Carbon stocks and flows in forest ecosystems based on forest inventory data

Abstract

Countries are currently reporting changes in carbon pools of forests to UNFCCC. According to the reporting guidelines methods should be transparent and verifiable, and also the quantification of the uncertainty is asked.The objective of the thesis was to develop methods for quantifying carbon stocks and fluxes at national scale based on forest inventory data.To estimate tree biomass of forests, representative BEFs (biomass expansion factors) with uncertainty estimate were developed for Finland. A method for quantifying carbon flux of branches to soil was also developed. Both biomass and branch litterfall estimates were tested against independent measurements. Biomass estimation method and litterfall estimates were applied with Finnish forest inventory data to estimate carbon stocks and their changes for Finnish forests for . In this application main sources of litter were quantified based on forest inventory data and fed into dynamic soil decomposition model in order to estimate soil carbon stocks and its changes.Application of BEFs, litterfall estimates and soil model gave time series of carbon stocks in Finnish forests. Results showed that tree carbon stock of Finland increased from 510 Tg to 780 Tg, while carbon in mineral soils increased from 850 Tg to 960 Tg during 80 year period. It was also found that there were high inter annual variation with soil-and tree carbon stocks caused by harvestings and temperature. According to the results, the NPP (net primary production) of Finnish forests has increased from 0.3 to 0.4 kg m -2 during studied period, while NBP (net biome production) was positive since 1970s.Results emphasize the importance of complete counting of changes of forest carbon pools i.e., trees, litter, soil and dead wood. Completeness will be important especially if forest management is used as a tool to mitigate climate change by enhancing carbon sinks of forests.

Modelling fine root biomass of boreal tree stands using site and stand variables

“…Fine root production has earlier been estimated to contribute from 33% to 75% of the annual net primary production in forest ecosystems (Grier et al, 1981;Santantonio and Grace, 1987;Vogt, 1991;Jackson et al, 1997), and more recent estimates suggest these percentages to be from 13% to 27% (McCormack et al, 2015b). Fine roots represent one of the largest litter inputs to the soil, especially in boreal forests (Vogt et al, 1986;Lehtonen, 2005;Clemmensen et al, 2013;Leppälammi-Kujansuu et al, 2014;Ojanen et al, 2014). Unfortunately, the quantity of fine roots and their lifespan are poorly known (Brunner et al, 2013) compared to aboveground compartments, and this may lead to severe uncertainties in ecosystem simulation models and C budget estimates (Peltoniemi et al, 2006;Strand et al, 2008;Smithwick et al, 2014;McCormack et al, 2015a).…”

“…Hitherto, fine root biomass in the GHG inventories of Finnish upland forests has been estimated using statistical models that describe the relation between modelled foliage and measured fine root biomass using data from 16 sites on upland soils across Finland . Foliage biomass is the most difficult aboveground biomass pool to model and the systematic errors of foliage biomass estimates can be high (Lehtonen, 2005;Somogyi et al, 2007).…”

The influence of altitude and management on carbon stock quantities in rungwe forest, southern highland of Tanzania

“…In Africa, for example, deforestation accounts for nearly 70% of total emissions (FAO, 2005) [3] while in Tanzania various sources has reported about the forest depletion and degradation (Kangalawe et al, 2005;Majule et al, 2010) [4,5] contributing to almost 20% of the total emission. Carbon circulates among the oceans; terrestrial biosphere and atmosphere, in addition to human activities, such as fuel combustion and deforestation affect the carbon dioxide (CO 2 ) concentration in the atmosphere (Lehtonen, 2005) [6]. Forests are also the largest terrestrial reservoir for atmospheric carbon because they remove CO 2 from the atmosphere and store it in the soil litter, trees and other organic matter.…”

Coupling a Forest Growth Model with a Soil Carbon Simulator

“…-In this work the annual branch litterfall was intuitively set to 3% of the total branch mass, leading to a lifespan of 33.3 years. Only little is known about the senescence rate of coarse roots [59]. Following a common practice we set it to the same level as branch litterfall [52].…”