Remotely sensed vegetation greening along a restoration gradient of a tropical forest, Kibale National Park, Uganda

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.

Processes and mechanisms of vegetation ecosystem responding to climate and ecological restoration in China

“…In accordance with previous studies using time-unvarying methods, most vegetated lands have experienced overall greening over nearly four decades, and occurred in central and south China ( Jong et al., 2011 ; Zhu et al., 2016 ). Actually, most of the browning trends were detected in this study by nonlinear methods, and this was supported by other studies at regional and continental scales ( Cunha et al., 2015 ; Nyamekye et al., 2020 ; Valtonen et al., 2021 ). Some studies have pointed out that the 1990s was an important turning point for global vegetation changes ( Wen et al., 2017 ; Zhang et al., 2021a ), which is consistent with the results obtained in this study, where half pixels in China showed breakpoints in interannual NDVI variations in the 1990s.…”

Comparative Analysis of Old-Growth Stands Janj and Lom Using Vegetation Indices

“…On the other side, EVI index could be more sensitive for detecting the different successional stages between intermediate-aged regenerating and primary forest [17] higher values of the index indicate a more mature phase of old-growth forest development, Figure 3. Higher values of VARI index in OG Lom can be related to an average volume of Coarse Woody Debris (CWD) in OG Lom (327 m 3 •ha −1 ) compared to OG Janj (386,5 m 3 •ha −1 ).…”

Restoration of Vegetation Greenness and Possible Changes in Mature Forest Communities in Two Forests Damaged by the Vaia Storm in Northern Italy

“…To evaluate whether the model with which the NDVI trend was estimated ( Figure 3 ) is correct, it would be good to calculate the NDVI of the two study areas over the next 5–20 years by applying methods/tools that can minimize the errors due to technical limitations [ 50 , 51 ]. In fact, according to Valtonen et al [ 52 ], the NDVI values of areas affected by forest restoration increase only in the first 10 years of forest regeneration and then stabilize (from 10 to 25 years) around 0.8. The results of the research of Sun et al [ 50 ] also showed a “greening” phase in the 10 years that followed the environmental restoration works of a river corridor in China.…”

“…The results of the research of Sun et al [ 50 ] also showed a “greening” phase in the 10 years that followed the environmental restoration works of a river corridor in China. This “greening” phase, if it is also be observed for the regeneration of forests in the Alps (such as those under study), could be used as an indicator of the success of forest recovery [ 52 ] in combination with other ecological indices (based on the floristic features of the vegetation) developed to evaluate the success of environmental restoration works [ 53 ].…”