Oak health and leaf spectral response

Pu et al. 2008. GeoCarto International. The spectroscopic determination of two health levels of the coast live oak leaves was conducted with three sets of spectra. Based on our experimental results and previous work, existing remote sensing techniques, including airborne or satellite remote sensing and multispectral or hyperspectral remote sensing, may be insufficient for monitoring and mapping disease-induced moisture stress in trees that have recently been infected.

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Mapping SOD related stress with CASI

Pu, R., M. Kelly, G. L. Anderson, and P. Gong. 2008. Using CASI hyperspectral imagery to detect mortality and vegetation stress associated with a new hardwood forest disease. Photogrammetric Engineering & Remote Sensing 74(1): 65‐75

A CASI dataset was used for detecting mortality and vegetation stress associated with a new forest disease. Pdf download.

Spatial‐temporal tree mortality patterns associated with SOD

Liu, et al. 2007. Forest Ecology and Management. Inhomogeneous cross-K-functions of SOD and California bay trees: the peak in the dark line indicates co-clusteringWe analyzed the spatial–temporal patterns of overstory oak tree mortality in China Camp State Park, CA over 4 years using the point patterns mapped from high spatial resolution remotely sensed imagery. Both univariate and multivariate spatial point pattern analyses were performed (inhomogeneous K-functions and Neyman–Scott point processes) to characterize the spatial dependence among dead oak trees in each year, and between dead oaks and CA bay trees.

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Obia for mapping dead trees

Guo, Q. C., M. Kelly, P. Gong and D. Liu. 2007. GIScience and Remote Sensing. An object, defined by spectral similarity of neighboring pixelsWe developed an object-based approach, including an image segmentation process and a knowledge-based classifier, to detect individual tree mortality in imagery of 1 m spatial resolution.

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Isolating individual trees in a savanna woodland using lidar

Chen et al. 2006. Photogrammetric Engineering and Remote Sensing. Individual trees delineated.This study presents a new method of detecting individual treetops from lidar data and applies marker-controlled watershed segmentation into isolating individual trees in savanna woodland. The treetops were detected by searching local maxima in a canopy maxima model (CMM) with variable window sizes.

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Spatial‐temporal monitoring of forest disease dynamics

Liu et al. 2006. Remote Sensing of Environment. Traditional mapping approaches using per-pixel, single-date image classifications have not generated consistently satisfactory results. Incorporation of spatial–temporal contextual information can improve these results. In this paper, we propose a spatial–temporally explicit algorithm to classify individual images using the spectral and spatial–temporal information derived from multiple co-registered images.

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Spectral absorption and water status in coast live oak leaves

Pu, R., S. Ge, N. M. Kelly, and P. Gong. 2003. International Journal of Remote Sensing. A total of 139 reflectance spectra (between 350 and 2500 nm) from coast live oak (Quercus agrifolia) leaves were measured in the laboratory with a spectrometer. Correlation analysis was conducted between absorption features, three-band ratio indices derived from the spectra and corresponding relative water content (RWC, %) of oak leaves.

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