关于航空中气象地面观测作用的研究

本文主要论述了影响航空中气象地面观测的因素以及仪器安装原则,并针对如何提高仪器的使用提出了相关的建议和意见,以期对航空中气象地面观测工作起到促进作用。     

区域尺度无人机涡动相关通量观测系统的应用研究

陆地生态系统的水热循环与碳循环是陆地表层系统中物质能量循环的核心,其中区域尺度地表水、热、碳通量的直接观测是当下陆地生态系统通量观测与模拟研究中的热点与难点。机载涡动相关方法能够直接观测区域尺度生态系统通量,基于无人机平台的涡动相关通量观测技术同时兼具了区域覆盖性与经济灵活性等优点,是机载通量观测技术的最新发展方向。在介绍机载涡动相关通量观测方法的主要技术原理、观测特点以及无人机通量观测系统组成的基础上,通过在相对均匀的区域开展无人机与地面通量观测对比试验,采用谱分析、观测结果对比以及源区分析等方式对无人机通量观测系统的性能进行了初步评价。结果表明：无人机通量观测系统能够实现对大气高频湍流信号的有效采样;无人机与地面观测的湍流通量具有较好的一致性,但是感热和CO₂通量出现了低估、潜热和摩擦风速出现了高估;观测平台与仪器的差异、垂直通量辐散、大气边界层条件、不同的地面源区及地表异质性的影响是造成二者差异的潜在主要因素。最后对未来研究目标进行了展望,以进一步推动该技术在相关领域中的应用。     

典型森林生态系统总辐射和光合有效辐射长期观测中的仪器性能衰变和数据校正

利用中国通量网( ChinaFLUX)4个森林台站(长白山、千烟洲、鼎湖山和西双版纳)2003-2008年总辐射和光合有效辐射(PAR)观测资料,研究了CNR1总辐射表和Li-190SB光量子仪在长期观测中可能出现的不确定性和仪器性能变化等问题.结果表明:98％以上的CNR1总辐射观测精度满足技术标准,但在西双版纳站,CNR1观测的总辐射(QCNR1)比高精度短波辐射仪CM11观测的总辐射(QCM11)平均低7％;虽然温度对CNR1观测的总辐射有一定影响,但其影响大都在仪器允许的精度范围内,在西双版纳站,CNR1除了受温度影响外,还受到热带雨林特有的季节性雾的影响;通过分析光合有效辐射数据(特别是其与总辐射比值)的长期变化发现,光量子仪Li-190SB的性能衰减较明显,平均年衰减率达4％左右,为了校正PAR仪器性能衰减产生的系统误差,本文尝试给出了PAR的后期补偿校正方法,该方法可基本消除由于野外长期使用所造成的Li-190SB性能衰减.     

通量梯度法在温室气体及同位素通量观测研究中的应用与展望

通量梯度法与涡度相关法均是微气象学的物质和能量通量观测方法,在没有高频气体分析仪或下垫面风浪区较小的情况下,通量梯度法可以有效观测生态系统(或土壤)与大气之间的温室气体及其同位素通量,同时也可以作为涡度相关法的配套观测和有益补充。该文回顾了通量梯度法的基本原理、概念和假设,重点综述了温室气体浓度梯度以及相关湍流扩散系数的观测与计算的方法和理论,概述了通量梯度法在森林、农田、草地、湿地和水体等生态系统观测温室气体通量的应用进展,特别是在稳定同位素通量观测中的应用,最后从影响温室气体和同位素的浓度梯度以及湍流扩散系数测定与计算等方面概述了应用注意事项及建议。     

通量梯度法在温室气体及同位素通量观测研究中的应用与展望

通量梯度法与涡度相关法均是微气象学的物质和能量通量观测方法, 在没有高频气体分析仪或下垫面风浪区较小的情况下, 通量梯度法可以有效观测生态系统(或土壤)与大气之间的温室气体及其同位素通量, 同时也可以作为涡度相关法的配套观测和有益补充。该文回顾了通量梯度法的基本原理、概念和假设, 重点综述了温室气体浓度梯度以及相关湍流扩散系数的观测与计算的方法和理论, 概述了通量梯度法在森林、农田、草地、湿地和水体等生态系统观测温室气体通量的应用进展, 特别是在稳定同位素通量观测中的应用, 最后从影响温室气体和同位素的浓度梯度以及湍流扩散系数测定与计算等方面概述了应用注意事项及建议。     

六出花属DUS测试性状筛选与评价

以39份六出花品种为试材,对51个候选性状进行观测,比对不同测量方式对花相关数量性状的影响,并同时研究了同品种中外花被片与侧外花被片长度的相关性。结果表明:"花序:花序梗长度"和"花:花梗长度"不满足DUS测试性状要求,最后筛选出43个性状作为DUS测试性状。12个数量性状可分别划分为3~7级;不同观测方式对花相关数量性状具有影响,推荐DUS测试时采用随机观测方式;不同批次的同一品种观测结果部分性状上存在差异;多数品种的中外花被片长度与侧外花被片长度之间呈线性正相关;形态性状的聚类分析结果支持将"花:主色"作为分组性状。     

箱体特征对箱式法观测水-气界面CO2和CH4通量的影响

箱式法是广泛运用于内陆水体CO₂和CH₄通量监测的重要方法,但各研究中使用的箱体特征存在差异,箱体设计缺少统一标准,从而会影响观测结果。为明确箱体透光性、箱体内外气压差以及箱体内气体混合状态对水-气界面CO₂和CH₄通量观测的影响,本研究基于多通道闭路式动态箱观测系统,分别对比明箱和暗箱、箱体是否配备气压平衡阀及风扇对养殖塘水-气界面CO₂和CH₄通量观测的影响。结果表明: 夏季白天观测期间,与可观测CO₂实际通量的明箱相比,当CO₂呈现排放状态时,暗箱高估了90%的CO₂通量;当CO₂呈现吸收状态时,暗箱低估了50%的CO₂通量。暗箱测得的CH₄扩散通量比明箱低40%。箱体内气压是否与外界气压保持平衡对CO₂和CH₄通量影响均不显著。无风扇的箱体观测的CO₂通量代表性较差,在本研究中较有风扇的箱体高20%。无风扇的箱体难以区分不同途径排放的CH₄通量。在运用箱式法观测水-气界面CO₂、CH₄通量时,应使用透明箱体,并在其中安装风扇辅助气体混合。     

用于测定陆地生态系统与大气间CO2交换通量的多通道全自动通量箱系统

陆地生态系统与大气间CO2交换是全球碳循环的最重要组成部分,科学地测定其CO2交换通量一直是陆地生态系统碳循环研究的核心工作之一。提高观测的效率和减少观测对自然的干扰,是科学精确地估算区域和全球尺度上的陆地生态系统与大气间CO2交换量的关键。在参考国内外已有的陆地生态系统与大气间CO2交换通量箱式法观测技术的基础上,发展了一套多通道全自动通量箱系统用来连续观测陆地生态系统或土壤与大气间的CO2交换通量。在黄土高原中国科学院长武农业生态试验站的麦田和苹果园中进行了系统测试,结果表明,该系统不但能够实现自动、连续、多点观测,而且对自然环境的影响比较小,在田间的实验观测中,该系统运行稳定,能够比较客观地得到陆地生态系统与大气间的CO2交换通量。     

海洋二甲基硫观测技术及其海-气通量分析研究进展

二甲基硫(DMS)海-气交换是全球硫循环的主要参与者,对全球气候变化产生重要影响。有关海洋DMS排放及其海-气交换过程研究已引起人们的广泛关注,并成为现今国际上的研究热点之一。从海洋DMS观测技术及海-气通量估算两方面进行了系统总结,并指出了它们的最新进展和发展趋势,具体包括:虽然遥感技术在获取DMS时空分布及大面数据方面具有独特优势,但气相色谱法是目前应用最为广泛的观测技术,而质谱也越来越受到研究者们的青睐;直接观测技术在提升分析性能的同时朝着自动化、智能化现场实时观测的方向发展;观测对象从单一DMS扩展至其前体、二甲基亚砜等其他物质,同时所获数据呈多元化趋势,准确度也逐渐提升;以滞膜模型为代表的模型估算和以涡旋相关法为代表的直接测量法是目前DMS海-气通量分析的主要方法,而多元化数据则促进了两种或两种以上通量分析方法的联合及对比;深入探究海洋环境因素对海-气交换过程的影响,进一步完善速率常数计算和通量估算方法,是获得适用性更广、准确度更高的DMS传输率常数及提高通量估算准确度的重要途径;将直接观测技术和遥感卫星观测技术相结合,开展时间、空间维度上的全球海域DMS大数据调查研究,并深入评估DMS对海洋环境及气候变化的影响将是未来研究的重要内容;基于大数据基础构建海洋DMS排放趋势模型,实现未来DMS排放的准确预测是DMS观测及其海-气通量分析研究的重要目标。     

大田环境下转Bt基因玉米对土壤酶活性的影响

在大田自然条件下,比较研究了转Bt基因玉米和非转基因亲本玉米在种植和秸秆分解时对土壤酶活性影响的差异。结果表明,与亲本非转基因玉米相比,在各生育期内种植转Bt玉米对土壤蛋白酶和土壤脲酶活性均没有显著影响;在喇叭口期和抽雄期,土壤蔗糖酶和土壤酸性磷酸酶活性显著提高。在秸秆还田后,两种玉米秸秆对土壤酸性磷酸酶活性的影响没有显著差异,但使用转Bt玉米秸秆的土壤蔗糖酶、土壤脲酶和土壤蛋白酶的活性则有显著提高。与亲本玉米相比,在所有观测期内,种植Bt玉米及秸秆还田对土壤酶活性的影响,在影响的幅度及趋势上随玉米生育期和土壤酶种类的不同而产生差异,但没有观测到显著不利影响;商业化Bt玉米的环境释放仍有待长期定位观测和评价。     

Seasonal availability of resources and habitat degradation for the western tree-hole mosquito, <Emphasis Type="Italic">Aedes sierrensis</Emphasis>

The nutrient base of aquatic tree-hole communities is derived from leaf litter, benthic detritus, and water flowing down the tree trunk (stemflow water). Previous studies in eastern North America with the mosquito, Aedes triseriatus, have identified leaf litter as a major and stemflow water as a minor source of mosquito nutrition, but did not consider the role of the benthic detritus or how the aggregate or relative contribution of these sources of mosquito nutrition changed during the year. We use the leaf litter, benthic detritus, and stemflow water from tree holes in western Oregon (USA) to determine how these substrates affect mass at metamorphosis, biomass yield, and fitness (cohort replacement rate; R ₀) of the mosquito, Aedes sierrensis, through both natural and simulated winters, the normal growing season for larvae in tree holes. We found that fresh leaf litter constitutes the major determinant of mosquito fitness by a factor of >15:1 over any other substrate taken directly from tree holes in nature. The other substrates, including the benthic detritus, individually make only a meager contribution to mosquito fitness but, when added to the leaf litter, can sustain yield and improve fitness at high, limiting larval densities. Nutritional quality of tree-hole substrates declines by >90% from early (fall) to late (spring) in the larval growing season. At both times of year, the coarse or fine detritus provide minor resources, and stemflow water provides no detectable contribution to mosquito nutrition. The resources in the litter are not transported during the year to the benthic detritus; rather, these resources are either exploited by mosquitoes when they first become available, or they deteriorate and become progressively more unavailable to them. Growth and development of A. sierrensis feeding on dried and reconstituted tree-hole contents during a 6-month simulated winter in the laboratory showed: (1) the same relative contributions of leaf litter, benthic detritus, and stemflow water to mosquito nutrition, (2) that the winter deterioration of substrate quality is a direct consequence of microbial decomposition, and (3) that pre-emptive competition from pre-existing A. sierrensis greatly increases substrate deterioration. We conclude that the progressive winter deterioration of larval resources in combination with the dry summers of western North America are the most likely environmental factors that limit species diversity in tree holes and that have selected for early recruitment (autumnal hatching) of A. sierrensis and for its univoltine life cycle from Mexico to Canada. Received: 28 December 1999 / Accepted: 10 April 2000     

祁连山青海云杉林冠生态水文效应及其影响因素

以位于祁连山中段大野口关滩森林站的青海云杉林为研究对象,利用2008年观测期间(6月12日至10月8日)34场降雨的大气降雨量、穿透雨量和树干茎流量观测资料,对青海云杉林的降雨再分配特征及其影响因素进行综合分析。结果表明:青海云杉林的总穿透雨量、截留量和干流量分别为212.6、64.5 mm和3.4 mm,分别占大气降雨量的75.8%、23.0%和1.2%;穿透雨在林内具有较大的空间变异性,其变异程度随降雨量的增大而减小,叶面积指数和冠层郁闭度在一定程度上也影响穿透雨的空间分布,且降雨量越小其影响效果越明显;青海云杉林的总干流量为3.4 mm,平均干流率为0.58%,雨前林冠的湿润程度对树干流的产生有很大影响,导致当降雨量为5.6 mm时就开始产生树干茎流;青海云杉林冠截留率的大小主要取决于降雨量,且随着降雨量的增大先减小并逐渐趋于稳定,林冠截留量总体上随冠层郁闭度和叶面积指数的增大而增大,但当观测点位于树冠边缘或多个树冠重叠处时出现负截留现象。所以,就特定林分而言,冠层结构特征对于其林冠生态水文效应起着重要的作用。     

三种阔叶次生林的茎流研究

本文测定了白桦林、水曲柳林、蒙古栎林的树干茎流量及其养分元素含量,结果表明:三个林分的茎流差异十分明显(白桦:水曲柳:蒙古栎≈1:2:3),这种差异与树叶形态、枝条分枝角度及林分的叶面积指数有关。茎流中绝大多数元素的含量显著地高于降雨中的含量。蒙古栎林借助于它的形态结构使其根系区域获得的水分、养分最多,从而有助于它适应干旱、瘠薄的立地环境。     

六盘山华山松(Pinus armandii)林降雨再分配及其空间变异特征

利用2004和2005年生长季(6～9月份)六盘山自然保护区的香水河小流域内华山松天然林的穿透降雨、树干径流和冠层截留量观测资料,通过对华山松林降雨再分配特征和穿透降雨空间变异及其影响因素的综合分析,所得结果表明华山松天然林的穿透降雨量、树干径流量和冠层截留量,分别占大气降雨量的84.34%、0.72%和14.94%.穿透降雨在林内具有较大的空间变异,其变异程度随降雨量的增加而减小,冠层对穿透降雨具有一定的聚集效应,降雨量越高时效应越明显; 华山松冠层结构特征是影响穿透降雨的重要因素, 叶面积指数、冠层覆盖度、冠层厚度及距树干的距离等都会影响穿透降雨的空间分布,其中以叶面积指数的影响最大.由分析结果可知,冠层结构特征是决定大气降雨再分配和空间变异的重要生态因素之一.     

华北暖温带山地落叶阔叶混交林的茎流研究

测定华北暖温带山地落叶阔叶混交林的树干茎流量及其元素含量,并比较了不同树种是的差异。通过８２次孤立降雨的测量,得到了辽东栋、棘皮桦、五角枫、大叶白腊和蒙椴５种主要树种及整个林分茎流量Ｓ与降雨Ｐ的关系,经多种方程拟合,仍以直线方程为最佳。降雨水质分析的结果给出了Ｎ、Ｐ、Ｋ、Ｃａ、Ｍｇ、Ａｌ、Ｓ元素各次测量的美元浓度及其变异系数,以及年输入量的估测值,茎流元素含量的分析结果表明,５种乔木中,以棘皮桦的     

树干径流过程的动态响应模型

本文用实验测试法测量了干流过程。结果表明,干流过程曲线与R-L-C电路瞬态响应过程(包括输入、输出曲线)极为相似。据此,可用R-L-C电路瞬态响应过程曲线拟合干流过程,求出解析解。在计算机上调试参数,讨论其水文学意义,定性分析参数与影响干流因子的关系,取得了满意的结果。     

Physical and biological processes in a Macrocystis pyrifera community near Valdivia,Chile

Summary Experimental studies support four main conclusions about the effects of the chemical composition of stemflow on the growth, development, and survivorship of larvae of the tree hole mosquito Aedes triseratus Say, a vector of human encephalitis. (1) The presence and type of leaf litter is more critical for larval growth and development than the type of stemflow found in tree holes. (2) However, variations in stemflow chemical composition within the natural range of concentrations have substantial effects on growth, development, and survivorship of the larvae. Effects of pH, ammonia, nitrate, and sulfate are especially pronounced. (3) Acidification of stemflow caused increased mortality, prolonged development times, and reduced size of individual pupae, similar to effects of acid precipitation on the insect detritivores of lakes and streams. The stimulatory effects of nitrate and sulfate in acid precipitation do not compensate for the deleterious effects of the acidity. (4) Changes in stemflow characteristics sometimes had opposite effects on detritivores and detritus. The vigor of the larval population was not dependent on litter decomposition alone. In general, emergence patterns of adult treehole mosquitoes depend strongly on the chemical composition of stemflow.A fractional factorial experiment was successfully used. Fractional designs are advocated for experiments that screen a large number of nutrients or toxins for their effects on ecosystem components.     

Throughfall,stemflow and interception of rainwater in an evergreen broadleaved forest

In order to analyze the dyanmics of heavy metals in a forest ecosystem, throughfall and stemflow were collected for individual rain showers in an evergreen broad-leaved forest dominated byCastanopsis cuspidata. The relation between throughfall (or stemflow) (Px) and gross rainfall (P) was approximated by a linear regression equationPx=a(P-b). The values of coefficient “a” were 0.32–2.02 for throughfall at each sampling point and the mean values for 1976 and 1977–1978 were 0.682 and 0.767, respectively. The stemflow volume differed widely among individual trees, depending mainly on the tree form of each species. In particular, the tree form ofPasania edulis was found to be especially suited to collecting stemflow. OneP. edulis tree collected 64% of the rainwater that fell onto its crown as stemflow. The ratio of stemflow to gross rainfall decreased in summer resulting from an increase in leaf biomass and an increase in air temperature. In fact, the values of coefficient “a” for mean stemflow per unit area were 0.180 for summer and 0.229 for other seasons in 1976, and 0.145 for summer and 0.155 for other seasons in 1977–1978 for different sampled trees.     

Solute fluxes in throughfall and stemflow in four forest ecosystems in northwest Amazonia

The contribution of throughfall and stemflow as pathways for solute inputs into the forest floor in four mature forests in northwest Amazonia was investigated. Total solute inputs, resulting from the changes of atmospheric deposition after rainfall passes through the forest canopy, are presented in the form of throughfall and stemflow nutrient inputs and their possible sources are discussed. Throughfall is by far the most important solute input into the forest floor of the forests studied. On average, it represents about 98% of the total solute inputs. Although trends in solute enrichment varied among the forests, there is a general tendency in all ecosystems towards a distinct enrichment of SO₄, K, Cl, NO₃ and NH₄ in throughfall and stemflow and a small increase of protons, Mn, orthoP and Fe. When comparing the net enrichment between the forests, the relative increase of solutes in throughfall and stemflow was higher in the flood plain and low terrace than in the high terrace and sedimentary plain forests. While highest values for total cation inputs were observed in the flood plain, the low terrace showed the highest value for total inorganic anions. The length of the antecedent dry period was the main factor affecting throughfall and stemflow composition, concentrations increasing with increasing length. A second, less important factor was the amount of throughfall and stemflow, which showed a poor and negative correlation with solute concentrations. The increased activity of frugivores in the canopy during fruiting periods seemed to lead to temporary increased solute concentrations in throughfall and stemflow as a result of the wash off of deposited faecal materials and detritus in the canopy. Leaching from leaves and wash off of exudes, of solutes deposited on the foliage after evaporation of intercepted rainfall and of dry deposited materials were all found to contribute to the concentration of solutes in the throughfall and stemflow. Gross rainfall enrichment after passing the forest canopy, mainly by nutrient leaching, is considerably lower than the amounts of nutrients released in litterfall implying a tight nutrient cycling and nutrient conserving mechanisms by forests studied.     

辽东山区次生林生态系统不同林型树干茎流的理化性质

为明确森林对降雨水质的影响,于2011年6-8月,对辽东山区次生林生态系统5种主要林型:落叶松人工林(Larix olgensis)(Lo)、花曲柳林(Fraxinus rhynchophulla)(Fr)、杂木林(Mb)、红松人工林(Pinus koraiensis(Pk)和蒙古栎林(Querus mongolica)(Om)中树干茎流和林外雨理化性质进行了监测.与林外雨相比,5种林型树干茎流均出现明显酸化(P＜0.05),酸化程度为:Pk＞ Lo＞ Fr＞ Om＞ Mb;各林型树干茎流的电导率、总溶解固体含量、氯离子浓度、硝酸根离子浓度、铵根离子浓度浓度和总磷浓度显著升高(P＜0.05),溶解氧浓度明显下降(P＜0.05).林型间相比,Lo与Pk的电导率和总溶解固体含量和Lo的氯离子浓度较高;Lo和Pk的硝酸根离子浓度和总磷浓度明显低于其它林型(P＜0.05);Mb的硝酸根离子浓度和总磷浓度显著高于其它林型(P＜0.05).各林型树干茎流的硝酸根离子浓度和胸径与树高的乘积呈显著正相关.上述结果主要受降雨因素(降雨前干沉降时间长度等)、林分特征(叶面积指数、树皮特征)、树木枝叶表层积累物质的理化性质等影响.结论:各林型树干茎流水质均明显下降,其中Mb树干茎流对雨水化学性质影响较大;Pk和Lo树干茎流水体纯度下降最为显著.