Tropentag, October 6 - 8, 2009 in Hamburg "Biophysical and Socio-economic Frame Conditions for the Sustainable Management of Natural Resources"

Model for Estimation of Acacia senegal Volume from NDVI

¹College of Forestry and Range Science, Forestry, Sudan
²Technische Universität Dresden, Institute of Photogrammetry and Remote Sensing, Germany
³Technische Universität Dresden, Institute of Forest Growth and Forest Computer Sciences, Germany

Abstract

This study has been conducted to produce a model for the estimation of the stand volume of Acacia senegal using the Normalized Difference Vegetation Index (NDVI) and a field inventory. The study has been carried out during 2007-2008 in the southern Kordofan state in Sudan where this species has a great economic and environmental importance ranging from gum Arabic production to soil reclamation.
The study used NDVI values produced from the Terra ASTER satellite imagery data and normal forest inventory data. A stratified random sampling design has been used for the collection of the field data to estimate the Acacia stand volume (tree height and diameter), in order to calculate the volume for each sample plot. The satellite data were used to produce NDVI maps and to calculate the pixel value for each sample plot. Finally the calculated stand volume has been correlated with the NDVI values using SPSS. An algorithmic model has been produced to estimate the stand volume of A. senegal from the NDVI value: Volume = a0+a1*ln(NDVI) with a0= .420; a1= .750; ln = the natural logarithm; NDVI= Mean NDVI for sample plot of 0.36 ha.
The model will help to quickly estimate the standing volume for A. senegal which could assist the forecast for gum Arabic production and the estimation of tree damage by insects, fire or other factors. This study also showed the possibility to use remotelty-sened data of medium resolution together with field inventory for providing data for forest management. This study could be an initiative for replication and production of models for other (tree) species.

Keywords: Acacia senegal, modelling, NDVI

Contact Address: Mahgoub Suliman Mohamedain, College of Forestry and Range Science, Forestry, Wad Madani, 11113 Khartoum, Sudan, e-mail: mahgoubsulyahoo.co.uk