Combining ground and remote sensing data to estimate forest canopy damage and recovery from tropical cyclones over a pantropical soil phosphorus gradient

This project is a part of the NGEE-tropics initiative. This specific research was conducted through Lawrence Berkeley National Laboratory and University of California, Berkeley and administered by the principle investigator, Dr. Lara Kueppers. Dellena Bloom is the main author of this repository, data produced, and manuscript detailing results of this project, with coauthors including Dr. Barbara Bomfim, and Yanlei Feng.

– Status: Completed

Objective

This project is under the RFA2 section of NGEE-tropics, tasked to study variations in forest composition and structure with varying resource availability and disturbance. Here we studied the correlation between tropical forest damage due to cyclone events and soil phosphorus concentrations utilizing vegetative indices attained from Google Earth Engine.

Acknowledgements

• This work was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internship (SULI) program.

Methods Used

• Correlations
• Data Visualization
• Regressions
• Mixed Effects Models

Technologies

• R
• Google Earth Engine

Project Overview

Cyclones alter tropical forest function, composition and structure, making effects of intensifying cyclones on carbon-rich forests a critical topic of study. Here, we quantified cyclone-induced damage and recovery of 21 cyclone disturbances affecting 9 sites between 2004-2017 through pantropical forests utilizing selected leaf area index (LAI) and enhanced vegetation index (EVI). Although LAI and EVI were chosen to report, seven vegetative indices total were collected including normalized difference vegetation index (NDVI) at three different resolutions, EVI at two different resolutions, LAI, and transformed NDVI (kNDVI). Field observations collected in a meta-analysis were used to ground-truth and test effects of soil resource availability and disturbance factors on damage and recovery. We found large variations of cyclone-induced deltaLAI and deltaEVI across the tropics. The highest reduction in LAI, -76.6%, and EVI, -76.7%, occurred in Mexico and Puerto Rico, respectively. Pantropical deltaLAI (r = -0.52) and deltaEVI (r = -0.60) correlated with delta litterfall. Post-cyclone data showed recovery of LAI by 4 months, EVI by 2 months, and litterfall by 10 months post-cyclone. deltaLAI was correlated with soil phosphorus (r = -0.47, P-value = 0.031). PCA demonstrates grouping of regions among variables. Results show higher cyclone-induced damage in areas with high soil phosphorus, corroborating previous studies, and in areas with higher litterfall. This study demonstrates the potential for extrapolation of relationships established using ground-based observations across a wider array of cyclone prone tropical forests and for observing effects of tropical cyclone regime alterations under climate change.

Getting Started

1. Clone this repo (for help see this tutorial).
2. Published raw Data is being kept here.
3. GEE documented data extraction code is kept here.
   • Bloom_GEE_code_doc.pdf
4. Data visualization code is kept here.
   • Code to produce all plots found in Bloom_NGEEtropics_paper_plots.R
5. Code used to run statistical analyses is kept here.
   • Bloom_NGEEtropics_paper_stats.R

Featured Deliverables

• Data product
  • Dellena Bloom, Barbara Bomfim, Lara Kueppers, Yanlei Feng(2022). LAI, EVI, NDVI, and kNDVI in 23 pantropical forests affected by 21 cyclones. NGEE Tropics Data Collection. Accessed at http://dx.doi.org/10.15486/ngt/1847332.
• Manuscript
  • Citation

Collaborators

Project lead: Dellena Bloom([email protected])

Other Members:

Name	GitHub Handle
Barbara Bomfim	@bdbomfim
Yanlei Feng	@
Lara Kueppers	@lmkueppers

Contact

• Dellena Bloom ([email protected])