陕西省旬邑县耕地面积变化及驱动力分析

根据旬邑县1989-2009年统计资料,分析该县近二十年来耕地面积动态变化过程,并选取GDP、人口、城镇化水平等10个社会经济因子,采用单因子关联分析和多因子主成分分析法,研究社会经济发展对耕地面积变化的影响,并揭示了引起耕地数量变化的驱动机制,为生态脆弱区合理保护耕地资源提供参考.结果表明:1989-2009年旬邑县耕地面积总体上呈现下降趋势,经历了稳步减少(1989-2000年)、缓慢减少(2000-2003年)到平稳(2003-2009年)的发展阶段.主成分分析结果表明导致该县耕地面积变化的驱动因素为经济发展、人口增长和农业科技进步.     

青岛市近10年来耕地变化及其驱动力分析

利用耕地利用动态度和区域差异指数、环境—收入理论关系曲线及经济理论、灰色关联度分析、主成分分析、多元回归分析对2000-2009年间青岛市耕地的变化特点和驱动因子统计分析与比较.结果表明:耕地面积变化速度由强烈(2000-2003年动态度0.106)变为缓慢(2006-2009年动态度0.014);主要驱动因子为人口城市化、经济建设和产业结构.青岛市耕地变化的区域差异和阶段性特征显著;受经济发展的惯性影响,耕地阶段性变化的时间相对于类比性的工业化阶段性变化的时间要滞后1～2 a;耕地变化与人均GDP的关系呈倒N型曲线;产业结构和人口城市化分别是耕地面积变化的直接与深层次的影响因素.     

韩江流域下游耕地变化趋势及其驱动力——以汕头市为例

利用1949-2003年的统计资料，分析了近55年来汕头市耕地面积变化的总体趋势、空间差异和驱动因子。应用GIS进行空间分析，通过建立多元回归模型，对汕头市2010年、2015年和2020年的耕地数量进行了初步预测。分析结果表明；汕头市耕地总面积、人均耕地面积呈明显递减态势，经济发展、人口压力、农业产业结构调整和农业科技进步4类因素是影响耕地数量变化的4个主成分，其结果将为进一步研究粤东北潮汕平原耕地变化提供借鉴，为合理利用和保护耕地、促进区域可持续发展提供科学依据。     

太原市耕地变化趋势及驱动力研究

根据统计资料,分析了1997～2007年太原市耕地面积变化的总体趋势,指出耕地数量的变化整体上呈下降趋势.结合近十年来太原市社会经济统计数据,应用主成分分析方法分析了影响耕地变化的因子,得出社会发展水平、经济发展因素、人口因素、农业产业结构调整因素是引起耕地变化最主要的因子,并且建立多元回归模型,对耕地面积变化的驱动力进行了定量分析.     

河南省耕地变化及其人文驱动力研究

根据河南省历年耕地及其相关统计数据,对河南省耕地时间(数量和质量)、空间变化和驱动因子进行了深入分析.结果显示:57a期间,耕地总量自1954年最高峰9.06万km²以来,整体上呈逐年减少趋势;1984~2005年耕地标准面积和标准系数均呈现波动增长趋势;耕地空间分布重心整体上向东南方向变化;采用主成分分析方法,得出影响河南省耕地变化的驱动力归纳为农业科技进步、社会发展水平和经济发展水平.     

江西省耕地的动态变化及驱动因子

利用江西省1990—2009年耕地变化数据以及社会经济资料,分析了该区域耕地动态变化的时空特征,并将主成分分析和多元线性回归分析相结合,揭示了江西省耕地数量变化的主要驱动力。结果表明,江西省耕地数量变化在时序上呈现出先减少后增加的趋势;在空间上区域差异性较大,不同时期各市耕地利用动态度波动较大;江西省耕地动态变化的主要驱动因子包括经济增长、社会发展和农业科技提高3个主要类别,总体上,耕地数量变化与人口、GDP、全社会固定资产投资、3大产业、耕地产出率以及农机机械总动力之间存在着显著相关性,在第1主成分中经济和人口两大因子是主要的驱动因素,第2主成分中农业科技进步是主要因子。     

塔里木河流域耕地面积动态变化特征及驱动因子

[目的]对塔里木河流域耕地面积动态变化特征及驱动因子进行分析,为实现区域内耕地保护与可持续利用提供理论依据。[方法]依据1990—2014年塔里木河"九源一干"区域各地州的统计资料,分析塔里木河流域耕地面积和重心的变化特点,将主成分分析与多元回归分析相结合,探讨耕地面积变化的驱动因子。[结果](1)1990—2014年,耕地总面积由1.01×106 hm~2增加到2.05×106 hm~2,人均耕地面积由0.131hm~2增加到0.194hm~2,耕地面积重心向东偏北方向移动61.10km;(2)社会经济发展、人口增加和农业生产发展是耕地面积变化的主要驱动因子;(3)建立了耕地面积与驱动因子之间的多元线性回归模型(R2=0.960),检验结果表明模拟值与实际值之间没有显著差异(p0.05)。[结论]耕地的面积和重心始终处于一个动态变化的过程中,人文因素是影响耕地特征变化的主要原因。     

湖南省耕地资源动态变化及其驱动力

[目的]研究湖南省1996—2011年耕地资源的变化过程,定量分析耕地变化的驱动因子,并对该区域耕地的变化趋势进行预测,为合理利用和保护耕地资源,促进区域经济的可持续发展和粮食安全生产提供重要参考。[方法]利用湖南省近16a的土地利用调查数据及相关社会经济资料,根据研究区域的特点选取了总人口、地区生产总值、农业机械化水平等14个指标,利用主成分分析法对耕地变化的驱动力进行分析,最后采用灰色系统GM(1,1)模型对研究区域耕地的变化趋势进行预测。[结果]1996—2011年湖南省人均耕地面积下降趋势明显,由1996年的0.066 9hm2减少到2011年的0.058 0hm2,该省耕地数量变化存在明显的区域差异。耕地面积变化驱动力主要由人口增长、社会发展、农业生产能力、人民生活水平4个方面构成。预测结果表明,研究区域2014—2020年的耕地面积继续呈下降趋势。[结论]湖南省耕地减少速度快,土地垦殖率高,且后备资源贫乏,应加大耕地的保护力度,以促进区域的粮食安全和可持续发展。     

半干旱地区典型城市耕地面积变化空间差异及驱动力分析——以西安市为例

以西安市为例,分析了其2000—2012年耕地面积变化及空间差异,并采用主成分分析法,从人口、经济、产业结构、生活水平和城镇化水平5个方面共选择14个因子,揭示了近13年来西安市耕地面积变化的作用机制,从而为制定合理的耕地保护制度和政策提供参考依据。研究结果表明:(1)西安市耕地面积总体呈逐渐下降趋势,年平均递减率为1.38%;(2)西安市耕地面积变化的主要驱动力因素是经济发展、城镇化水平、农业因素,这三者构成了西安市耕地面积变化的主要驱动力;(3)可以从减少建设用地占用、促进经济发展模式的转变和加强对农业结构调整的引导3个方面来遏制西安市耕地面积锐减的趋势。     

伊敏露天煤矿排土场自然恢复植被群落特征研究

根据乌拉特前旗1957—2006年的统计资料,分析了耕地变化特征及现状,发现该区可开发利用的耕地已经用尽,人地矛盾形势严峻。利用主成分分析方法对乌拉特前旗1957—2006年耕地动态变化的社会驱动力进行了分析,结果表明,人口增长、经济发展和农耕业现代化水平是影响耕地变化的2个主要驱动因子。用GM(1,1)模型对未来25a的耕地和人口进行了预测,结果得出,该区1957—2006年期间人口持续增加,耕地面积减少,人地矛盾加剧。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【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。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

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.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

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,     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

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.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

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,     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

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,     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

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.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.