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Synchronizing hyperspectral data acquisition with phenological changes in a tropical forest can generate comprehensive information for their effective management. The present study was performed to identify a suitable dimensionality reduction method for better classification and to evaluate the impact of seasonality on classification accuracy of tropical forest cover, EO-1 Hyperion images were acquired for three different seasons (summer (April), monsoon (October), and winter (January)). Spectral signatures of pure patches of Teak, Bamboo, and mixed species covers are significantly different across the three seasons indicating distinctive phenology of each cover. Kernel Principal Component Analysis (k-PCA) is more suitable for dimensionality reduction for these covers. The three vegetation covers classified using images of three seasons achieved the best classification accuracies using k-PCA with maximum likelihood classifier for the monsoon season with overall accuracies of 83 to 100 percent for single species, 74 to 81 percent for two species, and 72 percent for three species respectively. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article regarding the implication of carbon sink to soil quality.

In order to determine the differences in the response of tropical evergreen and deciduous trees towards air pollution, three different species belonging to each category were studied. The study was undertaken in field conditions, where the trees were exposed to industrial air pollution. A reference site was selected 25 km away from the industrial area. Glutathione, peroxidase and ascorbic acid (antioxidant pool), total chlorophyll, lipid peroxidation, carbohydrate.. levels wereestimated. Phloem exudates were collected and soluble sugars were estimated to monitor translocation of photosynthates. Differences in the recorded observations between the polluted and'control sites were significant (P<0.05). The results indicate a decline in chlorophyll content in trees growing in the industrial area. The antioxidant pool was maintained at elevated levels. Higher levels of starch accumulation were observed in the deciduous species. The seasonal variations recorded in the deciduous species antioxidant levels at the control sitewere not conspicuous at the polluted sites. The amount of photosynthate translocated from the leaves was reduced on exposure to pollutants. The leaf longevity and shoot growth declined. The evergreens showed higher translocation of photosynthates and continuous growth was observed. Changes in the other observed parameters were moderate. [ABSTRACT FROM AUTHOR]