Introduction
Observing Laramie Basin Grassland
Phenology Using MODIS
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.
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:
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Purpose Statement
This research will investigate the use of the
MODIS in detecting phenological changes in
grasslands in the Laramie Basin’s varying
environmental conditions.
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Dr. Steve
Prager
Dr. Ramesh
Sivanpillai
Geography
Department
Botany and
WyGISC
Study Area
Hypothesis
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.
with
PROPOSED RESEARCH PROJECT
 Ranchers in identifying prime grazing
locations
 Those attempting to predict drought
conditions
 Firefighters in predicting areas susceptible
to fire
Josh Reynolds
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 eastwest (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.
Example MODIS Imagery
Further Readings
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.
Example of growth period curve (Zhang).
Point 1: Green-up, Point 2: Maturity
Point 3: Senescence, Point 4: Dormancy
Background image courtesy of Snowbird Homes and Land, Inc.
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MODIS Website
modis.gsfc.nasa.gov/
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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.
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Zhang, et. al: Monitoring Vegetation Phenology using
MODIS. Remote Sensing Of Environment 84.3 (2003): 471.
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