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1.
利用熵值综合评价法和耦合法,研究了2003—2012年中国新型城镇化质量和土城镇化地集约利用状况及二者的协调发展水平。研究发现:总体上,中国新型城镇化城镇化与土地集约利用水平都在缓慢上升,但二者的协调发展水平不够高。运用灰色GM(1,1)模型的预测表明,从2014—2023年中国新型城镇化质量与土地利用的耦合协调度将稳步增长。最后,就如何提高新型城镇化质量及土地集约利用水平质量及二者的耦合协调度提出了对策建议。  相似文献   

2.
[目的]通过对2005—2011年河北省石家庄市低碳经济发展和城市土地集约利用的动态演变情况进行实证分析和测算,探究两大系统的耦合互动关系及其耦合协调度发展趋势。[方法]以"精明增长"理念为指导,以石家庄市作为样本区域,引入物理学中的耦合度概念,构建低碳经济发展和城市土地集约利用的综合评价指标体系及其耦合协调度模型。[结果]两大系统大体趋于同步发展,具有明显的正相关性,表明二者存在良好的耦合互动关系;耦合协调水平由2005年的严重失调阶段发展到2011年的优质协调阶段,整体呈现由低级向高级过渡、耦合互动效应增强的趋势,客观地诠释了石家庄市低碳经济发展和土地集约利用的发展动向。[结论]伴随时间的推进和政策建议的相继落实,二者耦合协调关系将逐渐优化。  相似文献   

3.
为了阐释西安市土地利用效益与城镇化的耦合协调机理,明确二者的耦合协调程度,通过构建土地利用效益与城镇化水平指标体系和评价模型,计算了土地利用效益与城镇化水平评价指数、耦合协调度以及灰色关联度,剖析了二者的耦合协调发展关系和相互影响程度。结果表明:(1) 2005—2015年西安市土地利用效益指数、城镇化指数以及综合评价指数逐年增长,两者在发展中相互促进,土地利用效益指数增长速度略大于城镇化指数,经济效益在土地利用效益中占据主导地位,经济、生态城镇化指数在城镇化水平指数中占比最大;(2)土地利用效益与城镇化的耦合协调度逐年递增,耦合协调阶段由失调衰退阶段最终转变为协调发展阶段,耦合协调状态由濒临失调转变为优质协调,两者的协调发展关系更加紧密;(3)土地利用效益与城镇化水平之间存在相互影响的关系,经济效益以及生态效益对城镇化水平的影响程度较高,经济城镇化、生态城镇化、社会城镇化以及教育城镇化对土地利用效益均有较为重要的影响;(4)土地利用效益与城镇化是两个相互促进、紧密相关的协调发展系统,在推动经济社会不断发展的同时,也要加强生态环境保护以及合理规划城市用地,实现土地利用效益与城镇化协调发展。  相似文献   

4.
[目的]探究甘肃省庆阳市土地集约利用与土地利用结构之间的协调关系,为该市土地利用结构优化和社会经济的可持续发展提供理论依据。[方法]以庆阳市为例,采用多因素综合评价法计算2007—2016年土地集约利用、土地利用结构的综合指数,应用耦合协调模型,分析二者变化特征及耦合协调关系。[结果]①庆阳市土地集约利用综合指数呈上升趋势,达到了高度集约利用水平。②庆阳市土地利用结构信息熵总体呈下降趋势,均衡度逐渐降低,优势度逐渐增强。③土地集约利用与土地利用结构耦合度呈先上升后下降的趋势,耦合协调度都呈上升趋势,二者耦合性越来越强,相对呈现出协调、稳定的发展趋势。[结论] 2007—2016年庆阳市土地集约水平总体变化呈逐年上升状态,但信息熵呈下降趋势,是由于大力开发未利用地,植树造林使得土地利用结构调整。土地集约利用和土地利用结构两系统协调度都呈上升趋势,二者耦合性越来越强。说明庆阳市在大力推动经济发展的同时,也注重提高土地利用的效率,调整土地利用结构,优化布局。  相似文献   

5.
京津冀地区城市土地集约利用与城镇化耦合协调关系研究   总被引:7,自引:0,他引:7  
以京津冀地区作为研究区域,建立城市土地集约利用指标体系与城镇化指标体系,采用均方差权值法,并建立耦合协调模型,计算2011年13个地级以上城市的土地集约利用和城镇化指数及二者的耦合度和协调发展度。按照耦合协调度的高低将13个城市划分为4大类;每个大类内部再按照城市土地集约利用与城镇化指数的关系,分为城市土地集约利用滞后和城镇化滞后的2个亚类。结果表明:京津冀地区城市土地集约利用和城镇化之间关系密切,二者相互作用,但并非同步发展;城市土地集约利用程度与城镇化耦合程度基本上处于颉颃阶段,耦合协调度水平总体不高,区域差异明显。  相似文献   

6.
北部湾经济区作为中国第一个国际区域经济合作区,研究城市土地集约利用与经济高质量发展的协调关系对促进该地区新型城市化发展具有深远意义。运用多因素综合评价、耦合协调度以及障碍度等模型分析了2008—2018年北部湾经济区的城市土地集约利用与经济高质量发展耦合协调关系的时空特征及其影响因素。结果表明:(1)北部湾经济区各市土地集约利用水平和经济高质量发展指数显著提升且空间差异减小,区域均值分别由0.175,0.153升至0.863,0.763;(2)研究区二者耦合协调性趋于优化,由轻度失调转为优质协调,各市均处于良好及以上水平的高度协调发展阶段;(3)各市“土地-经济”两大基本发展系统明显改善,城市竞争力增强,除防城港市属于土地集约利用超前型外,南宁市、北海市、钦州市、玉林市和崇左市实现了土地集约利用与经济高质量同步发展;(4)土地利用结构、社会经济水平、生态环境压力和区域发展政策是影响二者协调发展的主导因素,优化土地利用结构、加强生态环境保护和提升科技创新能力是促进北部湾经济区城市土地集约利用与经济高质量优质协调发展的关键。研究结果可为北部湾经济区制定一体化的区域城市发展政策提供参考依据。  相似文献   

7.
西宁市土地利用效益与新型城镇化耦合协调度研究   总被引:2,自引:0,他引:2  
基于城市土地利用效率和新型城镇化内涵的分析,建立西宁市土地利用效率和新型城镇化耦合协调指标体系,用熵权法计算了各指标权重,结合耦合度、协调度模型计算了西宁市耦合度和协调度。结果表明:2000—2013年西宁市土地利用效益和新型城镇化综合指数不断升高,土地利用效益相对发展趋势为"超前—滞后"型;土地利用效益和新型城镇化耦合演变过程处于颉颃阶段,由低强度向高强度耦合发展;土地利用效益与新型城镇化协调度总体呈上升趋势,具有逐步优化的趋势。西宁市作为土地资源稀缺的河谷型城市,随着新型城镇化的发展,土地资源紧缺的矛盾将长期存在。今后的发展中应更加注重提高土地资源利用率,合理布局城市结构,从而促进新型城镇化的可持续发展。  相似文献   

8.
[目的]研究2000—2014年浙江省城镇—环境协调发展的动态计量特征,为浙江省制定新型城镇化可持续发展政策提供决策依据。[方法]基于耦合协调度模型,评价城镇化和生态环境的相互影响程度,并将其划分为4种类型,研究了城镇化和生态环境的协调关系。[结果](1)经济、社会、人口城镇化及其综合发展水平和生态环境响应、状态、压力及其综合发展水平均持续增长;协调度稳定增长,由低度协调发展为良好协调、城镇化滞后转变为生态环境滞后。(2)城镇化和生态环境的协调关系可划分为4种类型:良好协调—生态环境滞后、中度协调—生态环境滞后、良好协调—城镇化滞后、中度协调—城镇化滞后。[结论]各城市必须对应各自协调与滞后的现状,做到在保护生态环境的同时,继续加强城镇化建设,以推动二者协同发展。  相似文献   

9.
城市群土地集约利用与新型城镇化耦合协调发展是土地管理学研究的核心问题,探讨长江中上游城市群——长江中游和成渝城市群的耦合协调发展水平,以期为中国其他城市群的相关研究提供参考。利用全局主成分分析法、均方差权值法、熵权法进行综合确权以提高评价指标权重精度,采用耦合度模型、协调发展度模型对长江中游和成渝城市群协调发展水平进行了测算、分析与比较,进而利用空间自相关模型探究各城市群土地集约利用与城镇化协调发展水平的空间集聚特征与规律。结果表明:成渝城市群土地集约利用与新型城镇化协调发展水平与长江中游相当,成渝城市群耦合协调态势优于长江中游城市群。具体体现在(1)2004—2013年长江中上游城市群土地集约利用与新型城镇化协调发展水平呈现出持续递增的态势,2013年长江中游和成渝协调发展度相近,均在0.75以上,处于中度协调期,成都、重庆、长沙、武汉、南昌等城市为协调度高值区,德阳、黄石为协调度低值区,其他城市的协调发展水平居中。(2)长江中游协调发展度空间相关性有所降低,由随机分布向弱相异属性集聚转化,而成渝协调发展度空间相关性有所提升,由相异属性集聚向随机分布状态转化,未来有逐步优化为相似属性集聚的态势。  相似文献   

10.
广西城市土地集约利用与生态文明建设耦合时空分异   总被引:3,自引:1,他引:2  
为了分析广西城市土地集约利用与生态文明建设耦合协调程度及其时空规律,以广西为研究对象,采用TOPSIS模型开展2008-2017年城市土地集约利用与生态文明建设综合评分,并利用耦合协调模型测度了两者耦合协调水平。结果表明:(1)广西城市土地集约利用水平与生态文明建设成效综合评分呈波动式上升趋势,城市之间差异明显;(2)广西城市土地集约利用与生态文明建设耦合协调性逐渐提高,各市由中低度协调发展转向中高度协调发展并以中度协调发展为主,协调类型呈现由片状分布向线性排列的空间演变特征;(3)广西各市城市土地集约利用与生态文明建设之间以同步发展型为主,部分城市两个子系统之间发展差异呈逐步缩小态势;(4)广西城市间的协调性呈弱相似随机分布状态,空间集聚效应不断减弱,空间分异愈加突出,桂林市和梧州市成为区域极化两翼。协同推进城市土地集约利用和自然生态修复工作是实现城市土地集约利用与生态文明建设高水平耦合协调发展的重要路径。  相似文献   

11.
低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响   总被引:2,自引:2,他引:0  
【目的】以富士(Fuji)、 秦冠(Qinguan)嫁接在平邑甜茶(Malus hupehensis Rehd.)上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水(ZZ)、 低氮正常水(DZ)、 正常氮干旱(ZG)、 低氮干旱(DG)。氮素和水分均设置两个水平,分别为正常氮(6 mmol/L NO-3-N)、 低氮(0.3 mmol/LNO-3-N)、 正常供水(保持盆中砂子相对含水量为饱和含水量的80%~85%)、 干旱处理(保持盆中砂子相对含水量为饱和含水量的60%~65%)。【结果】富士和秦冠的生物量(茎和叶)、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水(ZZ)>低氮正常水(DZ)>正常氮干旱(ZG)>低氮干旱(DG),并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水(ZZ)>低氮正常水(DZ)>正常氮干旱(ZG)>低氮干旱(DG); 氮、 钾元素含量在植株各部位的分布顺序依次是叶>根>茎,磷元素则是根>叶>茎;光合氮素利用效率(PNUE)和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水(DZ)处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱(DG)处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。  相似文献   

12.
Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.  相似文献   

13.
“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.  相似文献   

14.
Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.  相似文献   

15.
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,  相似文献   

16.
The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.  相似文献   

17.
Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.  相似文献   

18.
To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.  相似文献   

19.
Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.  相似文献   

20.
Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.  相似文献   

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