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Variation in stream organic matter processing among years and benthic habitats in response to forest clearfelling


Burrows, RM and Magierowski, RH and Fellman, JB and Clapcott, JE and Munks, SA and Roberts, S and Davies, PE and Barmuta, LA, Variation in stream organic matter processing among years and benthic habitats in response to forest clearfelling, Forest Ecology and Management, 327 pp. 136-147. ISSN 0378-1127 (2014) [Refereed Article]

Copyright Statement

Copyright 2014 Elsevier

DOI: doi:10.1016/j.foreco.2014.04.041


We assessed rates of organic matter (OM) processing in coarse gravel and fine benthic sediment, along with water temperature, in four clearfell harvested and two undisturbed headwater streams flowing through wet eucalypt forest in southern Tasmania, Australia. Clearfell forestry in Tasmanian wet eucalypt forest involves felling of all timber followed by a high intensity regeneration burn to provide a receptive mineral seedbed for seedling growth. Bacterial carbon production and cellulose decomposition potential (together referred to as OM processing) were measured seasonally 3–5 years before and 2–4 years after harvesting in each stream. We employed a staircase design (staggered harvesting treatments) within a multiple before–after control–impact design to distinguish harvesting effects from natural variation. Clearfell harvesting raised the yearly mean water temperature by between 0.25 °C and 0.94 °C, and raised the maximum water temperature by between 0.84 and 1.6 °C. Rates of cellulose decomposition were not significantly correlated with sediment temperature but bacterial carbon production showed weak, significant correlations with temperature in fine (r = 0.20, P = 0.01, n = 137) and coarse gravel sediment (r = 0.39, P < 0.001, n = 137). The response in OM processing to clearfell harvesting differed between years and among benthic habitats. In coarse gravel habitat, there was a significant decrease in rates of cellulose decomposition potential in the 2nd and 4th year after harvesting, and a significant decrease in bacterial carbon production in the 3rd year after harvesting. However, we found a significant increase in rates of bacterial carbon production of fine sediment habitat in the 2nd and 4th year after harvesting. The contrasting response of OM processing between habitats indicates that habitat-specific changes occur after clearfell harvesting, which inhibit attempts to quantitatively predict downstream cumulative effects. Scaling up the habitat-specific responses will not only require estimates of the relative abundances of the distinct habitats, but may also require research into how different spatial configurations of habitats may affect reach- and catchment-scale estimates of OM processing.

Item Details

Item Type:Refereed Article
Keywords:disturbance, forestry, staircase design, microbial decomposition, organic matter, headwater stream
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Freshwater ecology
Objective Division:Environmental Management
Objective Group:Fresh, ground and surface water systems and management
Objective Field:Assessment and management of freshwater ecosystems
UTAS Author:Burrows, RM (Mr Ryan Burrows)
UTAS Author:Magierowski, RH (Dr Regina Magierowski)
UTAS Author:Munks, SA (Dr Sarah Munks)
UTAS Author:Roberts, S (Ms Sandra Roberts)
UTAS Author:Davies, PE (Professor Peter Davies)
UTAS Author:Barmuta, LA (Associate Professor Leon Barmuta)
ID Code:92023
Year Published:2014
Funding Support:Australian Research Council (LP0210383)
Web of Science® Times Cited:8
Deposited By:Centre for Environment
Deposited On:2014-06-04
Last Modified:2017-11-01

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