对北京市流动人口聚居区治理的再思考

通过拆除违章建筑的城市改造办法以压缩流动人口聚居区人口规模,遏制公共安全隐患,是各地城市政府治理“城中村”的通常措施,北京也不例外,但多年实践证明成效甚微。本文从北京的实际出发,通过分析流动人口聚居区对当地政府和村民的积极作用、流动人口融入当地社会的有利条件,指出流动人口聚居区治理需要管理制度的创新,同时提出了标本兼治、拆建结合等建议。     

The plastic reproductive allocation of the cruciferous perennialRorippa indica in response to different degrees of feeding damage

Summary The degree of feeding damage in the wild to the cruciferous perennialRorippa indica (L.) Hieron ranged from 0% (not damaged) to 100% (heavily damaged). However, “not damaged” and “heavily damaged” individuals did not differ in the relative suitability of their intrinsic traits forP. rapae, which caused the heaviest damage on the plant. Therefore, the different degrees of feeding damage may be due to variability in the extrinsic traits of the plant, that is, it may be determined by the habitat conditions where individual plants exist. Furthermore,R. indica allocated more resource to seed production at the expense of the roots when it was experimentally subjected to heavy leaf damage. The result suggested thatR. indica individuals may escape, by means of seed dispersal and seed dormancy, from unfavorable habitats where they are heavily damaged by herbivores.     

加快发展中国科技工业园区建设

探讨了美国硅谷长盛不衰的原因 ,指出创新和营造适合的创业环境是发展中国科技工业园区的必要条件 ;通过对北京、上海、深圳等地高新技术产业园区发展情况的分析介绍 ,强调加快发展作为企业栖息地的科技工业园区建设 ,将推动中国高新技术革命的进程 ,促进经济的腾飞     

Detecting the scales at which birds respond to structure in urban landscapes

Little empirical information exists about how birds respond to urban landscape structure across multiple scales. We explored how the variation in percent tree canopy cover, at four different scales, affected the abundance of bird species across various urban sites in North America. Bird counts were derived from previous studies, and tree patches were measured from aerial photographs that represented areas of 0.2 km², 1.5 km², 25.0 km², and 85.0 km². At each of the four areas, we conducted regressions between bird counts and percent cover of various tree patch sizes. From these analyses, we determined the area (called the best prediction area—BPA) and the patch size (called the best patch size—BPS) that accounted for a significant amount of the variation in bird counts, beyond the variation accounted for by these parameters measured at other scales. BPA and BPS were calculated primarily to take into account the high degree of collinearity that existed among the amount of tree canopy cover measured across the four scales.We calculated BPA and BPS values for a variety of bird species and ascertained whether larger species had relatively larger BPS and BPA values. In the spring, middle-sized to large birds (16.6 g–184.0 g) had relatively larger BPS values than did smaller birds (3.2 g–16.5 g), but in the summer, the largest birds (61.7 g–576.0 g) had small BPS values. Spring BPA values showed a similar result but summer BPA values did not. A majority of birds of all sizes had summer BPA values at the finer scales of 0.2 km² and 1.5 km². Overall, body size was an approximate predictor of the area and patch size at which a species responds to trees in a landscape, but many exceptions did occur. These exceptions could be related to a variety of factors, one being the difficulty in relating human-biased measurements to avian measurements of a landscape. The method described in this study will help researchers design multi-scale studies to address the effect of landscape pattern on different animal species.     

Assessing the structural heterogeneity of urban areas: an example from the Black Country (UK)

The increasing acknowledgement of the importance of urban habitats in the maintenance of biodiversity has brought with it a need to quantify this importance at a scale appropriate to the characteristic patch sizes encountered in urban areas. Taking a study area in the Black Country (UK) we used a spatially complete, rapid assessment method to evaluate habitat patches in terms of their internal structural heterogeneity. This method recognises the importance of both natural and anthropogenic processes in providing a diverse range of habitats and niches for both flora and fauna. It also recognises the key role of context in determining the ecological significance of each patch within the urban landscape.All habitats studied had a complex mix of both natural and artificial structural elements, where an element is a within-patch contributor to structural diversity, with each habitat type having a large range of element totals. Characteristic totals, reflecting the level of habitat structural diversity, were observed in some habitat types with residential areas having high values and industrial and commercial areas having low values. Certain structural elements were also associated with each habitat type allowing characteristic element assemblages to be derived. If structural diversity is linked with biodiversity, as seems to be the case in many (though not all) habitat types, then this unique method of viewing the urban landscape becomes a powerful tool for informing wildlife ecologists, nature conservationists, urban planners, environmental managers and landscape architects.     

Bird and butterfly communities associated with two types of urban riparian areas

We examined the distribution of birds and butterflies at two types of urban riparian areas in the metropolitan area of Denver, Colorado, USA. The sites consisted of relatively natural areas containing native woody vegetation, and those that had been highly modified with trees and shrubs removed and planted with lawn grass. Species richness of both butterflies and birds differed significantly between the two types of sites. Species richness, however, was not significantly correlated between birds and butterflies. Bird abundance was similar between site types but consisted of two assemblages. Brewer's blackbirds, common grackles, bank swallows, and mourning doves were abundant at wooded sites while American robins, European starlings, house sparrows, house finches, and mallards were more abundant at lawned riparian sites. Butterfly abundance was less at lawned sites. This contrast in bird and butterfly response to habitats suggests they respond to different habitats in distinct ways. Both taxon groups, however, were important discriminators between habitat types. Overall, butterfly and bird species richness was 44% less at highly modified riparian sites.     

Impact of urbanization on the water quality,fish habitat,and fish community of a Lake Ontario marsh,Frenchman’s Bay

Frenchman’s Bay is a barrier beach wetland with a highly urbanized watershed located east of Toronto, along the north shore of Lake Ontario. Degradation of water quality has reduced the historically large stand of emergent vegetation to fringe emergent beds to the north and south of the Bay. Altered hydrology and runoff from the urban watershed and a nearby major highway have resulted in poor water quality, and warmer waters at the northern site. By contrast, the southern site has considerably cleaner and cooler water, as it is influenced by exchange of good-quality water with Lake Ontario. These differences in water quality were reflected in the composition of the fish assemblages that were sampled at the two sites over a 2-year period. Comparisons with past studies indicate that the dominant fish community of Frenchman’s Bay has been relatively stable for the last 20 years. Scores for the Wetland Fish Index, an indicator of wetland condition, were significantly higher in the south site than in the north site, which corresponded to significant differences in Water Quality Index scores. Although the northern portion of Frenchman’s Bay shows clear signs of degradation, the southern portion contains important fish habitat for western Lake Ontario.     

人类活动对翼手类生存环境的影响

翼手类捕食农林昆虫,对人类有益。其粪便和肉可入药,与人类关系密切。人类活动主要通过对其栖息环境和食等方面,影响翼手类的种类、数量和分布。影响翼手类栖息地的主要因素有：人类生产活动对森林的砍伐和开垦、自然洞穴的开发利用、房屋结构的改变和水工建筑等。影响翼手类的保护,随着人为活动的增加,翼手类的栖息环境将更加恶化,种类和数量将愈来愈少。     

Use of urban habitats by coyotes in the vicinity of Banff Alberta

Little information is available on the degree to which coyotes (Canis latrans) use urban habitats. In the past, interactions between coyotes and humans have precipitated several instances of coyote aggression towards humans. Consequently, I analyzed use of urban habitats by coyotes and the possibilities for aggressive encounters with humans. In this study, 11 radio-collared coyotes were monitored between July 1991 and September 1992. Use/availability analysis demonstrated a clear difference in use of natural habitats between summer and winter. Urban habitats were used in direct proportion to availability during all time periods, except during the day in summer when coyotes avoided intense human activity. Campgrounds were not an attraction during either season. For the most part, coyotes in the vicinity of Banff used habitats available to them regardless of human activity. Evidence does not suggest the coyote population in the vicinity of Banff is predisposed to aggression due to familiarity with humans. The relationship between the data and coyote aggression towards humans is discussed.     

The natural South Florida system II: Predrainage ecology

The goal of the South Florida restoration process is to reestablish a sustainable ecological system that approximates the predrainage system (i.e., the system that existed before canals and water control structures were built). A critical step in the restoration process is to describe the predrainage system with sufficient detail to capture the essential landscape features (e.g., space, connectivity, patterns) that gave the region its defining character and supported its natural abundance and diversity of plants and wildlife.A previous attempt at reconstruction of predrainage (circa 1870) vegetation patterns covered only the Everglades (Davis et al., 1994) but introduced a concept of landscape mosaics that should be extended to South Florida. We propose 16 landscape units that include freshwater landscapes, upland landscapes, coastal wetlands, and estuaries (particularly Florida and Biscayne Bays), the Florida Keys and Reef Tract, and the Inner Southwest Florida Shelf.The predrainage area, because of its enormous size, supported a landscape heterogeneity that was advantageous to animals with several distinct habitat-related life strategies. Five species have been selected to illustrate different dependencies on landscape patterns in predrainage South Florida: wood stork (Mycteria americana), American alligator (Alligator mississippiensis), snail kite (Rostrhamus sociabilis), Cape Sable seaside sparrow (Ammodramus maritimus mirabilis), and pink shrimp (Penaeus duorarum). As individuals or as populations, these animals operated across several spatial and temporal scales. The predrainage system's large spatial extent and complex hydropatterns allowed wood storks and other animals with large feeding ranges to take advantage of the strongly seasonal rainfall pattern, while at the same time providing a refuge somewhere in the system for survival of all other species. Landscape heterogeneity and large spatial extent promoted the region's natural wildlife abundance and species diversity.