利用HJ-1B遥感数据反演西北地区近地表气温

近地表气温是一个重要的气候参数,为了给农业研究提供空间上连续的气温信息,以西北地区为研究区,利用HJ-1B数据运用温度-植被指数方法（temperature-vegetation index, TVX）反演近地表气温。首先采用修正普适性单通道算法反演地表温度,并利用同一地区的MODIS温度产品进行了对比验证,然后利用2010年7月20日、2010年8月28日、2011年8月8日3景影像结合研究区气象站点观测的气温资料推算饱和NDVI值,最后将推算结果应用到2011年8月28日影像,利用气象站点观测资料对TVX方法反演的气温进行了精度验证。结果表明,反演地表温度与 MODIS 温度产品空间分布趋势基本一致,符合研究区的地表覆盖状况;反演气温与反演地表温度空间分布格局具有较好的一致性,可以提供比气象站点观测数据更理想的空间异质性信息;反演气温值比观测值偏高,二者平均绝对误差MAE为2.16 K,均方根误差RMSE为2.72 K。为快速有效获取大范围的气温时空信息提供了一种新思路,对科学指导农业生产、合理利用农业资源具有一定的可参考性。     

海南岛植被指数季节性变化及植被覆盖分析

以海南岛接收的2003-2005年接收的MODIS遥感数据为基础,通过提取归一化植被指数,分析了多年来海南岛植被指数变化的时空分布规律。由于海南岛植被指数空间变化特征与温度有着密切关系,借助NDVI-Ts空间特征分析了海南岛7个代表性区域的植被覆盖的情况,并与实际情况进行了对比,结果表明:通过遥感数据反演NDVI-Ts空间特征分析能适合海南岛地区植被覆盖范围的确定,为今后热带地区利用NDVI和地表温度（Ts）确定植被覆盖类型提供了一种有效的方法。     

基于温度植被旱情指数的徐州市郊干旱遥感监测

利用Landsat TM/ETM+数据,以徐州市郊为研究区,获取归一化植被指数(NDVI)、土壤调整植被指数(SAVI)和地表温度(Ts)信息,分别构建NDVI-Ts和SAVI-Ts特征空间,依据这两个特征空间计算出研究区2001年4月3日和2007年5月14日的温度植被旱情指数TVDI(NDVI)和TVDI(SAVI),并分别与地表温度(Ts)和降水量进行了相关评价.结果表明,TVDI可用于实现大范围的干旱监测,SAVI能够修正NDVI对土壤背景的敏感,基于SAVI的反演结果明显优于基于NDVI的反演结果,能够有效地运用于干旱监测.     

利用EOS-MODIS数据提取作物冠层温度研究

利用EOS-MODIS遥感数据，基于线性混合模型，提出了一种新的作物冠层温度反演方法。首先，利用EOS-MODIS数据提取了陆地表面温度LST和植被指数NDVI。然后，假定地表只有植被和裸地两种组分，通过植被指数温度VI-Ts方法来估算裸土的组分温度，作物冠层温度通过线性混合模型来求解。为了验证反演的地表温度和冠层温度的精度，把反演的地表温度与NASA MODIS地表温度产品进行差值运算，在差值图像中90%以上的像元灰度值分布在-1和1之间，像元灰度的平均值小于0.5；同时在河北固城农业气象试验站对冬小麦冠层温度进行同步观测，通过与反演的冠层温度进行比较，其误差在±1.5℃左右。结果表明，文中所提出的作物冠层温度反演方法精度较高，其结果能够满足有关作物生长模型以及土壤水分模型对输入参数的精度要求。     

利用EOS—MODIS数据提取作物冠层温度研究

利用EO S-M OD IS遥感数据,基于线性混合模型,提出了一种新的作物冠层温度反演方法。首先,利用EO S-M OD IS数据提取了陆地表面温度LST和植被指数NDV I。然后,假定地表只有植被和裸地两种组分,通过植被指数温度V I-T s方法来估算裸土的组分温度,作物冠层温度通过线性混合模型来求解。为了验证反演的地表温度和冠层温度的精度,把反演的地表温度与NA SA M OD IS地表温度产品进行差值运算,在差值图像中90%以上的像元灰度值分布在-1和1之间,像元灰度的平均值小于0.5;同时在河北固城农业气象试验站对冬小麦冠层温度进行同步观测,通过与反演的冠层温度进行比较,其误差在±1.5℃左右。结果表明,文中所提出的作物冠层温度反演方法精度较高,其结果能够满足有关作物生长模型以及土壤水分模型对输入参数的精度要求。     

基于地表温度和植被指数特征空间的农业干旱遥感监测方法研究综述

遥感技术以其便捷、反映迅速、大范围监测等优点在农业旱情监测中得到广泛使用。通过遥感资料反演的地表温度（Ts）和植被指数（NDVI）不仅可以表征绿色植被的生理和生长状况,还能揭示植被土壤水分信息,反映作物受旱状况,但两者单独使用时存在缺陷。而基于地表温度和植被指数特征空间的干旱监测方法有利于统一定量标准来判别植被干旱情况,同时还解决了植物在受水分胁迫时短期内仍能保持原有绿色的时间滞后的问题,提高了旱情监测的准确度和实用性。该文以地表温度和植被指数特征空间干旱监测方法为基础,较为详细地阐述了各个方法的基本原理和适用范围,并结合实例归纳总结了与之相关的四种方法的优、缺点,进一步探讨了今后研究的重点。     

基于MODIS数据的山东省2014-2016年干旱监测分析

针对近年频发的干旱情况不能准确及时监测评估的问题,以山东省为研究区,基于温度植被干旱指数方法（TVDI）,利用S-G加权滤波对MODIS地表温度产品MOD11A2和植被指数产品MOD13A2数据进行了重建,根据重建后的数据计算2014—2016年山东省的温度植被干旱指数,在比较NDVI-LST与EVI-LST构建的温度植被指数干旱模型（TVDI）的基础上,利用效果更好的EVI-LST构建的TVDI模型反演山东省2014—2016年的干旱情况,最后利用气象站观测数据对TVDI结果进行了相关性分析。研究表明,山东省在2014—2015年全年平均干旱面积占比分别为37.62%,41.7%,2016年基本无旱情发生。气象站观测的降水、温度与TVDI的相关性均在0.32以上,且均通过显著性检验,说明植被覆盖信息和陆地表面温度信息相结合反演的TVDI空间和时间分布能够较好地反映表层土壤水分变化趋势,其作为旱情评价指标是合理的。     

呼和浩特市不同植被指数与地表温度的定量遥感关系

利用Landsat 8影像数据,提取呼和浩特市地表温度（LST）、4种典型植被参数:归一化植被指数（NDVI）、修正土壤植被指数（MSAVI）、比值植被指数（RVI）及植被覆盖度（FV）,并结合研究区土地覆被信息,探讨了LST与4种典型植被参数的定量遥感关系,不同下垫面类型对地表温度—植被参数的影响及其二者之间的空间尺度效应。结果表明:地表温度—植被参数呈现出显著负相关关系,NDVI,RVI,MSAVI,FV每增加0.1,对应的LST分别下降:0.99℃,0.83℃,1.02℃,0.64℃;不同土地覆被类型中二者相关性差异显著,其中林地LST与4种植被参数相关性最强,RVI与LST相关性最稳定;在不同的空间尺度下（30～1 920 m）,地表温度—植被参数空间相关性呈现出先增大后减小的趋势,NDVI,FV,MSAVI,RVI与LST的空间相关性分别在120 m,240 m,60 m,120 m达到最高。     

应用地表温度与植被指数梯形空间关系估算陆面蒸散量

提出了以Priestley-Taylor方程为基础,综合利用地面气象观测数据与卫星遥感观测数据的陆面蒸散量估算方法。其基本思路是:基于地表能量平衡原理,利用遥感观测与地面气象观测数据,计算给定气温条件下全植被覆盖与祼土地面在极湿、极干状况下的地表温度,构建每个像元的地表温度(Ts)与植被指数(VI)的理论梯形空间,进而根据该象元Ts-VI坐标点在该梯形中的位置,计算其Priestley-Taylor系数,并利用Priestley-Taylor方程估算像元的蒸散比。利用美国一个半干旱地区的地面观测数据进行了精度验证,结果表明该方法具有较理想的精度,蒸散量估算的平均绝对误差约为35.5%。     

基于NDVI-LST模型对辽宁月尺度土壤水分的反演

利用MODIS卫星数据集中的归一化植被指数NDVI(Normalized Difference Vegetation Index,NDVI)与地表温度LST(Land Surface Temperature,LST)数据建立NDVI-LST模型,对辽宁省2015年5-8月的土壤水分进行反演,建立土壤水分与干边斜率的相关关系,得到该模型反演下的土壤水分。结果表明:(1)该时间段的NDVI-LST实际模型能够形成类似"三角"的特征空间,与理论模型吻合,利用该模型反演的5-8月土壤水分含量与地面实际监测结果相关性较高,除8月外,相关系数均在0.8以上,反演结果空间布局与地面实际土壤水分基本一致;(2)8月土壤水分反演结果不理想,相关系数为0.48,反演和地面实际空间特征差异也较大,其原因是8月NDVI对7月降水极少的响应时间的延后。整体而言,NDVI-LST模型反演土壤水分的试验结果较理想,可为利用卫星遥感手段快速反演辽宁月尺度的土壤水分、干旱灾害防御评估等决策工作提供一种新思路。     

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,     

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.     

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.     

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.     

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.     

Responses of native legume desert trees used for reforestation in the Sonoran Desert to plant growth-promoting microorganisms in screen house

Three slow-growing legume trees used for desert reforestation and urban gardening in the Sonoran Desert of Northwestern Mexico and the Southwestern USA were evaluated whether their growth can be promoted by inoculation with plant growth-promoting bacteria (Azospirillum brasilense and Bacillus pumilus), unidentified arbuscular mycorrhizal (AM) fungi (mainly Glomus sp.), and supplementation with common compost under regular screenhouse cultivation common to these trees in nurseries. Mesquite amargo (Prosopis articulata) and yellow palo verde (Parkinsonia microphylla) had different positive responses to several of the parameters tested while blue palo verde (Parkinsonia florida) did not respond. Survival of all tree species was over 80% and survival of mesquite was almost 100% after 10 months of cultivation. Inoculation with growth-promoting microorganisms induced significant effects on the leaf gas exchange of these trees, measured as transpiration and diffusive resistance, when these trees were cultivated without water restrictions.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.