umu.sePublications
Change search
ReferencesLink to record
Permanent link

Direct link
Dwelling in the deep – permafrost thawing strongly increases plant root growth and root litter input
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. (Climate Impacts Research Centre)
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. (Climate Impacts Research Centre)
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. (Climate Impacts Research Centre)
Lund University.
Show others and affiliations
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Plant roots play a key role in ecosystem carbon and nutrient cycling. Climate warming induced thawing of permafrost exposes large amounts of carbon and nitrogen at greater soil depths that hitherto have been detached from plant influences. Whether plant roots can reach and interact with these carbon and nitrogen sources upon permafrost thaw remains unknown. Here, we use a long-term permafrost thaw experiment and a short-term deep fertilization experiment in northern Sweden to assess changes in vegetation composition and root dynamics (deep nitrogen uptake, root depth distribution, root growth and phenology, root mortality and litter input) related to permafrost thaw, both in active layer and in newly thawed permafrost. We show that Eriophorum vaginatum and Rubus chamaemorus, both relatively deep-rooting species, can take up nitrogen released at depth of permafrost thaw, despite the late release time in autumn when plant activity is expected to have ceased. Also, root dynamics changed drastically after a decade of experimental permafrost thaw. Total root length, root growth and root litter input all strongly increased, not only in the active layer but also in the newly thawed permafrost, and the timing of root growth was related to the seasonality of soil thaw. These responses were driven by Eriophorum vaginatum, which differed greatly in root dynamics compared to the other species and thus worked as an ecosystem engineer. This study demonstrates that soil organic matter currently locked-up at depth in permafrost is no longer detached from plant processes upon thaw. Given the pivotal role that roots have in the carbon cycle and the importance of the large carbon stocks in arctic soils, the changes observed here have the potential to feedback onto the global climate system.

Keyword [en]
permafrost, root phenology, fine roots, minirhizotron, belowground, permafrost thaw, root biomass, root exudation, root litter
National Category
Ecology
Identifiers
URN: urn:nbn:se:umu:diva-124753OAI: oai:DiVA.org:umu-124753DiVA: diva2:954744
Available from: 2016-08-23 Created: 2016-08-23 Last updated: 2016-08-25
In thesis
1. The hidden life of plants: fine root dynamics in northern ecosystems
Open this publication in new window or tab >>The hidden life of plants: fine root dynamics in northern ecosystems
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Fine roots constitute a large part of the primary production in northern (arctic and boreal) ecosystems, and are key players in ecosystem fluxes of water, nutrients and carbon. Data on root dynamics are generally rare, especially so in northern ecosystems. However, those ecosystems undergo the most rapid climatic changes on the planet and a profound understanding of form, function and dynamics of roots in such ecosystems is essential.

This thesis aimed to advance our knowledge about fine root dynamics in northern ecosystems, with a focus on fine root phenology in natural plant communities and how climate change might alter it. Factors considered included thickness and duration of snow cover, thawing of permafrost, as well as natural gradients in temperature. Experiments and observational studies were located around Abisko (68°21' N, 18°45' E), and in a boreal forest close to Vindeln (64°14'N, 19°46'E), northern Sweden. Root responses included root growth, total root length, and root litter input, always involving seasonal changes therein, measured with minirhizotrons. Root biomass was also determined with destructive soil sampling. Additionally, aboveground response parameters, such as phenology and growth, and environmental parameters, such as air and soil temperatures, were assessed.

This thesis reveals that aboveground patterns or responses cannot be directly translated belowground and urges a decoupling of above- and belowground phenology in terrestrial biosphere models. Specifically, root growth occurred outside of the photosynthetically active period of tundra plants. Moreover, patterns observed in arctic and boreal ecosystems diverged from those of temperate systems, and models including root parameters may thus need specific parameterization for northern ecosystems. In addition, this thesis showed that plant communities differ in root properties, and that changes in plant community compositions can thus induce changes in root dynamics and functioning. This underlines the importance of a thorough understanding of root dynamics in different plant community types in order to understand and predict how changes in plant communities in response to climate change will translate into root dynamics. Overall, this thesis describes root dynamics in response to a variety of factors, because a deeper knowledge about root dynamics will enable a better understanding of ecosystem processes, as well as improve model prediction of how northern ecosystems will respond to climate change.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, 2016. 24 p.
Keyword
Arctic, belowground, boreal, climate change, fine roots, heath, meadow, minirhizotron, permafrost, phenology, plant community, root biomass, root growth, root litter, root production, subarctic, tundra
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-124757 (URN)978-91-7601-533-9 (ISBN)
Public defence
2016-09-16, Björken, Sveriges Lantbruksuniversitet, Umeå, 09:00 (English)
Opponent
Supervisors
Available from: 2016-08-26 Created: 2016-08-23 Last updated: 2016-09-23Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Blume-Werry, GescheMilbau, AnnTeuber, Laurenz M.Dorrepaal, Ellen
By organisation
Department of Ecology and Environmental Sciences
Ecology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 39 hits
ReferencesLink to record
Permanent link

Direct link