|M.Sc Student||Bar Massada Avi|
|Subject||Multi-Temporal Assessment of Above-Ground Forest Biomass|
Using Allometric Equations and Aerial Photographs
|Department||Department of Agricultural Engineering||Supervisors||PROF. Yohay Carmel|
|PROF. Dan Yakir|
|ASSOCIATE PROF. Gilad Even-Tzur|
Studies of forest biomass dynamics typically use long-term forest inventory data, available only in few places around the world. In places were no such data exist, it is desirable to develop alternative methods for the assessment of biomass dynamics. Here, a novel methodology is presented, where photogrammetric measurements of aerial photos are used as an alternative to time-series of field measurements. The objective of this study is to develop a method for multi-temporal assessment of forest biomass dynamics, using aerial photos and allometric equations. Photogrammetric methods were used to measure tree height and tree crown diameter, using aerial photographs of Yatir forest, Israel, in the years 1978, 1987, 1992, 1996 and 2003. The measurements were then transformed to biomass, using an allometric equation generated with data from 28 trees. The validity of the biomass estimate in 2003 was assessed with a randomization test that used empirically estimated measurement errors from 60 trees.
The allometric equation was highly significant, which is surprising since tree height and crown diameter are rarely significant predictors of biomass. Mean tree biomass grew linearly in the past 10 years. Stand density had a large effect on tree growth, as the forest was subject to frequent thinning treatments. Mean tree biomass in 2003 was 91.8 (± 59.12) Kg, and mean plot biomass was 2.39 Kg/m2. It is concluded that the method performed fairly well in the case study of Yatir Forest. This method might serve as an alternative to field sampling for forest biomass dynamics studies.