自工業(yè)革命以來,，人口的快速增長,，經(jīng)濟的飛速發(fā)展,，對自然資源的掠奪式開發(fā)利用,，使原有的自然生態(tài)系統(tǒng)遭到了極大的破壞，產(chǎn)生了諸如環(huán)境污染,、氣候變化,、水土流失、生物多樣性喪失等一系列危害人類自身生存的嚴重問題,。如何在自然資源環(huán)境可承受的范圍之內(nèi),，實現(xiàn)人類和經(jīng)濟的可持續(xù)發(fā)展是人類面臨的突出問題。為此,，首先需要一種可以客觀衡量和評價自然環(huán)境與人類經(jīng)濟關(guān)系的共同量化平臺,。
20世紀80年代以美國著名的生態(tài)學(xué)家、“系統(tǒng)生態(tài)學(xué)”之父H.T. Odum為首創(chuàng)立的能值理論方法,，以能值為量綱實現(xiàn)了物質(zhì)流,、能量流與經(jīng)濟流的統(tǒng)一量化評價，正日益發(fā)展成為生態(tài)經(jīng)濟系統(tǒng)整合研究評價的主流方法,，被譽為“環(huán)境與經(jīng)濟間的橋梁”,。但目前，大多數(shù)的能值分析評價結(jié)果由于缺乏不確定性分析,，而常常遭受到一定的質(zhì)疑,。雖然Ingwersen(2010)提出使用蒙特卡洛法模擬計算能值表格模型的不確定性，但需要事先確定參數(shù)的概率分布和相關(guān)性,，從而限制了它的使用,。
中科院華南植物園植被與景觀生態(tài)學(xué)研究組的博士研究生李林軍在導(dǎo)師任海研究員和陸宏芳研究員的指導(dǎo)下，借鑒國際通用的《測量不確定度評定與表示指南》,，辨識了能值表格模型的兩種數(shù)據(jù)類型,，并分別引進了方差法和泰勒法計算能值表格模型的不確定度，然后用案例加以了驗證,。結(jié)果表明,，當有多個系統(tǒng)重復(fù)樣本時,，方差法由于不需要任何假設(shè)且考慮了模型參數(shù)間潛在的相關(guān)性，而計算精度更可靠,，且計算方法簡單,；當只有系統(tǒng)組分的重復(fù)樣本數(shù)據(jù)時，泰勒法由于不需要作概率分布假設(shè),，而比蒙特卡洛法更為適用,，且計算也更為方便和簡單。
本研究補充完善了能值理論的不確定性評估,，是將不確定性分析納入能值分析與評價實踐的重要成果,，一定程度上將促進能值理論和方法的更廣泛接受和應(yīng)用。另外,，這兩種不確定性評價方法不僅適用于能值分析,，理論上也能用于尺度推繹和其它生態(tài)模型的生態(tài)學(xué)研究中。
目前,，該研究成果已被國際生態(tài)學(xué)研究主流期刊《生態(tài)模擬》（Ecological Modelling）登載發(fā)表,。（生物谷Bioon.com）
生物谷推薦原文出處：
Ecological Modelling DOI： 10.1016/j.ecolmodel.2011.04.023
Methods for estimating the uncertainty in emergy table-form models
Linjun Li, Hongfang Lu, Daniel E. Campbell and Hai Ren
Emergy studies have suffered criticism due to the lack of uncertainty analysis and this shortcoming may have directly hindered the wider application and acceptance of this methodology. Recently, to fill this gap, the sources of uncertainty in emergy analysis were described and analytical and stochastic methods were put forward to estimate the uncertainty in unit emergy values (UEVs). However, the most common method used to determine UEVs is the emergy table-form model, and only a stochastic method (i.e., the Monte Carlo method) was provided to estimate the uncertainty of values calculated in this way. To simplify the determination of uncertainties in emergy analysis using table-form calculations, we introduced two analytical methods provided by the Guide to the Expression of Uncertainty in Measurement (GUM), i.e., the Variance method and the Taylor method, to estimate the uncertainty of emergy table-form calculations for two different types of data, and compared them with the stochastic method in two case studies. The results showed that, when replicate data are available at the system level, i.e., the same data on inputs and output are measured repeatedly in several independent systems, the Variance method is the simplest and most reliable method for determining the uncertainty of the model output, since it considers the underlying covariance of the inputs and requires no assumptions about the probability distributions of the inputs. However, when replicate data are only available at the subsystem level, i.e., repeat samples are measured on subsystems without specific correspondence between an output and a certain suite of inputs, the Taylor method will be a better option for calculating uncertainty, since it requires less information and is easier to understand and perform than the Monte Carlo method.
