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Title: Decomposition and microbial activity in natural temperate and boreal forests: the influence of microsite, proximity to woody debris and interception by ferns
Author: Dearden, Fiona M.
ISNI:       0000 0001 3421 2237
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2008
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There is a growing but inconclusive body of work on effects of litter-mixing on ecological processes, but few have considered interactions among foliar and woody litters. Further, most work on litter decomposition assumes that litterfall reaches the ground, and the effects of interception of litter (e.g. by ferns or logs) remains largely unexplored. Three studies were perfonned to investigate these issues. The first study was in a long-tenn chronosequence in the Swedish boreal forest where decomposition' rate declined with ecosystem retrogression. Field measurements showed that the ratio of twig to foliage in litterfall increased with prolonged absence ofdisturbance. In a mesocosm experiment, combining foliar and twig litters in their natural proportions reduced overall decomposition rates, suggesting that the increased twig proportion may contribute to the large increase in humus build-up found with prolonged absence of disturbance. The second study was in a New Zealand temperate rainforest, and showed that logs fonned an important microsite for decomposition, with strongly contrasting microbial activity and organic matter content compared with ~e ground. Microbial activity on logs was variable, probably linked to differences in phenolics and decay stage. The third study, also in a New Zealand temperate rainforest, showed that the fern Blechnum discolor has the potential to intercept and retain 10% of falling litter. A higher twig to foliage ratio was found in the litter accumulated in fern crowns than in the incoming litterfall or on the forest floor. Organic matter content, basal respiration and microbial activity were significantly higher in fein crowns than on the forest floor. Further, foliar litter decomposed significantly faster in fern crowns than away from the crown, but not faster than at the trunk base. Consequently, litter interception by ferns may affect nutrient cycling through concentrating nutrients and organic matter in and under ferns.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available