Decomposition of Abies faxoniana litter varies with freeze–thaw stages and altitudes in subalpine/alpine forests of southwest China

Abstract

Freeze–thaw events in winter may affect litter decomposition in cold biomes but few reports are available. We characterized the fir (Abies faxoniana) litter decomposition over a whole winter (November 2008 to April 2009) during the late autumn, deep winter, and early spring stages. The mass loss, nutrient release, and quality change of fir litter were determined using the litterbag method at 2700, 3000, 3300, and 3600 m altitude in southwest China. Over the winter an average of 18% mass, 27% C, 50% N, 40% P, 36% K, 30% cellulose, and 14% lignin were lost. Of these total losses, a majority loss of mass (70%), C (65%), N (50%), P (58%), K (42%), cellulose (70%), and lignin (68%) occurred during the deep winter stage. The highest loss rate of mass (19.2%) and lignin (16.4%) but the lowest N loss (47.9%) was at the highest 3600 m altitude. Soil freeze–thaw cycle resulted in significant losses of mass, while mass loss rate did not increase under the higher mean soil temperature during each stage. Our results confirmed that the physical process seemed to be the most important process for cold season decomposition in the cold biome.

Keywords:

• Abies faxoniana
• altitude
• freeze–thaw cycle
• litter decomposition
• nutrient release
• subalpine/alpine forest

Acknowledgements

This research was carried out in compliance with the laws of People's Republic of China and supported by grants from National Natural Science Foundation of China (30771702, 31000213), Program for New Century Excellent Talents in Chinese Universities (NCET-07-0592), National Key Technologies R & D Program of China (No. 2006BAC01A11), and Sichuan Excellent Youth Science and Technology Foundation (07ZQ026-022). We thank Professor Jianping Tao at Southwest University. We also thank Professor Barry R. Taylor at St. Francis Xavier University, Canada, and another anonymous reviewer for their constructive comments on an earlier version of this manuscript.