景观指数之间的相关分析

应用辽宁省1997~1998年的TM 5影像数据,编制了景观类型图,以78个县市区为单位,分割成78个景观,共计算39个景观格局指数,对它们进行了相关分析。总面积是最基本的景观指数,它决定景观总边界长度、斑块数、类型密度等基本指数,同时与多个指数有显著的相关关系(相关系数绝对值大于0.75)。形状指数的独立性强,极少数指数与其它指数有显著的相关关系;多样性指数和蔓延度指数之间信息重复量最多,都表示景观的异质性,但多样性指数以面积百分比表示景观异质性,而蔓延度指数以类型之间相邻边界的百分比表示景观异质性。研究发现,如果两个指数之间存在显著的相关关系,而由它们两个构成的指数与它们之间没有显著的相关关系。如果指数平均值之间存在显著的相关关系,则它们的变异系数之间不存在显著的相关关系。景观指数间的相关系数不仅与景观格局本身有关,还与空间尺度,分类系统、计算公式及其参数、计算单元和生态学意义关系密切。指数之间影响因子的相同之处越多,它们之间存在显著相关关系的概率越大。     

Relationships between landscape patterns and species richness of trees,shrubs and vines in a tropical forest

The present study aims to identify and characterize the relationships among landscape structure and plant diversity in a tropical landscape forest in Quintana Roo, Mexico. Total species richness as well as that of trees, shrubs and vines species were identified from 141 sampling quadrats (16,543 individuals sampled). Based on vegetation classes obtained from multi-spectral satellite image classification, I constructed plant diversity maps of the landscape under study using stratified kriging. I calculated the mean number of species in individual patches as the average values of kriging estimates inside of each patch. I then explored the relationships between landscape pattern metrics and the species richness of trees, shrubs and vines, as well as all groups combined using regression analysis. I employed Akaike Information Criterion (AIC) to select a set of candidate models. Based on akaike weights, I calculated model-averaged parameters. Results show that plant diversity of the patches depends on both the quality of the surrounding habitats and the proximity of surrounding patches (i.e., patch isolation).     

Correlations between forest stand diversity and landscape pattern in Otepää Nature Park, Estonia

Rank correlations between tree species diversity in forest stands and parameters of landscape pattern were calculated using data from 4933 locations in Otepää Nature Park. Stand diversity was characterised by the number of tree species in the stand formula and by the index of dominance of tree species’ coverage. Landscape diversity was characterised by locally calculated pattern parameters from three categorical map layers (1:10 000 base map, 1:10 000 soil map, combination of these maps) and from six numerical variables (elevation, slope angle, four channels of a Landsat 7 ETM image).A weak trend appeared for more diverse forest stands to be located in more diverse landscapes according to the base map. Forest stand diversity is also higher on steeper slopes and in places surrounded by slopes of varying steepness. The correlation between landscape diversity and biodiversity depends on the radius of the kernel in which landscape characteristics are calculated. Evidence of an indicative neighbourhood could be seen in many spatial relationships. The spatial correlation between stand diversity and indices calculated from the base map was most visible at distances ranging from 400 to 500 m; surface elevation and its variation correlates with stand diversity at distances of 100–200 m. Some relationships between forest diversity and landscape diversity that had a different sign of correlation in proximate and distant kernels can be interpreted as a need to standardise local landscape indices with the index values in a wider neighbourhood as a reference.     

浑善达克沙地中部斑块格局影响植物多样性及功能性状

景观格局与植物多样性之间的关系已被广泛研究,然而,斑块格局如何影响植物多样性,以及这些影响的边缘类型差异尚不清楚。为从植物功能性状角度揭示斑块格局影响植物多样性的机制,该研究采用不同边缘类型的斑块,利用两年调查的705个样方数据,结合遥感卫星图像解译和空间信息分析,根据植物群落的空间位置和斑块格局,按照向内、向外、向内成核和向外成核4种边缘类型将浑善达克沙地中部的斑块进行分类,采用Duncan新复极差法比较了4种边缘类型斑块格局与植物功能性状多样性关系的差异,应用Pearson相关系数和冗余分析(RDA)法量化了斑块格局对植物多样性的影响。结果发现,植物丰富度和多样性指数与斑块格局密切相关,这些关系存在着边缘类型的显著差异,表现出不同的功能性状。对于向内边缘,边缘指数与丰富度负相关,和C₄植物比例正相关;对于向外边缘,边缘指数与C₄植物比例正相关;对于向内成核边缘,边缘密度与多年生植物和虫媒植物比例正相关;对于向外成核边缘,边缘角度和指数与物种Shannon-Wiener指数和Simpson指数正相关,与Pielou指数、丰富度和动物传播植物...     

景观指数耦合景观格局与土壤侵蚀的有效性

景观格局分析是景观生态学中揭示景观变化及其生态效应的主要方法,而景观指数是景观格局分析中广泛使用的工具。土壤侵蚀是土壤物质在景观中的迁移和再分配过程,受地形、植被和人类活动及其空间格局的调控。运用景观格局分析揭示景观格局变化特别是土地利用/覆被格局变化对土壤侵蚀的影响是土壤侵蚀研究中应用景观生态学原理和方法的典型。在当前的研究中,斑块-廊道-基质范式下建立的景观指数对侵蚀过程的解释能力不断受到质疑,建立筛选适用的景观指数的原则和方法十分必要。以延河流域碾庄沟小流域为例,利用WATEM/SEDEM模型模拟多个年份流域侵蚀产沙和输沙量;基于土地利用/覆被数据,利用Fragstat4.2软件,计算了相应年份流域斑块、边界密度、形状、集聚与分散和斑块类型多样性4个方面的代表性景观指数。在此基础上,分析了景观指数与流域侵蚀产沙和输沙之间的关系,讨论了景观指数在土壤侵蚀研究中的有效性,在景观和斑块类型水平上分析了景观指数表达"源"、"汇"两大类景观类型的空间格局与侵蚀产沙和输沙之间的关系的一致性。结果表明:斑块-廊道-基底范式下发展的景观指数在指示景观格局的土壤侵蚀效应时存在局限。相对而言,斑块类型尺度的景观指数更能有效表达景观格局与土壤侵蚀的关系。基于景观类型在土壤侵蚀过程中的"源"、"汇"功能,提出了在土壤侵蚀研究中筛选适用的景观指数的原则:(1)对"源"、"汇"两类景观类型,景观指数与土壤侵蚀状况表征变量的相关系数符号相反;(2)对同为"源"或"汇"景观类型的多个景观类型,景观指数与土壤侵蚀表征变量的相关系数应具有符号一致性。尽管景观指数在斑块类型水平上具有一定的有效性,但用其预测景观格局变化的侵蚀效应有很大的不确定性。因此,基于土壤侵蚀过程与景观格局的作用机制发展新型的景观指数是增强景观格局分析预测土壤侵蚀过程的能力的途径。     

北京东灵山地区景观格局及破碎化评价

 人类活动已将北京东灵山地区地带性原生暖温带落叶阔叶林破坏殆尽。本项研究基于植被图,在地理信息系统(GIS)支持下,选择多种景观格局指数,从斑块面积、斑块数、斑块周长、分形维数和多样性的角度进行了格局分析和破碎化评价。结果表明,该区景观类型以次生林和灌丛为主,面积分布极不均衡,且多呈小面积零散分布。各森林类型的分布面积、周长和斑块数一般小于灌丛、草地和农田,且边界密度和斑块密度较高,显示出较高程度的破碎化。各景观类型的平均斑块面积和周长遵从分形规律,分形维数1.30,景观整体的斑块边界的褶皱程度较低。景观多样性的Shannon指数,景观组分的类型面积(2.262)<类型周长(2.435)<类型斑块数(2.675),均小于等概率情形(2.940)。上述结果均显示,该区森林景观破碎化程度较高。     

Entropy increase of fragmented habitats: A sign of human impact?

Analysis of a recently validated fragmentation index, named ‘coherence’, shows a direct relationship with the Simpson and Shannon indices. Since these diversity metrics are also denoted as ‘entropy metrics’, it can be accepted that patch size heterogeneity can adequately be described by an entropy metric. Since both indices are used to determine the entropy of a sample, the Brillouin index should be applied instead to correctly determine the entropy of a landscape pattern, this because this latter index is developed for fully censused data sets, such as landscapes when a complete coverage by cartographic data or imagery is available. Calculation of the Brillouin entropy index for three specific sites located in Cadiz Township (USA), the Poole Basin (Dorset, UK) and Sao Paulo State (Brazil), respectively, and using long-term data of patch size diversity, reveals increasing entropy levels associated with anthropogenic land cover dynamics (fragmentation). The observed entropy trends defy the laws of thermodynamics and signal the impact of human action on landscape integrity.     

Classification of vegetational diversity in managed boreal forests in eastern Finland

Diversity of vegetation in managed forests is studied. A classification based on forest stand structure, the abundances of vegetation species and variations in these abundances is developed and diversity indices are calculated for the classes to describe the diversity of the vegetation within the classes. The classes were formed using detrended correspondence analysis (DCA), global nonmetric multidimensional scaling (GNMDS) and TWINSPAN classification. Discriminant analysis was used to determine the environmental variables differentiating between the classes, and Duncan's multiple range test was used to examine the ability of the diversity measures to distinguish the classes. Beta diversity was estimated with Økland's method based on DCA ordination of the sample plots. The results point to fertility and the successional stage of the stand as the main factors affecting species diversity, in addition to which soil type, the number of tree species, crown cover, basal area and certain variables describing the management of the stand were relevant to the classification. The most distinct diversity indices were the reciprocal of Simpson, Pielou's J' and species richness, while the highest alpha diversity was found in young stands with a low crown cover on herb-rich or mesic forest sites. Beta diversity was quite high, its highest values of all for the whole data being recorded along the fertility gradient.     

景观格局指数间相关关系对植被覆盖度等级分类数的响应

运用景观指数进行景观格局分析已成为景观生态学的主要研究方法。但是,由于景观本身的复杂性以及景观格局指数之间的相关性,其应用与发展受到制约。选用面积/周长/密度、形状和蔓延度等3类共28个指数,以广州市中心城区为研究区域,以TM遥感影像为数据源形成植被覆盖度等级图,在景观类型水平上探讨各类型内指数之间的相关性及其对景观分类数的敏感程度。相关性分析表明:景观格局指数间都存在一定的相关性,但是相关程度差异较大,其中面积/周长/密度类指数间的相关性最强,蔓延度类指数其次,形状类指数间独立性相对较强。敏感性分析结果显示:117个指数对的相关关系都随景观分类数发生变化,根据其变化类型和程度,可以分为简单型、分段型、复杂型等3种指数关系响应的类型,分别包括12、31和74对指数;敏感曲线还表明4或5是指数对之间相关关系最敏感的分类数;不仅如此,分类数对景观格局指数之间相关关系的影响程度因景观格局指数所属的类别而异,面积/周长/密度类型指数不敏感,其次是蔓延度类指数,最敏感的是形状类指数;最后,研究结果表明景观格局指数间的相关性对分类数的敏感性存在较大的空间变异。     

辽东山区次生林物种多样性的空间分布及尺度效应

以辽东山区次生林为研究对象,分析4 hm²样地Gleason丰富度指数、Simpson优势度指数、Shannon多样性指数和Pielou均匀度指数的空间分布特征及其与尺度的关系.结果表明: 4个多样性指数的空间分布均表现出较高的空间异质性;4个多样性指数的方差随尺度的增加其变化趋势有所差异;4个多样性指数的变异系数随尺度的增加呈下降趋势;乔木层的4个多样性指数值高于灌木层,且随尺度增加其变化趋势有所差异.在分析辽东山区次生林物种多样性时应考虑尺度效应.     

荒漠景观破碎化条件下啮齿动物群落beta 多样性变化特征

2002 ～2010 年,采用夹日法对内蒙古阿拉善荒漠区禁牧、轮牧、过牧和开垦4 种不同人为干扰生境中啮齿动物群落β 多样性进行了研究,同时分析不同生境的灌木植物群落特征来探讨人为干扰下的景观破碎化。依据人为干扰下景观破碎的情况将研究区域内生境梯度的变化按照:禁牧到轮牧、轮牧到过牧、过牧到开垦、禁牧到过牧、禁牧到开垦、轮牧到开垦进行划分,分别利用Jaccard 指数、Sorenson 指数和Cody 指数分析景观破碎化条件下啮齿动物群落β 多样性变化特征。结果表明,不同生境梯度间3 种β 多样性指数差异均显著(P <0. 05),禁牧到过牧梯度β 多样性差异最大。不同干扰生境间的灌木植物群落特征差异极显著(P < 0. 01),Shannon-Wiener 指数、Simpson 指数和物种数均表现为轮牧区> 过牧区> 禁牧区> 开垦区。环境变化程度与β 多样性变化的程度一致。人为干扰是该区域景观破碎化的主要原因,特别是放牧活动,导致环境异质性显著增加。在荒漠区,这种随环境梯度造成异质性加大而增加的β 多样性,并不是由物种增加较大导致,而是由啮齿动物群落物种组成差异和变化增大所致.     

Predictors of mammal species richness in KwaZulu-Natal,South Africa

The management of multi-functional landscapes warrants better knowledge of environment-richness associations at varying disturbance levels and habitat gradients. Intensive land-use patterns for agricultural purposes lead to fragmentation of natural habitat resulting in biodiversity loss that can be measured using landscape metrics to assess mammalian richness. Since carnivores and herbivores are likely to show different responses to disturbance, we calculated carnivore, non-carnivore, and total mammal species richness from camera surveys using a first order Jackknife Estimator. Richness was compared along a habitat gradient comprising coastal forest, Acacia thicket, and highland in KwaZulu-Natal, South Africa. We used standardized OLS regression models to identify climatic and disturbance variables, and landscape metrics as predictors of species richness. The estimated total and non-carnivore species richness were highest in coastal forest, while carnivore species richness was highest in highland followed by coastal forest and Acacia thicket. Average monthly maximum temperature was a significant predictor of all richness groups, and precipitation of the wettest month and isothermality determined total and non-carnivore species richness, respectively. These climatic variables possibly limit species distribution because of physiological tolerance of the species. Total mammal richness was determined by mean shape (+) and habitat division (−) while diversity (+) and patch richness (−) explained carnivore species richness. Mean shape index (+) influenced non-carnivore richness. However, habitat division and patch richness negatively influenced total mammal richness. Though habitat patch size and contiguity had a weak positive prediction, these metrics demonstrated the importance of habitat connectivity for maintaining mammal richness. The identification of these climatic and landscape patterns is important to facilitate future landscape management for mammal conservation in forest-mosaics.     

Scale dependence of landscape metrics and their indicatory value for nutrient and organic matter losses from catchments

We investigated scale dependence of landscape metrics and the relationship between land use parameters and FRAGSTATS-based landscape metrics (edge density (ED), patch density (PD), mean shape index (SHAPE_MN), mean euclidean nearest neighbor index (ENN_MN), contagion (CONTAG), patch richness density (PRD), and Shannon's diversity index (SHDI)) and nutrient/organic-matter-based water quality indicators (BOD₇ and COD_KMnO4 values, total-N and total-P concentrations in water) in 24 catchments with various land use patterns in Estonia. We used the Basic Map of Estonia (1:10,000), the Base Map of Estonia (1:50,000) and the CORINE Land Cover Map (1:100,000). In scale analysis, we calculated landscape metrics on artificial and real landscapes. Scale analysis showed that responses of landscape metrics to changing grain size vary among landscapes and metrics. Analysis of artificial landscapes showed that mean euclidean nearest neighbor distance and contagion are directly dependent on grain size and should therefore be used carefully. When finding relationships between landscape metrics and water quality indicators, significant differences between the relationships derived from the Base Map and the CORINE Land Cover Map were found. In the case of the Base Map, landscape metrics correlated strongly with land use and showed no expected relationships with water quality data. This underlines the importance of land use classification in such kind of analysis. Correlation between the landscape metrics calculated on the basis of the CORINE Land Cover Map and water quality data was stronger than in the case of the Base Map. The COD_KMnO4 value significantly correlated with all land use types. For instance, the COD_KMnO4 values are higher when fens and natural areas form a higher proportion of the catchments’ land use. Except for the BOD₇ value, all the water quality indicators showed significant correlation with urban land use proportions. Strong relationship between the patch density and the COD_KMnO4 value is most likely caused by the fact that both parameters were significantly correlated with the proportion of natural areas. As the landscape metrics depend on pixel size, topographic scale, and land use classification, and as the effect of land use on water quality in catchments is the most significant of the factors, it was impossible to separate the influence of land use pattern from the influence of FRAGSTATS-based landscape metrics.     

高寒草地植物物种多样性与功能多样性的关系

物种多样性与功能多样性的关系是生态学当前研究的热点问题之一,不同区域典型生态系统物种多样性和功能多样性的关系研究有利于生物多样性保护理论的全面发展。以青藏高原地区的主要草地生态系统—高寒草甸和高寒草原为研究对象,采用4个物种多样性指数(Patrick丰富度指数、Shannon-Weiner多样性指数、Pielou均匀度指数和Simpson优势度指数)和9个功能多样性指数(FAD功能性状距离指数、MFAD功能性状平均距离指数、基于样地的FDp和基于群落的FDc功能树状图指数、FRic功能体积指数、FEve功能均匀度指数、Rao功能离散度常二次熵指数、FDiv功能离散指数、FDis功能分散指数),分析了高寒草地植物物种多样性、功能多样性关系及其与初级生产力的关系,以期阐明3个科学问题:不同草地类型的高寒草地生态系统植物物种多样性和功能多样性有何差异?高寒草地生态系统的植物物种多样性和功能多样性有何关系?高寒草地生态系统物种多样性、功能多样性对生态系统功能的影响有何异同?研究结果表明:(1)与高寒草原相比,高寒草甸具有更高的物种多样性、功能丰富度和功能离散度;(2)高寒草甸中,Patrick丰富度与功能丰富度指数(FAD、MFAD、FDp、FDc)和功能离散度指数(FDiv)的具有较强的相关性,最优拟合方程分别为幂函数和二次多项式函数;(3)高寒草原中,Patrick丰富度与功能丰富度指数(FAD、MFAD、FDp、FDc、FRic)、Shannon指数和Simpson指数与FEve指数的相关性较强,最优拟合方程为二次多项式函数,Pielou指数与FEve指数的相关性较强,最优拟合方程为指数函数;(4)高寒草甸的初级生产力分别与物种丰富度指数Patrick、功能离散指数FDiv具有较强的相关性;而高寒草原的初级生产力与4个物种多样性指数间均具有较强的相关性,与功能离散指数FDiv具有较强的相关性,最佳拟合方程均为二次多项式函数。研究的总体结论为:物种多样性、功能多样性、二者之间的关系以及二者与生态系统服务功能(以初级生产力为例)之间的关系在高寒草甸和高寒草原群落中表现迥异,因此在研究青藏高原高寒草地的生态功能时,不能仅仅测度传统的物种多样性,还应测度与物种多样性、生态功能密切相关的功能多样性。     

Spatio‐temporal analysis of the relationship between landscape structure and the olive fruit fly Bactrocera oleae (Diptera: Tephritidae)

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不同干扰背景下景观指数与物种多样性的多尺度效应——以巩义市为例

以黄河中下游山地丘陵区的巩义市为研究区,采用典型样地法对灌草丛、人工林和农田边缘3种不同干扰背景下的自然、半自然生境内的植物进行调查。基于景观生态学原理,在地理信息系统技术支持下,借助于Fragstatta3.3软件,以调查样地为中心,计算了150、250、500、750、1000、1250、1500m不同半径缓冲区内表征景观形状(Edge and patch shape)、边缘对照(Edge contrast)、相似度和邻近度(Proximity and similarity)、景观多样性(Diversity)、基质(Texture)、斑块大小和密度(Patch size and patch density)共6类52个指数,运用冗余分析(RDA)筛选出不同尺度下对该区农业景观中植物多样性有显著影响的景观指数。结果表明:不同尺度,景观指数对物种多样性的影响变化显著。灌草丛生境,在500—750m范围内,SHAPE_AM指数和PARA_AM指数能够很好的解释物种多样性,解释量为33.6%;人工林生境,SHAPE_AM指数、AREA_CV指数、SIMI指数和PAFRAC指数在1000—1250m范围内对物种多样性的解释量达到48.1%;农田边缘生境,GYRATE_CV指数、ENN_CV指数、PARA_MN指数和FRAC_AM指数在750—1250m范围内对物种多样性影响显著,解释量为32%。其中,辛普森多样性指数(SIDI)与灌草丛物种多样性在750—1250m范围内作用显著,ENN_CV指数仅对农田边缘物种多样性影响较大。景观指数对物种多样性的影响具有尺度依赖性,未来应全面综合探讨这些指数的尺度效应及在景观生态学中的应用。     

How does forest landscape structure explain tree species richness in a Mediterranean context?

Although the strong relationship between vegetation and climatic factors is widely accepted, other landscape composition and configuration characteristics could be significantly related with vegetation diversity patterns at different scales. Variation partitioning was conducted in order to analyse to what degree forest landscape structure, compared to other spatial and environmental factors, explained forest tree species richness in 278 UTM 10 × 10 km cells in the Mediterranean region of Catalonia (NE Spain). Tree species richness variation was decomposed through linear regression into three groups of explanatory variables: forest landscape (composition and configuration), environmental (topography and climate) and spatial variables. Additionally, the forest landscape characteristics which significantly contributed to explain richness variation were identified through a multiple regression model. About 60% of tree species richness variation was explained by the whole set of variables, while their joint effects explained nearly 28%. Forest landscape variables were those with a greater pure explanatory power for tree species richness (about 15% of total variation), much larger than the pure effect of environmental or spatial variables (about 2% each). Forest canopy cover, forest area and land cover diversity were the most significant composition variables in the regression model. Landscape configuration metrics had a minor effect on forest tree species richness, with the exception of some shape complexity indices, as indicators of land use intensity and edge effects. Our results highlight the importance of considering the forest landscape structure in order to understand the distribution of vegetation diversity in strongly human-modified regions like the Mediterranean.     

A conceptual guide to measuring species diversity

Three metrics of species diversity – species richness, the Shannon index and the Simpson index – are still widely used in ecology, despite decades of valid critiques leveled against them. Developing a robust diversity metric has been challenging because, unlike many variables ecologists measure, the diversity of a community often cannot be estimated in an unbiased way based on a random sample from that community. Over the past decade, ecologists have begun to incorporate two important tools for estimating diversity: coverage and Hill diversity. Coverage is a method for equalizing samples that is, on theoretical grounds, preferable to other commonly used methods such as equal-effort sampling, or rarefying datasets to equal sample size. Hill diversity comprises a spectrum of diversity metrics and is based on three key insights. First, species richness and variants of the Shannon and Simpson indices are all special cases of one general equation. Second, richness, Shannon and Simpson can be expressed on the same scale and in units of species. Third, there is no way to eliminate the effect of relative abundance from estimates of any of these diversity metrics, including species richness. Rather, a researcher must choose the relative sensitivity of the metric towards rare and common species, a concept which we describe as ‘leverage.' In this paper we explain coverage and Hill diversity, provide guidelines for how to use them together to measure species diversity, and demonstrate their use with examples from our own data. We show why researchers will obtain more robust results when they estimate the Hill diversity of equal-coverage samples, rather than using other methods such as equal-effort sampling or traditional sample rarefaction.     

内蒙古托克托地区景观格局特征分析

内蒙古托克拖地区位于我国农牧交错带黄河中游,农业历史悠久、应用遥感影像,结合地面调查,绘制了研究区植被类型现状图,在GIS支持下,选取多种景观指数,分别从斑块数、斑块面积、班块周长和多样性指数等方面对研究区景观结构特征和多样性进行分析,结果表明,整个研究区景观是一个显著的农林牧景观嵌体,农田面积281.72km^2,占研究区总面积的34.64%,林地景观占22.0%,草地景观占6.65%。研究区东北部景观基底为农田景观,在该基底上,基本上以居民点为中心较密集与规律地分布着杨树＋榆树林班块,共89块,斑块密度达2.568个·km^-2,斑块平均面积仅为0.39km^2,基底与斑块2种景观单元在该区域十分典型。杨树＋榆树林和丘陵沟壑景观类型边界密度值较大,说明杨树＋榆树林景观类型的破碎化程度较大,而丘陵沟壑边界切割破碎,可以认为,该地区在人类活动的影响下,景观结构呈现较明显的人类干扰特征。