Measuring Forest Biodiversity on the Ground and in the Air: Comparing
Biodiversity Estimates from Ground-Based Surveys and Areal Imagery
Abstract
Forest biodiversity has been declining across the globe due to
anthropogenic activities. Losses of biodiversity have led to reduced
forest health and ecosystem services. Therefore, it has become necessary
to monitor changes in biodiversity over wide geographic areas. Remote
sensing has the potential to monitor biodiversity changes, but the
accuracy in which it can be estimated is under debate. In this study, we
tested 1) the relationship among distinct metrics of biodiversity, 2)
the role topographic measures have on determining biodiversity, and 3)
the ability of hyperspectral remote sensing to estimate biodiversity in
temperate forests of the Northeastern United States. We characterized
biodiversity according to four different metrics: species, functional,
structural, and phylogenetic diversity. All four metrics were quantified
using species inventory data as well as Light Detecting and Ranging
(LiDAR) to calculate additional indices of structural diversity. A
digital elevation model was used to obtain measures of slope, aspect,
and other topographic indices such as topographic wetness. Hyperspectral
imagery was used to obtain reflectance, entropy, and several vegetation
indices. In our analyses, species, functional, and phylogenetic
diversity were shown to be moderately correlated suggesting similarities
between the metrics while correlations between structural diversity and
the other metrics were weak. The calculated topographic indices also
showed weak correlations with the biodiversity metrics suggesting that
topography does not influence measures of biodiversity at the plot
level. Depending on the biodiversity metric, relationships between the
hyperspectral analyses and biodiversity were weak to moderately strong.
These findings suggest that hyperspectral imagery holds some potential
for estimating multiple metrics of biodiversity.