区域尺度土壤固碳量估算方法评述

增加陆地生态系统碳汇已成为一项重要的减排手段,被纳入有关国际气候变化协定。区域尺度土壤固碳量估算成为当前研究的热点与难点。本文综述了目前国内外常用的区域土壤固碳量估算方法,并依据估算精度与方法差异将这些方法总结为四类:简易模型、清查法、经验模型和基于GIS的机理模型。同时对这四类方法的特点和适用性进行了评述,建议根据研究地区及目的不同选择合适的方法。此后,通过分析土壤固碳机理、数据收集、尺度推移、情景分析和土壤有机质机理模型发展等与区域土壤固碳量估算密切相关的各方面中存在的不足,提出今后区域尺度土壤固碳量估算方法将向耦合土壤有机质机理模型、土壤可溶性碳模型、土地利用模型和区域水文模型的基于GIS平台的区域综合模型方向发展。

Review on the methods for soil carbon sequestration at regional scale

The study on soil carbon sequestration at regional scale is of great significance, as the Kyoto Protocol and other accords of the United Nations Framework Convention on Climate Change have prescribed that carbon (C) sequestration in soil can be included in the measures to meet the Quantified Emission Limitation or Reduction Commitments in the first period (2008~2012). The methods on estimating the amount of C sequestration in soil at regional scale were reviewed, and the development of the methods was prospected. According to the estimation accuracy and principle, the approaches could be categorized into four methods: (1) Simple model, which scaled up the estimation of SOC sequestration from local plots to region simply or by statistical model, was used widely but with low accuracy. The method was recommended in the region without sufficient data. (2) Inventory method, which was used in soil database of different periods to estimate the change of soil carbon between the two periods, could be used to estimate the amount of carbon sequestered in soil in the past with higher precision, but it could not be used to predict the change of soil carbon in the future. (3) Empirical model including the Book-keeping Model and the Tier 1 and Tier 2 recommended in IPCC Report (2006 IPCC Guidelines for National Greenhouse Gas Inventories) could provide environmental interpretation in soil carbon sequestration with no mechanism explanation. (4) Mechanism model developed from soil organic matter mechanism model (e.g. CENTURY model) based on geographic information system (GIS) could estimate SOC sequestration with highest accuracy among these four methods, which could also provide mechanism explanation in the process of the change in SOC. In summary, each type of the four methods had its own limitation and applicability, so the methods should be chosen based on the site-specific conditions and the research purposes. Finally, based on the analysis of some gaps in the mechanism of soil carbon sequestration, scaling, scenario analysis and soil organic matter model, we proposed that the integrated model,based on GIS, coupling SOM mechanism model, land-use model, econometrical model and regional scale eco-hydrological model, would be developed for studying soil carbon sequestration at regional scale in the future.