ABSTRACT

Detection and monitoring of vigour decline are certainly useful for forest managers to support future interventions. In this work a new index, from Sentinel-2 retrieved NDVI (Normalized Difference Vegetation Index) time series, is proposed, hereafter called ‘normalized Vegetation Vigour Index (nVVI)’, which is specifically designed to quantify and map tree vigour decline. Results proved that nVVI is negatively correlated to tree age (r = −0.815, p < 0.001): older or unhealthy trees showed low nVVI values; younger trees showed high nVVI possibly related to vigour increase. nVVI was, finally used within a Decision Support System (DSS) specifically designed to support tree failure risk management in wide areas, like the natural parks. It was found that such approach can result in an economic saving of about 52% compared to more traditional tree stability surveys. If present, a nVVI map can highlight incipient vegetative anomalies permitting tree stability surveys to be better prioritized.

摘要

对活力下降的检测和监测对于森林经营者支持未来的干预活动肯定是有用的。在这项工作中，从Sentinel-2检索到的NDVI（归一化植被指数）时间序列中提出了一个新指标，以下称为“归一化植被活力指数（nVVI）”，该指数专门用于量化和绘制树势下降。结果证明nVVI与树龄呈负相关（r = −0.815，p<0.001）：较老或不健康的树木显示出较低的nVVI值；年轻的树木显示出较高的nVVI，可能与活力增加有关。nVVI最终用于决策支持系统（DSS）中，该系统专门设计用于支持广泛的区域（如自然公园）的树木衰竭风险管理。已发现，与更传统的树木稳定性调查相比，这种方法可节省约52％的经济。如果存在，nVVI图可以突出显示初期的植物异常，从而可以更好地确定树木的稳定性。