【作者】 陈荣蓉；

【导师】 宋光煜； 魏朝富； 谢德体；

【作者基本信息】 西南大学 ， 土壤学， 2012， 博士

【摘要】 在影响土地利用变化的人类活动中,农村土地整治是改善农业生产条件和生态环境的重要手段,也是一种强制性、时效性很强的干扰活动,在短期内会对生态系统及景观格局产生剧烈影响。目前,我国农村土地整治偏重于新增耕地目标,对农村土地利用及生态环境问题关注和治理力度不够,致使乡村景观严重受损,生物多样性降低,并对耕地保护、粮食安全和食品安全及农产品质量构成潜在的威胁。因此,作为未来应对全球气候变化、生态环境和粮食安全及国家、区域层面城乡统筹、一体化发展的战略需求的重要手段——农村土地整治,在技术需求上应如何响应；在工程措施上应如何适应；这些工程技术措施又将造成什么样的生态景观效应,尤其在小尺度上对生境质量、景观多样性、土地产能、生态景观服务功能及水文生态过程等将产生怎样的影响等,都急需在理论和实践层面上有更为深入和全面的认识或理解。本文立足重庆,基于“一圈两翼”的区域发展格局,选取5个国土整治整村推进示范村项目为样点,结合土地利用变化理论、农村土地整治理论和景观生态学理论,构建了“农村土地整治—土地利用变化—景观格局及生态学过程”分析框架,试图从工程技术的角度揭示小尺度上工程技术措施治理土地破碎化过程的机理；同时,借助于对土地整治景观生态学过程的分析,阐明土地利用、农业生物多样化与地块异质性间的联系,为评估乡村景观建设的技术需求和土地整治工程措施的适应性,以及制定农村土地整治建设乡村生态景观的技术策略,提供科学的认识途径和有针对性的解决方案,由此以期为土地整治景观建设理论和技术创新提供科学指引。研究取得的主要结果和结论如下：(1)农村居民点复垦工程及其景观效应：①依据不同的用地控制标准,5样点村农村居民点人均用地水平相对集约,但户均表现相对粗放;从格局来看,在横向水平上,农村居民点从丘陵到山地由小聚居向大分散过渡;在纵向梯度上,随着海拔的上升,农村居民点的数量和面积总体呈明显减少趋势。②农村居民点复垦作为一项系统工程加以实施,并参与产业规划,不仅促进了样点村自发形成的分散农村聚落向具有相对规模且有序的农村聚落转变,也加快了丘陵山区土地利用方式转型和生态恢复。③数量特征上,农村居民点复垦导致样点村居民点个数和面积均大幅减少,而聚落规模则明显增大,其用地格局由复杂趋于简单。④景观特征上,农村居民点复垦导致样点村景观多样性水平下降,SHDI均值由0.9209降至0.8829;而斑块形状规则化程度提高,LSI均值由23.2451降至21.3039；景观的空间集聚性有所提高,CONT均值由93.9518升至94.8299。可见,农村居民点复垦,在一定程度上尊重了村域土地利用、农业生物多样化与地块异质性间的联系,既消除了自然村落的弊端,又实现了乡村景观的重塑,同时也给当地创造了发展契机。(2)土地平整工程及其景观效应：①从浅丘到低山丘陵再到中低山槽谷,土地利用的主要矛盾从人多地少转向地形地貌约束；就耕地而言,水田均分布于15°以下,而旱地的78.28%分布于15°以上：水田和旱地的破碎化表现形式不同。制约水田利用的是田坎曲折、占地宽,制约早地利用则是坡耕旱地,生产耕作困难,水土流失和作物减产现象普遍。②在土地平整中,采取田块归并和条田整治治理水田、采取坡改梯治理旱地是丘陵山区降低破碎化、提高土地利用率较适宜的方式。③土地平整工程显著改变了水田和旱地的农田景观,田块形状趋于规整。因此,对土地破(细)碎化的治理,不仅限于单纯的地块调整和归并,在丘陵山区更应注重条田整治和坡改梯的治理方式。(3)农村道路工程及其景观效应：①农村道路优化布局和整治设计,提升了项目区道路结构、质量和通行能力,且减少了占地。除YD-Ⅱ外,其余样点田间道与生产路之比提高2%-11%;砼质生产路、硬化田间道比重增加,路面宽度增加：道路环通度(αα)、连通度(y)变化范围分别由0.32～0.37、0.54～0.58提升至0.37～0.46、0.58-0.64。②在景观水平上,新建道路会加剧景观斑块分割,导致破碎化程度增加；而道路减少,则有助于降低景观破碎化程度。不过,因工程规模有限,农村道路建设对区域景观斑块间连接程度和景观多样性不会造成显著影响。在类型水平上,农村道路整治则一定程度地改变了耕地、农村居民点和生态用地的形状及格局,发挥了对乡村景观的重塑和优化作用。(4)农田水利工程及其景观效应：①农田水利工程整治不同程度地改善了项目区农田水利工程的数量、质量及网络结构特征,增加了有效灌面。经整治,5样点村水源工程新增蓄水池65口,灌溉渠总长由19.94km增至27.25km,排水沟由80.60km增至136.03km,渠网密度(D)、环通度(α)、连通度(y)变化范围分别由10.98～22.94、0.16～0.25、0.45～0.50提升至16.73～50.60、0.20～0.28、0.47-0.52。②在景观水平上,新建农田水利工程会加剧对区域景观斑块的分割,增强景观的破碎性,导致斑块形状规则化程度降低,但对区域景观的多样性和连通性影响不明显：在类型水平上,农田水利工程整治作用于土地利用过程会明显改变耕地和生态用地的形状及格局,但对农村居民点影响较小。(5)土地整治前后土地利用(景观)变化效应及其景观生态学过程：①土地利用景观结构变化表现为：农业生产景观显著增加,农业生态景观显著减少,农业服务设施景观有所减少。②在类型水平上,耕地景观受到较强干扰,变化显著,破碎度增加；农村居民点景观受到强烈干扰,变化剧烈,破碎度显著下降；生态用地景观受到一定干扰,但变化较小,破碎度有所下降。在景观水平上,总体景观破碎度下降,最大斑块面积和斑块聚集度提高,斑块间的廊道连通性增强,斑块形状的规则性和景观多样性降低；从样点间比较看,从丘陵平坝到中低山区土地整治带来的景观变化存在差异,但不显著。③土地整治使生态总价值均实现了不同程度的增值,且其作用于不同类型的景观产生了不同的景观生态效应。其中,农业生产景观和农业服务设施景观(水域)的生态价值普遍增加,如YD-I分别有10.25%和9.94%的显著增幅,而农业生态景观的生态价值变化不一致。④与土地整治相关的景观生态过程表现为,a)土地整治中,土地利用结构调整改变了景观结构,土地用途转变改变了景观功能,由此导致了景观格局的演变,并带来不同的景观生态效应。b)丘陵山区农村建设用地的复垦还耕、还园、还林,在一定程度上提高了生态景观要素之间的连接度水平,有利于保持景观生态的稳定;而土地整治实施的田间道路工程、农田水利工程改善了景观的连通性。c)土地整治易导致耕作层土壤发生改变,给土壤肥力和生物多样性带来负面影响,导致土壤的水分和养分循环不能充分进行。d)在土地利用结构调整中,通过尊重地块异质性,发展农业生物多样化,优化村域土地利用,有助于协调人与自然的关系,保护景观多样性。(6)研究建议在土地整治的规划设计中,适当引入基于生物多样性保护的景观规划方法,注重核心生物栖息地的保护、缓冲区的建立、廊道的构筑以及景观异质性的加强和栖息地的恢复。综上所述,在农村土地整治生态景观建设战略的指向下,本文构建了“农村土地整治—土地利用变化—景观格局及生态学过程”分析框架,为解释土地整治在微观尺度上导致的土地利用及景观变化和由此带来的景观生态效应问题,以及揭示不同区域土地利用、农业生物多样化与地块异质性间的联系提供了途径,有助于深入把握土地整治与土地生态环境的作用机理,并为评估乡村景观建设的技术需求以及土地整治工程措施的适应性,以及制定农村土地整治建设乡村生态景观的技术策略,提供了较为科学的依据。研究有望为开展土地整治景观建设理论和技术创新的综合研究提供有益的尝试。更多还原

【Abstract】 As a human activity inducing land use change, rural land consolidation is an important tool to facilitate agricultural production and improve eco-environment, and is a compulsory and short-term tool that would have dramatic impact on ecosystem and landscape pattern instantly. The present rural land consolidation projects aim at increasing arable land in China, with less attention on rural land use and eco-environmental problems. Emprical studies show that land consolidation projects bring out disturbance of rural landscape, loss of biodiversity, and a potential threat on cultivated land protection, food security and quality of agricultural products. Instead, the rural land consolidation should be an important strategic tool of adpatating to climate change, improving eco-environment, ensuring food security, and coordinationg the development of urban and rural development. Consequently, there are still many questions to answer, such as how to use the technological and engineering measures of land consoliation to meet with the above objectives, what impacts of land consolidation on eco-environment, especially on habitats stablity, landscape diversity, land productivity, ecological services and hydrological process. There is a need for better theoretical and practical knowledge or understanding on land consolidation.This paper selected five "entire-village advancement" projects of land consolidation as cases, which distributed at different locations of Chongqing, such as the core urbanized area, and the southwest and southeast area, called as "one round and two wings". First, based on theories of land use change, rural land consolidation and landscape ecology, this paper attempted to discover how engineering and technical measures reduced land fragmentation through land consolidation, from an aspect of "rural land consolidation-land use change-landscape pattern and ecological process" The second objective was to explore the relationship between land use, agricultural bio-diversity and land parcels heterogeneity, based on landscape ecology. That would help improve our understanding about technical requirement of rural landscape rehabilitation and engineering adaptability of land consolidation. Finally, technical policies and alternatives were suggested to improve rural landscape pattern through land consolidation, from theoretic and technical aspect. The main findings and conclusions are as follows: (1) Rural settlements consolidation and its landscape effects:First, according to the relevant national standards, rural settlements area per capita approached at the standard in the five villages, while the area per household was larger than the standard, which reflects extensive land use. The rural settlements distributed scatter in the mountains and compact in the hills for those villages. The number and area of rural settlements decreased with altitude increased. Second, rural settlements consolidation was a systematic engineering, because it incorporated agricultural industrial development, and speed the transformation from disorder and dispersed rural settlements to large-scale and well-planned ones, and accelerated the land use transformation and the ecological restoration in those villages. Third, the density of rural settlements decreased significantly, while their size increased and their distribution became simple in those villages, through rural settlements consolidation. Fourth, the landscape diversity declined after consolidation, as indicated by the decrease of average SHDI from0.9209to0.8829. Average LSI decreased from23.2451to21.3039, reflecting that the shape of rural settlements became simple. The rural settlements get a higher level of spatial aggregation, since average CONT increased from93.9518to94.8299. We can infer from it that rural settlements consolidation was good for rural areas to some extent, because it decreased the dispersed pattern of natural villages, and rehabilitated the rural landscape, as well as provided more opportunities for local people. Espcially, it improved the links among rural land use, agricultural biological diversity and land parcles heterogeneity.(2) Land leveling and its landscape effects:First, the major problem confronting by shallow or low hilly areas was scarce land for a large population, while that confronting by mountainous or valley areas was extensive land use due to topography constraints. In general, most of paddy fields located in the areas with a slope less than15degree, while78.28%of rainfed land located in the areas above15degree. As a result, the fragmentation of paddy field and rainfed land had different meanings. That is, the use of paddy fields was contrained by curved and land-consuming path throuth fields. In constrast, the use of rainfed land was contrained by the sloping terrians, which made agricultural production more inconvenient due to soil erosion and crop reduction. Second, it was workable to eliminate small parcels of paddy fields, strip and regulate paddy field pattern, while it was good to change sloping rainfed land to rainfed terraces for land leveling, for reducing land fragementation and improve land use effiency. Third, with land leveling, rural landscape including paddy fields and rainfed land changed since the shape became regular. Therefore, to reduce land fragmentation, a few measures were suggested, including eliminating small parcels of paddy fields, striping and regulating paddy field pattern, and changing sloping land into terraces.(3) Rural roads construction and its landscape effects:First, the constuction of rural roads enhanced carrying capacity of roads and decreased transportation land occupation, by improving the distribution and quality of them. Excluding YD-Ⅱ village, the other villages had an increase about2%-11%of the ratio between major field roads and minor ones. The roads built by concrete increased and the width of them enlarged. The looping index of rural roads (a) increased from0.32-0.37to0.37-0.46, while the connectivity index of rural roads (y) increased from0.54-0.58to0.58-0.64. Second, rural roads construction fragemented rural landscape, while the demolishing of rural roads reduced landscape fragementation. However, there were no significant impacts of rural roads construction on the connectivity and diversity of landscape, due to relatively small change of rural roads. As for the landscape types level, it was found that rural roads construction optimized road network and the pattern of arable land, rural settlements and ecological land, thus rebuilding and optimizing rural landscape.(4) Farmland water conservancy and its landscape effects:First, the characteristics of quantity, quality and network became better after implementation of farmland water conservancy than before. The irrigated areas were enlarged through land consolidation in the five villages. The number of newly built tanks amounted at65in those villages, the total length of irrigation cannals increased from19.94km to27.25km, and the length of drainage ditches increased from80.60km to136.03km. As a result, the density of irrigation and drainage network (D) increased from10.98-22.94to16.73-50.60, and their looping index increased from0.16-0.25to0.20-0.28, and their connectivity index from0.45-0.50to0.47-0.52, respectively. Second, at the landscape level, the provision of farmland water conservancy fragemented rural landscape by separating land patches and increasing shape complexity, but it had no significant impacts on the diversity and connectivity of rural landscape. At landscape type level, the provision of farmland water conservancy significantly changed the spaital pattern of cultivated and ecological land and resulted in land use change, but it had little impacts on the pattern of rural settlements.(5) The overall land use change and its landscape ecological effects before and after land consolidation:First, after land consolidation, agricultural land significantly increased, ecological land significantly decreased, and rural facilities land decreased slightly. Second, cultivated land was disturbed and fragmentated by land consolidation, rural settlements was disturbed and regularized by land consolidation, and ecological land was disturbed and regularized slightly. At landscape level, the overall landscape fragmentation reduced, the largest patch area and patch aggregation increased, the corridor connectivity of patches increased, and the regularity of shape and landscape diversity reduced. Among different villages, there were a few differences of landscape change by land consoliation, due to the impacts of terrain such as hills, flat land or mountainous areas. Third, the total ecological value increased after land consoliation among those villages, but the change of ecological value varied with land use types. For example, the ecological value of agricultural land and facilities land generally increased, with an increment of10.25percent and9.94percent respectively in the village of YD-I. However, the value of ecological land varied with villages. Fourth, the adjustment of land use structure resulted in the change of landscape configuration, and the land use conversion led to the change of landscape function. Consequently, through land consolidation, landscape pattern evolved and landscape ecological effect changed. Rural residential land was converted to cultivated land, orchard and forest in hilly areas by land consolidation, which increased the connectivity of ecological land patches and the stability of landscape. Rural roads construction and farmland water conservancy increased the connectivity of landscape. After land consolidation, the cultivated soil was disturbed, which had a negative effect on soil fertility and biodiversity by interrupting the moisture and nutrient cycling in soil. The adjustment of land use structure should take biodiversity conservation and rural land use optimization into consider, based on land heterogeneity. The results indicated that land consolidation harmonized the relationship between man and nature, and it also increased landscape diversity.(6) It was suggested that landscape plan methods should be incoprated into the designs of land consolidation projects, for the purpose of biodiversity protection. For instance, we should took those methods into practices, such as the protection of core habitat, the establishment of buffer, the construction of corridor, the enhancement of landscape heterogeneity and the recovery of habitat.To sum up, this paper provided an analytical framework of "rural land consolidation-land use change-landscape pattern and ecological process", based on strategy of rural land consolidation and ecological landscape construction. The framework provided possible solutions at local scales to those problems resulted from land use and landscape change by land consolidation, and revealed the links among land use, agricultural biodiversity and land heterogeneity. The results would help better understand of the relationships between land consolidation and ecological effects, and provided better technological suggestions or strategies of how to consolidate rural landscape and conduct land consolidation, as well as how to adjust land consolidation to improve ecological landscape. The results would also help testify and further the theories and technical innovations of land consolidation, based on landscape construction.更多还原