用地空间结构对城市土地集约利用评价尺度效应的影响

Effects of Land Use Pattern on Urban Land Intensive Use Evaluation at Different Spatial Scales

尺度效应是当前城市土地集约利用研究中一个鲜有涉及的领域,本文以深圳市宝安区为例,考察了利用地均投资额和地均产值两个指标在街道、地块两级尺度上对全区工业用地集约利用水平的评价结果,经过比较证实了城市土地集约利用评价的尺度效应是客观存在的。文章还通过计算用地的数量结构和格局指数进一步探讨了用地空间结构对尺度效应的影响。研究表明:用地数量结构对更高尺度空间的土地集约利用水平起主导作用,但用地空间布局却决定了土地集约利用水平的空间表现形态;在用地数量结构相似的情况下,用地空间布局中的优势度指数和均匀度指数对整体集约利用水平有着重要影响;在实际土地管理中,应考虑尺度效应的影响,尽量避免仅从单一尺度评价土地集约利用状况。

Scale effects of urban land intensive use evaluation was of utmost importance but are rarely drawn attention in much research.In the present work,the authors selected commonly used land intensive use assessment indices,i.e.,investment per area and output value per area,to investigate intensive use levels of industry plots in Baoan district of Shenzhen City.By comparing the assessment results at neighborhood scale and plot scale,it was found that scale effect clearly existed when the same index was used at different spatial scales to describe spatial characteristics of urban land intensive use.For instance,there showed a relatively high value of investment per area at the plot scale for the region near the boundary between Longhua and Dalang.However,at neighborhood scale,the investment per area of Longhua was ranked two of Baoan district,and Dalang only ranked six of these ten neighborhoods.Furthermore,the authors discussed in detail the influence of land use pattern including land quantity structure and land distribution pattern on the scale effects.First,the plots were classified into several levels by the evaluation indices.Then,land quantity structure of each neighborhood was calculated as the sum of plots＇evaluation index value with its area weighted.Last,each neighborhood＇s pattern index was calculated using Fragstats3.3,namely the Shannon diversity index,dominance index,evenness index and contagion index.Results indicated that land quantity structure leaded to significant effects on urban intensive use evaluation at higher spatial scale,and land distribution pattern determined the spatial form of urban land intensive use（the contagion index was a useful indicator to land aggregation）.So some places might show high land intensive use levels at macro-scale,but had no high value plot gathering in micro-scale.In addition,if the land quantity structure of two neighborhoods were similar with each other,the land distribution pattern showed a notable effect on urban land intensive use level.The dominance index and evenness index reflected the importance of reasonable distribution of urban land use.The study suggested that using the same index to evaluate urban land intensive use at different scales would obtain different results or even adverse results.So it would be difficult to evaluate urban land intensive use and obtain reasonable results only by accounting for one scale.It is not appropriate to use evaluation results at one spatial scale to decide land management at another scale.