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Responses of vegetation and soil microbial communities to warming and simulated herbivory in a subarctic heath

Rinnan, Riikka LU ; Stark, Sari and Tolvanen, Anne (2009) In Journal of Ecology 97(4). p.788-800
Abstract
1. Climate warming increases the cover of deciduous shrubs in arctic ecosystems and herbivory is also known to have a strong influence on the biomass and composition of vegetation. However, research combining herbivory with warming is largely lacking. Our study describes how warming and simulated herbivory affect vegetation, soil nutrient concentrations and soil microbial communities after 10-13 years of exposure. 2. We established a factorial warming and herbivory-simulation experiment at a subarctic tundra heath in Kilpisjarvi, Finland, in 1994. Warming was carried out using the open-top chamber setup of the International Tundra Experiment (ITEX). Wounding of the dominant deciduous dwarf shrub Vaccinium myrtillus L. to simulate herbivory... (More)
1. Climate warming increases the cover of deciduous shrubs in arctic ecosystems and herbivory is also known to have a strong influence on the biomass and composition of vegetation. However, research combining herbivory with warming is largely lacking. Our study describes how warming and simulated herbivory affect vegetation, soil nutrient concentrations and soil microbial communities after 10-13 years of exposure. 2. We established a factorial warming and herbivory-simulation experiment at a subarctic tundra heath in Kilpisjarvi, Finland, in 1994. Warming was carried out using the open-top chamber setup of the International Tundra Experiment (ITEX). Wounding of the dominant deciduous dwarf shrub Vaccinium myrtillus L. to simulate herbivory was carried out annually. We measured vegetation cover in 2003 and 2007, soil nutrient concentrations in 2003 and 2006, soil microbial respiration in 2003, and composition and function of soil microbial communities in 2006. 3. Warming increased the cover of V. myrtillus, whereas other plant groups did not show any response. Simulated herbivory of V. myrtillus cancelled out the impact of warming on the species cover, and increased the cover of other dwarf shrubs. 4. The concentrations of NH4+-N, and microbial biomass C and N in the soil were significantly reduced by warming after 10 treatment years but not after 13 treatment years. The reduction in NH4+-N by warming was significant only without simultaneous herbivory treatment, which indicates that simulated herbivory reduced N uptake by vegetation. 5. Soil microbial community composition, based on phospholipid fatty acid (PLFA) analysis, was slightly altered by warming. The activity of cultivable bacterial and fungal communities was significantly increased by warming and the substrate utilization patterns were influenced by warming and herbivory. 6. Synthesis. Our results show that warming increases the cover of V. myrtillus, which seems to enhance the nutrient sink strength of vegetation in the studied ecosystem. However, herbivory partially negates the effect of warming on plant N uptake and interacts with the effect of warming on microbial N immobilization. Our study demonstrates that effects of warming on soil microorganisms are likely to differ in the presence and absence of herbivores. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Vaccinium myrtillus, vegetation cover, temperature, soil microbial community, PLFA, nutrient cycling, ITEX, microbial biomass, climate change, Biolog
in
Journal of Ecology
volume
97
issue
4
pages
788 - 800
publisher
Wiley-Blackwell
external identifiers
  • wos:000267071500020
  • scopus:67549117093
ISSN
1365-2745
DOI
10.1111/j.1365-2745.2009.01506.x
project
Climate Initiative
language
English
LU publication?
yes
id
c5505f01-d6fd-4d9c-9b06-76dd5d3a5df0 (old id 1441647)
date added to LUP
2009-07-27 15:43:42
date last changed
2017-12-10 03:52:18
@article{c5505f01-d6fd-4d9c-9b06-76dd5d3a5df0,
  abstract     = {1. Climate warming increases the cover of deciduous shrubs in arctic ecosystems and herbivory is also known to have a strong influence on the biomass and composition of vegetation. However, research combining herbivory with warming is largely lacking. Our study describes how warming and simulated herbivory affect vegetation, soil nutrient concentrations and soil microbial communities after 10-13 years of exposure. 2. We established a factorial warming and herbivory-simulation experiment at a subarctic tundra heath in Kilpisjarvi, Finland, in 1994. Warming was carried out using the open-top chamber setup of the International Tundra Experiment (ITEX). Wounding of the dominant deciduous dwarf shrub Vaccinium myrtillus L. to simulate herbivory was carried out annually. We measured vegetation cover in 2003 and 2007, soil nutrient concentrations in 2003 and 2006, soil microbial respiration in 2003, and composition and function of soil microbial communities in 2006. 3. Warming increased the cover of V. myrtillus, whereas other plant groups did not show any response. Simulated herbivory of V. myrtillus cancelled out the impact of warming on the species cover, and increased the cover of other dwarf shrubs. 4. The concentrations of NH4+-N, and microbial biomass C and N in the soil were significantly reduced by warming after 10 treatment years but not after 13 treatment years. The reduction in NH4+-N by warming was significant only without simultaneous herbivory treatment, which indicates that simulated herbivory reduced N uptake by vegetation. 5. Soil microbial community composition, based on phospholipid fatty acid (PLFA) analysis, was slightly altered by warming. The activity of cultivable bacterial and fungal communities was significantly increased by warming and the substrate utilization patterns were influenced by warming and herbivory. 6. Synthesis. Our results show that warming increases the cover of V. myrtillus, which seems to enhance the nutrient sink strength of vegetation in the studied ecosystem. However, herbivory partially negates the effect of warming on plant N uptake and interacts with the effect of warming on microbial N immobilization. Our study demonstrates that effects of warming on soil microorganisms are likely to differ in the presence and absence of herbivores.},
  author       = {Rinnan, Riikka and Stark, Sari and Tolvanen, Anne},
  issn         = {1365-2745},
  keyword      = {Vaccinium myrtillus,vegetation cover,temperature,soil microbial community,PLFA,nutrient cycling,ITEX,microbial biomass,climate change,Biolog},
  language     = {eng},
  number       = {4},
  pages        = {788--800},
  publisher    = {Wiley-Blackwell},
  series       = {Journal of Ecology},
  title        = {Responses of vegetation and soil microbial communities to warming and simulated herbivory in a subarctic heath},
  url          = {http://dx.doi.org/10.1111/j.1365-2745.2009.01506.x},
  volume       = {97},
  year         = {2009},
}