control treatment, season changes of profile （mean） soil water were pronounced, while interannual changes among them were not significant. More comparisons indicated that, in the study stages, contour ridge culture had better effects than cross-sloping tillage. And under the same tillage, the combination of organic manure could achieve more than straw mulch. These management practices should be recommended considering the effectiveness of soil and water management techniques in the southwestern mountainous area, China.

Relationship Between Soil and Water Conservation Practices and Soil Conditions in Low Mountain and Hilly Region of Northeast China

The soil and water conservation practices of ecological restoration(ER),fish scale pit(FP),furrow and ridge tillage across the slope(FR),shrub strips(SS),and vegetation-covered ridge(VR)are characteristic of the Jixing small watershed of the low mountain and hilly region of Jilin Province,Northeast China.This study aims to elucidate the effects of soil and water conservation practices on soil conditions after the short-term implementation of practices.Soil samples were collected from five soil and water conservation sites(ER,FP,FR,SS,and VR)and two controls(BL and CT)to investigate their properties.To evaluate the influence of soil and water conservation practices on soil quality,an integrated quantitative index,soil quality index(QI),was developed to compare the soil quality under the different soil and water conservation practices.The results show that not all soil and water conservation practices can improve the soil conditions and not all soil properties,especially soil organic carbon(SOC),can be recovered under soil and water conservation practice in short-term.Moreover,the QI in the five soil and water conservation practices and two controls was in the following order:ER>VR>BL>FR>CT>SS>FP.ER exhibited a higher soil quality value on a slope scale.In the low mountain and hilly region of Northeast China,ER is a better choice than the conversion of farmlands to planted grasslands and woodlands early in the soil and water conservation program.

Land degradation in the subtropical hilly andmountain regions of South China

Land degradation, caused by water erosion. closely related to inherent vulnerabilities of itseco-environment in South China. Spatial variation of land degradation from top to foot of a slope wasmainly induced by differentiation of surface materials and their erodibility, nutrient and moisture dueto downslope variation of land erosion. It was showed by comparing maps of land degradationbetween the 1950s and the 1980s that changes of land degradation varied from one area to anotherbecause of differences of human activities, including land reclamation and vegetation depletion.

Spatio-Temporal Impact of Rural Livelihood Capital on Labor Migra- tion in Panxi, Southwestern Mountainous Region of China

Labor migration to urban centers is a common phenomenon in the Panxi region of the southwestern mountainous region of China, mainly owing to inadequate livelihood capital in rural areas. Numerous studies have been conducted to explore the relationship between labor migration and its causes, such as individual and family characteristics, but few studies have focused on livelihood capital. This paper examines the impact factors on labor migration employment location selection and duration from a household livelihood capital perspective. A case study of 279 households from 10 villages in the area was carried out in February 2016. We used both qualitative and quantitative methods to analyze the data. On the basis of the 279 questionnaires, the proportion of households with non-labor migration is 48.4%, whereas households with labor migration within a local city and migration across regions account for 28.7% and 22.9%, respectively. Social, financial, and human capitals are the primary factors that influence migrants' employment location choice positively. Among them, social capital has a significant impact on both migration within a local city and across regions; each of the regression coefficients is 1.111 and 1.183. Social, human, and financial capitals also have a positive impact on the duration of labor migration, and similarly, social capital is the highest coefficient with 2.489. However, physical capital only partly impacts labor migration across regions, whereas the impact of labor migration within a local city, and the duration, are not significant. Furthermore, the impact of household natural capital on migration space and time are all negative relationships, especially for labor migration across the regions and duration, with coefficient scores of 4.836 and 3.450, respectively. That is to say, a laborer is inclined to migrate within a local city for a short term, or not migrate at all, if natural capital is abundant. Our analysis results show that household livelihood capital has a strong spatio-temporal impact on labor migration.

Research on Structure Innovation of Agricultural Organization in China's Southwestern Mountainous Regions

Taking agricultural organization in China's southwestern mountainous regions as research object,on the basis of analysis of the status quo of agricultural organization development in China's southwestern mountainous regions,we use related theoretical knowledge on economics and organization science,we probe into the process of innovation and mechanism of action concerning the structure of agricultural organization in China's southwestern mountainous regions over the past 30 years.Finally we draw several general conclusions regarding structure innovation of agricultural organization in China's southwestern mountainous regions as follows:first,the structure innovation of agricultural organization,a gradual process,proceeds ceaselessly along with ongoing progress and development of agriculture,and in this process,farmers always play a fundamental role;second,the structure innovation of agricultural organization is affected by many factors,and government institutional arrangement and change in market conditions is undoubtedly the most critical factor;third,the probable evolving direction of structure innovation of agricultural organization includes internal differentiation of the same form of agricultural organization,association of different forms of agricultural organization,and emergence of other forms of agricultural organization.

Relic Oceanic Crust at Sub-arc Depth: an Example from UHP Eclogites Enclosed in Serpentinites from the Southwestern Tianshan Mountains, China

Ultra-high pressure(UHP)eclogites that derive from subducted oceanic crust are rarely found at the Earth’s surface because they need to be enclosed in a buoyant host rock such as serpentinites that facilitate exhumation

考古科学视角下的山地社会:探索中国西南山地史前史的新方法

山地长期以来被视为文明的边缘地带。然而,近年来的考古发现和理论发展表明,山地不仅是人类活动的重要场所,也是技术传播与文化交流的关键通道。本文回顾中国西南山地史前农业、牧业以及文化交流研究的最新成果,从考古科学视角提出未来一些重要研究方向和议题。用跨学科方法探索中国西南山地丰富的生态多样性和多元文化景观,将为理解人类如何适应复杂环境、实现可持续发展提供独特视角。

山坝结构与族际共生:历史时期西南边疆民族交往交流交融的文化生态学考察

历史上西南边疆地区不同的经济文化类型和民族分布格局,反映了山坝结构形态下多元民族互嵌共生的社会结构特点。在山坝结构的空间单位中,各民族既发展出适应各自生境的经济文化类型,又通过不同群体的交流互动形成既相互区别又相互联系的社会文化系统。以山坝结构为研究对象,不仅能够较为清晰地呈现“人地关系”下西南边疆各民族交往互动的空间特征,而且还可以从民族共生的整体逻辑来认识西南边疆民族社会历史发展的多样性以及边疆各民族交往交流交融历史演进的区域特性。在认识论层面,相关研究或许能够在传统认知基础上,为当下中华民族共同体形成路径等议题提供一种新的观察视角。

多源时序数据特征优选的南方丘陵山区农作物分类研究

以广东省揭阳市揭西县为例,基于Sentinel-2多光谱影像、Sentinel-1时序雷达数据、时序植被指数和地形数据,通过计算J-M距离和特征分析对18个特征波段进行特征组合优选,并对比分析了支持向量机(SVM)、随机森林(RF)、最大似然比(MLC) 3种分类器对南方丘陵山区农作物的分类效果。结果表明,时序植被指数特征中NDVI效果最优,时序雷达特征中VH极化方式最优,地形特征中DEM最优;从不同农作物类型来看,时序植被指数特征和时序雷达特征均能提升晚稻、秋玉米的分类精度;对于晚稻而言,时序雷达特征和地形特征对其分类精度均有提升作用。不同分类器对比结果表明,SVM的总体精度比RF和MLC分别高4.67%和7.84%;Kappa系数分别高5.88%和10.48%,可为南方丘陵山区农作物分类提供有效思路和方法参考。

西南丘陵山区土地整理方案比选研究

新增耕地潜力是土地整理项目立项决策的重要依据,而新增耕地率是新增耕地潜力的反映,直接影响项目工程布局、投资预算以及效益问题。该文以重庆市忠县拔山土地整理项目为例,依据国土资源部不同土地开发整理项目新增耕地的两种最低门槛值10%和3%,进行土地整理方案比选设计,计算得到两种土地整理方案的新增耕地率分别为10.3%和4.02%,并从经济、生态和社会3方面,分别采用动态投资评估法、可拓物元分析法、综合指数法对两方案进行比选分析。结果表明:旱地坡改梯工程布局是造成两种土地整理方案新增耕地面积差异的主要原因;农田水利、道路工程以及防护林工程布局差异不大,只存在布局力度上的差异;从方案的系统效益看,新增耕地率10.3%的方案无论是动态投资回收年、生态环境关联度、社会效益指数,还是系统效益指数均优于新增耕地率为4.02%的方案;通过典型田块采用加权算法计算净耕地系数,可以作为西南丘陵山区土地整理项目净耕地系数的计算方法,但该方法中修正系数确定需要经过实地勘测和类比,这样可避免典型田块选择的主观性。

气候变化对贡嘎山森林原生演替影响的模拟研究

林窗模型是研究森林生态系统对全球气候变化响应的有效工具。应用贡嘎山森林演替模型(GFSM)模拟气候变化对贡嘎山东坡冰川退缩和泥石流迹地森林演替过程的影响,并根据IPCC第4次评估报告,选择最具代表性的3种气候变化情景(B1、A1B和A2),比较分析了不同情景下森林树种组成、优势树种径级结构和林地土壤碳氮动态特征。结果表明:维持目前气候状况不变时,贡嘎山东坡冰川退缩和泥石流形成的迹地,经过典型的川滇柳、冬瓜杨和桦树先锋群落演替阶段,最终将恢复为冷杉林。若气候变化情景(A1B和A2)发生,繁殖能力和耐性较强的树种,如高山松和桦树,可能取代喜冷湿环境的冷杉,成为这一地区的优势树种。届时,森林生物量和土壤碳氮含量将随优势树种的改变而下降。不同气候情景之间的模拟结果存在一定的差别,若B1情景发生,迹地还会恢复为冷杉林,但是其抗干扰能力和稳定性明显下降。总之,无论哪种气候情景发生,都将不利于冷杉林的恢复和更新。

东北丘陵区沟蚀发展现状及影响因素分析

选取第一次全国水利普查土壤水蚀普查中吉林省梅河口市6个野外调查单元作为典型研究区,采用野外实地调查与地理信息技术相结合的方法,对东北低山丘陵区坡耕地沟蚀发展现状及影响因素进行调查分析。结果表明:(1)研究区6个调查单元总面积为142.9 hm2,侵蚀沟数量共93条,沟长共5 476 m,沟壑密度3.83 km km-2,总侵蚀量为4 575 m3。其中切沟沟长占总沟长的61.03%,侵蚀量占总侵蚀量的92.35%。(2)研究区沟蚀发展现状严峻,其中小杨乡、红梅镇、双兴乡和一座营镇沟蚀强度为剧烈,沟道密度分别为7.12、4.63、5.55和4.25 km km-2。牛心顶镇和海龙镇沟蚀强度分别为强烈和中度。(3)坡度是研究区坡耕地沟蚀发育发展的重要因子,与沟壑密度存在较强线性相关,相关系数为0.71(p<0.05),在坡度大于8°时沟壑密度最大。(4)沟壑密度随坡长的增大而先增大后减小,在坡长200～299 m内最大,超过500 m后逐渐降低。(5)沟壑密度与流域长宽比具有较强的相关性,相关系数为0.83(p<0.05),沟壑密度随流域长宽比的增大而减少。

南方丘陵山地生态系统服务与农村社区协同发展模式研究——以广东乐昌市8个乡村为例

生态系统服务是保障农村经济可持续发展和生态环境健康的重要基础,农村社区作为乡村社会经济的基本构成单位以及小尺度复合生态系统,其经济活动将直接扰动自然生态系统服务。南方丘陵山地是我国重要的生态屏障带,生态保护的意义重大。以该地带重要生态功能区的广东乐昌市的8个地形地貌相似、但发展存有较大差异的乡村为研究对象,利用遥感影像和实地调查数据,综合分析各村土地利用及经济发展状况;基于国际通用生态系统服务分类标准和评估方法,构建乡村生态系统服务指标体系,对各村生态系统服务进行价值评估,并探讨生态系统服务与农村社区协同发展的典型模式。研究表明:(1)从生态服务功能总价值来看,浆源村最高,为16585.173万元/a,前村次之,为13152.621万元/a,车头园村最低,为1611.611万元/a;单位面积生态系统服务价值量总体呈相似的格局,但局部略有差异。前村、上丛村较高,分别为8.739万元hm^-2 a^-1、8.080万元hm^-2 a^-1。(2)土地利用以及经济发展方式的差异,影响了生态系统服务的保持、维护及利用,各村农户经济收入与从生态系统服务获得的福利,以及乡村生态系统服务价值与经济发展水平呈现不均衡的特征。(3)基于发展基础、生态条件等,适度发展乡村特色种植和生态旅游等低影响经济发展模式,有利于降低对生态系统服务,尤其是调节、支持类等功能的影响,并促进生态系统服务非商业价值向商业价值转变,提升乡村经济发展水平。研究结果以期为维护重点生态功能区的生态安全,优化乡村经济结构与发展模式,推进生态服务功能提升及农村社区协同发展提供参考。

西南丘陵山区农村居民点整理潜力测算方法探讨——以重庆市渝北区为例

探讨西南丘陵山区 (以渝北区为例 )农村居民点整理潜力的测算方法。研究方法 :人均建设用地标准计算法、闲置宅基地抽样调查法、城镇体系规划法 ,层次分析法 (AHP)。综合 3种潜力测算法 ,运用层次分析法获取各方案权数 ,得出渝北区规划目标年的居民点整理潜力值。西南丘陵山区农村居民点整理潜力可综合人均建设用地标准、闲置宅基地抽样调查与城镇体系规划 3种方法 ,通过对各方案赋权重值得出潜力。

西南丘陵山区土地整理现状与对策研究

西南丘陵山区的土地整理工程受其独特的地形地貌条件、变化无常的气候、破碎的土地资源、不均的水资源分布以及频发的自然灾害等因素的影响,具有一定的特殊性.根据对多个已实施的土地整理项目调查研究发现:目前西南丘陵山区土地存在重视增加耕地数量,但忽视提高耕地质量,工程设计脱离实际,与相关规划衔接不够等关键问题,并对这些问题的产生原因进行了深入分析,提出了相应的解决这些关键问题的对策和措施.

南方丘陵山地水土保持与循环农业发展策略研究

从南方丘陵山地水土流失现状分析入手,阐述南方丘陵红壤侵蚀退化地的水土流失特征与主要防控成效,总结4种具有示范推广意义的治理型循环农业开发模式:(1)以合理统筹兼顾为主线的特色农业开发模式;(2)以资源合理配置为核心的立体农业开发模式;(3)以沼气综合利用为纽带的循环农业开发模式;(4)以拓展生态旅游为特色的观光农业开发模式,并据此提出与南方山区农村社会、经济、生态的实际情况相适应的乡村循环农业发展对策:一是结合区域实际,制定山区科学发展规划;二是优化产业结构,引领乡村循环农业开发;三是科技创新驱动,实施科企工农有机结合;四是创新管理机制,充分发挥投入要素作用;五是加强培训工作,提高劳动者的综合素质。

西南丘陵山区土地整理规划设计的制约因素分析

土地整理规划设计是土地整理项目的核心,不同地区进行规划设计所受到的限制因素不同。分析不同区域环境的地域条件对土地整理规划设计的影响,能够使土地整理规划设计更具操作性。文中阐述了西南丘陵山区开展土地整理项目规划设计的特点,对其限制因素进行了分析、总结,并根据贵州省黎平县土地整理项目规划设计的内容,分析了因地制宜进行土地整理规划设计的重要性。并提出了相应的解决思路。

西南丘陵山区农村居民点整理:难点与对策

以重庆市部分区县的实地调研为依据,分析了西南丘陵山区农村居民点的分布特点,阐述了农村居民点整理所面临的种种困难;提出了实现土地承包经营权的流转是解决问题的关键,并以新颁布施行的《农村土地承包法》为法律和政策依据,根据区内条件差别提出相应的农村居民点整理对策和相关政策建议。