广州快速城市化进程中近自然林的景观和活力演变

Landscape and dynamic evolution of near natural forest in the process ofrapid urbanization in Guangzhou

我国快速城市化过程中城市森林的结构、功能及服务受到了强烈的人为干扰。快速城市化过程中如何规划和保护森林资源,使其更有效地服务于城市生态系统,是当前亟需解决的问题。以高度城市化的广州市近自然林为研究对象,从城市化的时间尺度(1979—2013年)和空间尺度(市中心-近郊-远郊)两个方面探讨了广州市近自然林的景观及活力对快速城市化的响应过程。研究结果一致表明:快速城市化导致广州市近自然林的景观破碎化。近自然林的面积及活力在快速城市化进程中先迅速降低,随后降速减缓并缓慢回升。城市不透水面和产业结构是影响近自然林景观和活力的关键因子。城市化程度较低时,近自然林对城市化因子的响应为线性响应,随着城市化的推进,这种线性响应逐渐转变为非线性。城市化因子对近自然林的景观和活力的影响随着城市化进程先增强后减弱并逐渐趋于多元化和去中心化。对城市近自然林景观和活力调控的最佳时期是快速城市化早期。高度城市化背景下的政策和管理等行政因素可显著改善近自然林的景观和活力。

The structure,function,and services of urban forest are intensely disturbed by human activities during the rapid urbanization in China.How to plan and protect the forest resources during rapid urbanization and make it effectively serve the urban ecosystem,is an urgent issue.This study takes the near-natural forests in highly urbanized city Guangzhou as the study objects.The processes of near-natural forest in Guangzhou responded to urbanization were discussed from two aspects,i.e.,temporal scale(1979-2013)and spatial scale(urban-rural gradient).The results consistently showed that urbanization caused landscape fragmentation of near-natural forest.The area and vigor of near-natural forest decreased rapidly,and then the trend slowed down and finally increased slowly during the rapid urbanization.The impervious surface coverage and industrial structure were the key factors influencing the landscape and vigor of near-natural forest.There was a linear response to urbanization in near-natural forest when the urbanization level was low,and the response turned to non-linear when the urbanization level increased.Accompanying with the rapid urbanization process,the influences of urbanization factors on the landscape and vigor of near-natural forest increased and then decreased.The urbanization factors that influenced urban near-natural forest turned to multivariate and non-dominant. The best period to adjust the landscape and vigor of near-natural forest was in the early urbanization stage.The administrative factor, such as policy and management could play a vital role for the improvement of the landscape and vigor ofnear-natural forest in late urbanization stage.