Shapefiles of canopy disturbances for the 50-ha plot on Barro Colorado Island, Panama, for 2014-2019

Shapefiles of canopy disturbances for the 50-ha Smithsonian ForestGEO plot on
Barro Colorado Island, Panama, for 46 successive time intervals (47 dates)
between 2 October 2014 and 28 November 2019. We defined a canopy disturbance
as a substantial decrease in canopy height in a contiguous patch of canopy
occurring over one measurement interval. We identified canopy disturbances
through a combination of analysis of the canopy surface model changes and
visual interpretation of the orthomosaics. We first differenced surface
elevation models for successive dates to obtain a raster of the canopy height
changes for the associated interval. We then pre-delineated major canopy
disturbances by filtering for areas in which canopy height decreased more than
10 m in contiguous areas of at least 25 m2, and that had an area-to-perimeter
ratio greater than 0.6. We note that 25 m2 is the minimum gap area used in
previous studies of this site by Brokaw (1982) and Hubbell et al. (1999). The
area-to-perimeter condition removes artifacts associated with slight shifts in
the measured positions of individual trees from one image set to another,
whether due to wind or alignment errors (note that this criterion involves a
combination of shape and size). Finally, we systematically examined 1-ha
square subplots for each pair of successive dates and edited the pre-
delineated polygons, removed false positives, and added visible new canopy
disturbances that were not previously delineated (whether because they were
too small in area or in canopy height drop). We also classified disturbances
as being due to treefalls (a whole previously live tree fell, creating a
clearly visible gap on the forest floor, or the whole live crown disappeared),
branchfalls (a portion of a live crown broke), or standing dead trees
disintegrating based on visual inspection of the orthomosaics. Before and
after orthomosaic classifications are shown in Figure S2 of the associated
Biogeosciences article by Araujo et al.

These data are licensed under CC BY, meaning use of the data is allowed so
long as attribution is given via citation. These data should be cited either
as an individual dataset or as part of the larger collection:

Araujo, Raquel F., Samuel Grubinger, Milton Garcia, Jonathan P. Dandois, and
Helene C. Muller-Landau. 2021. Shapefiles of canopy disturbances for the 50-ha
plot on Barro Colorado Island, Panama, for 2014-2019. Smithsonian Figshare.
DOI:10.25573/data.14417915

or

Araujo, Raquel F., Samuel Grubinger, Milton Garcia, Jonathan P. Dandois, and
Helene C. Muller-Landau. 2021. Collection of datasets: Strong temporal
variation in treefall and branchfall rates in a tropical forest is related to
extreme rainfall: results from 5 years of monthly drone data for a 50-ha plot.
Smithsonian Figshare. DOI: 10.25573/data.c.5389043

These datasets were used in the following peer-reviewed journal article:

Araujo, R. F., S. Grubinger, C. H. S. Celes, R. I. Negrón-Juárez, M. Garcia,
J. P. Dandois, and H. C. Muller-Landau. 2021. Strong temporal variation in
treefall and branchfall rates in a tropical forest is related to extreme
rainfall: results from 5 years of monthly drone data for a 50-ha plot.
Biogeosciences.

The code used to analyze these data for this article are available in GitHub,
at https://github.com/Raquel-Araujo/gap_dynamics_BCI50ha

Author contribution for datasets for 2014-2015: Helene C. Muller-Landau
conceived the research, wrote the grant proposal that funded the research, and
designed data collection. Jonathan Dandois constructed the drones, led drone
data collection, performed photogrammetry processing, and did preliminary
horizontal alignment. Samuel Grubinger finalized horizontal and vertical
alignment and identified canopy disturbances. Raquel F. Araujo revised canopy
disturbances and classified them as branchfalls, treefalls, or standing dead
trees.

Author contribution for datasets for 2016-2019: Helene C. Muller-Landau
conceived the research and designed the data collection. Milton Garcia led
drone data collection and processed drone imagery. Raquel F. Araujo performed
horizontal and vertical alignment, identified canopy disturbances, and
classified disturbances as branchfalls, treefalls, or standing dead trees.

Acknowledgments: We thank Marino Ramirez, Pablo Ramos, Paulino Villareal and
others for assistance with drone data collection; and Milton Solano for
assistance with data processing and organization. We gratefully acknowledge
the financial support of the Smithsonian Institution Competitive Grants
Program for Science; the Next Generation Ecosystem Experiments-Tropics, funded
by the U.S. Department of Energy, Office of Science, Office of Biological and
Environmental Research; and the Smithsonian Tropical Research Institute
fellowship program. Kristina Anderson-Teixeira, Stephanie Bolman, Richard
Condit, Stuart Davies, Matteo Detto, Jefferson Hall, Patrick Jansen, Stefan
Schnitzer, Edmund Tanner, and S. Joseph Wright were co-PIs on the original
Smithsonian proposal, and we thank them for their contributions to the
proposal and input on the research.