Life is a banquet. You are invited and should enjoy it! Research is the juicy beef!

I have strong interests in LiDAR (Light Detection and Ranging), an exciting remote sensing technology. I am looking for graduate students who have interest/skills in any or combination of these fields: remote sensing, ecological/biogeochemical modeling, statistics, and wildlife ecology. I am working on some projects as follow:

• Characterizing canopy structure for palila (Loxioides bailleui) habitat assessment using a ground-based three-dimensional laser scanner: Abstract: Linking vertical canopy structure to birds’ abundance is an important but not well-explored research topic. This project proposes to use a ground-based 3D laser scanner to map canopy structure features on the western and northern slopes of Mauna Kea where there is distinct abundance of palila (Loxioides bailleui), an endangered bird species in Hawaii. I will investigate the capability of ground-based lidar to extract canopy information critical to palila with a focus on the tree density of high mamane trees, which provide seeds and caterpillars for the birds. This pilot study will facilitate the study of landscape-level bird-habitat linkage by integrating field survey, airborne lidar and hyperspectral remotely sensed data.
• Improving water source assessment in Hawai’i by using lidar measurements of canopy structure to estimate rainfall interception: Abstract: Water resources in Hawaii continue to experience increasing demand, putting pressure on existing sources and increasing the need for better estimates of resource capacity (Oki 2002). For ground-water sources, in particular, reliable estimates of sustainable yield limits are critically important. Groundwater recharge estimates, in turn, are needed to determine accurate safe yield limits. Recharge is highly spatially variable in Hawaii (Giambelluca 1983), because of extreme gradients in precipitation and evapotranspiration (ET). The accuracy of recharge estimates in Hawaii has been limited by a lack of direct measurements of ET within forested recharge areas. Recent research has improved our knowledge of stand-level ET in Hawaii and pointed to the need to better understand interception loss, the amount of rainfall intercepted by leaves and stems and subsequently evaporated (Giambelluca et al. in prep.). The amount of interception loss, which can vary from 10 to 50% of incoming precipitation (Roth et al. 2007), is strongly influenced by canopy structure, especially canopy gap fraction, leaf, stem and epiphyte storage capacity, and branch angle (Rutter et al. 1975; Gash 1995), and, hence, is highly variable across the forested landscape. Alien trees, some of which such as Psidium cattleianum (strawberry guava)are highly invasive, are markedly different in structure from native trees, such as Metrosideros polymorpha (ohia). Very little is known about the rate and spatial variability of interception loss and the effects of alien tree introductions on interception in Hawaii. The traditional method for measuring interception, based on canopy water balance, is difficult and very limited in spatial coverage. But, recent advances in ground-based and airborne LiDAR technology offer the promise of spatially-distributed estimates of interception using a physically-based approach (Roth et al. 2007). The objective of this project is to utilize a newly-acquired LiDAR system and existing state-of-the-art field measurement facilities to develop and test a new method for estimating interception in Hawaiis native and invaded forests.
• The expansion of rubber and its implications for water and carbon dynamics in Montane Mainland Southeast Asia: Abstract: MMSEA is experiencing major land-use change as subsistence farmers transition from shifting cultivation, which tends to maintain large areas of secondary forest, to commercial agriculture. Rubber is the major commercial crop replacing secondary forests, a direct result of strong market demands from China. Under a previous grant from NASA we documented that the timing and amount of water use by rubber during the dry season differs dramatically from that of secondary forest and traditional agriculture in the region. Others have shown that conversion of forest to plantation agriculture in other regions results in significant changes in stored carbon. Our objectives are to determine how the conversion from existing land covers to rubber affects local energy, water, and carbon fluxes, how extensive rubber will become in MMSEA, and what the consequences will be for regional hydrology and carbon sequestration. To characterize the extent of rubber in MMSEA, we will develop land-cover/use (LCLU) time-series maps for emerging, rubber-growing sites in MMSEA using knowledge-based classification of multi-sensor, multi-date remotely sensed imagery with a focus on identifying rubber cultivation as a distinct land use among forests, grasslands and other types of agriculture. Expansion of rubber to 2050 will be simulated by combining a regional suitability model for rubber with a dynamic, spatially-explicit, land cover/use change (LCLUC) model. We will use eddy covariance to measure water and carbon fluxes over rubber and secondary vegetation. The Ecosystem Demography model, parameterized by satellite-derived LCLU and observations of stand characteristics, including ground-based LiDAR, and calibrated by flux measurements, will be used to develop spatially-distributed estimates of water and carbon fluxes throughout MMSEA.
• Revision of the rainfall atlas of Hawai‘i (Research Assistant Position Available 2009/1-2010/12): Abstract: The objective of this project is to revise the rainfall atlas of Hawai'i combining 1) raingage data, 2) PRISM maps, 3) NEXRAD radar data, 4) mean MM5 rainfall estimate, and 5) vegetation distribution using data assimilation methods and stochastic models.