Methodology for assessment of desertification based on vegetation degradation using net primary productivity (NPP) as a key indicator
Methodology for assessment of desertification based on vegetation degradation using net primary productivity (NPP) as a key indicator
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发表时间：
2005
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通讯作者：
A. Tsunekawa;T. Ito;M. Shinoda;M. Nemoto;T. Suhama;H. Ju;H. Shimizu
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作者：
A. Tsunekawa;T. Ito;M. Shinoda;M. Nemoto;T. Suhama;H. Ju;H. Shimizu
到目前为止，在评估区域荒漠化和土地退化时，经常使用基于主观信息的“结构化知情意见分析”。虽然在时间、金钱和人力有限的情况下，这可能是最合适的评估方法，但这种方法既不客观，也不量化;客观和量化往往与效率存在权衡关系。在本研究报告中，我们提出了一种既客观又定量的监测和评估区域荒漠化/土地退化的新方法。这种新方法依赖于净初级生产力（NPP）作为生物生产力的关键指标。利用1981 - 2000年的数据集，比较了潜在NPP（由气候参数确定）和实际NPP。为了估计潜在的NPP，我们使用了观测结果。这一修改后的模型，即“旱地调整的CASA”（D-CASA）模型，被用来估计亚洲旱地的实际净初级生产力。我们根据植被退化情况确定了亚洲潜在的荒漠化/土地退化热点。具体而言，这些地区是内蒙古中部（中国），中纬度和南部蒙古，印度西北部和德干高原（印度）。我们还确定了未被全球人类引起的土壤退化评估（GLASOD）数据库确定为受中纬度哈萨克斯坦和Betpak-Dala（哈什湖西南）土壤退化影响的植被退化地区。由于我们能够通过客观和可重复的方法评估荒漠化，并能够确定现有土壤退化图（GLASOD）未确定的荒漠化热点，我们得出结论，这里提出的荒漠化评估新方法是有效和有用的。
Up to now, a "structured informed opinion analysis" based on subjective information has often been used to assess regional desertification and land degradation. Although this might be the most appropriate assessment method given limitations of time, money and labor, the method is neither objective nor quantitative; objectivity and quantitativeness often have a trade-off relationship with efficiency. In the present study, we propose a new methodology for monitoring and assessing regional desertification/land degradation that is both objective and quantitative. This new method relies on net primary productivity (NPP) as a key indicator of biological productivity. We compared the potential NPP (determined from climatological parameters) and actual NPP using a dataset for the 20 years from 1981 to 2000. To estimate the potential NPP, we used the observations. This modified model, the "Dryland-adjusted CASA" (D-CASA) model, was used to estimate the actual NPP of Asian drylands. We identified potential desertification/land degradation hotspots in Asia based on vegetation degradation. Specifically, these were the regions of central Inner Mongolia (China), mid-latitudinal and south Mongolia, northwest India, and the Deccan Plateau (India). We also identified vegetation degradation regions that were not identified by the Global Assessment of Human Induced Soil Degradation (GLASOD) database as being affected by soil degradation in mid-latitudinal Kazakhstan and Betpak-Dala (southwest of Lake Balkhash). Because we were able to assess desertification by objective and reproducible methods and were able to identify desertification hotspots not identified by the existing soil degradation map (GLASOD), we conclude that the new methodology proposed here for desertification assessment is valid and useful.