丝绸之路经济带陆路西北段城市体系与开放性研究

随着丝绸之路经济带建设上升为国家战略,对经济带城市等级及城市类型进行科学定位迫在眉睫。以丝绸之路经济带陆路西北段为例,运用城市流强度模型和城市生态经济位模型对研究区18个地级以上城市的城市流强度和城市生态经济位进行测度,并将二者综合,划分城市体系和城市开放性类型。结果显示:研究区城市流强度介于3.80亿~1 158.92亿元,城市流强度不仅与城市规模息息相关,城市类型也是其重要影响因素;城市生态经济位介于0.020~0.231,超过半数城市位于系统底部,主要限制性因素为经济滞后;结合城市流强度和城市生态经济位,将城市划分为4级,西安为核心城市,乌鲁木齐和兰州为副核心城市,重要节点城市5个,一般节点城市10个;创建城市开放性指数,将城市划分为开放型和内敛型,西安、乌鲁木齐等6个城市为开放型,兰州等12个城市为内敛型。     

Spatial conservation planning framework for assessing conservation opportunities in the Atlantic Forest of Brazil

Historic rates of habitat change and growing exploitation of natural resources threaten avian biodiversity in the Brazilian Atlantic Forest, a global biodiversity hotspot. We implemented a twostage framework for conservation planning in the Atlantic Forest. First, we used ecological niche modeling to predict the distributions of 23 endemic bird species using 19 climatic metrics and 12 spectral and radar remote sensing metrics. Second, we utilized the principle of complementarity to prioritize new sites to augment the Atlantic Forest's existing reserves. The best predictors of bird distributions were precipitation metrics (the seasonality of rainfall) and radar remote sensing metrics (QSCAT). The existing protected areas do not include 10% of the habitat of each of the 23 endemic species. We propose a more economical set of protected areas by reducing the extent to which new sites duplicate the biodiversity content of existing protected areas. There is a high concordance between the proposed conservation areas that we designed using computerized algorithms and Important Bird Areas prioritized by BirdLife International. Insofar as deforestation in the Atlantic Forest is similar to land conversion in other biodiversity hotspots, our methodology is applicable to conservation efforts elsewhere in the world.     

Food and habitat resource partitioning between three estuarine fish species on the Swedish west coast

In 1978 the food and habitat resource partitioning of three small and common fish species, viz. Pomatoschistus microps (Krøyer), Gasterosteus aculeatus (L.) and Pungitius pungitius (L.) were studied in river Broälven estuary on the Swedish west coast (58°22′N, 11°29′E). The area was divided into three habitats, based on environmental features. In July, September, and October stomach contents and size distribution of each species present were analysed.In July there was high food and habitat overlap between the species. Interference interactions probably occurred between some size classes of P. microps and the other two species. P. pungitius was exposed to both intra- and interspecific interactions. In September the food and habitat overlaps between G. aculeatus and P. pungitius were high, while both had low food and habitat overlaps in relation to P. microps. Interactions between G. aculeatus and P. pungitius were probably influenced by more severe abiotic conditions in one habitat, which caused lower abundances there, and higher abundances in the other two habitats. In October no interactions were observed. These results indicate that competition for food at least temporarily determines the species distribution in a temperate estuary, and that estuarine fish populations are sometimes food limited.     

Distribution and Migrations of two Cerithid Snails on a Sand Flat in Bermuda

Abstract. Two species of cerithid prosobranchs live on a sand flat in Bermuda. At low tide during day light Batillaria minima is found on the surface whereas Cerithium lutosum remains buried in the sediment. This correlates with much higher lethal and coma temperatures, as well as much greater resistance to desiccation, of the former species. However, at other diurnal or tidal stages the two species co-occur in the same layer of sand. Despite greater resistance to physical factors the population of B. minima seems to be declining since in 1980 juveniles of this species were rare on Tuckers Town Flat whereas the population of C. lutosum was thriving.     

Adaptive Ecology, Growth Strategies and the Global Bloom Expansion of Dinoflagellates

Dinoflagellates exhibit unique differences from diatoms in their adaptive ecologies that may be favoring their increasingly successful exploitation of coastal waters and global bloom expansion. Dinoflagellates behave as annual species, bloom soloists, are ecophysiologically diverse and habitat specialists, whereas diatoms behave as perennial species, guild members and are habitat cosmopolites. Diatoms have a relatively uniform bloom strategy based on species-rich pools and exhibit limited habitat specialization. Dinoflagellates have multiple life-form strategies consistent with their diverse habitat specializations, but rely on impoverished bloom species pools. Niche structure and dinoflagellate competition for niche space are considered. The “open niche period” formulated originally for Narragansett Bay is extrapolated as a general bloom paradigm. It is suggested that successful niche occupancy leading to blooms involves adaptive strategies at three heirarchic taxonomic elements: phylogenetic, generic and species-specific, and in that sequence. Transoceanic expatriation of emigrant species leading to indigenous status and blooms requires completion of a three-stage colonization process. Anthropogenic seedings are not, in themselves, bloom stimulation events; they are only the first phase of a multiple-step process. The organismal and niche features required for a hidden flora member to become a bloom species are considered, and the interplay between niche structure, habitat carrying capacity, colonization requirements and stochasticity as factors in the changing global bloom behavior of dinoflagellates discussed. The question is posed whether traditional perspectives of phytoplankton behavior apply completely to dinoflagellates. This revised version was published online in August 2006 with corrections to the Cover Date.     

Tethya (Porifera,Demosponglae) Species Coexisting in a Maldivian Coral Reef Lagoon: Taxonomical,Genetic and Ecological Data

Abstract. Tethya microstella, T. orphei, T. robusta, and T. seychellensis live in sympatry in a Maldivian coral reef lagoon (Gangehi Island, Ari Atoll). A morphological, morphometric, and electrophoretical study of these species show that their Maldivian populations are well separated morphologically and genetically. The genetic distances and the other data are more consistent with an immigration than with a local speciation hypothesis. Their coexistence may be explained by a differentiation in ecological requirements. The four species inhabit the shallow water biotope of the lagoon among the rubble of dead corals. Our data show that T. orphei and T. seychellensis occupy the upper rubble layer, T. microstella and T. robusta the lower one. This distinction agrees with the different morpho-functional features of the two pairs of species.     

Niche characterization of dominant estuarine benthic species

Benthic macroinfaunal species in a south Texas estuarine environment were studied over a 2·5 year period to characterize their distributions and ecology. The 13 dominant taxa chosen for investigation exhibited distinct habitat usage differences as judged both by the use of discriminant analysis and the differentiation of behavioral characteristics. Species coexistence in the estuarine bethic community of Corpus Christi Bay was examined with respect to resource partitioning for such parameters as food and space. Utilization of these resources by the dominant taxa differed in both temporal and spatial dimensions, with the spatial dimension consisting of horizontal and vertical attributes. Benthic species were separated according to (1) occurrences in certain sediment types with varying organic content, (2) presence in estuarine regions characterized by different phytoplankton productivity rates, (3) different periods of annual occurrence, and (4) occurrence in different sediment microhabitats characterized by varying sediment depth and relation to depth of oxygenated sediments. Superimposed upon differences in habitat usage of these species were behavioral traits, such as feeding differences, which further discriminated how benthic species obtained resources. Based upon species occurrence in a certain characteristic environment, we speculated on the structural division of the benthic habitat by various taxa often classified as common members of the same species' assemblages in the past. Although other investigators have demonstrated interactions among co-occurring benthic infaunal species, the information presented here illustrated how these species could minimize interactions in order to maintain their populations.     

Urban niche dynamics of Kaifeng city

Niche theory is one of the most important ecological theories. It is widely applied to analyzing such phenomena as competition among, and evolution of, urban ecosystem func-tional modules. This paper describes a study concerning different functional modules of Kaifeng city urban ecosystem. Niche theory and techniques were used to analyze the changes of these functional modules in the period 1994–2003. The results showed that, in the period 1994–2003: (1) Niche value of the atmospheric environment and urban virescence modules increased, while niche value of the water environment and sound environment modules decreased; (2) niche value of the tertiary industry module increased, niche value of the secondary industry module decreased, while niche value of the primary industry module showed little change; and (3) niche value of the infrastructure, resource distribution, and production & social security modules increased, while niche value of the population module decreased. This study may contribute to macroscopic planning of urban functional modules, economic development, and environmental protection.     

基于碳氮稳定同位素技术的小清河口邻近海域底栖食物网结构研究

为了掌握小清河口邻近海域底栖食物网结构特征,于2020年10月在小清河口邻近海域采集沉积物有机质、悬浮颗粒有机物、浮游动物和浮游植物4种潜在食源及35种生物样本,应用碳氮稳定同位素技术以及贝叶斯混合模型(MixSIAR)分析了小清河口邻近海域底栖食物网结构和营养关系.结果显示,潜在食源的δ13C值范围为-25.56‰～...     

小生境遗传算法在地震CT中的应用研究

针对含单相饱和流体的孔隙介质,综合费马原理、等效孔隙介质理论、Radon变换等,提出了基于地震CT技术求解速度、孔隙度和岩石密度的小生境多参数反演算法．以此为基础,经过改进,形成了物性参数的隔离小生境反演算法．理论分析与实例计算结果表明,该方法简化了波在层状介质中的传播方程,具有一定的实用价值,可以有效解决井间测井地层问题,获得较高精度的地层物性参数;而且模型简单,有精度高、多峰优化等特点,可用于地下层状介质中油气的寻找,满足油气预测与勘探开发的要求．