Mechanistic understandings is my favourit topic of uptake of nutrients and water; nutrition and growth of trees; carbon partitioning and allocation; soil carbon and nitrogen dynamics; and their interactions and feedbacks with a changing climate and forest management practices.
Under this framework, I employ various skillsets, including isotopes (14C, 13C, 15N, 2H), soil microdialysis technique (in situ monitoring of soil water and nitrogen fluxes), and statistical/process-based modelling.
I am currently working on two main projects. One examines factors controlling the fertilization response of forest nutrition and growth. I hypothesize that root uptake of nitrogen and, thus, growth of trees are interactivley affected by the chemical form of available soil nitrogen, soil water availability, and atmospheric water demand. A combination of greenhouse experiements and field based manupulation studies helps disentangle the combined effects and provide the mechanisms underlying the responses. This project is funded by Formas (4 467k SEK, 2021-2024), collaborating with scientists in University of Tartu (Estonia) and IIASA (Austria).
The second project quantifies forest carbon accumulation capacity in response to combinations of forest management, a changing climate, and disturbances (e.g., insect outbreaks). Forest fertilization generally increases both biomass and soil carbon accumulation. It is yet largely untested whether the accumulation would remain conserved even after forest disturbances or with a chaning climate. To tackle the task, I employ advanced techniques of carbon and nitrogen isotopes (13C,14C,15N), and unique archives of field-samples (1986-). I expect the project to advance understandings of coupled carbon-nitrogen dynamics between plants and soils that interact with a changing climate. This project is funded by SLU Future Silviculture (500k SEK, 2021), Kempe foundation (1 100k SEK, 2022-2024), and SLU Stiftelsen Fonden (120k SEK, 2022). I collaborate with researchers in Max Planck Institute (Gemany), Estonian University of Life Sciences (Estonia), IIASA (Austria), and University of Helsinki (Finland).
Postdoc. in Silviculture, Jan. 2018-Dec. 2020 SLU Umeå
Supervisor: Prof. Tomas Lundmark (SLU)
PhD in Ecophysiology, Dec. 2017 SLU Umeå
Supervisors: Prof. Torgny Näsholm (SLU); Prof. Ram Oren (Duke Univ.)
Topic #1. Interactive effects of water and nitrogen dynamics on forest nutrition and growth
H Lim, S Jämtgård, R Oren et al. 2022. Organic nitrogen enhances nitrogen nutrition and early growth of Pinus sylvestris seedlings. Tree Physiol
--Employing a seedling experiment combined with microdialysis monitoring of soil nitrogen fluxes, we show that an arginine-based organic fertiliser enhances seedlings' nutrition and growth, owing to the arginin's strong retention capacity in the soil medium, so producing a stable nitrogen supply.
Henriksson N, Lim H, Marshall J et al. 2021. Tree water uptake enhances nitrogen acquisition in a fertilized boreal forest – but not under nitrogen‐poor conditions. New Phytol
R Lutter, N Henriksson, H Lim et al. 2021. Belowground resource utilization in monocultures and mixtures of Scots pine and Norway spruce. For Ecol Manag
--Employ a novel dual labelling technique (D2O and 15NO3) in field conditions, we reveal a distinctive interaction between water and nitrogen uptake depending on soil feritlity (Henriksson et al.) or on spcies mixture (Lutter et al.).
H Lim, R Oren, S Linder et al. 2017. Annual climate variation modifies nitrogen induced carbon accumulation of Pinus sylvestris forests. Ecol Appl
-- Assessing three Scots pine forests, we show altered the fertilization responses of forest biomass growth by water availability.
Topic #2. Forest responses to management practices and a chaning climate
H Lim, BA Olsson, T Lundmark et al. 2020. Effects of whole-tree harvesting at thinning and subsequent compensatory nutrient additions on carbon sequestration and soil acidification in a boreal forest. Global Chang Biology Bioenergy
-- Whole-tree harvesting at thinning is believed to reduce growth of remaining trees and to lead soil acidification. A long-term observation (20 years) does not support that.
H Lim, CA Alvares, MG Ryan, D Binkley. 2020. Assessing the cross-site and within-site response of potential production to atmospheric demand for water in Eucalyptus plantations. For Ecol Manag
-- Employing 3-PG model and intensive field data, we examine the effect of VPD on forest carbon balance.
H Lim, R Oren, T Näsholm et al. 2019. Boreal forest biomass accumulation is not increased by two decades of soil warming. Nature Climate Change
-- Boreal biomass growth is nitrogen limited, and it is thus hypothesized that increased soil temperatures lead to enhanced nitrogen availability and, therefore, forest biomass growth. Our empirical observation, unprecedented in scale and duration, does not support that.