Estimating Stand Volume and Stand Density Using Sentinel-2 Sattelite Imagery and ICESat-2 LIDAR Data: A Case Study in Kocayaren Planning Unit


Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Karadeniz Teknik Üniversitesi, Orman Fakültesi, Orman Mühendisliği, Türkiye

Tezin Dili: İngilizce

Öğrenci: Matthew Wojcik

Danışman: Uzay Karahalil

Özet:

Conducting a forest inventory is a crucial component of any forest management plan.

Traditional methods of taking field measurements are both time and labor intensive, in addition

to being cost prohibitive. Progressive developments in remote sensing technology have

provided an enhanced opportunity to collect increasingly precise forest stand parameter

estimations with less need for field surveys. This study makes use of spectral data and LiDAR

data from Sentinel-2 and ICESat-2 missions, respectively, as well as TIN-derived topographic

features to estimate stand volume and stand density in the Kocayaren Planning Unit, Turkey.

First, spectral data for 109 total plots extracted from Sentinel-2 including band reflectance

values and vegetation indices were compared. A combination of band reflectance values and

vegetation indices provided the best results. Spectral data was better able to predict stand

volume than tree density. The best model developed for stand volume using only spectral data

included the RVI and the NDMI, and bands 2, 3, 8a, 9, and 11, and yielded an adjusted R2 of

0.669 and RMSE of 39.125 m3 ha-1. The best model developed for number of trees included

the SAVI, EVI, RVI, IRECI, and bands 5 and 6, with a resulting adjusted R2 of 0.483 and

RMSE of 274 n ha-1. Secondly, further models including TIN-derived topographic features

were examined. The best models developed from variables that included topographic features

exhibited adjusted R2 values of 0.658 and 0.514 and RMSEs of 39.795 m3 ha-1 and 265 n ha-1

for stand volume and number of trees, respectively. Slope was the only topographic feature that

showed up in both models. Through the process of validation, it was determined that a

statistically significant relationship exists between the explanatory variables and stand volume,

but not with the number of trees, thereby rendering models for number of trees unsuitable.

Lastly, select plots that harbored ICESat-2 LiDAR data points were separated and models

including these data were created. It was found that the ICESat-2 LiDAR was not effective in

tree height estimation, and therefore did not have a significant relationship with stand volume

or the number of trees.