Defoliation reduces soil biota - and modifies stimulating effects of elevated CO2
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Defoliation reduces soil biota - and modifies stimulating effects of elevated CO2. / Dam, Marie; Christensen, Søren.
In: Ecology and Evolution, Vol. 5, No. 21, 2015, p. 4840-4848.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Defoliation reduces soil biota - and modifies stimulating effects of elevated CO2
AU - Dam, Marie
AU - Christensen, Søren
PY - 2015
Y1 - 2015
N2 - To understand the responses to external disturbance such as defoliation and possible feedback mechanisms at global change in terrestrial ecosystems, it is necessary to examine the extent and nature of effects on aboveground-belowground interactions. We studied a temperate heathland system subjected to experimental climate and atmospheric factors based on prognoses for year 2075 and further exposed to defoliation. By defoliating plants, we were able to study how global change modifies the interactions of the plant-soil system. Shoot production, root biomass, microbial biomass, and nematode abundance were assessed in the rhizosphere of manually defoliated patches of Deschampsia flexuosa in June in a full-factorial FACE experiment with the treatments: increased atmospheric CO2, increased nighttime temperatures, summer droughts, and all of their combinations. We found a negative effect of defoliation on microbial biomass that was not apparently affected by global change. The negative effect of defoliation cascades through to soil nematodes as dependent on CO2 and drought. At ambient CO2, drought and defoliation each reduced nematodes. In contrast, at elevated CO2, a combination of drought and defoliation was needed to reduce nematodes. We found positive effects of CO2 on root density and microbial biomass. Defoliation affected soil biota negatively, whereas elevated CO2 stimulated the plant-soil system. This effect seen in June is contrasted by the effects seen in September at the same site. Late season defoliation increased activity and biomass of soil biota and more so at elevated CO2. Based on soil biota responses, plants defoliated in active growth therefore conserve resources, whereas defoliation after termination of growth results in release of resources. This result challenges the idea that plants via exudation of organic carbon stimulate their rhizosphere biota when in apparent need of nutrients for growth.
AB - To understand the responses to external disturbance such as defoliation and possible feedback mechanisms at global change in terrestrial ecosystems, it is necessary to examine the extent and nature of effects on aboveground-belowground interactions. We studied a temperate heathland system subjected to experimental climate and atmospheric factors based on prognoses for year 2075 and further exposed to defoliation. By defoliating plants, we were able to study how global change modifies the interactions of the plant-soil system. Shoot production, root biomass, microbial biomass, and nematode abundance were assessed in the rhizosphere of manually defoliated patches of Deschampsia flexuosa in June in a full-factorial FACE experiment with the treatments: increased atmospheric CO2, increased nighttime temperatures, summer droughts, and all of their combinations. We found a negative effect of defoliation on microbial biomass that was not apparently affected by global change. The negative effect of defoliation cascades through to soil nematodes as dependent on CO2 and drought. At ambient CO2, drought and defoliation each reduced nematodes. In contrast, at elevated CO2, a combination of drought and defoliation was needed to reduce nematodes. We found positive effects of CO2 on root density and microbial biomass. Defoliation affected soil biota negatively, whereas elevated CO2 stimulated the plant-soil system. This effect seen in June is contrasted by the effects seen in September at the same site. Late season defoliation increased activity and biomass of soil biota and more so at elevated CO2. Based on soil biota responses, plants defoliated in active growth therefore conserve resources, whereas defoliation after termination of growth results in release of resources. This result challenges the idea that plants via exudation of organic carbon stimulate their rhizosphere biota when in apparent need of nutrients for growth.
KW - Deschampsia
KW - Global change
KW - Grass
KW - Growing season
KW - Microbial biomass
KW - Microbial loop
KW - Nematodes
KW - Nutrient
KW - Rhizodeposition
KW - Soil
U2 - 10.1002/ece3.1739
DO - 10.1002/ece3.1739
M3 - Journal article
C2 - 26640664
AN - SCOPUS:84946478582
VL - 5
SP - 4840
EP - 4848
JO - Ecology and Evolution
JF - Ecology and Evolution
SN - 2045-7758
IS - 21
ER -
ID: 153447778