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

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.