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Finding a method for simplified biomass measurements on Sahelian grasslands

Palm, Elise LU (2013) In Student thesis series INES NGEM01 20112
Dept of Physical Geography and Ecosystem Science
Abstract
Traditional measurements for determination of aboveground biomass (AGB) are widely used in ecological studies. However, they are labor demanding and time consuming, why this study performed on a grassland in Senegal has focused on finding a simplified AGB estimation method that could be applied on larger areas in the Sahel. The brightness values in the visible spectral range of digital camera images (DCIs) have been tested for correlation with traditional AGB using three already established indices leading to r2 values of 0.57, 0.56 and 0.43 (all attained p=<0.0001) when including all four measurement occasions, and r2 values of 0.63, 0.61 and 0.51 (p=<0.0001) when excluding the last occasion, which had a high amount of yellowing grasses.... (More)
Traditional measurements for determination of aboveground biomass (AGB) are widely used in ecological studies. However, they are labor demanding and time consuming, why this study performed on a grassland in Senegal has focused on finding a simplified AGB estimation method that could be applied on larger areas in the Sahel. The brightness values in the visible spectral range of digital camera images (DCIs) have been tested for correlation with traditional AGB using three already established indices leading to r2 values of 0.57, 0.56 and 0.43 (all attained p=<0.0001) when including all four measurement occasions, and r2 values of 0.63, 0.61 and 0.51 (p=<0.0001) when excluding the last occasion, which had a high amount of yellowing grasses. Some of the DCIs were also visually interpreted after performing an unsupervised image classification in two groups. This did not seem to reveal any new insights in the usage of DCIs as estimation of AGB. Grass height, on the other hand, showed a higher correspondence with AGB (r2=0.79 and p<=0.0001 for all occasions and r2=0.70 and p<=0.0001 when excluding the last occasion). In addition to the higher correlation, measuring grass height is also the least expensive and the quickest of the methods investigated in this study and can hopefully be applied on larger areas by local farmers. (Less)
Please use this url to cite or link to this publication:
author
Palm, Elise LU
supervisor
organization
course
NGEM01 20112
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Geography, Physical geography, biomass, grasslands, Sahel, digital camera images, LAI
publication/series
Student thesis series INES
report number
286
funder
SIDA, Minor Field Study programme (MFS)
language
English
additional info
Supported with funding from SIDA's Minor Field Study (MFS) Programme.
id
4145588
date added to LUP
2013-11-18 08:51:53
date last changed
2013-11-18 08:51:53
@misc{4145588,
  abstract     = {Traditional measurements for determination of aboveground biomass (AGB) are widely used in ecological studies. However, they are labor demanding and time consuming, why this study performed on a grassland in Senegal has focused on finding a simplified AGB estimation method that could be applied on larger areas in the Sahel. The brightness values in the visible spectral range of digital camera images (DCIs) have been tested for correlation with traditional AGB using three already established indices leading to r2 values of 0.57, 0.56 and 0.43 (all attained p=<0.0001) when including all four measurement occasions, and r2 values of 0.63, 0.61 and 0.51 (p=<0.0001) when excluding the last occasion, which had a high amount of yellowing grasses. Some of the DCIs were also visually interpreted after performing an unsupervised image classification in two groups. This did not seem to reveal any new insights in the usage of DCIs as estimation of AGB. Grass height, on the other hand, showed a higher correspondence with AGB (r2=0.79 and p<=0.0001 for all occasions and r2=0.70 and p<=0.0001 when excluding the last occasion). In addition to the higher correlation, measuring grass height is also the least expensive and the quickest of the methods investigated in this study and can hopefully be applied on larger areas by local farmers.},
  author       = {Palm, Elise},
  keyword      = {Geography,Physical geography,biomass,grasslands,Sahel,digital camera images,LAI},
  language     = {eng},
  note         = {Student Paper},
  series       = {Student thesis series INES},
  title        = {Finding a method for simplified biomass measurements on Sahelian grasslands},
  year         = {2013},
}