Greater carbon allocation to mycorrhizal fungi reduces tree nitrogen uptake in a boreal forest

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Greater carbon allocation to mycorrhizal fungi reduces tree nitrogen uptake in a boreal forest. / Hasselquist, Niles J.; Metcalfe, Daniel B.; Inselsbacher, Erich; Stangl, Zsofia; Oren, Ram; Näsholm, Torgny; Högberg, Peter.

In: Ecology, Vol. 97, No. 4, 01.04.2016, p. 1012-1022.

Research output: Contribution to journalArticle

Harvard

Hasselquist, NJ, Metcalfe, DB, Inselsbacher, E, Stangl, Z, Oren, R, Näsholm, T & Högberg, P 2016, 'Greater carbon allocation to mycorrhizal fungi reduces tree nitrogen uptake in a boreal forest', Ecology, vol. 97, no. 4, pp. 1012-1022. https://doi.org/10.1890/15-1222.1

APA

Hasselquist, N. J., Metcalfe, D. B., Inselsbacher, E., Stangl, Z., Oren, R., Näsholm, T., & Högberg, P. (2016). Greater carbon allocation to mycorrhizal fungi reduces tree nitrogen uptake in a boreal forest. Ecology, 97(4), 1012-1022. https://doi.org/10.1890/15-1222.1

CBE

Hasselquist NJ, Metcalfe DB, Inselsbacher E, Stangl Z, Oren R, Näsholm T, Högberg P. 2016. Greater carbon allocation to mycorrhizal fungi reduces tree nitrogen uptake in a boreal forest. Ecology. 97(4):1012-1022. https://doi.org/10.1890/15-1222.1

MLA

Vancouver

Hasselquist NJ, Metcalfe DB, Inselsbacher E, Stangl Z, Oren R, Näsholm T et al. Greater carbon allocation to mycorrhizal fungi reduces tree nitrogen uptake in a boreal forest. Ecology. 2016 Apr 1;97(4):1012-1022. https://doi.org/10.1890/15-1222.1

Author

Hasselquist, Niles J. ; Metcalfe, Daniel B. ; Inselsbacher, Erich ; Stangl, Zsofia ; Oren, Ram ; Näsholm, Torgny ; Högberg, Peter. / Greater carbon allocation to mycorrhizal fungi reduces tree nitrogen uptake in a boreal forest. In: Ecology. 2016 ; Vol. 97, No. 4. pp. 1012-1022.

RIS

TY - JOUR

T1 - Greater carbon allocation to mycorrhizal fungi reduces tree nitrogen uptake in a boreal forest

AU - Hasselquist, Niles J.

AU - Metcalfe, Daniel B.

AU - Inselsbacher, Erich

AU - Stangl, Zsofia

AU - Oren, Ram

AU - Näsholm, Torgny

AU - Högberg, Peter

PY - 2016/4/1

Y1 - 2016/4/1

N2 - The central role that ectomycorrhizal (EM) symbioses play in the structure and function of boreal forests pivots around the common assumption that carbon (C) and nitrogen (N) are exchanged at rates favorable for plant growth. However, this may not always be the case. It has been hypothesized that the benefits mycorrhizal fungi convey to their host plants strongly depends upon the availability of C and N, both of which are rapidly changing as a result of intensified human land use and climate change. Using large-scale shading and N addition treatments, we assessed the independent and interactive effects of changes in C and N supply on the transfer of N in intact EM associations with ∼15 yr. old Scots pine trees. To assess the dynamics of N transfer in EM symbioses, we added trace amounts of highly enriched 15NO3 - label to the EM-dominated mor-layer and followed the fate of the 15N label in tree foliage, fungal chitin on EM root tips, and EM sporocarps. Despite no change in leaf biomass, shading resulted in reduced tree C uptake, ca. 40% lower fungal biomass on EM root tips, and greater 15N label in tree foliage compared to unshaded control plots, where more 15N label was found in fungal biomass on EM colonized root tips. Short-term addition of N shifted the incorporation of 15N label from EM fungi to tree foliage, despite no significant changes in below-ground tree C allocation to EM fungi. Contrary to the common assumption that C and N are exchanged at rates favorable for plant growth, our results show for the first time that under N-limited conditions greater C allocation to EM fungi in the field results in reduced, not increased, N transfer to host trees. Moreover, given the ubiquitous nature of mycorrhizal symbioses, our results stress the need to incorporate mycorrhizal dynamics into process-based ecosystem models to better predict forest C and N cycles in light of global climate change.

AB - The central role that ectomycorrhizal (EM) symbioses play in the structure and function of boreal forests pivots around the common assumption that carbon (C) and nitrogen (N) are exchanged at rates favorable for plant growth. However, this may not always be the case. It has been hypothesized that the benefits mycorrhizal fungi convey to their host plants strongly depends upon the availability of C and N, both of which are rapidly changing as a result of intensified human land use and climate change. Using large-scale shading and N addition treatments, we assessed the independent and interactive effects of changes in C and N supply on the transfer of N in intact EM associations with ∼15 yr. old Scots pine trees. To assess the dynamics of N transfer in EM symbioses, we added trace amounts of highly enriched 15NO3 - label to the EM-dominated mor-layer and followed the fate of the 15N label in tree foliage, fungal chitin on EM root tips, and EM sporocarps. Despite no change in leaf biomass, shading resulted in reduced tree C uptake, ca. 40% lower fungal biomass on EM root tips, and greater 15N label in tree foliage compared to unshaded control plots, where more 15N label was found in fungal biomass on EM colonized root tips. Short-term addition of N shifted the incorporation of 15N label from EM fungi to tree foliage, despite no significant changes in below-ground tree C allocation to EM fungi. Contrary to the common assumption that C and N are exchanged at rates favorable for plant growth, our results show for the first time that under N-limited conditions greater C allocation to EM fungi in the field results in reduced, not increased, N transfer to host trees. Moreover, given the ubiquitous nature of mycorrhizal symbioses, our results stress the need to incorporate mycorrhizal dynamics into process-based ecosystem models to better predict forest C and N cycles in light of global climate change.

KW - N pulse labeling

KW - Carbon supply

KW - Ectomycorrhizas

KW - Field experiment

KW - Mutualism

KW - Nitrogen availability

KW - Nitrogen limitation

KW - Scots pine

U2 - 10.1890/15-1222.1

DO - 10.1890/15-1222.1

M3 - Article

C2 - 27220217

AN - SCOPUS:84963984087

VL - 97

SP - 1012

EP - 1022

JO - Ecology

JF - Ecology

SN - 0012-9658

IS - 4

ER -