Defoliation reduces soil biota - and modifies stimulating effects of elevated CO2

Marie Dam; Søren Christensen

doi:10.1002/ece3.1739

Defoliation reduces soil biota - and modifies stimulating effects of elevated CO₂

Marie Dam^*, Søren Christensen

^*Corresponding author af dette arbejde

Terrestrial Ecology

4 Citationer (Scopus)

171 Downloads (Pure)

Abstract

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.

Originalsprog	Engelsk
Tidsskrift	Ecology and Evolution
Vol/bind	5
Udgave nummer	21
Sider (fra-til)	4840-4848
Antal sider	9
ISSN	2045-7758
DOI	https://doi.org/10.1002/ece3.1739
Status	Udgivet - 2015

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Defoliation reduces soil biota - and modifies stimulating effects of elevated CO2Forlagets udgivne version, 980 KBLicens: CC BY

Citationsformater

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title = "Defoliation reduces soil biota - and modifies stimulating effects of elevated CO2",

abstract = "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.",

keywords = "Deschampsia, Global change, Grass, Growing season, Microbial biomass, Microbial loop, Nematodes, Nutrient, Rhizodeposition, Soil",

author = "Marie Dam and S{\o}ren Christensen",

year = "2015",

doi = "10.1002/ece3.1739",

language = "English",

volume = "5",

pages = "4840--4848",

journal = "Ecology and Evolution",

issn = "2045-7758",

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number = "21",

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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

SN - 2045-7758

VL - 5

SP - 4840

EP - 4848

JO - Ecology and Evolution

JF - Ecology and Evolution

IS - 21

ER -