面向21世纪城市绿化发展的思路与对策——以上海为例

本文以上海为例,探讨了生态平衡、生态位配置、互惠共生和物种多样性等生态学原理在绿地生态建设中的理论和实际应用意义,并从城市绿地指标确定、合理规划布局、丰富植物材料、城市自然公园建设及立体绿化等方面分析讨论了面向２１世纪我国城市绿化发展的思路与对策。     

湖北枝江市石子岭水库蓝藻水华研究

2009年8月21日对枝江市作为饮用水源的石子岭水库浮游植物和水体营养盐状况进行了调查.结果表明,该水库已经发生了微囊藻水华;浮游植物群落结构定量分析和多样性指数计算表明石子岭水库明显富营养化,惠氏微囊藻是是群落中绝对优势种.同时浮游植物生态位测度值表明微囊藻等蓝藻在时下的生态因子作用下将呈现逐渐衰退,而绿藻种群扩张,水库中浮游植物明显呈现由蓝藻优势向绿藻优势群落演替趋势.测定叶绿素荧光参数,以了解微囊藻水华的生长状态,比较研究中午强光下和经过24 h暗恢复及与室内培养的惠氏微囊藻三者的差异,表明夏末秋初阶段水库中微囊藻受到了一定的光照胁迫.水库中营养盐分析表明过高的总氮、总磷浓度和适宜的N/P比可能是水华暴发的主要原因,同时也是导致石子岭水库浮游植物呈现特定的群落结构特征的关键因素.     

An improved approach for identifying suitable habitat of Sambar Deer (Cervus unicolor Kerr) using ecological niche analysis and environmental categorization: Case study at Phu-Khieo Wildlife Sanctuary,Thailand

To assess habitat suitability (HS) has become an increasingly important component of species/ecosystem management. HS assessment is usually based on presence/absence data related to environmental variables. An exception is Ecological Niche Factor Analysis (ENFA), which uses only presence data and which does not require absence data. Most HS modelling is based on input of all environmental parameters (EnvPs) without environmental categorization, and does not take into account species interaction and human intervention for an assessment of HS. In this study, the EnvPs are arranged into four features: geographical features, consumable features, human-factor features, and species–human interaction features. These features affect species with respect to movement, behavior and activity. The research presented here has used an already existing dataset of wildlife species and human activities/visitations, which was compiled during 2004–2006 in Phu-Khieo Wildlife Sanctuary (PKWS). Data from 2004 to 2005 were used to produce HS maps, while the data of 2006 were used for evaluating these maps. Sambar Deer (SD) was chosen to predict its own HS. Six HS maps of SD were analyzed using ENFA in the following manner: (1) inputting all EnvPs together, (2) inputting each feature, separately and (3) integrating the four resulting HS maps by model averaging. It was found that model averaging was capable of predicting the HS of SD more reliably than the model with all EnvPs put in together. Multiple linear regressions were computed between the HS map with all EnvPs and the HS maps with each feature. The results show that the HS map with only geographical features has the highest coefficient value (0.516) while the coefficient values of other HS maps with the above features are 0.296, 0.53 and −0.006, respectively. This indicates that the geographical features have an influence on the other features and that the predicting power is lower when all EnvPs are computed in the ENFA model. Therefore, in order to generate HS, each feature should at first be put into the model separately. Following that, the average of all features will be combined.     

基于生态位适宜度理念的城镇用地空间优化配置研究

城镇用地空间优化配置是地理学、城市规划学一直关注的话题,不仅关系着城镇空间形态,对土地资源整体利用效率也有重要影响。考虑空间单元自身属性的同时,城镇用地空间优化配置也应考虑邻域单元作用的"外溢性",这与生态位适宜度中的"态"与"势"理念吻合,于是论文根据生态适宜度理论提出了一种城镇用地空间优化配置法,并通过Matlab编程予以实现,最后以扬州市区为例进行实证研究。结果显示:城镇用地空间优化配置不应只考虑空间单元自身属性,还要考虑空间连续性;单元自身属性是城镇用地空间优化配置的根本,可看作生态位适宜度中的"态"值;城镇用地扩张的空间连续性是通过单元作用的传递来实现,于是邻域单元的作用大小可看作生态位适宜度中的"势"值。本文基于生态位适宜度的城镇用地空间优化配置法综合考虑了单元自身属性与空间连续性两方面需求,具有较好科学性,可用于规划中城镇边界的划定。     

The crucial role of the accessible area in ecological niche modeling and species distribution modeling

Using known occurrences of species and correlational modeling approaches has become a common paradigm in broad-scale ecology and biogeography, yet important aspects of the methodology remain little-explored in terms of conceptual basis. Here, we explore the conceptual and empirical reasons behind choice of extent of study area in such analyses, and offer practical, but conceptually justified, reasoning for such decisions. We assert that the area that has been accessible to the species of interest over relevant time periods represents the ideal area for model development, testing, and comparison.     

汾河太原段水体浮游藻类生态位的研究

采用Levins生态位宽度公式和Petrailis生态位重叠指数测定了汾河太原段34个优势藻种的生态位宽度和生态位重叠,并对生态位宽度和生态位重叠的关系进行了初步探讨。结果表明,在清洁河段,优美曲壳藻的生态位最大,在水质较差的断面,以纤维藻属的2个种和中间菱形藻的生态位最宽。从生态响应速率值看,清洁河段中,扭曲小环藻的进攻性最强;在污染段,平片针杆藻的进攻性最强。从生态位普遍重叠指数分析,清洁带高于污染带,表明在污染水体中,藻类分化明显,而清洁水体中,藻类对资源的利用充分。     

Equivalency of Galápagos Giant Tortoises Used as Ecological Replacement Species to Restore Ecosystem Functions

Loss of key plant–animal interactions (e.g., disturbance, seed dispersal, and herbivory) due to extinctions of large herbivores has diminished ecosystem functioning nearly worldwide. Mitigating for the ecological consequences of large herbivore losses through the use of ecological replacements to fill extinct species’ niches and thereby replicate missing ecological functions has been proposed. It is unknown how different morphologically and ecologically a replacement can be from the extinct species and still provide similar functions. We studied niche equivalency between 2 phenotypes of Galápagos giant tortoises (domed and saddlebacked) that were translocated to Pinta Island in the Galápagos Archipelago as ecological replacements for the extinct saddlebacked giant tortoise (Chelonoidis abingdonii). Thirty‐nine adult, nonreproductive tortoises were introduced to Pinta Island in May 2010, and we observed tortoise resource use in relation to phenotype during the first year following release. Domed tortoises settled in higher, moister elevations than saddlebacked tortoises, which favored lower elevation arid zones. The areas where the tortoises settled are consistent with the ecological conditions each phenotype occupies in its native range. Saddlebacked tortoises selected areas with high densities of the arboreal prickly pear cactus (Opuntia galapageia) and mostly foraged on the cactus, which likely relied on the extinct saddlebacked Pinta tortoise for seed dispersal. In contrast, domed tortoises did not select areas with cactus and therefore would not provide the same seed‐dispersal functions for the cactus as the introduced or the original, now extinct, saddlebacked tortoises. Interchangeability of extant megaherbivores as replacements for extinct forms therefore should be scrutinized given the lack of equivalency we observed in closely related forms of giant tortoises. Our results also demonstrate the value of trial introductions of sterilized individuals to test niche equivalency among candidate analog species. Equivalencia de Tortugas Gigantes de las Galápagos Utilizadas como Especie de Reemplazo Ecológico para Restaurar las Funciones de los Ecosistemas     

Incorporating fragmentation and non‐native species into distribution models to inform fluvial fish conservation

Fluvial fishes face increased imperilment from anthropogenic activities, but the specific factors contributing most to range declines are often poorly understood. For example, the range of the fluvial‐specialist shoal bass (Micropterus cataractae) continues to decrease, yet how perceived threats have contributed to range loss is largely unknown. We used species distribution models to determine which factors contributed most to shoal bass range loss. We estimated a potential distribution based on natural abiotic factors and a series of currently occupied distributions that incorporated variables characterizing land cover, non‐native species, and river fragmentation intensity (no fragmentation, dams only, and dams and large impoundments). We allowed interspecific relationships between non‐native congeners and shoal bass to vary across fragmentation intensities. Results from the potential distribution model estimated shoal bass presence throughout much of their native basin, whereas models of currently occupied distribution showed that range loss increased as fragmentation intensified. Response curves from models of currently occupied distribution indicated a potential interaction between fragmentation intensity and the relationship between shoal bass and non‐native congeners, wherein non‐natives may be favored at the highest fragmentation intensity. Response curves also suggested that >100 km of interconnected, free‐flowing stream fragments were necessary to support shoal bass presence. Model evaluation, including an independent validation, suggested that models had favorable predictive and discriminative abilities. Similar approaches that use readily available, diverse, geospatial data sets may deliver insights into the biology and conservation needs of other fluvial species facing similar threats.     

Introduction of Relative Abundance Distribution (RAD) Indices, Estimated from the Rank-Frequency Diagrams (RFD), to Assess Changes in Community Diversity

Quantifying a relative abundance distribution based on thesampling of a set of species is a widespread problem in ecology.A number of diversity indices have been proposed and used in numerous works in spite of a lack of statistical characteristics and tests of comparison. The relative abundancedistribution can also be described using rank-frequency diagrams but fitting these diagrams to mathematical models such as the Zipf-Mandelbrot model remains problematic. Strong correlation between the Zipf-Mandelbrot model parameters prevent their estimation by optimization algorithm. In light of this, new indices of sampled communities are introduced here. These indices are two linear regression slopes estimated from rank-frequency diagrams. The numerous statistical studies that have been carried out on linear regression models are used to compare sampled communities. These new indices possesscharacteristic properties with an ecological meaning.Correlations between these indices, the Zipf-Mandelbrot modelparameters and an evenness diversity index are examined. Anecological application is made using entomological data as anexample. This example consists of a transect from the edge of apond to a dry forest along which 60,000 insects were sampledfrom six different sampling stations. Using the new indicesdescribed here, station C, located at the edge of that areasubject to influence from the pond, is differentiated from theother stations. This station would seem to present the lowestdegree of niche diversity and the lowest evenness, and recent observations confirm the deterioration of this station.     

Increase in Quantity and Quality of Suitable Areas for Invasive Species as Climate Changes

As climatically suitable range projections become increasingly used to assess distributions of species, we recommend systematic assessments of the quality of habitat in addition to the classical binary classification of habitat. We devised a method to assess occurrence probability, captured by a climatic suitability index, through which we could determine variations in the quality of potential habitat. This relative risk assessment circumvents the use of an arbitrary suitability threshold. We illustrated our method with 2 case studies on invasive ant species. We estimated invasion potential of the destroyer ant (Monomorium destructor) and the European fire ant (Myrmica rubra) on a global scale currently and by 2080 with climate change. We found that 21.1% of the world's landmass currently has a suitable climate for the destroyer ant and 16% has a suitable climate for European fire ant. Our climatic suitability index showed that both ant species would benefit from climate change, but in different ways. The size of the potential distribution increased by 35.8% for the destroyer ant. Meanwhile, the total area of potential distribution remained the same for the European fire ant (>0.05%), but the level of climatic suitability within this range increased greatly and led to an improvement in habitat quality (i.e., of invasive species’ establishment likelihood). Either through quantity or quality of suitable areas, both invasive ant species are likely to increase the extent of their invasion in the future, following global climate change. Our results show that species may increase their range if either more areas become suitable or if the available areas present improved suitability. Studies in which an arbitrary suitability threshold was used may overlook changes in area quality within climatically suitable areas and as a result reach incorrect predictions. Incremento de la Cantidad y Calidad de Áreas Idóneas para Especies Invasoras a Medida que Cambia el Clima