Research On The Spatial Scale Of Eco-environment Based On Wavelet Transform

Eco-environmental system is a complex system with the character of non-linear, whose attributes can be expressed as a series of numbers with the development and wide use of the technique "Remote Sensing-Geographical information system-Global position system".On the background,how to illustrate the large-scale geographical principles and the ecological principles in small scope with these numerous data is a critical problem, and is involved in the role scale of the principles.Additionally,the common dilemma about the controversial opinions or knowledge conflicts among experts,as well as the blur zoning boundaries and arbitrary decisions during the process of ecological regionalization, ecological assessment and other decision-making cases referred to ecological environment,are also closely related to scale problem.Scale problem has been the highlight of eco-environmental research,The paper reviewed the results,data and mathematical tools for the scale research,,and made some meaningful assessments on the typical research cases.Based on the review,the essay proposed that scale research should stress on the connection and transformation of ecological principles among different scales,apart from the concrete principle on one scale.Furthermore,the essay focused on five scientific questions:identification of the characteristic scale of eco-environmental indicators and its geographical causes,spatial pattern-scale effects of eco-environmental indicators,scale effects of correlations between eco-environmental indicators,discrimination of the eco-environmental thresholds on the characteristic scale,temporal influence on the eco-environmental pattern-scale effect by use of Remote Sensing data and multi-resolution wavelet analysis for scale transfer. Finally,a fresh understanding on the scale is proposed,as well as the advanced directions and details of eco-environmental scale research.Significant conclusions of the essay are listed as following1)To realize the spatially quantitative analysis of eco-environmental analysisThe paper successfully imports the multi-resolution mathematic tools which were widely used in time-frequency analysis into the eco-environmental spatial analysis,and realizes the quantitative analysis on spatial signals.The technique of the quantitative analysis of eco-environmental spatial analysis is introduced in detail as following:with Remote Sensing data as the information resource of eco-environment,by use of wavelet analysis,the first step is to decompose the eco-environmental information into different scales.Next,it aims to get the characteristic scale of eco-environment through the spatial statistic analysis such as auto-correlation analysis,scale variance and wavelet entropy calculation.Finally,based on the results of characteristic scale,it developes to identify the eco-environmental thresholds according to the results of statistic classification.2)To construct the related standard systems for eco-environmental scale analysisThe eco-environmental scale analysis includes the characteristic scale and eco-environmental threshold.The standard of the characteristic scale firstly regarded the characteristic scale as a scale scope,not a concrete scale point or resolution.The method to select the characteristic scale is the corresponding scale on the local peak of wavelet detailed information variance-scale diagram and on the penk of wavelet detailed information entropy-scale diagram,the two particular scales make up of the characteristic scale scope.Meanwhile,on the characteristic scale scope,the gradient of wavelet smooth information reaches to the maximum,so the spatial variance of auto-correlations.Eco-environmental thresholds are the transfer zones of different eco-environmental types,in which eco-environmental indicators varied fiercely with a higher speed than those outside the thresholds.The standards to distinguish the thresholds clearly are proposed as following,firstly,the gradients of wavelet smooth information reflected the sketch feature of eco-environment should be on the peak,meanwhile the wavelet detailed information reflected the fluctuation of eco-environment should be on the peak, additionally,the thresholds should be keep continuously in space,and the width of the threshold should be limited on the pixel numbers of the characteristic scale and the pixel length between two peaks of wavelet detailed information.If the length of threshold is longer than that of the neighbor eco-environmental type,the threshold will be changed into one of the eco-environmental types.3)To partly enrich the understanding of the eco-environmental scaleScale is closely associated with the spatial and temporal rhythm of nature.Scale is the measurement unit of the principles of eco-environment referred to the frame of space and time.Under such conception frame of scale,eco-environmental principles either large-scale geographical rules or local experimental conclusions will be positioned on the spatial & temporal coordinates,in which the uncertainties can also be calculated quantitatively.