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Basic Farmland Construction And Effect Evaluation In Chongqing

Posted on:2017-04-01Degree:DoctorType:Dissertation
Country:ChinaCandidate:J B CengFull Text:PDF
GTID:1109330509454503Subject:Land Resource Science
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The national food security and social stability has always been a major issue in China. The "rice bowls" firmly in their own hands, is a major issue which must face up to and solve at present and even after a long time. In order to guarantee the healthy and sustainable development on social and economy of our country, a series of related policy of protecting cultivated land have been proposed. A series of engineering and biological measures have taken ultimately to ensure the bottom line of 1.8-billion-mu of arable land, food production and realization of the dynamic equilibrium of the total cultivated land in the country. Meanwhile, Chongqing is the grain production and marketing balance areas and rice demonstration zone in the South, and recently has been set up as the reform testing area of urban and rural coordinator. However, the current per capita arable land is only about 0.65 mu in Chongqing, the low mountain area caunts for the city’s total land area of 75.98%, the ratio of the mountains, hills and plateaus, flat area is 76:22:2. According to the influence of complex topography, there have been some problems, such as land fragmentation, the bad quality, the poor production conditions, the low yield, poor infrastructure, shortage of resources. Thus the tasks of improving quality, increasing food production and creating basic farmland needs to be imminently addressed. Therefore, the objectives of this study were, where were the basic farmland? How were the construction difficulties and timing? What were the key indicators to be verified? How to evaluate the effects after the construction? Taking Dianjiang County in Chongqing c1 ity as an example, Various aspects were analysed like the basement of the delineation of permanent basic farmland → differential construction of basic farmland → the verifications of oil carbon sink in basic farmland in recent 30 years→the conclusion of the comprehensive effect of evaluation of basic farmland construction, etc. To protect cultivated land, we should research the method of global climate change in the view of soil carbon sequestration management. The effort to promote the "double target" path of soil carbon sink management and farmland protection could contribute to establish appropriate strategies to provide scientific basis and reference in Chongqing and even the Southwest Mountain Region.(1)Permanent basic farmland demarcated in ChongqingIn the standardized normal outcome of farmland decision index, the optimum conditions were farmland irrigation, rainfall, transportation, and rural residential radiation. For most soil quality indexes, the range of equal value, STD and CV are [0.2, 0.6], [0.1, 0.3], and [40, 75], As variation in subjective and objective weights of those indexes, after normalization, the maximum weight was farmland irrigation and farmland connectivity, the minimum weight was more than 10 ℃ accumulated temperature, average rainfall in natural condition, organic carbon in soil quality by analytic hierarchy process, and transportation, rural residential radiation and towns radiation in distance condition. The most important conditions for selecting permanent farmland were farmland irrigation and>farmland connectivity>towns radiation>soil organic carbon. According to measure and closeness of positive and negative ideal points, the quality of farmland was generally close to each other, and the distance condition was the best and comparatively stable, therefore the whole performance was better. Four grades were divided such as key, proper, adjusting and reserved, where farmland were chosen as permanent basic farmlands. Local department prefer to select superior farmlands, which were in “key” and “proper” grades, in the selection under constraint condition. In this study, the proportion of proper and adjusting grades increased, while the proportion of key and reserved grades decreased. which was suitable for the southwest hilly area permanent basic farmland delimitation, could realize double target "protect arable land red line, guarantee the economic growth". It’s conducted by three aspects: data comparison analysis, the decision model of rationality. The standardization and the feasibility was verified, for next step southwest hilly area of fill designated to provide theoretical basis and scientific reference.(2)Basic farmland construction differential in ChongqingThe comprehensive quality of basic farmland in Dianjiang county had a significant regional difference in space. The highest quality IV, mainly distributed in the lower edge of the inner edge of the MingYue mountain, HuangHuashan, and the central area of the East and the West, presenting a pattern of "H" type distribution. The comprehensive quality in Ⅲ with a Mosaic distribution pattern in the spatial pattern in dianjiang county territory, but mainly with the center line of the north and south to stretch, as a "dual-core" type distribution pattern. The qulity Ⅱ,which distribution was similar to Ⅲ. mainly concentrated in North north-south center line on both sides, South to the Crane platform as the center of the Gao Tan River on the right bank of the northeast region. The qulity Ⅰ showing a decorative mosaic pattern, mainly distributed in the Ming Yue mountain, Huang Hua shan and the lower edge of the area and the Crane platform. The comprehensive index of difficulty coefficient and quality of basic farmland construction in Dianjiang County, showing a good correspondence in the space, the quality index was higher, the coefficient of difficulty of construction of basic farmland was smaller. But in detail vary, the comprehensive quality index and construction difficulty coefficient in space did not exist a one-to-one relationship, just the overall pattern of the integrated quality index control with the difficulty of the construction of basic farmland. The qulity Ⅳ with lowest part of the construction difficulty coefficient and comprehensive quality index, showed strong consistency in the spatial distribution; Construction difficulty coefficient III, the space agglomeration degree was significantly higher than that of comprehensive quality index III; construction difficulty coefficient II in space by the comprehensive quality index of "dual-core" change was "the core of single core" pattern. The timing of the construction of the basic farmland in Dianjiang County was divided into four zones: the construction of priority areas, the focus of the remediation area, with the conditions and conditions of poor areas. And it was set to three times: the recent(2016-2020), medium-term(2021-2030) and long-term(2031-2050). The construction area and the construction period showed significant regional differences, however, they had a good spatial correspondence, and the priority areas were mostly arranged in the near future. Construction schedule and construction area was closely related to eact other. The construction of priority areas was delineated on the basis of construction sequence, but construction zone settings should be not only consided for the actual needs of the development of concrete industry, but also for the introduction of owners of geographic preferences. The division of the construction of the basic farmland in Dianjiang was divided into three major areas: the Yu Wu Road along the edge of the western lower edge of the Ming Yue mountain, serving the multi functional agricultural development zone. Ming Yue shan-Huang Hua shan clip service in the valley area, standardization of grain and oil base area. The Crane platform as the center of the high right bank of the river, serving the three-dimensional circulation agricultural area. The managements were set up into three types: vertical type and location, facilities leading. Differences in both the construction of difference or differentiated management, resource endowment, site conditions, infrastructure, location should be considered, and industry development, the main business expansion, and could not be stereotyped.(3)Basic farmland soil carbon sinks in ChongqingSOC dynamics of basic farmland during 1980 s and 2011 were both below non-basic farmland. Carbon increment per unit area reached to 682.89 kg ha-1 and 365.75 kg ha-1. The change rate of SOC dynamics of different cross section years was basic farmland>non-basic farmland. The increase of SOC dynamics of basic farmland during 1980-2011 was 11.28% while non-basic farmland was 9.47%. The paddy soil and purple soil were the main soil types which were related to the change of SOC dynamics of farmland. The reserves of SOC and SOC dynamics of basic farmland and non-basic farmland showed remarkable spatial differences, but the SOC dynamics was more obviously. During 1980 s and 2011, the spatial pattern of the reserves of SOC was a “mountain” pattern among with Mingyue Mountain, Nanhua Mountain and Huangcao Mountain. While the non-basic farmland’s spatial pattern was a “s” pattern from northwest to southeast. The average annual growth rate of SOC dynamics of basic farmland during recently 30 years was 79.56 kg C hm-2 a-1. The average annual growth rate of SOC dynamics of non-basic farmland during recently 30 years was 79.56 kg C hm-2 a-1, which was 10.57 kg C hm-2 a-1 more than basic farmland. During 1980-2011, the average annual change rate of SOC dynamics showed remarkable differences no matter what kinds of soil types and farmland were. During the past 30 years, between the basic and other farmland, the carbon sequestration, relatively balanced and proportion of carbon lost area did not show significant differences. The basic farmland carbon sequestration and the relative balance of the cumulative area ratio was only slightly higher than the non-basic farmland for 62.73% to 61.98%. From the area ratio of carbon sequestration, the basic farmland was slightly lower than that of the other farmland, which were 48.86% and 49.27%. The spatial pattern of fixed carbon, relative balance and carbon loss was consistent with the corresponding SOCD average annual rate of change. The main factor that affects the basic and non basic farmland SOCD average annual rate of change in the past 30 years was SOCD 1980s>The density of N >C/N ratio, while the influence of terrain factors and soil management factors was smaller. Among them, SOCD1980 s had negative effect, and the density of N and C/N ratio was just the opposite. Therefore, to increase dianjiang county farmland SOC storage, we should increase the soil organic matter in the basic farmland area, and the basic farmland area was not only to increase the organic matter, but also to improve increase soil physical and chemical properties. In increasing the inorganic nitrogen fertilizer application at the same time, more phosphate and potash should be applied. It was than better to adjust crop planting structure, emplay out crop rotation and fallow, and increase high C/N ratio of plant cultivation.(4)Basic farmland effect evaluation in ChongqingBefore and after the construction of basic farmland, the effect of the implementation of the project was significantly different. Before and after the construction of basic farmland, the area of cultivated land had a great change in the project area. After construction, the area of cultivated land was increased by an average of about 14.44%, In contrast, the farmland connectivity was increased after the construction rate was relatively obvious, the average slope of arable land was reduced(Average decrease of 1 degree or above), road accessibility, drainage and irrigation conditions, landscape ecological functions were also significantly changed. After the basic farmland constructed, the spatial variability of farmland connectivity was more significant, it increased from 5.26% to 14.95%, and the valley area was increased more than the terrace area, the connectivity of spatial difference of cultivated land was basically the same as before, just after the construction of the discrete degree was more obvious. The variation coefficient of cultivated land in the space also showed a significant increasing trend, and the high value areas of the cultivated land fragmentation were all in the southern part of the terrace area. The degree of dispersion of the road was slightly increasing in the construction, it increased from 15.92% to 16.74%, before the construction of the road access showed significant spatial difference, valley area was significantly higher than terrace area, and after the construction of this difference was more significant, the degree of dispersion in space showed the effect of agglomeration. The spatial variability of road hardening rate increased significantly, it increased from 22.39% to 30.78%, the spatial discretization was enhanced. Contrary to other indicators, the density of road network was decreased after construction; After the construction, the increase of the degree of the irrigation guarantee rate was more significant, which was from 22.36% to 31.53% after construction. After construction, the irrigation guarantee rate showed well spatial difference, and the dispersion degree was high. The proportion of forest and grassland in the construction of the spatial variability was slightly reduced by the construction of the former 35.23% down to 34.44% after the construction. Whether before or after construction, the proportion of the forest and grassland in the terrace area and the surrounding area was the highest, which was substantially related with the terrain fluctuation and the industrial choice of the decision. After the construction, the degree of spatial variation of farmers’ satisfaction was significantly reduced, which was reduced from 32.72% to 27.52% after construction. After the construction of the high value area of farmers satisfaction mainly appeared in the valley area, and low values occurred in the terrace area, but the low value area in space was narrow. In the county scale, after the construction of basic farmland, the comprehensive effects were significantly improved compared with the former construction, except the Gaotan River and Dasha river at the confluence of the northern Gaotan river and the small portion of the project in the north of Caohui town, the overall effectiveness of the construction of other regions was more than 2.5 times before the construction, especially the comprehensive effects in right beneath of Gaotan river. Due to different terrain, industrial development, the people in the land use and the investment in the basic construction of farmland were substantially different, and thus reflected the high standard of basic farmland construction of the comprehensive effect of the heterogeneity. These results shawed a great significance to guide the construction of basic farmland in the future.
Keywords/Search Tags:Basic Farmland, Delimitation, Differentiation, SOC Sink, Effect Evaluation
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