Decadal landscape and species level greenness patterns in a northern Chihuahuan Desert Shrubland

William Beamon, Gesuri Ramirez, Libia Gonzalez-Alonso, Robin Luna, Alina Jaimes, Craig Tweedie, Marguerite Mauritz

In desert ecosystems the appearance of greenness in plants signifies the presence of adequate temporal and spatial resources along with tolerance of the desert climate that allows for cellular respiration and development through phenological events.  The duration of a plants phenological event such as leaf growth, flower and fruit production, and seed release are sensitive to a variety climate conditions; as these events have annual and seasonal variability.  To better understand the significance of desert plant greenness, four hard-mounted digital cameras set to capture repeat imagery from a fixed field of view collected landscape images at the Jornada Long Term Ecological Research site in the Chihuahuan desert starting in June 2010.  For quantifying greenness, these images will be analyzed using Photoanalyzer software within the red, green, blue (RGB) color spectrum by identifying of regions of interest (ROI) within the images to create relevant spectral landscape or specific greenness data.  From the this data we hope to research and understand the following questions:

            • How does the greenness signal of the landscape vary over time? 

            • How have species-specific greenness patterns of Honey mesquite (Prosopis glandulosa) and Creosotebush (Larrea tridentata) change over time and how do phenological process relate to these changes

            • How is data relating to patterns of greenness effected by increasing proportion of bare- ground cover in ROIs?

            • How do site-level spectra RGB patterns correlate to eddy covariance, climate, or NDVI indices?

In dryland ecosystems phenological variability expressed as plant greenness may provide insight on the capacity of shrubland plants to act as a sink and sequester carbon from the from the atmosphere.  Assessing variations in the greenness of desert landscapes and greenness attributes of specific desert shrub species may also lead to below ground inference in how desert plants interact with the abiotic environment, allocate water seasonally, and spatial heterogeneity of desert soils.