Remote sensing evaluation of the impacts of fog on vegetation dynamics in the Namib Desert

Nonrainfall waters (e.g., fog and dew) are important water sources for many ecosystems, especially in drylands. Identifying the vegetation responses to nonrainfall water is essential to predict the climate change impacts to dryland ecosystems. It has been reported that fog water could be utilized by various vegetation forms and fog could alleviate the vegetation drought responses. However, majority of the fog-vegetation studies focus on individual plant scale, the relationship between fog and vegetation dynamics in larger spatial scales has not been reported in literature. To this end, we examined how fog influences the vegetation dynamics utilizing both optical and microwave remote sensing derived vegetation data and observed fog data in the Namib Desert. Vegetation dynamics were represented by vegetation indices from optical data and vegetation optical depth from passive microwave data. Daily fog data during non-rainfall and rainfall periods were used to investigate the vegetation responses to fog occurrences. Significant relationships were found between fog and vegetation dynamics. The relationships were observed for both optical and microwave data. These findings suggested that fog impacts on vegetation can be observed from space and remote sensing data can be used in monitoring and quantification of fog contributions to vegetation activity in the fog-dominated ecosystems.