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You searched for subject:(decomposer efficiency). Showing records 1 – 2 of 2 total matches.

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Swedish University of Agricultural Sciences

1. Franklin, Oskar. Plant and forest dynamics in response to nitrogen availability.

Degree: 2003, Swedish University of Agricultural Sciences

Theories and mathematical models were derived to analyse and predict plant and forest response to soil nitrogen (N) availability and atmospheric CO2 concentration. Soil carbon accumulation in response to long-term fertilisation was studied using measured soil C and 14C of the organic layer in a pine forest in Northern Sweden. Fertilisation increased forest growth and drastically reduced long-term litter decomposition through effects on the decomposers. In 100 years, twice as much carbon would be accumulated in the forest soil where N addition is high as where no N addition occurs. Root:shoot allocation of small plants was modelled using maximisation of relative growth rate, with and without explicit inclusion of N based maintenance respiration. The results agreed qualitatively with experimental data from birch and tomato plants and the agreement was considerably improved by the inclusion of maintenance respiration. Senescence and resorption as mechanisms of maximising photosynthetic production were used to predict LAI and resorption efficiency in relation to canopy N. This theory explained the observed LAI for four investigated plant species: red amaranth (Amaranthus cruentus), soybean (Glycine max), rice (Oryza sativa), and sorghum (Sorghum bicolor). Analytical expressions for forest photosynthesis, NPP, growth, LAI, root:leaf allocation and leaf N concentration were derived using a principle of maximal growth and optimisation of canopy N. Whole forest responses to N availability and atmospheric CO2 were predicted from basic physiological parameters. The results agreed well with results of elevated CO2 FACE experiments for sweetgum and loblolly pine trees. Finally, the findings of reduced decomposition and increased growth in response to fertilisation and elevated CO2 were evaluated in the context of the global carbon balance. A simple model of the responses of global carbon fluxes and pool turnover rates combined with a future scenario of CO2 emissions was subjected to a strong fertilisation effect on the boreal forest components. The results indicate that massive fertilisation could temporarily halt the rising of the atmospheric CO2.

Subjects/Keywords: carbon; plant litter; growth; nitrogen cycle; nutrient availability; soil respiration; mathematical models; carbon-14; decomposer efficiency; litter quality; mechanistic model; nitrogen deposition; NPP:GPP; optimality; plant theory; resorption effciency; soil respiration

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APA (6th Edition):

Franklin, O. (2003). Plant and forest dynamics in response to nitrogen availability. (Doctoral Dissertation). Swedish University of Agricultural Sciences. Retrieved from http://pub.epsilon.slu.se/345/

Chicago Manual of Style (16th Edition):

Franklin, Oskar. “Plant and forest dynamics in response to nitrogen availability.” 2003. Doctoral Dissertation, Swedish University of Agricultural Sciences. Accessed May 09, 2021. http://pub.epsilon.slu.se/345/.

MLA Handbook (7th Edition):

Franklin, Oskar. “Plant and forest dynamics in response to nitrogen availability.” 2003. Web. 09 May 2021.

Vancouver:

Franklin O. Plant and forest dynamics in response to nitrogen availability. [Internet] [Doctoral dissertation]. Swedish University of Agricultural Sciences; 2003. [cited 2021 May 09]. Available from: http://pub.epsilon.slu.se/345/.

Council of Science Editors:

Franklin O. Plant and forest dynamics in response to nitrogen availability. [Doctoral Dissertation]. Swedish University of Agricultural Sciences; 2003. Available from: http://pub.epsilon.slu.se/345/


Swedish University of Agricultural Sciences

2. Eliasson, Peter. Impacts of climate change on carbon and nitrogen cycles in boreal forest ecosystems.

Degree: 2007, Swedish University of Agricultural Sciences

It is well known that soil carbon stocks decrease considerably in response to soil warming, but experimental data have shown that the loss of carbon declines within decades in apparent acclimation. An explanation to such findings is offered under the theoretical framework of ecosystem models in this thesis. Simulations of forest ecosystem responses to increased soil temperatures showed that the labile carbon in soil was reduced considerably within years after warming, although the structure and function of decomposer organisms remained intact. Simulations of increased CO2 also confirmed positive growth response in the short term. The response of soil carbon was similar, however predicted to be less than the increase of biomass. Nitrogen availability and negative feedback mechanisms of the plant soil system were critical to the results, indicating that nitrogen progressively limited the growth response. Assumptions concerning the response of decomposing organisms to changes in soil nitrogen are crucial to the interpretation of the above. Positive nitrogen feedback was therefore implemented to test consequences of nitrogen additions, allowing for improved decomposer efficiency when inorganic nitrogen becomes available in the soil. Responses compared well with experimental results. Simulations of moderate inputs of slowly increasing inorganic nitrogen loads in the long term revealed counteracting feedback responses: the positive nitrogen feedback resulted in increased decomposer efficiency and biomass growth also increased as expected; negative nitrogen feedback appeared in the sense that the growth response was reduced due to decreased mineralisation. An economic estimation of the net value of carbon sink capacity was also performed. The value of the carbon sink was given in relation to conservative estimates of total net values of important stocks and flows of forest natural capital – factors such as recreational values or hydrological services omitted. The net value of the carbon sink was suggested to amount to 3-50% of the net value of Swedish forests.

Subjects/Keywords: boreal forests; climatic change; greenhouse effect; carbon cycle; mineralization; nitrogen cycle; photosynthesis; primary productivity; soil temperature; environmental impact; valuation; ecosystems; models; boreal forest; climate change; continuous-quality theory; decomposer efficiency; G’DAY; generic decomposition and yield model; natural capital; satellite net national accounts; nitrogen productivity; Q-model; soil decomposition; soil warming

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Eliasson, P. (2007). Impacts of climate change on carbon and nitrogen cycles in boreal forest ecosystems. (Doctoral Dissertation). Swedish University of Agricultural Sciences. Retrieved from http://pub.epsilon.slu.se/1525/

Chicago Manual of Style (16th Edition):

Eliasson, Peter. “Impacts of climate change on carbon and nitrogen cycles in boreal forest ecosystems.” 2007. Doctoral Dissertation, Swedish University of Agricultural Sciences. Accessed May 09, 2021. http://pub.epsilon.slu.se/1525/.

MLA Handbook (7th Edition):

Eliasson, Peter. “Impacts of climate change on carbon and nitrogen cycles in boreal forest ecosystems.” 2007. Web. 09 May 2021.

Vancouver:

Eliasson P. Impacts of climate change on carbon and nitrogen cycles in boreal forest ecosystems. [Internet] [Doctoral dissertation]. Swedish University of Agricultural Sciences; 2007. [cited 2021 May 09]. Available from: http://pub.epsilon.slu.se/1525/.

Council of Science Editors:

Eliasson P. Impacts of climate change on carbon and nitrogen cycles in boreal forest ecosystems. [Doctoral Dissertation]. Swedish University of Agricultural Sciences; 2007. Available from: http://pub.epsilon.slu.se/1525/

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