降雨因素对生态系统生产总值核算结果的影响

Impact of precipitation factors on gross ecosystem product

目前生态系统生产总值(GEP)核算工作已在全国多地开展,并在不少地方已将其纳入政绩考核指标,但GEP核算中相关生态系统服务多基于实际降雨数据和多年平均降雨数据,导致在进行年际间GEP变化分析时,结果难以反应实际的生态系统质量和数量的变化,从而影响GEP管理应用的效果。本文以深圳为研究案例,提出了更能代表本地降雨一般化特征的可比降雨条件,以及基于主成分分析的确定方法,并且在可比降雨条件和实际降雨条件下核算了可比降雨年和临近年共3种情景下的生态系统生产总值(GEP),分析了不同情景下的GEP构成以及降雨因素对年际间GEP变化的影响能力。研究发现:(1)2019年为深圳可比降雨年,且符合2008—2020年间各年《深圳市气候公报》对降雨情况的阐述;(2)可比降雨条件下,与降雨相关的4项生态系统服务价值(减少泥沙淤积、减少面源污染、涵养水源、削减洪涝)呈年际间增长趋势,实际降雨条件下,减少泥沙淤积、减少面源污染价值增长,涵养水源、削减洪涝价值下降;(3)降雨因素显著影响GEP年际变化,不同降雨条件下,深圳2019—2020年GEP变化差异高达24.78亿元,而可比降雨条件可以有效减少非人为因素对GEP变化的影响;(4)计算多年平均降雨过程中,数据“峰度”会被人为降低的,导致平均结果不能代表地区典型气候特征;(5)可比降雨条件下,年际间GEP变化特征更能反应生态系统质量和数量的实际变化特征。研究结果可为今后面向管理应用的GEP核算提供新的思路与方法。

The accounting of Gross Ecosystem Product(GEP)has been conducted in many cities across the country,which has been included in the performance assessment indicators.But the relevant ecosystem services in GEP accounting are mostly based on actual precipitation data and multi-year average precipitation data,which makes it difficult to reflect the actual changes in ecosystem quality and quantity when analyzing inter-annual GEP changes,thus affecting the application of GEP management.Taking Shenzhen as a case,this paper proposes the comparable precipitation conditions that are more representative of the generalized characteristics of local precipitation,and a method of determination based on principal component analysis.This paper calculates the GEP for two adjacent years under comparable and actual precipitation conditions,for a total of three scenarios,and analyses the composition of GEP under different scenarios and the ability of precipitation factors to influence inter-annual GEP variability.The study found that:(1)2019 was a comparable precipitation year in Shenzhen and was consistent with the precipitation situation described in the Shenzhen Climate Bulletin between 2008 and 2020;(2)The four ecosystem service values associated with precipitation(Sedimentation reduction,Non-point resource pollution retention,Water conservation and Flood reduction)showed an inter-annual increase under comparable precipitation conditions,while the values of Sedimentation reduction and Non-point resource pollution retention increased and the values of Water conservation and Flood reduction decreased under actual precipitation conditions;(3)Precipitation factors significantly affected the interannual variation of GEP,and the variation of GEP change in Shenzhen from 2019 to 2020 under different precipitation conditions was as high as RMB 2.478 billion,while comparable precipitation conditions could effectively reduce the influence of non-anthropogenic factors on GEP change;(4)In the process of calculating multi-year average precipitation,the“kurtosis”of the data would be artificially reduced,resulting in the results not representing the typical climate characteristics of the region;(5)Under comparable precipitation conditions,the inter-annual GEP variation characteristics better reflected the actual variation of ecosystem quality and quantity.The results of the study may provide new ideas and methods for future GEP accounting for management applications.