Data from: Linking grassland canopy structure and function responses to field experimental drought both seasonally and interannually

Shifts in species composition in water-limited ecosystems such as
temperate prairies during summer droughts can lead to community-level
changes. In both short-term experimental and long-term drought events, C4
species decline in abundance while C3 species increase, causing reductions
in above ground net primary productivity (ANPP). Thus, this study focused
on linking experimental drought-induced shifts in species composition with
changes in canopy structure and function using remote sensing approaches.
We took advantage of a long-term experimental precipitation study in
Central Oklahoma that has established a gradient of seven levels of
precipitation in a fully factorial randomized block design: −100%, −80%,
−60%, −40%, −20% rainfall exclusion, 0% change in precipitation (i.e.,
control) and precipitation addition +50%. Our aim was to answer the
following questions: (1) How does an experimental precipitation gradient
impact canopy spectral reflectance both seasonally and interannually? (2)
How does canopy structure and plant species composition vary seasonally
and interannually along an experimental precipitation gradient? (3) Can we
link variation in canopy reflectance to canopy structure and plant species
composition under experimental drought both seasonally and interannually?
Our results showed that variation in seasonal and interannual
precipitation can be observed in the near-infrared (NIR) portion of the
electromagnetic spectrum. A drier year has lower normalized vegetation
index (NDVI) values and higher leaf area index (LAI) values due to reduced
canopy greenness and increased plant litter, respectively, due to the
limited water availability. High abundance of C3 species such as Lespedeza
cuneata that have advantageous traits can mediate canopy responses to
drought. Thus, species specific abundance, in this case the high abundance
of L. cuneata, can influence canopy reflectance. Future studies should
focus on understanding the impacts of resource allocation to canopy
architecture as well as the relationship between leaf traits and canopy
response and how these affect canopy reflectance.