The intense use of fertilisers for agricultural and forest management purposes as well as atmospheric nitrogen (N) deposition has changed ecosystem stoichiometry in some parts of the planet, drawing great attention to the long-term impacts of N additions on carbon (C) sequestration. Soil organic matters (SOMs) are the major sink of C in terrestrial ecosystems and hence it is essential to understand the impacts of N addition to SOM not only quantitatively but also qualitatively. In temperate and boreal forests, chronic N addition generally suppresses SOM decomposition and increases C accumulation. The potential mechanisms for this have long been discussed and yet to be unearthed.
I examine the impacts of long-term N addition on the chemical composition of SOMs in boreal forests situated in northern Sweden under two vegetation types (Norway spruce or Scots pine) and a range of N addition regimes where N addition rates varied between 3 and 70 kg N ha-1 yr-1, duration between 15 and 30 years and total added amount between 50 and 2,000 kg N ha-1.
I collect soil samples from the organic layer (fragmented litter and humus layers) and analyse for the chemical composition of SOMs using two metrics: pyrolysis gas chromatography-mass spectrometry (GC/MS) and solid-state 13C nuclear magnetic resonance spectroscopy (13C-NMR).
2018 – Postdoctoral researcher, Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
2017 – 2018 Senior research technician, National Institute for Environmental Studies (Japan)
2016 – 2017 Research assistant, Hawkesbury Institute for the Environment, Western Sydney University (Australia)
2015 – 2016 Postdoctoral Research Fellow (Endeavour Fellowship), Hawkesbury Institute for the Environment, Western Sydney University
2011 – 2015 PhD Life Sciences Research, Imperial College London (UK); Project: Investigation into the effects of elevated carbon dioxide and temperature on nutrient cycling and understorey vegetation in a Eucalyptus woodland (supervised by Prof Sally Power, Dr Catriona Macdonald, Prof Michael Crawley and Prof Iain Colin Prentice). The thesis is available here.
Jiang, M., Medlyn, BE., Drake, JE., Duursma, RA., Anderson, IC., Barton, CVM., Boer, MM., Carrillo, Y., Castañeda-Gómez, L., Collins, L., Crous, KY., De Kauwe, MG., Emmerson, KM., Facey, SL., Gherlenda, AN., Gimeno, TE., Hasegawa, S., Johnson, SN., Macdonald, CA., Mahmud, K., Moore, BD., Nazaries, L., Nielsen, UN., Noh, NJ., Ochoa-Hueso, R., Pathare, VS., Pendall,E., Pineiro,J., Powell, JR., Power, SA., Reich, PB., Renchon, AA., Riegler,M., Rymer,P., Salomón, RL., Singh, BK., Smith,B., Tjoelker, MG., Walker, JKM., Wujeska-Klause, A., Yang, J., Zaehle, S., Ellsworth, DS., The fate of carbon in a mature forest under carbon dioxide enrichment, Nature, in press
Fry, EL., De Long, JR., Álvarez Garrido, L., Alvarez, N., Carrillo, Y., Castañeda‐Gómez, L., Chomel, M., Dondini, M., Drake, JE., Hasegawa, S., Hortal, S., Jackson, BG., Jiang, M., Lavallee, JM., Medlyn, BE., Rhymes, J, Singh, BK., Smith, P., Anderson, IC., Bardgett, RD., Baggs, EM. and Johnson, D., Using plant, microbe, and soil fauna traits to improve the predictive power of biogeochemical models, Methods in Ecology and Evolution, 10, 146–157, 2019
Watanabe, M., Miura, S., Nishina, K., Koshikawa, MK., Takamatsu, T., Hasegawa, S., Kohzu, A., Imai, A. and Hayashi, S., The influence of catchment topography and coniferous forest coverage on stream nitrate concentrations in a nitrogen-saturated forest in central Japan, Science of the Total Environment, 636, 539-546, 2018
Collins, L., Boer, M., Resco de Dios, V., Power, SA., Bendall, E.R., Hasegawa, S., Ochoa-Hueso, R., Piñeiro, J., and Bradstock, RA., Elevated atmospheric [CO2] alone may not cause woody thickening in temperate eucalypt woodlands, Oecologia, 187, 811-823, 2018
Hasegawa, S., Piñeiro, J., Ochoa-Hueso R., Haigh, AM., Rymer, PD., Barnett, KL. and Power, SA., Elevated CO2 concentrations reduce C4 abundance and decrease diversity of understorey plant community in a Eucalyptus woodland, Journal of Ecology, 106, 1483-1494, 2018
Hasegawa, S., Macdonald, CA. and Power, SA., Elevated carbon dioxide increases soil nitrogen and phosphorus availability in a phosphorus-limited Eucalyptus woodland, Global Change Biology, 22, 1628-1643, 2016
Fry, EL., Manning, P., Macdonald, C., Hasegawa, S., De Palma, A., Power, SA., and Singh, BK., Shifts in microbial communities do not explain the response of grassland ecosystem function to plant functional composition and rainfall change, Soil Biology and Biochemistry, 92, 199-210, 2016
Hall, AAG., Gherlenda, AN., Hasegawa, S., Johnson, SN., Cook, JM. and Riegler, M., Anatomy of an outbreak: the biology and population dynamics of a Cardiaspina psyllid species in an endangered woodland ecosystem, Agricultural and Forest Entomology, 17, 292–301, 2015
Hama, T., Kawashima, S., Shimotori, K., Satoh, Y., Omori, Y., Wada, S., Adachi, T., Hasegawa, S., Midorikawa, T., Ishii, M., Saito, S., Sasano, D., Endo, H., Nakayama, T. and Inouye, I., Effect of ocean acidification on coastal phytoplankton composition and accompanying organic nitrogen production, Journal of Oceanography, 68(1), 183-194, 2012