Extracting the vegetation phenology of tropical monsoon forest

Abstract:

The monsoon forests cover over 40% of tropical forests, and play a significant role in terrestrial ecosystem carbon exchange and water-use efficiency of tropical ecosystems. The monsoons are changing under the global changes, and then impact the vegetation growth. However, the vegetation phenology in this area are difficult to describe, where the “V”-shaped seasonal growth trajectories of tropical monsoon forests are totally different from the normal seasonal trajectories such as the boreal forests.

In this paper, a “V”-shaped curve is proposed to simulate the “V”-shaped seasonal trajectory. Current extractions of the onset of greenness are not suitable for “V”-shaped seasonal trajectory, which are seriously affected by the gaps in the rapid growth stage due to the heavy rain. For its insensitivity to the gaps or noise, the whole “V”-shaped curve was used to determine the phenology of tropical monsoon forest, and the lowest point in “V”-shaped curve was regarded as the phenology. The extracted phenology was showed to be correlated with the precipitation, and the validations with ground observations demonstrated that this new methodology has the ability to extract the phenology of tropical monsoon forest correctly. These phenology maps of tropical monsoon forest assist to understand the impact of climate changes in the monsoon regions.