Remotely sensed vegetation greening along a restoration gradient of a tropical forest, Kibale National Park, Uganda
Anu Valtonen, Eveliina Korkiatupa, Sille Holm, Geoffrey M. Malinga, Ryosuke Nakadai
Abstract
Abstract Restoration has now emerged as a global priority, with international initiatives such as the “UN Decade on Ecosystem Restoration (2021–2030)”. To fulfill the large‐scale global restoration ambitions, an essential step is the monitoring of vegetation recovery after restoration interventions. This study aimed to evaluate the utility of remotely sensed vegetation indices, using the normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI), to monitor the progress of forest regeneration across a tropical forest restoration project area in Kibale National Park, Uganda. Using the chronosequence approach, results indicated non‐linear patterns in NDVI and EVI across the first 25 years of recovery. Both NDVI and EVI increased for the first 10 years of forest regeneration. This 'greening' phase could be used as the indicator of the successful onset of forest recovery. In particular, the decline of elephant grass, and the consequent arrival of shrubs and trees, can be detected as an increase in NDVI. Primary forests differed from the 25‐year‐old regenerating forests based on the unique combination of low mean and low seasonal variation in EVI. Our results, therefore, suggest that the long‐term success of forest restoration could be monitored by evaluating how closely the combination of mean, and degree of seasonal variation in EVI, resembles that observed in the primary forest.