Modelling of Vegetation Dynamics from Satellite Time Series to Determine Proglacial Primary Succession in the Course of Global Warming - A Case Study in the Upper Martell Valley (Eastern Italian Alps)
Modelling of Vegetation Dynamics from Satellite Time Series to Determine Proglacial Primary Succession in the Course of Global Warming - A Case Study in the Upper Martell Valley (Eastern Italian Alps)
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DOI：
10.3390/rs13214450
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发表时间：
2021-11
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通讯作者：
Bettina Knoflach;K. Ramskogler;Matthew V. Talluto;F. Hofmeister;F. Haas;T. Heckmann;M. Pfeiffer;L. Piermattei;C. Ressl;Michael H. Wimmer;C. Geitner;B. Erschbamer;J. Stötter
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作者：
Bettina Knoflach;K. Ramskogler;Matthew V. Talluto;F. Hofmeister;F. Haas;T. Heckmann;M. Pfeiffer;L. Piermattei;C. Ressl;Michael H. Wimmer;C. Geitner;B. Erschbamer;J. Stötter
基于卫星的植被覆盖发展长期观测与最近的实地观测相结合，为更好地了解植被格局的时空变化、其对气候驱动因素的敏感性以及气候对冰前景观发展的影响提供了基础。在本研究中，我们将 Fürkele、Zufall 和 Langenferner（Ortles-Cevedale 群/意大利东部阿尔卑斯山）冰川前缘的实地调查与 Landsat 场景中的四种不同植被指数 (VI) 相结合，以测试使用贝叶斯 beta 回归模型 (RStan) 建模全区域植被覆盖图的适用性。由于以归一化植被指数（NDVI）作为预测因子的模型显示出最佳结果，因此用于计算植被覆盖时间序列（1986-2019）。通过基于机载激光扫描（ALS）数据和面积图像、正射影像、历史地图和野外测绘活动的数字高程模型，分析了自小冰河时代（LIA）结束以来冰川区域的变化。我们的结果表明，面积损失8.1平方公里（56.9%；LIA-2019）的大规模冰川退缩导致冰川前缘不断扩大，这对植被覆盖程度产生了统计学上的显着影响。植被覆盖面积从1986年的0.25平方公里（5.6%）增加到2019年的0.90平方公里（11.2%），年平均变化率显着加快。由于模型结果可以反映高海拔地区的致密化过程和植物定植的模式，因此我们认为现场观测与NDVI时间序列相结合是监测高山冰川区植被覆盖变化的有力工具。
Satellite-based long-term observations of vegetation cover development in combination with recent in-situ observations provide a basis to better understand the spatio-temporal changes of vegetation patterns, their sensitivity to climate drivers and thus climatic impact on proglacial landscape development. In this study we combined field investigations in the glacier forelands of Fürkele-, Zufall- and Langenferner (Ortles-Cevedale group/Eastern Italian Alps) with four different Vegetation Indices (VI) from Landsat scenes in order to test the suitability for modelling an area-wide vegetation cover map by using a Bayesian beta regression model (RStan). Since the model with the Normalized Difference Vegetation Index (NDVI) as predictor showed the best results, it was used to calculate a vegetation cover time series (1986–2019). The alteration of the proglacial areas since the end of the Little Ice Age (LIA) was analyzed from digital elevation models based on Airborne Laser Scanning (ALS) data and areal images, orthophotos, historical maps and field mapping campaigns. Our results show that a massive glacier retreat with an area loss of 8.1 km2 (56.9%; LIA–2019) resulted in a constant enlargement of the glacier forelands, which has a statistically significant impact on the degree of vegetation cover. The area covered by vegetation increased from 0.25 km2 (5.6%) in 1986 to 0.90 km2 (11.2%) in 2019 with a significant acceleration of the mean annual changing rate. As patterns of both densification processes and plant colonization at higher elevations can be reflected by the model results, we consider in-situ observations combined with NDVI time series to be powerful tools for monitoring vegetation cover changes in alpine proglacial areas.