生物多样性与濒危物种杂志

The urban forest is much more various than any surrounding natural forest in numerous parts of the United States. This “Created Biodiversity” is the result of the continuous introduction of new tree species to the urban forest. The three main driving forces behind this urban biodiversity are: alternatives of people (based primarily on socioeconomic factors and the preference to plant “something different” in their yards), the heterogeneity of urban habitats where we have set up many new and various habitats that are not necessarily natural environments for indigenous tree species, and the introduction of non-indigenous species which are sometimes potentially invasive and conduct to a change in the natural tree structure of the city. This created biodiversity is not a natural assemblage of tree species, but a makeshift company based on human desires and choices. A survey of the urban forest was managed in 1980 in ten selected Midwest, USA cities. The survey was then reproduced in six of these cities. The urban forest company was then compared to natural forests in the locality of the original cities surveyed. It was found that the species richness was much significant in the cities, with 47 to 82 species, than the natural forests in the vicinity area of those surveyed cities which only had 18 to 23 species.

Efforts at diminishing global biodiversity loss have often focused on preserving huge, intact natural habitats. However, preserving biodiversity should also be an important target in the urban environment, peculiarly in highly urbanized areas where little natural habitat remains. Escalating, research at the city/county scale as well as at the landscape scale disclose that urban areas can contain relatively high levels of biodiversity. Important percentages of species found in the vicinity natural habitat, including endangered species, have been found in the urban forest.This contribution laconic highlights some examples of urban biodiversity research from different areas of the world.

Key issues involved in understanding the motif and processes that affect urban biodiversity, such as the urban–rural gradient and biotic homogenization, are labeled. The potential for urban areas to harbor considerable sum of biodiversity needs to be recognized by city planners and urban foresters so that regulation practices that preserve and encourage that diversity can be pursued. Management alternative should focus on increasing biodiversity in all feature of the urban forest, from street trees to urban parks and woodlots.

In an urban ecosystem, the anthropogenic methods of vegetation dynamics was started from top landuse change to nursery trade and urban design, whereas the bottom-up anthropogenic forces were consider at a household scale of landscaping aesthetics and socioeconomics. In the past two decades, a number of factors have been inspected to influence urban forest diversity, such as neighborhood age and group affluence, the portion of immigrants , local stakeholders, different management regimes, residents' income  and exotic trees contribution. However, due to the problem of biodiversity itself and its interactions with human activities, the driving factors is not always the similar everywhere or every time.