Publications by category
Journal articles
Parker TC, Chomel M, Clemmensen KE, Friggens NL, Hartley IP, Johnson D, Kater I, Krab EJ, Lindahl BD, Street LE, et al (2022). Resistance of subarctic soil fungal and invertebrate communities to disruption of below‐ground carbon supply. Journal of Ecology, 110(12), 2883-2897.
Friggens NL, Hartley IP, Parker TC, Subke J, Wookey PA (2022). Trees out‐forage understorey shrubs for nitrogen patches in a subarctic mountain birch forest. Oikos
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.
Trees,
36(4), 1437-1445.
Abstract:
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.
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
Parker TC, Chomel M, Clemmensen KE, Friggens NL, Hartley IP, Johnson D, Kater I, Krab EJ, Lindahl BD, Street LE, et al (2022). Resistance of subarctic soil fungal and invertebrate communities to disruption of below‐ground carbon supply. Journal of Ecology, 110(12), 2883-2897.
Friggens NL, Hartley IP, Parker TC, Subke J, Wookey PA (2022). Trees out‐forage understorey shrubs for nitrogen patches in a subarctic mountain birch forest. Oikos
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.
Trees,
36(4), 1437-1445.
Abstract:
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.
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.