Analyzing canopy height variations in secondary tropical forests of Malaysia using NASA GEDI

Abstract

Tropical forests play a significant role in regulating the average global atmospheric temperature encompassing 25 % of the carbon present in the terrestrial biosphere. However, the rapid change in climate, arising from unsustainable human practices, can significantly affect their carbon uptake capability in the future. For understanding these deviations, it is important to identify and quantify the large-scale canopy height variations arising from previous anthropogenic disturbances. With the advent of NASA GEDI spaceborne LiDAR (light detection and ranging), it is now possible to acquire three-dimensional vertical structural data of forests globally. In this study, we evaluate the applicability of GEDI for analyzing relative canopy height variations of secondary tropical forests of different age groups located across multiple geographical regions of peninsular Malaysia. The results for RH98 GEDI metric trends for the lowland and hill forests category across 4 different disturbance groups show a positive correlation between mean relative height and secondary forest ages. The consistency of these findings with previous studies in the region indicate the usefulness of GEDI to provide valuable insights into the patterns and drivers of forest height variation. Thus, this study contributes toward the operationalization of spaceborne LiDAR technology for monitoring forest disturbances and measuring biomass recovery rates and should help support large-scale sustainable forest management initiatives with respect to the tropical forests of Malaysia.

Analyzing Canopy Height Patterns and Environmental Landscape Drivers in Tropical Forests Using NASA’s GEDI Spaceborne LiDAR

“…In this study, we validated the GEDI relative height metrics (rh50, rh75, rh90, rh95, rh100) using different resampling approaches (mean, 90th percentile, max aggregation) over different spatial resolutions (GEDI footprint level, 30, 90, 250, 1000 m) to derive the representative proxy of maximum canopy height over the Malaysian tropical forest based on GEDI L2A data. The study confirmed that canopy height obtained from GEDI has a strong correlation with ALS data over the different sites, as shown in previous studies, and thus, it is useful to assess canopy height variation across landscapes [49][50][51][52][53].…”

“…They found that the water limitation hypothesis was able to better explain the variance in canopy heights in tropical forests in China, while the same was true for the energy limitation hypothesis in temperate forests [11]. In another study, Fricker et al [14] made use of airborne LiDAR, often referred to as airborne laser scanning (ALS), for studying the association between canopy height and environmental variables (soil bulk density, pH, topographic wetness index, slope curvature and potential solar radiation) at six different spatial scales (25,50,100,250, 500, 1000 m) across an elevational gradient ranging from 200 to 3000 m above sea level (a.s.l.) in the Sierra Nevada mountains in the USA.…”

Retrieval of Tree Height Percentiles over Rugged Mountain Areas via Target Response Waveform of Satellite Lidar

“…Remote sensing technologies have been proved to be highly effective for acquiring the forest structure at regional and even global scales. Passive optical sensor and active radar systems can mainly obtain canopy height and stem volume, but vertical forest structural information is still missing due to poor penetration [5][6][7][8]. Light detection and ranging (lidar) is an active remote sensing technique that can overcome such problems and accurately represent vertical forest structure and underlying topography.…”

Forest Loss Related to Brazil Nut Production in Non-Timber Forest Product Concessions in a Micro-Watershed in the Peruvian Amazon

“…In Madre de Dios, during the same period, the rate was 13,584.15 ha/yr −1 [19]. Forest loss reduces the production of organic matter [1,2,20], generates carbon emissions into the atmosphere [21], contributes to climatic variability, and decreases water storage in the atmosphere and in soils [21]. Nevertheless, the effects of specific disturbances on forest ecosystems vary considerably, depending on their scale and frequency [22].…”

“…Nevertheless, the effects of specific disturbances on forest ecosystems vary considerably, depending on their scale and frequency [22]. Furthermore, deforestation causes changes in seed and fruit production [10] and leads to forest desiccation and changes in its floristic composition [21,23].…”