Future increase in temperature may stimulate litter decomposition in temperate mountain streams: evidence from a stream manipulation experiment
Summary Small woodland streams constitute the majority of water courses in many catchments. Given their generally low water temperature, high surface : volume ratio and primarily heterotrophic nature, such streams can be strongly affected by increases in temperature. It is therefore important to ass...
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| Published in | Freshwater biology Vol. 60; no. 5; pp. 881 - 892 |
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| Main Authors | , |
| Format | Journal Article |
| Language | English |
| Published |
Oxford
Blackwell Publishing Ltd
01.05.2015
Wiley Subscription Services, Inc |
| Subjects | |
| Online Access | Get full text |
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| Summary: | Summary
Small woodland streams constitute the majority of water courses in many catchments. Given their generally low water temperature, high surface : volume ratio and primarily heterotrophic nature, such streams can be strongly affected by increases in temperature. It is therefore important to assess how stream communities and processes respond to the global warming projected for this century.
We assessed the effects of a c. 3 °C experimental warming of stream water on decomposition of Quercus robur leaf litter and on the associated fungal biomass (ergosterol concentration), sporulation rates of aquatic hyphomycetes, and total macroinvertebrate and shredder abundance in spring, autumn and winter.
A mountain stream reach in central Portugal was divided longitudinally over 22 m with local stones. The study followed a before‐after control‐impact design, with both stream halves at ambient temperature during 1 year and one stream half being experimentally warmed in the second year.
Experimental warming of stream water stimulated litter decomposition only in winter, probably because at that time, the low natural temperature limited microbial activities. The effect of experimental warming did not depend on the presence of macroinvertebrates. Contrary to expectations, no significant effect of experimental warming was found on fungal biomass accrual, sporulation rate of aquatic hyphomycetes or macroinvertebrate abundance on decomposing litter.
Although the stimulation of litter decomposition in winter could lead to food depletion, this is unlikely when streams are subsidised by more recalcitrant leaves such as oak, which enter the stream in later winter and decompose slowly. |
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| Bibliography: | Table S1. Water variables in the control and experimental stream half during the seasonal litter decomposition experiments in the ambient and warmed year.Table S2. Summary table for RM ANOVAs performed on the proportion of Quercus robur litter mass remaining (ln-transformed) in coarse and fine mesh bags (mesh size) incubated over 60 days (time) in the control and experimental stream halves (stream half) in the ambient and warmed years (year), in spring, autumn and winter.Table S3. Summary table for RM ANOVAs performed on fungal biomass concentration (log [x + 1] transformed) associated with Quercus robur leaf litter incubated in fine mesh bags in the control and experimental stream half over 60 days in the ambient and warmed year, in spring, autumn and winter.Table S4. Summary table for RM ANOVAs performed on sporulation rate of aquatic hyphomycetes (log [x] transformed) associated with Quercus robur leaf litter incubated in fine mesh bags in the control and experimental stream half over 60 days in the ambient and warmed year, in spring, autumn and winter.Table S5. Summary table for RM ANOVAs performed on total macroinvertebrate abundance (log [x + 1] transformed) associated with Quercus robur leaf litter incubated in coarse mesh bags in the control and experimental stream half over 60 days in the ambient and warmed year, in spring, autumn and winter.Table S6. Summary table for RM ANOVAs performed on shredder abundance (log [x + 1] transformed) associated with Quercus robur leaf litter incubated in coarse mesh bags in the control and experimental stream half over 60 days in the ambient and warmed year, in spring, autumn and winter. Institute of Marine Research (IMAR) European Fund for Economic and Regional Development (FEDER) istex:85CEB2275D56FC5DC8C453D74C3DBD3289088537 Program Operational Factors of Competitiveness (COMPETE) ark:/67375/WNG-05WT37VR-X FCT - No. SFRH/BPD/34368/2006; No. SFRH/BPD/76482/2011 National Funds through Foundation for Science and Technology (FCT) - No. PTDC/CLI/67180/2006; No. FCOMP-01-0124-FEDER-007112 ArticleID:FWB12539 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 0046-5070 1365-2427 |
| DOI: | 10.1111/fwb.12539 |