基于时序突变检测的植被空间变化特征识别方法——以海河北部山区为例

长时序植被变化趋势分析是分析植被生长与退化状况的主要手段之一,但难以精细揭示分析时段内植被变化动态的时空特征。将归一化植被指数（NDVI）时序突变检测与趋势分析结合起来,建立了精细识别植被空间变化特征的方法,并以海河北部山区为案例,开展了实证研究。案例分析结果表明：2000-2018年间,海河北部山区有78.1%的区域NDVI发生了突变,其中1.7%的面积发生退化。应用基于时序突变检测的植被变化识别方法进一步发现：植被变化在2011年出现突变拐点,突变前（2000-2011年）在西北草原区和东南林农区存在1.6%的显著退化,突变后（2011-2018年）在东部林农区存在1.2%的显著退化。分析表明,海河北部山区植被整体改善与气象因子的关系不大,局部恶化则是气象因子与人类活动共同作用的结果。与常规长时序植被变化趋势分析相比,基于时序突变检测的植被空间变化特征识别方法揭示了评估时段内植被空间变化的动态趋势,可为明确区域植被的变化以及差异化的植被恢复策略提供决策信息。     

覆膜开孔土壤蒸发实验研究

为获得灌后覆膜开孔蒸发过程中土壤含水率分布的动态资料,研制了室内垂直一维入渗-覆膜开孔蒸发动态观测实验系统,并进行了不同覆膜开孔率和不同入渗定额下的覆膜开孔蒸发实验.根据实测资料分析了土表覆膜开孔率和入渗定额不同条件下,蒸发土壤含水率剖面的时间变化和蒸发结束的含水率剖面特征.累积蒸发量随时间变化趋势表明,两者关系符合Gardner理论关系,且该理论关系系数与不同覆膜开孔率和入渗定额存在进一步的函数关系,从而得出覆膜开孔率和入渗定额影响下的累积蒸发量随时间变化多因子模型.同时,采用类似的方法分析了覆膜开孔率和入渗定额对相对累积蒸发量和单位膜孔面积累积蒸发量的影响,得出了定量函数关系,其拟合的相关系数均很高.     

城市公园景观的热环境效应

城市热环境受到地表的物理性质和人类社会经济活动的共同影响,是城市生态环境状况的综合体现.而城市公园景观的热环境效应显著区别于其它景观类型.城市公园景观的热环境效应研究对城市规划以及城市生态环境评价都具有重要意义.论文以上海市为例,首先提取了城市公园景观斑块的空间分布数据,再利用Landsat7的ETM 为基本数据源,定量反演了城市热环境温度,然后利用GIS中的空间分析功能,重点探讨了城市公园景观的热环境效应.公园景观斑块的面积、周长与其对应的温度具有负相关关系,而形状复杂性指数则与环境温度具有显著的正相关关系,形状复杂性指数则与环境温度的相关程度远高于面积、周长与热环境温度的相关程度.公园斑块的面积以及周长与公园对周围热环境的影响在统计上相关性较差;而形状复杂性指数则与其影响力则具有显著的正相关关系,形状越复杂,公园对周围热环境影响力越强.因此,在城市公园建设中,除了公园类型、空间选址外,边界形状也应作为考虑因素之一.     

基于遥感及突变理论的生态环境脆弱性时空演变——以黄河三角洲垦利县为例

本文应用熵、突变论等非线性科学理论研究生态环境脆弱性问题,借助遥感手段,设置生态环境样方,对黄河三角洲垦利县典型生态脆弱区的生态环境脆弱性的时空演变进行了系统研究,建立了生态环境脆弱性的分析与判断方法.结果表明：在1987—2005年间,样方生态环境趋于恶化,其生态环境脆弱性在1997年和2004年发生了两次突变,前者主要源于风暴潮和黄河来水量的减少,主要表现为生境的变化和优势种的更替;后者主要源于黄河来水量的减少和蒸降比的升高及水库的大量修建、道路和人口密度的增加,生态环境脆弱性主要表现为植被类型和覆盖率的变化.在空间层面,从与黄河和海洋不同距离的两个方向上,分析了生态环境脆弱性的空间变化,证明了生态环境脆弱性空间上的渐变性.该研究对生态环境脆弱性的定量化研究是一个新的尝试,并提供了一种新的有效方法.     

莱州湾南岸滨海湿地的景观格局变化及累积环境效应

在湿地景观类型分类基础上,利用遥感技术及GIS技术提取了1987和2002年莱州湾南岸滨海湿地Landsat 5、Landsat 7 卫星假彩色合成影像的空间属性数据,利用斑块动态度、斑块密度指数、景观多样性指数、斑块破碎化指数研究了湿地景观格局变化及其累积环境效应.结果表明,15年间莱州湾南岸滨海湿地景观总面积基本不变,但自然湿地总面积减少了49.1%,减少的自然湿地主要转化为养殖池、盐田等人工湿地.湿地景观格局的变化还表现为景观多样性指数下降、斑块破碎化指数升高.湿地景观格局变化引起自然湿地的总净初级生产量下降,环境净化功能、抗御自然灾害功能降低,陆地中生植物、旱生植物外来及有害植物侵入湿地,湿地生态系统服务价值下降等累积环境效应.     

城市景观格局演变的生态环境效应研究进展

快速城市化过程剧烈影响着下垫面变化,直接带来了交通拥挤、资源短缺、环境污染、生态恶化等诸多问题,所有这些问题的出现均与景观格局演变密切相关,研究城市景观格局演变及其生态环境效应正在成为全社会关注的热点.系统总结了城市化过程对景观格局演变的影响,分析了城市景观格局演变的热环境效应、水环境效应、生态服务效应,以及城市生态用地与生态安全格局设计等方面的研究进展.指出了目前城市景观演变与生态环境效应研究中存在的问题与不足:(1)现有研究侧重于景观格局演变的量化分析和景观格局指数的计算,较少关注景观格局演变对生态环境及其区域生态安全的影响;(2)城市景观格局演变与热岛效应研究多局限于两者数理统计关系的分析,对于城市热环境形成的机理缺乏深入研究;(3)城市景观格局演变与大气环境效应方面更多研究关注绿地及其空间布局在吸收和降解大气污染物、固体颗粒物方面的作用,对城市景观格局演变的大气环境综合效应以及大气灰霾效应影响机理重视不够;(4)如何通过合理设置生态用地,有效提高城市生态服务功能和保障城市生态安全,目前仍缺乏深入而又系统的研究.下一步的研究中,需要综合多尺度的景观信息来揭示城市景观的演变机理和环境效应,构建基于城市空间扩展和生态服务效应评价的城市生态空间优化决策模型,探讨城市生态空间优化模式与安全格局.     

喜树人工复合群落生长发育动态变化与气象因子的关系

以国家二级重点保护植物喜树和国家一级重点保护植物南方红豆杉为目的树种,以在其林下种植长春花构建形成的喜树人工复合群落和纯种种植为对象,研究其在一个生长季节的生长发育动态特征、气象因子动态特征以及两者的关系。结果表明,喜树人工复合群落和纯种种植生长发育动态变化趋势相一致,而复合群落中喜树、南方红豆杉和长春花的株高和基径及其生长速率较其纯种种植差异较大。喜树人工复合群落和纯种种植生长发育动态特征与气象因子相关性方面,人工复合群落和纯种种植在一定范围内较高的土壤湿度均有利于喜树的高生长,一定的净辐射月累积均有利于喜树的基径生长;南方红豆杉株高方面,人工复合群落与降雨量月累积值呈较大的正相关,纯种种植则与土壤温度月均值呈较大的正相关,南方红豆杉基径方面,人工复合群落与气温月均值呈正相关,而纯种种植的基径与净辐射月累积值呈一定的正相关;人工复合群落和纯种种植,土壤温度均有利于长春花高生长和茎生长。利用喜树、南方红豆杉和长春花生长发育与各气象因子的相关关系分析,从而在其栽培过程中采取相应的人工定向培育措施,为这3种药用植物的人工复合群落的优质栽培提供理论依据。     

城市化与生态环境协调发展的动态耦合模型及其在干旱区的应用

在分析城市化进程与生态环境状况之间交互胁迫、动态演进关系的基础上,借助于系统科学理论建立了城市化与生态环境协调发展的动态耦合模型。认为整个城市化过程就是城市化的各个层面与生态环境的综合协调、交互胁迫的耦合发展过程。在这一过程中,城市化与生态环境协调发展系统的演化周期将经历低级协调共生、协调发展、极限发展和螺旋式上升4个阶段,城市化与生态环境协调发展耦合过程的实质,就是系统各要素相互作用、相互制约,由低级协调共生向高级协调发展的螺旋式上升的过程。以河西走廊为例,对干旱区城市化与生态环境协调发展的动态耦合规律进行了实证分析,认为1985~2003年间,河西走廊城市化水平不断提高,生态环境状况曲折下降,生态环境对城市化的响应较为明显,但相对于城市化进程,生态环境的响应又有一定的滞后性。目前河西走廊处于城市化与生态环境的协调发展阶段,然而协调耦合度的增长很快,整个协调发展系统即将进入极限发展阶段,生态环境危机正在进入潜伏期。基于动态耦合模型所建立的协调耦合度,能够较好地反映城市化与生态环境的交互胁迫、动态耦合的演变情况。根据河西走廊耦合度的变化可知,在城市化发展的初期,往往是需要一定的生态破坏为代价的,然而随着城市化的发展,生态环境必将随城市化而好转。因此,正确认识城市化与生态环境交互胁迫的动态耦合规律,采取适当的城市化发展模式,对于促进河西走廊城市化与生态环境的协调发展具有重大意义。     

甘肃省脆弱生态环境与贫困的耦合关系

保持生态环境与经济建设的协调发展是新阶段国家扶贫开发的重要策略之一。以甘肃省为例,运用系统耦合协调度理论,构建双系统发展多指标综合评价体系,对研究区2000—2014年脆弱生态环境与贫困评价得分、两者耦合协调度及时空分异进行测度和分析。结果表明:从时序角度看,甘肃省脆弱生态环境和贫困耦合协调度整体呈上升状态,受政策调整等因素的影响呈现低水平耦合协调、耦合协调度增长、高水平耦合协调生态环境滞后3个不同阶段;从空间分异角度看,甘肃省脆弱生态环境和贫困耦合协调度由东南向西北递增,耦合协调度空间分布不均衡,脆弱生态环境与贫困共生共存,需充分重视和保护贫困地区生态环境。     

湿地环境累积效应

近年来,湿地环境开发过程中出现了多种生态环境问题,由于多种开发方式和多种影响因素的共同作用,对湿地环境产生明显的累积效应,单一要素的环境评价和分析已满足不了湿地利用和保护的要求,亟需加强湿地环境累积效应研究。本文从累积效应研究的基础出发,提出湿地累积效应的概念和研究内容,界定湿地环境累积效应研究范围(空间和时间),并综述环境累积效应研究方法,阐明了目前研究的不足,最后指出了湿地环境累积效应的未来研究方向为:环境累积效应的途径、环境累积效应的长期监测和累积效应预测模型的建立。     

侵蚀环境小流域生态经济系统健康定量评价

生态经济系统健康是黄土丘陵区侵蚀环境下水土保持与生态建设的目标.在分析侵蚀环境下生态系统健康特征和诊断指标筛选原则的基础上,从资源环境支持、社会经济人文影响和生态综合功能3个方面,选择17个因素作为参评因子,建立了一套适合于侵蚀环境小流域生态经济系统健康诊断的指标体系.以均方差决策法确定各指标的权重,运用递阶多层次综合法、线性加权函数法分别建立二级层次和综合指标健康诊断模型——健康指数.分析研究侵蚀环境小流域生态经济系统健康动态,结果表明,该环境系统健康状况相对稳定,健康指数呈逐年波动式上升趋势（由1985年的0.370增大到2003年的0.573）,具有较强的可持续发展能力.同时,以现实生态经济最佳水平为目标,引入障碍度、优势度等概念,运用通经分析对该环境小流域系统健康进行障碍和优势诊断,并据此提出了建设对策和建议,为该环境小流域生态环境建设提供科学依据.     

Regional Scale Prioritisation for Key Ecosystem Services,Renewable Energy Production and Urban Development

Although the importance of addressing ecosystem service benefits in regional land use planning and decision-making is evident, substantial practical challenges remain. In particular, methods to identify priority areas for the provision of key ecosystem services and other environmental services (benefits from the environment not directly linked to the function of ecosystems) need to be developed. Priority areas are locations which provide disproportionally high benefits from one or more service. Here we map a set of ecosystem and environmental services and delineate priority areas according to different scenarios. Each scenario is produced by a set of weightings allocated to different services and corresponds to different landscape management strategies which decision makers could undertake. Using the county of Cornwall, U.K., as a case study, we processed gridded maps of key ecosystem services and environmental services, including renewable energy production and urban development. We explored their spatial distribution patterns and their spatial covariance and spatial stationarity within the region. Finally we applied a complementarity-based priority ranking algorithm (zonation) using different weighting schemes. Our conclusions are that (i) there are two main patterns of service distribution in this region, clustered services (including agriculture, carbon stocks, urban development and plant production) and dispersed services (including cultural services, energy production and floods mitigation); (ii) more than half of the services are spatially correlated and there is high non-stationarity in the spatial covariance between services; and (iii) it is important to consider both ecosystem services and other environmental services in identifying priority areas. Different weighting schemes provoke drastic changes in the delineation of priority areas and therefore decision making processes need to carefully consider the relative values attributed to different services.     

Evolution of phenotypic plasticity and environmental tolerance of a labile quantitative character in a fluctuating environment

Quantitative genetic models of evolution of phenotypic plasticity are used to derive environmental tolerance curves for a population in a changing environment, providing a theoretical foundation for integrating physiological and community ecology with evolutionary genetics of plasticity and norms of reaction. Plasticity is modelled for a labile quantitative character undergoing continuous reversible development and selection in a fluctuating environment. If there is no cost of plasticity, a labile character evolves expected plasticity equalling the slope of the optimal phenotype as a function of the environment. This contrasts with previous theory for plasticity influenced by the environment at a critical stage of early development determining a constant adult phenotype on which selection acts, for which the expected plasticity is reduced by the environmental predictability over the discrete time lag between development and selection. With a cost of plasticity in a labile character, the expected plasticity depends on the cost and on the environmental variance and predictability averaged over the continuous developmental time lag. Environmental tolerance curves derived from this model confirm traditional assumptions in physiological ecology and provide new insights. Tolerance curve width increases with larger environmental variance, but can only evolve within a limited range. The strength of the trade‐off between tolerance curve height and width depends on the cost of plasticity. Asymmetric tolerance curves caused by male sterility at high temperature are illustrated. A simple condition is given for a large transient increase in plasticity and tolerance curve width following a sudden change in average environment.     

Assessing the effect of prevalence on the predictive performance of species distribution models using simulated data

Aim The proportion of sampled sites where a species is present is known as prevalence. Empirical studies have shown that prevalence can affect the predictive performance of species distribution models. This paper uses simulated species data to examine how prevalence and the form of species environmental dependence affect the assessment of the predictive performance of models. Methods Simulated species data were based on various functions of simulated environmental data with differing degrees of spatial correlation. Seven model performance measures – sensitivity, specificity, class‐average (CA), overall prediction success, kappa (κ), normalized mutual information (NMI) and area under the receiver operating characteristic curve (AUC) – were applied to species models fitted by three regression methods. The response of the performance measures to prevalence was then assessed. Three probability threshold selection methods used to convert fitted logistic model values to presence or absence were also assessed. Results The study shows that the extent to which prevalence affects model performance depends on the modelling technique and its degree of success in capturing dominant environmental determinants. It also depends on the statistic used to measure model performance and the probability threshold method. The response based on κ generally preferred models with medium prevalence. All performance measures were least affected by prevalence when the probability threshold was chosen to maximize predictive performance or was based directly on prevalence. In these cases, the responses based on AUC, CA and NMI generally preferred models with small or large prevalence. Main conclusions The effect of prevalence on the predictive performance of species distribution models has a methodological basis. Relevant factors include the success of the fitted distribution model in capturing the dominant environmental determinant, the model performance measure and the probability threshold selection method. The fixed probability threshold method yields a marked response of model performance to prevalence and is therefore not recommended. The study explains previous empirical results obtained with real data.     

山地河流浅滩生境潜流层大型无脊椎动物群落拓殖

通过包埋人工基质法研究大型无脊椎动物在山地河流潜流层中的拓殖过程。结果表明:群落个体密度在7—29 d呈"J"型增长,在29 d后骤然降低,55 d后呈波动趋势;物种丰富度在1—29 d呈增加趋势,29 d后呈波动状态;群落的生物量总体呈增加趋势。群落的物种丰富度、密度和生物量在第29、71和83天时没有显著性差异(P0.05),Shannon-Wiener多样性指数和Pielou均匀度指数在第55、71、83天没有显著性差异(P0.05),综合不同拓殖时间段物种的主成分分析,表明潜流层大型无脊椎动物群落在55 d后趋于稳定。群落优势种为摇蚊(Camptochironomus sp.)、河蚬(Corbicula fluminea)、四节蜉(Baetis sp.)、动蜉(Cinygmina sp.)、纹石蛾(Hydropsyche sp.)和扁泥甲科的一种(Psephenidae)。滤食者和收集者在整个拓殖过程中均是优势功能摄食群。群落拓殖过程是一个群落自身恢复能力和外部环境影响相互作用的过程,拓殖初期潜流层的结构是影响着无脊椎动物迁入的主要因素,中期动物的生活史特征起主要作用,稳定期之后群落可能受到各因素的综合影响。     

间作对桑树和谷子生长和光合日变化的影响

以桑树和谷子为研究材料,探讨了大田条件下,桑树-谷子间作对桑树和谷子的干物质生产、土地利用率和光合日变化的影响.结果表明：桑树-谷子间作条件下,间作桑树的株高、地茎、根长和枝条数分别比单作桑树增加了6.0%、13.7%、6.8%和14.8%,且间作桑树的产叶量比单作桑树增加了31.3%;间作谷子与单作比较,其株高和根长的变化不大.桑树-谷子间作增加了土地当量比,提高了土地利用率.单作、间作桑树和谷子叶片在12:00时均表现出明显的光合午休现象,且单作桑树的光合午休现象比间作桑树严重.桑树-谷子间作提高了中午时桑树叶片气孔导度和水分利用率,增加了桑树光合碳同化能力,抑制了桑树叶片实际光化学效率、电子传递速率和最大光化学效率的下降,从而减缓了桑树的“光合午休”现象.桑树 谷子间作能明显提高桑树叶片的光合生产能力.     

Niche width and niche overlap: a method based on type-2 fuzzy sets

Complicated ecosystems and the high non-linearity of evolution has made biology more adaptable to a variety of environments. The relationship between life and environment demands a dynamic definition of niche and its measurement. In this paper we propose a model of niche with dynamic character based on the “broad band” effect in type-2 fuzzy sets. The niche in this definition is an interval in each ecological dimension which is dynamic in character and depends on the actual environment. We also give formulas for niche width and niche overlap. We compute the niche width and overlap for plants and animals and then compare these results with previous results. The results for niche width in this paper reflect the diversity of resources used by species or communities. The results for niche overlap demonstrate overlap under different environmental conditions. The results are, moreover, intervals, which could provide more information. The model in this paper could therefore be used to describe the state of every resource comprehensively, reflecting the interaction between species and environment.     

Phytoplankton–zooplankton dynamics in periodic environments taking into account eutrophication

In this paper, we derive and analyze a mathematical model for the interactions between phytoplankton and zooplankton in a periodic environment, in which the growth rate and the intrinsic carrying-capacity of phytoplankton are changing with respect to time and nutrient concentration. A threshold value: “Predator’s average growth rate” is introduced and it is proved that the phytoplankton–zooplankton ecosystem is permanent (both populations survive cronically) and possesses a periodic solution if and only if the value is positive. We use TP (Total Phosphorus) concentration to mark the degree of eutrophication. Based on experimental data, we fit the growth rate function and the environmental carrying capacity function with temperature and nutrient concentration as independent variables. Using measured data of temperature on water bodies we fit a periodic temperature function of time, and this leads the growth rate and intrinsic carrying-capacity of phytoplankton to be periodic functions of time. Thus we establish a periodic system with TP concentration as parameter. The simulation results reveal a high diversity of population levels of the ecosystem that are mainly sensitive to TP concentration and the death-rate of zooplankton. It illustrates that the eruption of algal bloom is mainly resulted from the increasing of nutrient concentration while zooplankton only plays a role to alleviate the scale of algal bloom, which might be used to explain the mechanism of algal bloom occurrence in many natural waters. What is more, our results provide a better understanding of the traditional manipulation method.     

海口市海岸带生态系统服务及其时空变异

海岸带位于陆地、海洋交汇地带,有着重要的生态价值,但也是生态环境较为脆弱的地区。以海口市为研究区,研究海口市海岸带生态系统服务及其时空变异。基于1990、1995、2004和2012年4期Landsat TM影像得到土地利用覆盖数据;采用基于当量因子的生态系统服务价值评价方法,结合海口市实际情况,构建了海口市海岸带生态系统服务价值动态评估模型;借助GIS空间分析技术,应用局部空间自相关模型,定量研究了生态系统服务价值(ESV)的时空变异特征。研究结果表明:(1)在生态系统服务的总值方面,过去20多年的ESV整体变化不大,但近年来ESV有所降低,生态环境出现退化趋势。(2)在生态系统服务的时空变异方面,海口市海岸带ESV的空间正相关性显著,空间集聚程度较高,高值区主要集中于中心城区西部和东寨港周围,低值区主要集中于中心城区;近来,在发展城市经济和保护生态环境的双重作用下,位于中心城区的低值区和位于东寨港红树林自然保护区的高值区都有所辐射扩张。     

Ecological Thresholds: The Key to Successful Environmental Management or an Important Concept with No Practical Application?

An ecological threshold is the point at which there is an abrupt change in an ecosystem quality, property or phenomenon, or where small changes in an environmental driver produce large responses in the ecosystem. Analysis of thresholds is complicated by nonlinear dynamics and by multiple factor controls that operate at diverse spatial and temporal scales. These complexities have challenged the use and utility of threshold concepts in environmental management despite great concern about preventing dramatic state changes in valued ecosystems, the need for determining critical pollutant loads and the ubiquity of other threshold-based environmental problems. In this paper we define the scope of the thresholds concept in ecological science and discuss methods for identifying and investigating thresholds using a variety of examples from terrestrial and aquatic environments, at ecosystem, landscape and regional scales. We end with a discussion of key research needs in this area.