Leaf litter Decomposition in Headwater Streams,Nam Nao National Park, Thailand

摘要

Objectives of this research are to investigate long-term responses of leaf litter decomposition ratesinvolved some abiotic factors and colonized macroinvertebrates in leaf litter bags at headwaterstreams, Nam Nao National Park by comparing data between 2002 and 2014. Three grams dryweight of Bambusa arundinacea Willd. was put in an individual nylon bag and they were placedin riffles and pools at 2 streams. These litter bags from each stream were retrieved every 2 weeks ofimmersion. Results showed that leaf breakdown rates were more rapidly in riffle than in pool andthe rate was faster at Phromlaeng stream than those of Yakruae stream in both years. Increasingof water velocity was considered to increase leaf decay. Macroinvertebrates colonizing in the leaflitter bags was similar in 2002 and 2014. In both years, Dipteran and Ephemeropteran larvae werethe most abundant (more than 50%) in the litter bags throughout the study, which were primarilycollector-gatherers in the leaf litter bags. Shredders directly consumed leaves and other coarseparticle organic matters were low abundance. Collector-filters were more abundant in riffle.Scrappers and predators did not feed on detritus, but they utilized the litter bag for shelter. Inconclusion, decomposition rate was more rapidly caused by increasing water velocity. Increasein water velocity was a consequence of increase in precipitation which was directly related toclimate change.