基于MODIS的中国陆地气溶胶光学厚度时空分布特征

利用MODIS 08_C5气溶胶产品2000—2008年月均值资料,通过线性回归和相关分析方法,探讨中国大陆地区550 nm气溶胶光学厚度的时空分布特征和变化趋势。结果表明:南疆盆地、长江中下游地区以及四川盆地常年处于气溶胶光学厚度高值区;全国各地气溶胶光学厚度季节变化有明显差异,大部分地区年内呈先增大后减小趋势,4月达到其年内最高值,且多年光学厚度月均值与全国每月发生沙尘总次数呈显著相关关系;沙尘月发生10次以上地区,沙尘月发生次数与光学厚度月均值之间呈显著线性相关关系,而沙尘月发生10次以下地区,沙尘月发生次数与光学厚度月均值之间没有明显的关系。     

北京地区改进SYNTAM算法反演AOT有效性验证

本文利用了改进的SYNTAM算法反演了北京地区气溶胶光学厚度,并利用AERONET站点观测值进行验证比对分析：（1）基于设定的卷积窗口统计计算反演的相应气溶胶光学厚度参量值;（2）利用匹配对应时间尺度范围的AERONET站点值进行相关性分析,合理评估双星协同反演算法的有效性。结果表明：在北京地区该算法具有良好的适用性和可用性,反演所得大气气溶胶光学厚度与地面监测值具有高度的一致性,其对该区大气质量环境监测和农业生产光照胁迫性分析具有很好的实用价值。     

拐子湖地区沙尘天气风蚀起沙量的估算

为研究沙尘暴中心在沙尘天气下风蚀起沙量和一些参数的具体情况,以巴丹吉林沙漠拐子湖地区一次沙尘天气过程为例,通过经验公式与野外仪器观测对比分析,对拐子湖地区风蚀起沙过程的一些参数进行了分析。结果表明:摩擦速度与风速成正相关,并影响着风蚀起沙量变化;临界摩擦速度为0.36m/s;估算了平均顺风向沙尘通量和垂直沙通量分别为1.7E-02kg/(m.s)和1.38E-07kg/(m2.s),顺风向沙尘通量要远大于垂直沙通量。这些参数的得出对防风治沙有着重要的意义。     

气溶胶辐射效应对作物及生态系统的影响综述

近年来大气气溶胶的增加对气候及环境的影响越来越受到科学界的关注,其中的气溶胶辐射效应对作物及生态系统的影响非常复杂。本文从气溶胶的辐射特性及其对气候变化的可能影响出发,来说明气溶胶造成的不同性质辐射量的重新分配对作物光合作用、产量以及生态系统的影响。详细讨论了散射辐射和直接辐射对光能利用率的不同影响,并着重说明分离阴叶和阳叶的重要性。得出大气气溶胶辐射效应主要是通过增加散射辐射,提高作物阴叶的光能利用率,从而改变作物光合作用响应的结论。并指出气溶胶浓度变化对作物产量的影响与天空状况有关。关于气溶胶辐射效应对生态系统的影响,主要从大气气溶胶浓度变化对净生态系统CO2交换以及大气气溶胶散射吸收对陆地净初级生产力的影响这两个方面进行了探讨,指出气溶胶辐射效应对生态系统的NEE和NPP的提高有正面作用。     

辽宁省土壤侵蚀空间尺度效应初探

土壤侵蚀的空间尺度效应和不同空间尺度土壤侵蚀定量评价的分析与研究是目前土壤侵蚀研究中的热点问题之一。通过对辽宁省34个典型水文站长序列水文资料和2000年辽宁省遥感资料进行汇总,运用沙量平衡分析方法,对辽宁省小流域-中尺度流域-区域大尺度3种尺度土壤侵蚀量进行不同空间尺度的对比研究。研究表明,辽宁省土壤侵蚀的空间尺度效应随着研究尺度的增大,主要表现在：1）通过对辽河流域的研究表明,研究区土壤流失量随流域面积的增大表现出递次减小的规律;2）通过对辽宁省9大流域的水文资料和遥感资料对比研究表明,随着研究尺度增大,土壤侵蚀的宏观特征表现更为显著。通过沙量平衡分析方法,沉积泥沙存蓄变化量是造成尺度效应的重要因素之一。深入研究沙量平衡计算的理论与方法,以沙量平衡计算辅助土壤侵蚀监测工作,是进一步促进土壤侵蚀监测工作的重要方法之一。     

基于薄云雾去除的ETM+影像大气校正

中国南方农业遥感监测中,遥感影像常常受到薄云雾影响,大气的散射与吸收作用会使传感器接收到的地物反射率与真实值之间存在差距,是导致数据质量下降的主要原因,薄云雾去除和大气校正处理是十分必要的。该研究利用LandSat-7/ETM+影像,结合背景抑制云雾厚度因子（BSHTI）云检测方法和虚拟云点（VCP）云去除方法进行薄云雾去除,并与暗元法去云处理结果对比分析,然后将去云处理后的影像进行FLAASH大气校正,选取校正前后典型地物的光谱特征和NDVI值进行分析评价。结果表明,BSHTI-VCP法可有效消除薄云雾对遥感数据的影响,提高了云雾覆盖范围的影像质量;FLAASH大气校正较好地消除了大气影响,获得了地物真实地表反射率。该研究为南方作物遥感监测中定量反演与信息解译提供了良好理论支持。     

土壤光学遥感研究进展

土壤是一个时空连续的变异体,传统土壤参数测定与监测方法难以揭示土壤的时空间异质性规律;土壤光学遥感可以实现土壤主要参数的快速、宏观测定。本文综合评述了土壤不同理化参数(有机质、土壤水分、矿物组成、土壤质地、土壤结皮)在光学波段的光谱特征与遥感反演,光学遥感在土壤分类与制图方面的应用;分析了土壤线的各种影响因素(外部因素及相关土壤理化参数),以及土壤线对植被指数定量监测植被状况的重要性;归纳了土壤光学遥感存在问题与发展趋势。     

MODIS数据辅助的GF-1影像晴空光合有效辐射反演

面向农作物产量监测对中高分辨率遥感数据光合有效辐射(photosynthetically available radiation,PAR)反演的实际需求,该文选择山东省禹城市2014年1月至2014年12月共13景GF-1/WFV卫星影像作为数据源,基于中分辨率成像光谱仪(moderate-resolution imaging spectroradiometer,MODIS)地表反射率产品作为辅助数据源,开发了适于业务运行的WFV数据气溶胶光学厚度(aerosol optical depth,AOD)及PAR的反演算法。算法核心是采用6S(second simulation of satellite signal in the solar spectrum)大气辐射传输模型,建立包括AOD在内的大气参数与查找表(look-up table,LUT),结合大气顶层太阳入射辐照度及卫星入瞳处辐射亮度值反演地表反射率数据,通过与WFV蓝光波段地表反射率数据对比获取大气参数。通过反演的大气参数计算400~700 nm连续光谱区间的PAR值,并建立WFV数据离散红、绿、蓝光波段与连续光谱区间PAR的转换系数,实现WFV数据PAR的反演。其中,WFV蓝光波段反射率数据与MODIS地表反射率数据关系、离散到连续谱段PAR的关系可以从美国地质勘探局(United States Geological Survey,USGS)提供的典型地物波谱库数据理论计算获取。利用中国生态系统研究网络(chinese ecosystem research network,CERN)禹城站地面观测值进行验证结果表明,该文提出的算法总体精度达到92.63%,平均绝对误差为14.56 W/m~2,平均相对误差7.37%,具有业务应用的潜力。     

基于MCD19-A2数据和GWR模型的2011－2020年中国大气PM2.5质量浓度反演

为探究MODIS高时空分辨率气溶胶产品数据在长时间序列下对于反演中国陆地PM2.5质量浓度的适用性和准确性。该研究基于MCD19-A2数据研究2011－2020年中国陆地气溶胶光学厚度（aerosol optical depth,AOD）的时空分布特征,以降水、风速等8个气象要素为辅助变量建立反演PM2.5的地理加权回归模型（geographically weighted regression,GWR）并分析中国陆地PM2.5的空间分布。结果表明：1）2011－2020年中国陆地气溶胶时空分布基本符合\     

基于图像的CBERS-CCD数据大气校正--以四川省紫坪铺库区为例

作为国产卫星遥感数据,CBERS—CCD的定量化研究和应用已受到我国学者高度重视,将其与汶川地震灾区恢复重建工作相结合更具实践价值。以四川省紫坪铺库区为例,建立了简化的大气校正模型,并采用改进的基于图像估计参数的方法,快速完成CBERS02B—CCD数据大气校正。结果证实,该模型方法能够消除大气影响,增强图像信息,并能满足一般遥感定量研究与应用的需要,具有较强的实用性和可推广性。     

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.     

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.     

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,     

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.