Swedish University of Agricultural Sciences

About: Swedish University of Agricultural Sciences is a education organization based out in Uppsala, Sweden. It is known for research contribution in the topics: Population & Soil water. The organization has 13510 authors who have published 35241 publications receiving 1414458 citations. The organization is also known as: Sveriges Lantbruksuniversitet & SLU.

Towards a Standard Methodology for Greenhouse Gas Balances of Bioenergy Systems in Comparison with Fossil Energy Systems

Abstract: In this paper, which was prepared as part of IEA Bioenergy Task XV (“Greenhouse Gas Balances of Bioenergy Systems”), we outline a standard methodology for comparing the greenhouse gas balances of bioenergy systems with those of fossil energy systems. Emphasis is on a careful definition of system boundaries. The following issues are dealt with in detail: time interval analysed and changes of carbon stocks; reference energy systems; energy inputs required to produce, process and transport fuels; mass and energy losses along the entire fuel chain; energy embodied in facility infrastructure; distribution systems; cogeneration systems; by-products; waste wood and other biomass waste for energy; reference land use; and other environmental issues. For each of these areas recommendations are given on how analyses of greenhouse gas balances should be performed. In some cases we also point out alternative ways of doing the greenhouse gas accounting. Finally, the paper gives some recommendations on how bioenergy systems should be optimized from a greenhouse-gas-emissions point of view.

Effects of excess nitrogen and phosphorus starvation on the extramatrical mycelium of ectomycorrhizas of Pinus sylvestris L.

Abstract: summary The effect of excess nitrogen alone, and in combination with phosphorus and magnesium starvation, on the production of extramatrical mycelium was studied in Scots pine seedlings ectomycorrhizal with Laccaria bicolor (R. Mre.) Orton, Hebeloma crustuliniforme (Bull, ex St-Amans) Quel. and Suillus bovinus (L. ex Fr.) O. Kuntze. Seedlings were grown in a semi-hydroponic cultivation system and the ergosterol assay was used to estimate fungal biomass. The mycelial biomass increased rapidly when N was kept low (10–20 mg l−1) and in balance with other nutrients, but no extramatrical mycelium was produced when the N concentration was raised to 200 mg l−1. The growth of the extramatrical mycelium resumed when the excess N treatment was terminated and the seedlings were returned to a low nutrient regime, Laccaria showing more complete resumption of growth than Suillus, while Hebeloma had a low production of extramatrical mycelium in all treatments. Compared with the external mycelium, the amount of fungal tissue on the mycorrhizal roots (mantle and Hartig net) was much less affected by the high N treatment. P starvation increased the production of extramatrical mycelium tenfold, with almost no difference between high and low N nutrient regimes, while Mg starvation had no effect on the fungal biomass. The high N treatment lowered P and particularly Mg concentration of the needles, regardless of the mycorrhizal status of the plant. It is suggested that nitrogen deposition from the atmosphere may damage the function of mycorrhiza even before root tip studies reveal any decline in the symbiotic state. On the other hand, moderate nitrogen fertilization of forest land unaffected by nitrogen pollution is likely to have only passing effects on mycorrhizal development.