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Data for: Landscape scale variation in the hydrologic niche of California coast redwood

Cite this dataset

Francis, Emily J.; Asner, Gregory P.; Mach, Katharine J.; Field, Christopher B. (2020). Data for: Landscape scale variation in the hydrologic niche of California coast redwood [Dataset]. Dryad.


Topoclimatic diversity within forest landscapes can underlie variation in water availability, which may correspond to patterns in habitat suitability of tree species with differing hydrologic niches. However, the trade-off between the collection of data at a fine grain size over large spatial extents has limited comprehensive analyses of landscape scale variation in habitat suitability. We present a fine scale analysis of the roles of topographic gradients in moisture availability, soil water storage, and fog frequency in the spatial pattern of habitat suitability for coast redwood (Sequoia sempervirens), at 10 m resolution across 34,800 hectares and three landscapes spanning approximately one-third of redwood’s latitudinal range. A new 10 m resolution presence-absence map derived from airborne imaging spectroscopy was used to characterize current redwood distributions in three landscapes. Access to belowground moisture was assessed through four measures calculated from a high-resolution LiDAR digital elevation model, soil water storage was mapped from the USDA Soil Survey Geographic Database, and fog frequency was calculated from MODIS cloud cover data. Access to belowground moisture and fog predicted variation in suitability as redwood habitat from 22–75% and predicted redwood presence and absence at 10 m resolution with 63–74% accuracy. Across all three landscapes, redwood density consistently decreased with increasing interpolated height above a stream (IHAS), but the role of other predictors varied among the sites. Our results challenge previous assumptions that redwood habitat suitability within much coarser resolutions (800 m x 800 m) can be described by a single value. The elevated habitat suitability of sites close to streams suggests that these sites should be evaluated for their potential to become microrefugia within landscapes that may become climatically unsuitable for redwoods at a regional scale. 


This is the dataset corresponding to the manuscript: Francis, E.J., Asner, G.P., Mach, K.J., and Field, C.B. 2020. Landscape Scale Variation 
in the Hydrologic Niche of California Coast Redwood. Ecography. doi: 10.1111/ecog.05080.

This dataset contains maps of redwood presence and absence and six measures of access to moisture in three redwood forest landscapes 
in California. All data are provided as GeoTiff files.

Four of the six measures of access to moisture have been calculated from a high-resolution LiDAR-derived digital elevation model (DEM) collected by 
the Global Airborne Observatory (GAO) from each site. 

Measures calculated from the GAO DEM include: Interpolated height above a stream (IHAS), Topographic Wetness Index (TWI), Curvature, and Heat load index (HLI)
Fog frequency was calculated from NASA MODIS (Moderate Resolution Imaging Spectroradiometer) Data on Cloud Cover.
Soil available water storage was taken from the US Department of Agriculture Natural Resource Conservation (USDA NRCS) Soil Survey Geographic Database.

Detailed methods describing how each measure of access to moisture was produced are provided in the corresponding publication and additional details are 
provided in Appendix S1 Supplementary Text, Supplementary Methods for the corresponding manuscript.

The maps of redwood presence and absence have been produced through a trained classification of airborne imaging spectroscopy data collected by the GAO. 
Detailed methods on the collection of the data, the development of the presence absence maps, and specification of map performance (overall accuracy, true positive rate, false positive rate, and kappa statistic) are provided in the following publication:
Francis, E.J., and Asner, G.P. 2019. High-Resolution Mapping of Redwood (Sequoia sempervirens) Distributions in Three Californian Forests. 
Remote Sensing. 11(3): 351, doi:10.3390/rs11030351.

Usage notes

Details are provided in the README.txt file; please read the file prior to use of the data.


The Global Airborne Obervatory (GAO) Flights over California were funded by the David and Lucile Packard Foundation. The Global Airborne Observatory is made possible by support provided by private foundations, visionary individuals, and Arizona State University.

E.J. Francis was funded by a Stanford Graduate Fellowship in Science and Engineering

Field work was funded by the Save the Redwoods League, Award: 10674

Field work was funded by the Save the Redwoods League, Award: 10674