AVHRR NDVI Baseline for Natural Vegetation Ecosystems in Northern Canadian National Parks

摘要

The establishment of a set of vegetation baseline values for the sub-arctic protected ecosystems would permit the identification of ecosystem change in the context of global change. A common satellite-based index, the Normalized Difference Vegetation Index (NDVI), has a long history of use and can be averaged to establish a “normal” vegetation condition in a given region for a given time. Based on an analysis of 23-year NDVI time series data derived from the Advanced Very High Resolution Radiometer (AVHRR) satellite imagery, this study investigated a simple method to establish a set of NDVI baseline for the sub-arctic natural ecosystems in the 12 Canadian northern National Parks. The key result of this study is that a set of annual and monthly NDVI baseline for each area of interest has been established. The NDVI baseline was further compared to a warm and a cool year to assess vegetation conditions. Comparison results indicated better vegetation conditions in warm years and worse vegetation conditions in cool year. The different deviation patterns over the years occurred in different parks, probably as the result of regional climatic properties, vegetation types, and elevations. The implication of this study is that newly-acquired NDVI values can be compared to this established baseline, both in a temporal and spatial dimension, to allow policy maker, land managers and other sub-arctic researchers to gauge the current conditions against those of previous years.