Overview
Nina is a plant-soil ecologist investigating the carbon cycle in the Arctic and permafrost regions. Her current work focuses on whether the formation of new soil organic matter through plant inputs can offset the predicted loss of carbon from thawing permafrost soils.
Nina’s academic career to date has been centered on understanding the dynamics of plant-soil interactions and their effects on soil carbon storage and climate change. The primary focus of her research is the dependent interactions between plants and soil mediated by mycorrhizal fungi and how this drives soil carbon storage dynamics in a changing world.
During her PhD at the University of Stirling (2016-2020) she investigated how planting native tree species onto heather moorlands in the Scottish uplands affects ecosystem carbon storage, both above and below ground, over decadal time scales. She also spent a considerable amount of time in the Swedish sub-Arctic exploring how tree-line forest species interact with soils via roots and mycorrhizas using stable isotopes of carbon and nitrogen.
Broad Research Specialisms
Plant-soil interactions, Soil carbon dynamics, tree planting, stable isotope labelling, Arctic ecology
Qualifications
PhD ‘Webs of influence: Investigating the effects of the forest mycorrhizosphere on soil carbon storage in a changing world’, University of Stirling
BSc (Hons) Plant Science, University of Edinburgh
Research
Research interests
Nina is interested in the links between plants and soil, how processes above ground affect processes below ground and vice versa, particularly in the context of global change. Globally soils store more carbon than vegetation and the atmosphere combined, most of which is stored at high latitudes and in the Arctic where the climate is warming faster than anywhere else on earth. This global change is altering Northern and Arctic plant communities and consequently soil carbon dynamics in ways we have yet to fully understand.
Nina’s current research aims to answer whether the formation of new soil organic matter can offset predicted thaw-induced permafrost soil carbon losses, and if yes, to what extent?
Research projects
NERC: ‘Can the formation of new soil organic matter offset decomposition losses from thawed permafrost soils?’ (2020-2023)
This NERC funded project led by Professor Iain Hartley will grow an Arctic sedge species Eriophorum vaginatum in contrasting permafrost soil types in a 13C enriched atmosphere. This will enable detection and quantification of plant-derived carbon inputs into different soil organic matter pools as well as soil carbon losses through decomposition and priming.
Publications
Key publications | Publications by category | Publications by year
Publications by category
Journal articles
Friggens NL, Hartley IP, Grant HK, Parker TC, Subke J-A, Wookey PA (2022). Whole-crown 13C-pulse labelling in a sub-arctic woodland to target canopy-specific carbon fluxes.
TreesAbstract:
Whole-crown 13C-pulse labelling in a sub-arctic woodland to target canopy-specific carbon fluxes
. Key message
. Whole-crown 13C-pulse labelling can target tree canopy C fluxes in regions with dense understorey cover and investigate how increased photosynthetic C inputs may affect whole-ecosystem C fluxes.
.
. Abstract
. Climate change-driven increases in plant productivity have been observed at high northern latitudes. These trends are driven, in part, by the increasing abundance of tall shrub and tree species in arctic ecosystems, and the advance of treelines. Higher plant productivity may alter carbon (C) allocation and, hence, ecosystem C cycling and soil C sequestration. It is important to understand the contributions that the newly established canopy forming overstorey species makes to C cycling in these ecosystems. However, the presence of a dense understorey cover makes this challenging, with established partitioning approaches causing disturbance and potentially introducing measurement artefacts. Here, we develop an in situ whole-crown 13C-pulse labelling technique to isolate canopy C fluxes in areas of dense understorey cover. The crowns of five mountain birch (Betula pubescens ssp. czerepanovii) trees were provided with a 13CO2 pulse using portable field equipment, and leaf samples were collected from neighbouring con-specific trees and hetero-specific understorey shrubs on days 1–10 and 377 post-crown labelling. We found effective and long-term enrichment of foliage in labelled trees, but no evidence of the 13C-signal in con- or hetero-specific neighbouring trees or woody shrubs. This method is promising and provides a valuable tool to isolate the role of canopy tree species in ecosystems with dense understorey cover.
.
Abstract.
Parker TC, Clemmensen KE, Friggens NL, Hartley IP, Johnson D, Lindahl BD, Olofsson J, Siewert MB, Street LE, Subke J-A, et al (2020). Rhizosphere allocation by canopy-forming species dominates soil CO2 efflux in a subarctic landscape.
New Phytol,
227(6), 1818-1830.
Abstract:
Rhizosphere allocation by canopy-forming species dominates soil CO2 efflux in a subarctic landscape.
In arctic ecosystems, climate change has increased plant productivity. As arctic carbon (C) stocks predominantly are located belowground, the effects of greater plant productivity on soil C storage will significantly determine the net sink/source potential of these ecosystems, but vegetation controls on soil CO2 efflux remain poorly resolved. In order to identify the role of canopy-forming species in belowground C dynamics, we conducted a girdling experiment with plots distributed across 1 km2 of treeline birch (Betula pubescens) forest and willow (Salix lapponum) patches in northern Sweden and quantified the contribution of canopy vegetation to soil CO2 fluxes and belowground productivity. Girdling birches reduced total soil CO2 efflux in the peak growing season by 53%, which is double the expected amount, given that trees contribute only half of the total leaf area in the forest. Root and mycorrhizal mycelial production also decreased substantially. At peak season, willow shrubs contributed 38% to soil CO2 efflux in their patches. Our findings indicate that C, recently fixed by trees and tall shrubs, makes a substantial contribution to soil respiration. It is critically important that these processes are taken into consideration in the context of a greening arctic because productivity and ecosystem C sequestration are not synonymous.
Abstract.
Author URL.
Full text.
Friggens NL, Hester AJ, Mitchell RJ, Parker TC, Subke J, Wookey PA (2020). Tree planting in organic soils does not result in net carbon sequestration on decadal timescales. Global Change Biology, 26(9), 5178-5188.
Friggens NL, Aspray TJ, Parker TC, Subke J-A, Wookey PA (2019). Spatial patterns in soil organic matter dynamics are shaped by mycorrhizosphere interactions in a treeline forest.
Plant and Soil,
447(1-2), 521-535.
Abstract:
Spatial patterns in soil organic matter dynamics are shaped by mycorrhizosphere interactions in a treeline forest
Abstract
. Aims
. In the Swedish sub-Arctic, mountain birch (Betula pubescens ssp. czerepanovii) forests mediate rapid soil C cycling relative to adjacent tundra heaths, but little is known about the role of individual trees within forests. Here we investigate the spatial extent over which trees influence soil processes.
.
. Methods
. We measured respiration, soil C stocks, root and mycorrhizal productivity and fungi:bacteria ratios at fine spatial scales along 3 m transects extending radially from mountain birch trees in a sub-Arctic ecotone forest. Root and mycorrhizal productivity was quantified using in-growth techniques and fungi:bacteria ratios were determined by qPCR.
.
. Results
. Neither respiration, nor root and mycorrhizal production, varied along transects. Fungi:bacteria ratios, soil organic C stocks and standing litter declined with increasing distance from trees.
.
. Conclusions
. As 3 m is half the average size of forest gaps, these findings suggest that forest soil environments are efficiently explored by roots and associated mycorrhizal networks of B. pubescens. Individual trees exert influence substantially away from their base, creating more uniform distributions of root, mycorrhizal and bacterial activity than expected. However, overall rates of soil C accumulation do vary with distance from trees, with potential implications for spatio-temporal soil organic matter dynamics and net ecosystem C sequestration.
.
Abstract.
Friggens NL (2017). Diversity and community composition of aquatic ascomycetes varies between freshwater, estuarine and marine habitats in western Scotland. Mycosphere, 8(9), 1267-1287.
Publications by year
2022
Friggens NL, Hartley IP, Grant HK, Parker TC, Subke J-A, Wookey PA (2022). Whole-crown 13C-pulse labelling in a sub-arctic woodland to target canopy-specific carbon fluxes.
TreesAbstract:
Whole-crown 13C-pulse labelling in a sub-arctic woodland to target canopy-specific carbon fluxes
. Key message
. Whole-crown 13C-pulse labelling can target tree canopy C fluxes in regions with dense understorey cover and investigate how increased photosynthetic C inputs may affect whole-ecosystem C fluxes.
.
. Abstract
. Climate change-driven increases in plant productivity have been observed at high northern latitudes. These trends are driven, in part, by the increasing abundance of tall shrub and tree species in arctic ecosystems, and the advance of treelines. Higher plant productivity may alter carbon (C) allocation and, hence, ecosystem C cycling and soil C sequestration. It is important to understand the contributions that the newly established canopy forming overstorey species makes to C cycling in these ecosystems. However, the presence of a dense understorey cover makes this challenging, with established partitioning approaches causing disturbance and potentially introducing measurement artefacts. Here, we develop an in situ whole-crown 13C-pulse labelling technique to isolate canopy C fluxes in areas of dense understorey cover. The crowns of five mountain birch (Betula pubescens ssp. czerepanovii) trees were provided with a 13CO2 pulse using portable field equipment, and leaf samples were collected from neighbouring con-specific trees and hetero-specific understorey shrubs on days 1–10 and 377 post-crown labelling. We found effective and long-term enrichment of foliage in labelled trees, but no evidence of the 13C-signal in con- or hetero-specific neighbouring trees or woody shrubs. This method is promising and provides a valuable tool to isolate the role of canopy tree species in ecosystems with dense understorey cover.
.
Abstract.
2020
Parker TC, Clemmensen KE, Friggens NL, Hartley IP, Johnson D, Lindahl BD, Olofsson J, Siewert MB, Street LE, Subke J-A, et al (2020). Rhizosphere allocation by canopy-forming species dominates soil CO2 efflux in a subarctic landscape.
New Phytol,
227(6), 1818-1830.
Abstract:
Rhizosphere allocation by canopy-forming species dominates soil CO2 efflux in a subarctic landscape.
In arctic ecosystems, climate change has increased plant productivity. As arctic carbon (C) stocks predominantly are located belowground, the effects of greater plant productivity on soil C storage will significantly determine the net sink/source potential of these ecosystems, but vegetation controls on soil CO2 efflux remain poorly resolved. In order to identify the role of canopy-forming species in belowground C dynamics, we conducted a girdling experiment with plots distributed across 1 km2 of treeline birch (Betula pubescens) forest and willow (Salix lapponum) patches in northern Sweden and quantified the contribution of canopy vegetation to soil CO2 fluxes and belowground productivity. Girdling birches reduced total soil CO2 efflux in the peak growing season by 53%, which is double the expected amount, given that trees contribute only half of the total leaf area in the forest. Root and mycorrhizal mycelial production also decreased substantially. At peak season, willow shrubs contributed 38% to soil CO2 efflux in their patches. Our findings indicate that C, recently fixed by trees and tall shrubs, makes a substantial contribution to soil respiration. It is critically important that these processes are taken into consideration in the context of a greening arctic because productivity and ecosystem C sequestration are not synonymous.
Abstract.
Author URL.
Full text.
Friggens NL, Hester AJ, Mitchell RJ, Parker TC, Subke J, Wookey PA (2020). Tree planting in organic soils does not result in net carbon sequestration on decadal timescales. Global Change Biology, 26(9), 5178-5188.
2019
Friggens NL, Aspray TJ, Parker TC, Subke J-A, Wookey PA (2019). Spatial patterns in soil organic matter dynamics are shaped by mycorrhizosphere interactions in a treeline forest.
Plant and Soil,
447(1-2), 521-535.
Abstract:
Spatial patterns in soil organic matter dynamics are shaped by mycorrhizosphere interactions in a treeline forest
Abstract
. Aims
. In the Swedish sub-Arctic, mountain birch (Betula pubescens ssp. czerepanovii) forests mediate rapid soil C cycling relative to adjacent tundra heaths, but little is known about the role of individual trees within forests. Here we investigate the spatial extent over which trees influence soil processes.
.
. Methods
. We measured respiration, soil C stocks, root and mycorrhizal productivity and fungi:bacteria ratios at fine spatial scales along 3 m transects extending radially from mountain birch trees in a sub-Arctic ecotone forest. Root and mycorrhizal productivity was quantified using in-growth techniques and fungi:bacteria ratios were determined by qPCR.
.
. Results
. Neither respiration, nor root and mycorrhizal production, varied along transects. Fungi:bacteria ratios, soil organic C stocks and standing litter declined with increasing distance from trees.
.
. Conclusions
. As 3 m is half the average size of forest gaps, these findings suggest that forest soil environments are efficiently explored by roots and associated mycorrhizal networks of B. pubescens. Individual trees exert influence substantially away from their base, creating more uniform distributions of root, mycorrhizal and bacterial activity than expected. However, overall rates of soil C accumulation do vary with distance from trees, with potential implications for spatio-temporal soil organic matter dynamics and net ecosystem C sequestration.
.
Abstract.
2017
Friggens NL (2017). Diversity and community composition of aquatic ascomycetes varies between freshwater, estuarine and marine habitats in western Scotland. Mycosphere, 8(9), 1267-1287.
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