Effects of variable temperature and moisture conditions on respiration and nonstructural carbohydrate dynamics of tree roots

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Ryhti , K , Schiestl-Aalto , P , Tang , Y , Rinne-Garmston , K T , Ding , Y , Pumpanen , J , Biasi , C , Saurer , M , Bäck , J & Kulmala , L 2022 , ' Effects of variable temperature and moisture conditions on respiration and nonstructural carbohydrate dynamics of tree roots ' , Agricultural and Forest Meteorology , vol. 323 , 109040 . https://doi.org/10.1016/j.agrformet.2022.109040

Title: Effects of variable temperature and moisture conditions on respiration and nonstructural carbohydrate dynamics of tree roots
Author: Ryhti, Kira; Schiestl-Aalto, Pauliina; Tang, Yu; Rinne-Garmston, Katja T.; Ding, Yiyang; Pumpanen, Jukka; Biasi, Christina; Saurer, Matthias; Bäck, Jaana; Kulmala, Liisa
Contributor organization: Department of Forest Sciences
Ecosystem processes (INAR Forest Sciences)
University of Helsinki
Institute for Atmospheric and Earth System Research (INAR)
Forest Soil Science and Biogeochemistry
Department of Microbiology
Viikki Plant Science Centre (ViPS)
Forest Ecology and Management
Date: 2022-08-15
Language: eng
Number of pages: 16
Belongs to series: Agricultural and Forest Meteorology
ISSN: 0168-1923
DOI: https://doi.org/10.1016/j.agrformet.2022.109040
URI: http://hdl.handle.net/10138/346723
Abstract: In warming climates, soil water content (SWC) may act as an important factor in determining belowground carbon dynamics in boreal forests. Here, we estimated the respiration and nonstructural carbohydrate (NSC) concentrations of tree roots in a mature Scots pine (Pinus sylvestris L.) stand in southern Finland during two growing seasons with contrasting weather conditions. Root respiration was estimated with four different methods: 1) incubating excised roots, 2) partitioning forest floor respirations with root exclusion, or 3) based on temperature response functions and 4) modelling with the whole-tree carbon model 'CASSIA'. In addition, we conducted a drought experiment in a greenhouse to determine the effect of reduced soil-water availability on respiration by incubating soil and roots of Scots pine saplings. We observed that the respiration of incubated roots of Scots pine saplings and soil decreased with drying after excluding the effect of temperature on respiration (RRES), soil being more sensitive to drought than roots. Similarly, RRES of incubated roots in the field was significantly decreased by lowered SWC, whereas respiration of the entire root system estimated with other methods was clearly higher in dryer and warmer than moister and cooler year. Nevertheless, incubated roots excavated from the topsoil are most affected by drying soil, which might not reflect the response of the entire root system. RRES of incubated roots was negatively associated with root fructose and glucose concentrations. At the same time, root fructose, glucose and sucrose concentrations were negatively associated with SWC due to their role in osmoregulation. Thereby it seems that RRES does not directly follow the changes in NSCs despite the apparent correlation. Our study highlights the responsive nature of root carbon dynamics in varying weather events that should be taken into account in estimating and modelling the impacts of warming climate.
Subject: Root respiration
Soil moisture
Boreal forest
Pinus sylvestris
4112 Forestry
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion

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