The biogeochemical consequences of litter transformation by insect herbivory in the Subarctic : a microcosm simulation experiment
(2018) In Biogeochemistry 138(3). p.323-336- Abstract
Warming may increase the extent and intensity of insect defoliations within Arctic ecosystems. A thorough understanding of the implications of this for litter decomposition is essential to make predictions of soil-atmosphere carbon (C) feedbacks. Soil nitrogen (N) and C cycles naturally are interlinked, but we lack a detailed understanding of how insect herbivores impact these cycles. In a laboratory microcosm study, we investigated the growth responses of heterotrophic soil fungi and bacteria as well as C and N mineralisation to simulated defoliator outbreaks (frass addition), long-term increased insect herbivory (litter addition at higher background N-level) and non-outbreak conditions (litter addition only) in soils from a Subarctic... (More)
Warming may increase the extent and intensity of insect defoliations within Arctic ecosystems. A thorough understanding of the implications of this for litter decomposition is essential to make predictions of soil-atmosphere carbon (C) feedbacks. Soil nitrogen (N) and C cycles naturally are interlinked, but we lack a detailed understanding of how insect herbivores impact these cycles. In a laboratory microcosm study, we investigated the growth responses of heterotrophic soil fungi and bacteria as well as C and N mineralisation to simulated defoliator outbreaks (frass addition), long-term increased insect herbivory (litter addition at higher background N-level) and non-outbreak conditions (litter addition only) in soils from a Subarctic birch forest. Larger amounts of the added organic matter were mineralised in the outbreak simulations compared to a normal year; yet, the fungal and bacterial growth rates and biomass were not significantly different. In the simulation of long-term increased herbivory, less litter C was respired per unit mineralised N (C:N of mineralisation decreased to 20 ± 1 from 38 ± 3 for pure litter), which suggests a directed microbial mining for N-rich substrates. This was accompanied by higher fungal dominance relative to bacteria and lower total microbial biomass. In conclusion, while a higher fraction of foliar C will be respired by insects and microbes during outbreak years, predicted long-term increases in herbivory linked to climate change may facilitate soil C-accumulation, as less foliar C is respired per unit mineralised N. Further work elucidating animal-plant-soil interactions is needed to improve model predictions of C-sink capacity in high latitude forest ecosystems.
(Less)
- author
- Kristensen, Jeppe A. LU ; Metcalfe, Daniel B. LU and Rousk, Johannes LU
- organization
- publishing date
- 2018-05-05
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Biogeochemistry, Herbivory, Nitrogen mineralisation, Soil microbial ecology, Soil respiration, Subarctic birch forest
- in
- Biogeochemistry
- volume
- 138
- issue
- 3
- pages
- 14 pages
- publisher
- Springer
- external identifiers
-
- scopus:85046488756
- ISSN
- 0168-2563
- DOI
- 10.1007/s10533-018-0448-8
- language
- English
- LU publication?
- yes
- id
- b0cd4749-263d-4b29-bfdb-38358ef2867d
- date added to LUP
- 2018-05-15 10:41:05
- date last changed
- 2024-05-13 09:47:54
@article{b0cd4749-263d-4b29-bfdb-38358ef2867d,
abstract = {{<p>Warming may increase the extent and intensity of insect defoliations within Arctic ecosystems. A thorough understanding of the implications of this for litter decomposition is essential to make predictions of soil-atmosphere carbon (C) feedbacks. Soil nitrogen (N) and C cycles naturally are interlinked, but we lack a detailed understanding of how insect herbivores impact these cycles. In a laboratory microcosm study, we investigated the growth responses of heterotrophic soil fungi and bacteria as well as C and N mineralisation to simulated defoliator outbreaks (frass addition), long-term increased insect herbivory (litter addition at higher background N-level) and non-outbreak conditions (litter addition only) in soils from a Subarctic birch forest. Larger amounts of the added organic matter were mineralised in the outbreak simulations compared to a normal year; yet, the fungal and bacterial growth rates and biomass were not significantly different. In the simulation of long-term increased herbivory, less litter C was respired per unit mineralised N (C:N of mineralisation decreased to 20 ± 1 from 38 ± 3 for pure litter), which suggests a directed microbial mining for N-rich substrates. This was accompanied by higher fungal dominance relative to bacteria and lower total microbial biomass. In conclusion, while a higher fraction of foliar C will be respired by insects and microbes during outbreak years, predicted long-term increases in herbivory linked to climate change may facilitate soil C-accumulation, as less foliar C is respired per unit mineralised N. Further work elucidating animal-plant-soil interactions is needed to improve model predictions of C-sink capacity in high latitude forest ecosystems.</p>}},
author = {{Kristensen, Jeppe A. and Metcalfe, Daniel B. and Rousk, Johannes}},
issn = {{0168-2563}},
keywords = {{Biogeochemistry; Herbivory; Nitrogen mineralisation; Soil microbial ecology; Soil respiration; Subarctic birch forest}},
language = {{eng}},
month = {{05}},
number = {{3}},
pages = {{323--336}},
publisher = {{Springer}},
series = {{Biogeochemistry}},
title = {{The biogeochemical consequences of litter transformation by insect herbivory in the Subarctic : a microcosm simulation experiment}},
url = {{http://dx.doi.org/10.1007/s10533-018-0448-8}},
doi = {{10.1007/s10533-018-0448-8}},
volume = {{138}},
year = {{2018}},
}