10:15 AM - 10:30 AM
[HTT19-06] Spatial pattern analysis of void spaces within forest canopy for forest connectivity
Keywords:Laser, Forest fire, Void space, Connectivity
Forest is composed of a group of trees with their various spatial patterns. Landscape ecology filed has focused on the distribution of trees and evaluate their connectivity among them. And forest connectivity is called as a corridor and important for animal migration, the wind, seed disposal through the corridor. About forest connectivity study, the data has been acquired above forest canopy and the void spaces within forest canopy have been hidden by the overstories. This study is aimed to quantify the void spaces inside forest canopy and understand their spatial patterns.
The void spaces inside forest are defined by the space underneath forest canopy and do not include the gap among trees. The gap is an open space created by disturbance. But the void spaces we focus are located inside forest canopy. This study utilizes terrestrial laser scanner which can take 3D data to get the fine resolution structure within forest canopy. With the fine data, three indices such as dominant cover, proximity, and isolation are applied to analyze their spatial patterns. Then hierarchical clustering is used to make groups with similar patterns.
Three dimensional data was acquired by terrestrial laser scanner at the Omucho, Hokkaido where the natural fire happened in 2019. The differential Normalized Burn Ratio (dNBR) was computed from Sentinel-2 images through Google Earth Engine and 20 plots were established based on different fire severity levels. Forest fire sites were used for this void space analysis, because the disturbance is the main driver to change their spatial patterns. When the void space distribution is compared with dNBR, the spatial pattern change caused by fire is evaluated. This study compares between dNBR values which indicates fire severity and classified void space derived from 3D data.
As a result, dominant cover and proximity indices were mainly related with fire severity. Forest fire changes the dominant cover and connectivity of the void space dramatically. Four groups were found from clustering analysis among 20 plots to show the different spatial patterns.
High frequent fire areas such as US and Australia have more serious issues of after-fire vegetation recovery. After sever fire, forest is lost and can be changed to a grass land permanently. The void space underneath forest canopy is the nursing place of small seedlings of next generation trees in moderating dramatic change of weather, controlling light environment, and keeping moisture and nutrient. As the next step, the hidden connectivity underneath forest canopy is evaluated in a larger area.
The void spaces inside forest are defined by the space underneath forest canopy and do not include the gap among trees. The gap is an open space created by disturbance. But the void spaces we focus are located inside forest canopy. This study utilizes terrestrial laser scanner which can take 3D data to get the fine resolution structure within forest canopy. With the fine data, three indices such as dominant cover, proximity, and isolation are applied to analyze their spatial patterns. Then hierarchical clustering is used to make groups with similar patterns.
Three dimensional data was acquired by terrestrial laser scanner at the Omucho, Hokkaido where the natural fire happened in 2019. The differential Normalized Burn Ratio (dNBR) was computed from Sentinel-2 images through Google Earth Engine and 20 plots were established based on different fire severity levels. Forest fire sites were used for this void space analysis, because the disturbance is the main driver to change their spatial patterns. When the void space distribution is compared with dNBR, the spatial pattern change caused by fire is evaluated. This study compares between dNBR values which indicates fire severity and classified void space derived from 3D data.
As a result, dominant cover and proximity indices were mainly related with fire severity. Forest fire changes the dominant cover and connectivity of the void space dramatically. Four groups were found from clustering analysis among 20 plots to show the different spatial patterns.
High frequent fire areas such as US and Australia have more serious issues of after-fire vegetation recovery. After sever fire, forest is lost and can be changed to a grass land permanently. The void space underneath forest canopy is the nursing place of small seedlings of next generation trees in moderating dramatic change of weather, controlling light environment, and keeping moisture and nutrient. As the next step, the hidden connectivity underneath forest canopy is evaluated in a larger area.