1982-2018年中国植被覆盖变化非线性趋势及其格局分析

探究植被覆盖变化是评估陆地生态系统环境变化的重要手段,但现有研究多采用线性趋势来表达植被覆盖的变化情况而忽略了趋势的非线性。本文使用GLASS FVC数据,利用BFAST方法和格局分析,探讨了1982-2018年我国植被覆盖变化的非线性趋势及其分布格局。结果表明：（1）与线性趋势方法的对比发现,BFAST的检测结果揭示了四川盆地、黄土高原等地的植被覆盖显著增加趋势其实存在中断,青海和东北等地植被覆盖经历了由退化到改善的过程而并非简单的线性增加,而青藏高原中东部等地则由原先的改善趋势变为了退化趋势。（2）将非线性趋势结果进行分类,其中单调型增加类型占比最多,达到33.58%,主要分布在内蒙古、陕西及河南等地;单调型减少占比1.82%,主要分布在东南沿海地区;中断型增加占比22.91%,主要分布在四川盆地东部和华北地区;中断型减少占比2.68%,主要分布在青藏高原东南部;由增到减占比4.20%,主要分布在青海等地;由减到增占比14.62%,主要分布在吉林等地。大范围的植被覆盖增加趋势充分反映了我国过去几十年植被的改善,但同时存在的减少趋势表明潜在的植被退化风险仍不可忽视。（3）不同趋势类型发生改变的时间有所差异,总体上1988-1999年间发生的改变较少,而2000-2011年间发生的改变较多,我国21世纪以来实施的大规模生态保护和恢复工程对植被的改善过程有重要影响。（4）分布格局上,植被覆盖改善趋势类型（单调型增加,中断型增加,由减到增）呈现大聚集,小分散的特点,具有复杂的形状;退化趋势类型（单调型减少,中断型减少,由增到减）的面积均较小,分布也相对离散。全国尺度上趋势空间格局呈现一定规律但分布的异质性较大,区域尺度上植被覆盖经受的干扰显著,变化过程实际也是较为复杂的。本研究表明,使用非线性趋势方法和格局分析,可以更准确地评估植被覆盖的时空变化,从而为生态环境相关工作的开展提供科学的参考。     

Responses of Epilithic Diatom Communities to Environmental Gradients in Some Finnish Rivers

Responses of the epilithic diatom communities to environmental gradients were analysed at 135 river stations in Finland. In addition, the biological quality of the water was evaluated using diatoms in five rivers having different types of human pressures. According to CCA, conductivity, total P, pH and humus content had the most significant effect on the diatom community structure. The ratio of the constrained axis (λ₁) and first unconstrained axis (λ₂) was highest for conductivity (1.21), total P (0.83) and pH (0.67). Physical factors had somewhat weaker effects. Five different diatom community types were separated in chemically different rivers using ordination. The effects of purified sewage on diatom‐inferred water quality estimates were strongest in late summer. The effects of cattle‐farming and cultivation were difficult to separate.     

塔里木河下游河岸带植被的空间结构特征

揭示我国内陆河流域下游河岸带植被的空间结构特征, 对于了解我国西北干旱区荒漠河岸带植被的空间分布规律、指导荒漠化治理和内陆河水资源管理具有重要意义。该研究基于野外大范围植被调查数据支持下的遥感监督分类方法, 利用Landsat-8 OLI遥感数字图像, 辨识了塔里木河下游柽柳(Tamarix spp.)灌丛、胡杨(Populus euphratica)疏林和芦苇(Phragmites australis)草地3类主要的河岸带植被, 并利用建立的叶面积指数(LAI)遥感反演经验模型反演了研究区柽柳灌丛和胡杨疏林的叶面积指数, 旨在从区域尺度和总体趋势上分析荒漠河岸带植被的空间结构和分布特征。结果表明: 在有详细地物资料的基础上, 遥感监督分类可以作为一种干旱区荒漠河岸带植被分类的有效方法; 遥感分类结果显示塔里木河下游胡杨疏林分布面积约336.4 km², 柽柳灌丛约为405.3 km², 胡杨疏林总体更靠近河道, 柽柳灌丛分布范围更广; 河岸带植被LAI整体很低, 柽柳灌丛和胡杨疏林平均LAI值分别为0.253和0.252, LAI小于0.5的植被对应面积分别占柽柳灌丛和胡杨疏林总面积的92.4%和90.1%, 表明了塔里木河下游荒漠河岸植被空间上稀疏分布的特征; 统计结果显示, 河岸带植被结构存在巨大的空间变异性, 其中胡杨疏林比柽柳灌丛的空间变异性更大; 河岸带植被LAI随距河道距离呈现显著负指数分布规律, 在离河道1 km范围内LAI随离河道距离快速下降, 而1 km外区域叶面积指数普遍低于0.1, 表明植被主要分布在河道两侧1 km范围内。整体稀疏的空间分布、显著的空间变异性, 以及由LAI体现的植被盖度随距河道距离的负指数下降规律是荒漠河岸带植被空间结构的3个基本特征。     

北京八达岭地区灌木群落空间分布格局与土壤环境因子的关系分析

于2007年8月,在北京八达岭地区野外实地踏查的基础上,按海拔梯度每升高100 m布设10个典型灌木样地,共40个样地,分别进行灌木群落调查.采用TWINSPAN方法、依据各样地灌木各物种的重要值对研究区灌木群落进行分类,采用DCCA方法对分类结果进行验证,并选取代表地形因素和土壤因素在内的环境因子共16个指标进行相关分析.结果显示:(1)北京八达岭地区灌木群落共划分为10个类型.(2)北京八达岭地区灌木群落与各环境因子之间有较好的独立性,土壤环境因素对灌木空间分布格局影响较大(特征值为0.90);土壤环境因素中,灌木群落格局与土壤容重因子具有极显著的相关性(P＜0.01).(3)土壤环境因子对灌木群落格局变异的解释能力达到36%;而单纯由地形环境因子的解释能力只有9%,二者交互解释能力为3%,说明土壤环境因素是影响北京八达岭地区灌木群落格局的主导因素. 研究结果表明,北京八达岭地区灌木群落分布格局与土壤容重和海拔因子间存在极显著相关性.     

Ecogeographical rules: elements of a synthesis

The development of a more synthetic approach to understanding spatial patterns in biogeography, particularly of the way in which these patterns interact, constitutes a major challenge for the field. Here we propose some key elements of such a synthesis for what can broadly be termed 'ecogeographical rules', that is spatial patterns in biological traits. These include understanding: (1) the different kinds of patterns (intraspecific, interspecific and assemblage), and the distinctions between them; (2) the unifying role that geographical ranges play in linking the patterns together; (3) that this unification can be obscured by the methodological assumptions made in documenting some patterns (e.g. assuming that intraspecific variation does not significantly influence interspecific and assemblage patterns in traits); (4) the implications of other methodological issues for the nature of observed patterns (e.g. how ranges are located on positional or environmental axes for interspecific patterns); (5) the need for further development of models linking different types of traits; (6) the nature of the generality of documented patterns at all levels, and particularly the difference between the frequency with which patterns are documented in the literature and the variety of extant species; and (7) the constraints that the form of intraspecific patterns place on interspecific and assemblage patterns, and that interspecific patterns place on assemblage patterns.     

异质景观年平均蒸发量空间格局模拟

理解景观格局如何影响生态过程是景观生态学的核心问题。建立了一个多尺度的空间显式景观过程模型 EPPML(Ecosystem Productivity Process- based Model at L andscape Scale) ,对中国东北长白山自然保护区生态系统碳 -水循环变量和生产力的时空格局进行了模拟 ,其中年平均蒸发量和蒸散量的空间格局是模型的主要输出结果之一。模拟值与实测值的数量级一致 ,这表明 EPPML 可以比较合理而准确地模拟该保护区主要生态系统的年平均蒸发量和蒸散量 ,但仍需进一步的模型验证和不确定性分析。年平均蒸发量的模拟值平均为 0 .198± 0 .0 93m / a,空间格局随海拔变化的趋势不明显 ,其中最高为云冷杉林(0 .2 76± 0 .0 81m/ a) ,最低为阔叶林 (0 .0 94± 0 .0 30 m / a)。环境因子 (气象因子和土壤含水量 )和植被因子 (植被类型和叶面积指数 L AI)等景观要素在空间格局上的变化会直接或间接地影响蒸发过程 ,进而调控整个景观的水平衡。环境因子对蒸发的影响比对蒸腾的影响要复杂得多。相对湿度对蒸发的影响最大 (R=0 .4 0 ) ,其它依次为气温、总辐射、降水量、风速和土壤含水量。年平均蒸发量与 L AI负相关 (R=- 0 .39) ,但两者并不呈简单的反比关系 :当 L AI较小时 ,蒸发量随 L AI的增加迅速地降低 ;当L AI进一步     

The Importance of Spatial Effects for Environmental Health Policy and Research

Issues of spatial scale and resolution are intrinsic to efforts aimed at protecting and improving environmental health. Deciding on an appropriate policy or selecting a suitable research design implies a decision, either implicit or explicit, about spatial scale and resolution. This article looks at issues in the context of environmental health, reviews crucial problems and questions, and examines examples of spatial effects on analytical results related to causal inference, disease clustering, and analysis and interpretation of census data. The discussion focuses on the need to consider spatial issues as a key component of informed, well- reasoned decisions about safeguarding environmental health.     

Environmental and historical imprints on beta diversity: insights from variation in rates of species turnover along gradients

A common approach for analysing geographical variation in biodiversity involves using linear models to determine the rate at which species similarity declines with geographical or environmental distance and comparing this rate among regions, taxa or communities. Implicit in this approach are weakly justified assumptions that the rate of species turnover remains constant along gradients and that this rate can therefore serve as a means to compare ecological systems. We use generalized dissimilarity modelling, a novel method that accommodates variation in rates of species turnover along gradients and between different gradients, to compare environmental and spatial controls on the floras of two regions with contrasting evolutionary and climatic histories: southwest Australia and northern Europe. We find stronger signals of climate history in the northern European flora and demonstrate that variation in rates of species turnover is persistent across regions, taxa and different gradients. Such variation may represent an important but often overlooked component of biodiversity that complicates comparisons of distance–decay relationships and underscores the importance of using methods that accommodate the curvilinear relationships expected when modelling beta diversity. Determining how rates of species turnover vary along and between gradients is relevant to understanding the sensitivity of ecological systems to environmental change.     

Genetic structure and colonization processes in European populations of the common vole, Microtus arvalis

The level of genetic differentiation within and between evolutionary lineages of the common vole (Microtus arvalis) in Europe was examined by analyzing mitochondrial sequences from the control region (mtDNA) and 12 nuclear microsatellite loci (nucDNA) for 338 voles from 18 populations. The distribution of evolutionary lineages and the affinity of populations to lineages were determined with additional sequence data from the mitochondrial cytochrome b gene. Our analyses demonstrated very high levels of differentiation between populations (overall FST: mtDNA 70%; nucDNA 17%). The affinity of populations to evolutionary lineages was strongly reflected in mtDNA but not in nucDNA variation. Patterns of genetic structure for both markers visualized in synthetic genetic maps suggest a postglacial range expansion of the species into the Alps, as well as a potentially more ancient colonization from the northeast to the southwest of Europe. This expansion is supported by estimates for the divergence times between evolutionary lineages and within the western European lineage, which predate the last glacial maximum (LGM). Furthermore, all measures of genetic diversity within populations increased significantly with longitude and showed a trend toward increase with latitude. We conclude that the detected patterns are difficult to explain only by range expansions from separate LGM refugia close to the Mediterranean. This suggests that some M. arvalis populations persisted during the LGM in suitable habitat further north and that the gradients in genetic diversity may represent traces of a more ancient colonization of Europe by the species.     

合成生物学技术在环境保护中的应用

合成生物学是一个基于生物学和工程学原理的科学领域,其目的是重新设计和重组微生物,以优化或创建具有增强功能的新生物系统。该领域利用分子工具、系统生物学和遗传框架的重编程,从而构建合成途径以获得具有替代功能的微生物。传统上,合成生物学方法通常旨在开发具有成本效益的微生物细胞工厂进而从可再生资源中生产化学物质。然而,近年来合成生物学技术开始在环境保护中发挥着更直接的作用。本综述介绍了基因工程中的合成生物学工具,讨论了基于基因工程的微生物修复策略,强调了合成生物学技术可以通过响应特定污染物进行生物修复来保护环境。其中,规律间隔成簇短回文重复序列(Clustered Regularly Interspersed Short Palindromic Repeats, CRISPR)技术在基因工程细菌和古细菌的生物修复中得到了广泛应用,生物修复领域也出现了很多新的先进技术,包括生物膜工程、人工微生物群落的构建、基因驱动、酶和蛋白质工程等。有了这些新的技术和工具,生物修复将成为当今最好和最有效的污染物去除方式之一。     

Altitudinal changes in composition and structure of mountain-temperate vegetation: a case study from the Western Carpathians

Changes in composition and structure of plant communities in relation tothe soil and snow cover variation were analyzed along an altitudinal transect(1150–1750 m) from the mountain-temperate forests to a woodyshrub community and alpine meadows on Mt Velký Gápel', Slovakia.The soils below the treeline (1510 m) had a more developedorganic layer above the mineral substratum. Generally, soil depth decreased asthe altitude increased, although the maximum values were recognized at a middlealtitude in a beech stand. Snow was redistributed by westerly winds from theridgeline down to the upper forest margin. Mean snow depth decreased withaltitude up to almost snow-free sites around the summit. In the 48 plots at 16sites we recorded 118 taxa including 6 tree, 7 shrub, 18 grass, 42 herb, 5fern,25 moss and 15 lichen species. The species diversity showed no distinctrelationship to altitude but declined with canopy consolidation. The TWINSPANfloristic classification distinguished five groups of community typescharacterised by different dominants, and a further three clusters of samplesfrom transition zones. Horizontal compositional heterogeneity increased inareaswhere trees were aggregated and tree basal area was smaller. Vegetationcomposition became more patchy at open-canopy Acerpseudoplatanus–Abies alba mixed forest at 1150 m,in Picea abies forest limit 1470 m, andin Pinus mugo krummholz at 1590 m. Speciesturnover of the entire transect was 6.1 half-changes as estimated by DCA.Despite this heterogeneity, none of the 15 elevational bands had significantaggregation of species' limits. Vegetation varied continuously, with individualspecies overlapping in transition zones delimited by dominant taxa. Thecoincident aggregation of up-slope and down-slope boundaries was found at abelt1430–1510 m. This discrete ecotone corresponds to a shiftfrom the closed coniferous forest to P. mugo krummholz.Thesecond inherent up-slope boundary aggregation indicated the P.mugo krummholz – alpine meadow vegetation transition at1700 m. Spatial analysis (K-function) of eight forest plots(0.12 ha each) showed that at lower elevation, adult trees of thebroad-leaf forest were closer to a random arrangement while at higherelevation,trees of evergreen coniferous stands became aggregated toward the forest limitwith the highest intensity from 2 to 4 m. Altitudinal gradient andrelated factors explained 35% of the variance in vegetation data.Canonical correspondence analysis also showed that main vegetation changesabovethe treeline area were associated with the topographic pattern of pine shrubsand snow cover.     

Determinants of bird species richness: role of climate and vegetation structure at a regional scale

We examined the respective roles of climate and vegetation structure on geographical variation in bird species richness. The Province of Buenos Aires (central-eastern Argentina) was divided into 146 squares of 50 km on a side. For each square we evaluated the number of bird species, the value of thirteen climatic variables, and the value of a vegetation strata index. The climatic matrix was analyzed by Principal Component Analysis (PCA), and the first factors resulting from PCA were considered as multifactorial climatic gradients. Simple and Partial Correlation Analysis among bird species richness, vegetation strata, and the first two factors derived from PCA (65% of total variation) indicated that bird richness distribution was determined by the availability of vegetation strata, associated with different vegetation types that, at the same time, were influenced by the climatic conditions summarized in the first climatic factor (a gradient of precipitation, relative humidity, annual termical amplitude, and frost occurrence). This relationships reflect the complexity of factors that can act directly as well as indirectly on the geographical patterns in species richness. Also, we evaluated the importance of study scale comparing our results with previous studies at macrogeographic and local scales, found out that the vegetation structure was the principal determinant of bird species richness at this three geographical scales.     

Revisiting Patterns of Tree Species Composition and their Driving Forces in the Atlantic Forests of Southeastern Brazil

The elucidation of phytogeographic patterns and their drivers in biodiversity hotspots is essential to the study of ecology and the conservation of these areas. In 2000, an important study by Oliveira‐Filho and Fontes led to changes in the paradigms that define our understanding of the Atlantic Forest (Brazil). Here, our aim was to revisit this study using a more comprehensive set of environmental predictors, an updated and much larger tree species dataset and checklist, and more refined data analyses. We performed exploratory and confirmatory analyses, including the modeling of the spatial components with Moran's Eigenvector Maps, using data from 483 sites in southeastern Brazil, which encompass a total of 3546 species and 33 geo‐climatic variables. We observed strong floristic similarities between rain‐ and seasonal forests and a species distribution continuum across the main gradients. The environmental and spatial variables were significantly correlated with floristic patterns, and we demonstrated that the tree flora of the seasonal forests should no longer be considered a simple subset of the rain forest flora. The findings of the original paper were not only confirmed but we also unveiled additional, important phytogeographic patterns. We also reinforced the main conclusion of the paper that the Atlantic Forest concept must encompass all of the forest types east of the dry corridor in South America, a designation of utmost importance for the conservation of this biodiversity hotspot.     

Analysing spatial patterns of spread of Lettuce necrotic yellows virus and lettuce big-vein disease in lettuce field plantings

Spatial patterns of spread of lettuce big‐vein disease (LBVD) and Lettuce necrotic yellows virus (LNYV) were examined in two plantings each consisting of two blocks of lettuce. LBVD came from planting land infested with viruliferous Olpidium brassicae resting spores, while LNYV was introduced by aphid vectors from external sources consisting of LNYV‐infected sowthistle (Sonchus oleraceus) weeds. Clustering of LBVD was obvious in an area where the soil was heavily infested with only sporadic occurrence elsewhere. There was a steep decline in LNYV incidence over distance from a concentrated external weed source, with clustering of LNYV‐infected plants at the crop edge closest to it. There was no evidence of secondary spread with LBVD or LNYV.     

中国城市空间形态的环境效应

中国城市需要更为紧凑的空间形态,但是城市空间紧凑性的环境效应并不十分清晰。采集城市管网设施指标、城市道路、交通设施指标、生态协同指标等建立环境因子指标集,选择标准化紧凑度指数NCI、标准化离散度指数NDIS、最大斑块面积指数LPI、景观形状指数LSI、平均形状指数SHAPE_MEAN、周长-面积分形维数PAFRAC等形态指标,运用统计分析的方法探索中国146座城市的空间形态的单因子环境效应、综合环境效应及环境效应的差异性。研究结果表明:(1)人均城市道路面积、供水管密度、排水管密度、万人拥有公交车辆、万人拥有出租车辆、人均公园绿地面积等环境因子与城市空间形态密切相关。城市紧凑度越高,城市管网系统密度越低,公共交通设施越少,人均公园绿地面积越少。城市形状越复杂,城市管网系统密度越高,公共交通投入越大,人均公园绿地面积越大。(2)综合环境因子与LSI呈中等强度的正相关(r=0.43,P0.01)。城市空间形状越复杂,城市资源环境相关设施总体投入越多。(3)在不同的紧凑及形状复杂性水平下,万人拥有公交车辆、万人拥有出租车辆、供水管道密度及综合环境因子的显著性差异再次表明城市越紧凑,交通越发达;城市形状越复杂,环境投入越多。本文研究证明了城市空间形态越紧凑、资源越是节约,紧凑型城市空间形态能够用于中国城市建设。     

Evolutionary mechanisms shaping the genetic population structure of marine fishes; lessons from the European flounder (Platichthys flesus L.)

A number of evolutionary mechanisms have been suggested for generating low but significant genetic structuring among marine fish populations. We used nine microsatellite loci and recently developed methods in landscape genetics and coalescence-based estimation of historical gene flow and effective population sizes to assess temporal and spatial dynamics of the population structure in European flounder (Platichthys flesus L.). We collected 1062 flounders from 13 localities in the northeast Atlantic and Baltic Seas and found temporally stable and highly significant genetic differentiation among samples covering a large part of the species' range (global F(ST) = 0.024, P < 0.0001). In addition to historical processes, a number of contemporary acting evolutionary mechanisms were associated with genetic structuring. Physical forces, such as oceanographic and bathymetric barriers, were most likely related with the extreme isolation of the island population at the Faroe Islands. A sharp genetic break was associated with a change in life history from pelagic to benthic spawners in the Baltic Sea. Partial Mantel tests showed that geographical distance per se was not related with genetic structuring among Atlantic and western Baltic Sea samples. Alternative factors, such as dispersal potential and/or environmental gradients, could be important for generating genetic divergence in this region. The results show that the magnitude and scale of structuring generated by a specific mechanism depend critically on its interplay with other evolutionary mechanisms, highlighting the importance of investigating species with wide geographical and ecological distributions to increase our understanding of evolution in the marine environment.     

Scale-related patterns in the spatial and environmental components of stream macroinvertebrate assemblage variation

Aim We examined the relative contributions of spatial gradients and local environmental conditions to macroinvertebrate assemblages of boreal headwater streams at three hierarchical extents: bioregion, ecoregion and drainage system. We also aimed to identify the environmental variables most strongly related to assemblage structure at each study scale, and to assess how the importance of these variables is related to regional context and spatial structuring at different scales. Location Northern Finland ( 62 – 68° N, 25–32° E). Methods Variation in macroinvertebrate data was partitioned using partial canonical correspondence analysis into components explained by spatial variables (nine terms from the cubic trend surface regression), local environmental variables (15 variables) and spatially structured environmental variation. Results The strength of the relationship between assemblage structure and local environmental variables increased with decreasing spatial extent, whereas assemblage variation related to spatial variables and spatially structured environmental variation showed the opposite pattern. At the largest extents, spatial variation was related to latitudinal gradients, whereas spatial autocorrelation among neighbouring streams was the likely mechanism creating spatial structure within drainage systems. Only stream size and water acidity were consistently important in explaining assemblage structure at all study scales, while the importance of other environmental variables was more context‐dependent. Main conclusions The importance of local environmental factors in explaining macroinvertebrate assemblage structure increases with decreasing spatial extent. This scale‐related pattern is not caused solely by changes in study extent, however, but also by variable sample sizes at different regional extents. The importance of environmental gradients is context‐dependent and few factors are likely to be universally important correlates of macroinvertebrate assemblage structure. Finally, our results suggest that bioassessment should give due attention to spatial structuring of stream assemblages, because important assemblage gradients may not only be related to local factors but also to biogeographical constraints and neighbourhood dispersal processes.