Dead Wood, Wildlife and Protected Area Management A Study on the Extent of Use of Dead Wood by Wildlife in Periyar Tiger Reserve, Kerala, India

Abstract

Dying, dead, and down trees form an integral component of forest ecosystems. They not only serve as critical microhabitats for many species, but also they are large reservoirs of organic matter and hence play a pivotal role in nutrient cycling. There are whole groups of organisms, which use and need dead wood for their survival in any forest ecosystem, ranging from conspicuous, well-known creatures like flying squirrels and owls to large numbers of invertebrates, fungi, lichens, mosses, and vascular plants. And not only these, there are microorganisms that exploit the pool of organic matter and nutrients deposited in the woody debris on the forest floor. Thus it becomes crucial to examine and study the wildlife use aspect of dead wood. In recent years, the subject of 'decaying wood' has become a major . conservation issue in managed forest ecosystems. This holds true for the Indian scenario as well, where disappearing forests and their far reaching consequences are a major focus of concern. The situation worsens in areas where extraction of different forms of dead wood from the existing forested areas . by local communities living in the vicinity goes unabated. Critical ecosystem functions of dead wood, coupled with incomplete knowledge for management, make the topic of decaying wood a priority for future research and adaptive management. Unfortunately, there is scanty work done in India on this issue. This short-term study was conducted in the Periyar Tiger Reserve, Kerala, from December 2002 to April 2003. The study focused primarily on following objectives: 1) To quantify the abundance of different types of dead wood in different forest/habitat types. 2) To relate dead wood abundance to live tree abundance. 3) To quantify the extent of use of dead wood by different vertebrate taxa particularly by reptiles, birds and mammals. An initial period of 15 days was spent in field for reconnaissance during which two different types of forests, namely Semi evergreen forest and moist deciduous forest were identified. Six areas were chosen in the forests around Edappalayam and Mullakudy such that each area had adjacent patches of semi evergreen forest and moist deciduous forest. The rationale behind this was that the disturbance levels in both the forest types within each of , the areas would be nearly equal. Three areas were categorized as disturbed and the rest three as undisturbed based on movement of people through these areas. After few trials 30 x 30 m plots were used in conjunction with short transects across the width of each forest patch to sample for different dead wood densities. In total 54 ha area was sampled in Semi Evergreen and Moist Deciduous Forests which is ca. 0.55 percent of the total range area. Tree densities were also estimated in the forest patches to relate with dead wood abundance. In the lake habitat eight stretches of 1 km each, with a gap of 0.5 km between successive stretches, were chosen for counting number of dead wood in water as well as shores in the high and low water level seasons.