Characterizing bracken fern phenological cycle using time series data derived from Sentinel-2 satellite sensor

Area of Science:

• Ecology
• Remote Sensing
• Invasive Species Management

Background:

• Bracken fern (Pteridium aquilinum) is an invasive plant causing significant ecosystem disturbances.
• Effective management of bracken fern requires understanding its phenological cycle.
• Satellite remote sensing offers a scalable approach to monitor vegetation dynamics.

Purpose of the Study:

• To characterize the phenological cycle of bracken fern using Sentinel-2 satellite data.
• To compare the performance of Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index 2 (EVI2) in tracking bracken fern phenology.
• To validate satellite-derived phenological metrics against ground observations.

Main Methods:

• Utilized Sentinel-2 satellite imagery for NDVI and EVI2 time series data.
• Employed the TIMESAT program for data processing, including outlier removal and model fitting.
• Compared satellite-derived phenological metrics with ground-observed bracken fern phenological events.

Main Results:

• Bracken fern phenological metrics derived from satellite data showed strong agreement with ground observations (R2 = 0.53–0.85, p < 0.05).
• EVI2 demonstrated superior performance over NDVI in estimating bracken fern phenological metrics.
• The study successfully extracted key phenological metrics crucial for management.

Conclusions:

• Satellite-derived vegetation indices, particularly EVI2, are reliable tools for monitoring bracken fern phenology.
• Accurate phenological data aids in precise control and active protection strategies against bracken fern invasion.
• This research provides critical insights for managing invasive bracken fern in susceptible rangelands.