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20 – 2007 – contents

TORKELL JÓHANNESSON, TRYGGVI EIRÍKSSON, KRISTÍN BJÖRG GUDMUNDSDÓTTIR, SIGURDUR SIGURDARSON AND JAKOB KRISTINSSON
Overview: Seven trace elements in Icelandic forage. Their value in animal health and with special relation to scrapie – 3

THORBERGUR HJALTI JONSSON AND ÚLFUR ÓSKARSSON
Shoot growth strategy of 29 black cottonwood (Populus trichocarpa) clones – 25

THORBERGUR HJALTI JONSSON AND MARGRET LILJA MAGNUSDOTTIR
Salt-related suppression of bud break in Populus trichocarpa: Cost of inclusion, ion-specific or osmotic effects? – 35

BROOKE PARRY HECHT, KRISTIINA A. VOGT, ÞRÖSTUR EYSTEINSSON AND DANIEL J. VOGT
Changes in air and soil temperatures in three Icelandic birch forests with different land-use histories – 49

ÁSA L. ARADÓTTIR, KRISTÍN SVAVARSDÓTTIR AND ANNE BAU
Clonal variability of native willows (Salix pylicifolia and Salix lanata) in Iceland and implications for use in restoration – 61

KARL SKÍRNISSON
Eimeria spp. (Coccidia, Protozoa) infections in a flock of sheep in Iceland: Species composition and seasonal abundance 73

HÓLMGEIR BJÖRNSSON
Fertilization of Nootka lupin (Lupinus nootkatensis) for biomass production and carbon sequestration – 81

JOHANN ORLYGSSON AND STEINAR RAFN BECK BALDURSSON
Phylogenetic and physiological studies of four hydrogen-producing thermoanareobes from Icelandic geothermal areas – 93

HÖRÐUR V. HARALDSSON, HARALD U. SVERDRUP, SALIM BELYAZID, BJARNI DIÐRIK SIGURÐSSON AND GUÐMUNDUR HALLDÓRSSON
Assessment of effects of afforestation on soil properties in Iceland, using Systems Analysisand System Dynamic methods – 107

BRYNHILDUR BJARNADOTTIR, ANNA CECILIA INGHAMMAR, MONA-MARIA BRINKER AND BJARNI D. SIGURDSSON
Single tree biomass and volume functions for young Siberian larch trees (Larix sibirica) in eastern Iceland 125