19 – 2006 – contents

FRIDRIK PÁLMASON
Nitrogen mineralization in situ and in laboratory in Icelandic Andosol – 3

ARNÓR SNORRASON AND STEFÁN FREYR EINARSSON
Single-tree biomass and stem volume functions for eleven tree species used in Icelandic forestry – 15

LILJA KARLSDÓTTIR AND ÁSA L. ARADÓTTIR 
Propagation of Dryas octopetala L. and Alchemilla alpina L. by direct seeding andplanting of stem cuttings – 25

JÓN ÁGÚST JÓNSSON, BJARNI D. SIGURDSSON AND GUÐMUNDUR HALLDÓRSSON
Changes in bird life, surface fauna and ground vegetation following afforestation by black cottonwood (Populus trichocarpa Torr. & Gray) – 33

KARL SKIRNISSON AND HAKON HANSSON
Causes of diarrhoea in lambs during autumn and early winter in an Icelandic flock of sheep – 43

THÓREY BJARNADÓTTIR, JÓHANNES SVEINBJÖRNSSON AND EMMA EYTHÓRSDÓTTIR
Effects of the timing of weaning lambs and transferring from rangeland grazing to forage rape and aftermath grazing, with respect to lamb growth and development – 59

THÓREY BJARNADÓTTIR, JÓHANNES SVEINBJÖRNSSON AND EMMA EYTHÓRSDÓTTIR
The effects of different grazing pasture systems and spring turn-out date on growth and development of lambs – 71