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

PLoS One. 2021 Oct 28;16(10):e0257196. doi: 10.1371/journal.pone.0257196. eCollection 2021.

Abstract

Bracken fern is an invasive plant that has caused serious disturbances in many ecosystems due to its ability to encroach into new areas swiftly. Adequate knowledge of the phenological cycle of bracken fern is required to serve as an important tool in formulating management plans to control the spread of the fern. This study aimed to characterize the phenological cycle of bracken fern using NDVI and EVI2 time series data derived from Sentinel-2 sensor. The TIMESAT program was used for removing low quality data values, model fitting and for extracting bracken fern phenological metrics. The Sentinel-2 satellite-derived phenological metrics were compared with the corresponding bracken fern phenological events observed on the ground. Findings from our study revealed that bracken fern phenological metrics estimated from satellite data were in close agreement with ground observed phenological events with R2 values ranging from 0.53-0.85 (p < 0.05). Although they are comparable, our study shows that NDVI and EVI2 differ in their ability to track the phenological cycle of bracken fern. Overall, EVI2 performed better in estimating bracken fern phenological metrics as it related more to ground observed phenological events compared to NDVI. The key phenological metrics extracted in this study are critical for improving the precision in the controlling of the spread of bracken fern as well as in implementing active protection strategies against the invasion of highly susceptible rangelands.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ecosystem
  • Introduced Species*
  • Pteridium / physiology*
  • Remote Sensing Technology
  • Satellite Communications

Grants and funding

This work is funded by the National Research Foundation of South Africa (NRF) Research Chair initiative in Land Use Planning and Management (Grant Numbers: 84157). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.