Effects of Forest Disturbances on Forest Biomass Retrieval Model from Lidar Waveform Data
Guoqing
Sun, University of Maryland, guoqing.sun@gmail.com
(Presenting)
K
Jon
Ranson, NASA Goddard Space Flight Center, kenneth.j.ranson@nasa.gov
Large-footprint lidar systems have been developed to provide high-resolution, geo-located measurements of vegetation vertical structure and ground elevations beneath dense canopies. The lidar waveform signature from large-footprint lidar instruments, such as the Laser Vegetation Imaging Sensor (LVIS) has been used to estimate the tree height and forest above-ground biomass [2-6]. The height of the waveform centroid, or the height of Median Energy (HOME) has been identified as a good parameter for predicting above-ground biomass of tropical forests at the plot-level of 0.25-0.5-ha. But in addition to the total biomass the HOME of a lidar waveform depends on other factors such as the reflectivity of ground surface and the spatial structure of the canopy. The relationship between forest carbon storage and the canopy vertical structure information from Lidar waveform is still relatively unexplored. Further studies on the lidar data properties are needed to verify and improve the retrieval algorithms. Forest degradation, which was defined by the UNFCCC (COP-13) as any forest that has experienced a loss, is an important aspect of forest disturbance. The changes in biomass is important for monitoring forest degradation. Other forest structural parameters may also be useful and can be mapped for monitoring forest degradation/disturbances.
The forests in the Howland, Maine area consist of undisturbed near-mature forest, and forests with early clear cuts, strip cuts, and recent selective cuts. These forest management approaches reduce the biomass, and have different effects on canopy heights. For example, selective harvesting may remove a significant proportion of the biomass without drastically changing top tree height. A lidar waveform model will be used to simulate the effects of various forest management practices on the lidar waveform. LVIS and field measurements were used to investigate the characteristics of lidar waveforms, identify the significant changes of the waveform, and correlate these changes with the forest structural changes based on the findings from simulated waveform data. We will present the changes of the prediction models for retrieving canopy height and biomass from lidar waveform due to the changes of forest spatial structure. The results from this study will provide insight and protocols for monitoring forest degradation from lidar waveform data.
Presentation Type: Poster
Poster Session: Ecosystems Science
NASA TE Funded Awards Represented:
Sun, Guoqing
Data Fusion Algorithms for Forest Biomass Mapping From Lidar and SAR Data