Modelling intra- and inter-annual growth dynamics of Scots pine in the whole-tree carbon framework

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http://hdl.handle.net/10138/337116

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Schiestl-Aalto , P P 2017 , ' Modelling intra- and inter-annual growth dynamics of Scots pine in the whole-tree carbon framework ' , University of Helsinki , Helsinki . https://doi.org/10.14214/df.234

Title: Modelling intra- and inter-annual growth dynamics of Scots pine in the whole-tree carbon framework
Author: Schiestl-Aalto, Piia Pauliina
Other contributor: Mäkelä, Annikki
Harri, Mäkinen
Kulmala, Liisa
Contributor organization: Ecosystem processes (INAR Forest Sciences)
Department of Forest Sciences
Forest Modelling Group
Publisher: Finnish Society of Forest Science
Date: 2017-04-19
Language: eng
Number of pages: 76
Belongs to series: Dissertationes Forestales
ISBN: 978-951-651-559-8
978-951-651-558-1
ISSN: 2323-9220
DOI: https://doi.org/10.14214/df.234
URI: http://hdl.handle.net/10138/337116
Abstract: Environmental factors have a dual effect on growth as they affect both the momentary growth rate (direct effect) and the rate of ontogenetic development (indirect effect). Photosynthesis on the other hand is the source of carbon that is needed for growth, respiration and other purposes. There are two opposite theories about the factor determining growth rate: 1) the availability of carbon for growth (source limitation) and 2) limitation that environmental factors cause on tissue ability to grow (sink limitation). Understanding the responses of the growth of tree organs (wood, needles, roots) to environmental and other factors is important to be able to understand the changes in tree growth and carbon balance in changing climatic conditions. The purpose of this study was to define the effects of temperature on Scots pine growth at different temporal scales and to estimate the relative importances of the source and sink effects on growth. For that, a dynamic growth model CASSIA (Carbon Allocation Sink Source InterAction) was constructed. CASSIA was able to predict daily primary and secondary wood and needle growth rate variation with indirect and direct effects of temperature. In addition, the temperature of warm previous late summer was observed to lead to enhanced length of the growth period (in temperature accumulation units) of shoots in the following year. Growth onset during spring was observed to be a continuous process determined by temperature accumulation, instead of momentary temperatures. Short-term growth variations in normal conditions were concluded to be sink limited because CASSIA was able to predict the within year growth with temperature and without direct effect of photosynthesis or stored carbon. On the other hand carbon source effect (gross primary production) was needed to produce the between year variation in growth. According to the results of this study, growth is limited by a complex combination of sink and source effects. Furthermore, environmental factors affect growth at different time scales varying from instantaneous effects to delayed effects from previous year(s). More research is needed to identify the factors determining the carbon flows to different processes.Environmental factors have a dual effect on growth as they affect both the momentary growth rate (direct effect) and the rate of ontogenetic development (indirect effect). Photosynthesis on the other hand is the source of carbon that is needed for growth, respiration and other purposes. There are two opposite theories about the factor determining growth rate: 1) the availability of carbon for growth (source limitation) and 2) limitation that environmental factors cause on tissue ability to grow (sink limitation). Understanding the responses of the growth of tree organs (wood, needles, roots) to environmental and other factors is important to be able to understand the changes in tree growth and carbon balance in changing climatic conditions. The purpose of this study was to define the effects of temperature on Scots pine growth at different temporal scales and to estimate the relative importances of the source and sink effects on growth. For that, a dynamic growth model CASSIA (Carbon Allocation Sink Source InterAction) was constructed. CASSIA was able to predict daily primary and secondary wood and needle growth rate variation with indirect and direct effects of temperature. In addition, the temperature of warm previous late summer was observed to lead to enhanced length of the growth period (in temperature accumulation units) of shoots in the following year. Growth onset during spring was observed to be a continuous process determined by temperature accumulation, instead of momentary temperatures. Short-term growth variations in normal conditions were concluded to be sink limited because CASSIA was able to predict the within year growth with temperature and without direct effect of photosynthesis or stored carbon. On the other hand carbon source effect (gross primary production) was needed to produce the between year variation in growth. According to the results of this study, growth is limited by a complex combination of sink and source effects. Furthermore, environmental factors affect growth at different time scales varying from instantaneous effects to delayed effects from previous year(s). More research is needed to identify the factors determining the carbon flows to different processes.
Subject: 4112 Forestry
fenologia
hiilitase
dynaaminen mallitus
kasvun vaihtelu
nielu-lähde -dynamiikka
Rights: cc_by_nc_nd
Usage restriction: openAccess
Self-archived version: publishedVersion


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