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1. Schiestl-Aalto, Pauliina. Modelling intra- and inter-annual growth dynamics of Scots pine in the whole-tree carbon framework.

Degree: Department of Forest Sciences, 2017, University of Helsinki

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.

Ympäristötekijät vaikuttavat puiden kasvuun kahta kautta; ne säätelevät sekä hetkellistä kasvunopeutta (suora vaikutus) että puun sisäisen tilan kehittymistä (epäsuora vaikutus). Fotosynteesi puolestaan on kasvuun, hengitykseen ja muihin elintoimintoihin tarvittavan hiilen lähde. Kahden vastakkaisen teorian mukaan kasvunopeuden määrittävä tekijä on joko 1) rajoitteet käytettävissä olevan hiilen määrässä (lähdeteoria) tai 2) ympäristötekijöiden aiheuttama rajoite kudosten kasvuedellytyksissä (nieluteoria). Jotta voisimme ymmärtää, miten muuttuvat ilmasto-olosuhteet vaikuttavat puiden kasvuun ja hiilitaseeseen, on välttämätöntä tietää, miten puun eri osien (puuaine, neulaset, juuret) kasvu reagoi ympäristö- ja muiden tekijöiden vaihteluun. Tämän tutkimuksen tarkoitus oli Kvantifioida lämpötilan vaikutusta männyn…

Subjects/Keywords: metsätieteet; metsätieteet

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APA (6th Edition):

Schiestl-Aalto, P. (2017). Modelling intra- and inter-annual growth dynamics of Scots pine in the whole-tree carbon framework. (Doctoral Dissertation). University of Helsinki. Retrieved from http://hdl.handle.net/10138/177885

Chicago Manual of Style (16th Edition):

Schiestl-Aalto, Pauliina. “Modelling intra- and inter-annual growth dynamics of Scots pine in the whole-tree carbon framework.” 2017. Doctoral Dissertation, University of Helsinki. Accessed April 28, 2017. http://hdl.handle.net/10138/177885.

MLA Handbook (7th Edition):

Schiestl-Aalto, Pauliina. “Modelling intra- and inter-annual growth dynamics of Scots pine in the whole-tree carbon framework.” 2017. Web. 28 Apr 2017.

Vancouver:

Schiestl-Aalto P. Modelling intra- and inter-annual growth dynamics of Scots pine in the whole-tree carbon framework. [Internet] [Doctoral dissertation]. University of Helsinki; 2017. [cited 2017 Apr 28]. Available from: http://hdl.handle.net/10138/177885.

Council of Science Editors:

Schiestl-Aalto P. Modelling intra- and inter-annual growth dynamics of Scots pine in the whole-tree carbon framework. [Doctoral Dissertation]. University of Helsinki; 2017. Available from: http://hdl.handle.net/10138/177885

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