Observing Laramie Basin Grassland Phenology Using MODIS

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Observing Laramie Basin Grassland Phenology Using
MODIS
Josh Reynoldswith
Introduction
Phenology is the study of the changes organisms
undergo in response to seasonality and
environmental factors. The Laramie Basin is an
excellent place to investigate this field because
of its broad range of vegetation types and its
different types of environmental conditions. The
location has areas with varying access to water
sources and areas situated at various elevations.
Mixed-grasses are the predominant vegetation type
and will be the subject of investigation.
Dr. Ramesh Sivanpillai Botany and WyGISC
Dr. Steve Prager Geography Department
PROPOSED RESEARCH PROJECT
Study Area
Hypothesis
It is hypothesized that analysis of MODIS imagery
is an effective tool in modeling grassland
phenological responses to the Laramie Basin
climate variability, specifically during drought
and wet periods.
Importance of Study
Methods

• Analysis of phenological information may aid
• Ranchers in identifying prime grazing locations
• Those attempting to predict drought conditions
• Firefighters in predicting areas susceptible to
  fire

• MODIS data collected from the year 2000 to
  present will be used to measure the amount of
  spectral reflectance corresponding to several
  sampling plots distributed along north-south
  (latitudinal) and east-west (longitudinal)
  gradients. 
• NVDI values can be plotted along a curve to
  identify phenological trends.
• Using these trends, different phenological stages
  or growth periods such as green-up, maturity,
  senescence, and dormancy will be approximated.
• Comparing growth periods between years will
  provide insights on how grasslands respond to
  environmental conditions. 
• Comparison of growth periods along the gradients
  will provide insights on how their geographic
  location influences their responses within and
  between years.  

Remote Sensing MODIS
Changes in phenology can be measured using remote
sensing. Remote sensing is a technique used to
obtain information about objects through the
analysis of data collected by instruments not in
physical contact with the objects. The Moderate
Resolution Imaging Spectroradiometer (MODIS) is a
remote sensing instrument aboard two different
satellites which acquires data in the red and
infrared bands of the spectrum at 250 m x 250 m
spatial resolution. Chlorophyll in healthy leaves
have high spectral reflectance in infrared and
low reflectance in red. In stressed or unhealthy
leaves this reflectance pattern changes, which
can be calculated in the form of the Normalized
Difference Vegetation Index (NDVI). The NDVI is a
measure of vigor and can be used to quantify
concentrations of green-leaf vegetation in the
desired study area.
Example MODIS Imagery
Further Readings

• MODIS Website
• modis.gsfc.nasa.gov/
• Soudani, et. al Evaluation of the potential of
  MODIS satellite data to predict vegetation
  phenology in different biomes. Remote Sensing Of
  Environment 132, (May 15, 2013) 145-158.
• Zhang, et. al Monitoring Vegetation Phenology
  using MODIS. Remote Sensing Of Environment 84.3
  (2003) 471.

Expected Results
When plotting growth periods of a specific year
against those of the average of the years, one
should be able to observe changes in phenological
response times. Wet years should have earlier
response periods and drought years should have
later response periods.
Purpose Statement
This research will investigate the use of the
MODIS in detecting phenological changes in
grasslands in the Laramie Basins varying
environmental conditions.
Example of growth period curve (Zhang). Point 1
Green-up, Point 2 Maturity Point 3 Senescence,
Point 4 Dormancy
Acknowledgments Steven Prager, Dept. of
Geography Ramesh Sivanpillai, Dept. of Botany
WyGISC University of Wyoming McNair Scholars
Program and Staff Zackie Salmon and Susan
Stoddard
Background image courtesy of Snowbird Homes and
Land, Inc.