A comparison of protein complexation capacity among six boreal species and the consequences for nitrogen mineralization

• Main Author: Sverker, Jennie
• Format: Text
• Language: Swedish; English
• Published: 2009
• Subjects: Forestry - General aspects; Arvidsjaur
• Online Access: https://stud.epsilon.slu.se/12339/1/sverker_j_171018.pdf

Nitrogen (N) is considered to be the most limiting nutrient for productivity in boreal forests, and the ability of plants to complex protein during decomposition is considered to be an important mechanism by which some plants regulate the N cycle. In this study I investigated whether six boreal plant species differed in their ability to complex proteins. I hypothesized 1) that species that dominate in late successional stands would exhibit higher complexation capacities than species that dominate in young stands, 2) that individual species would demonstrate an increase in their protein complexation capacity in response to nutrient limitation, and 3) that differences in protein complexation capacity among litter types would correspond to lower rates of N mineralization from an external protein source. I collected litters from ten forest stands located in the area of Arvidsjaur, Sweden (65˚35´-66˚07´N, 17˚15´-19˚26´E) with an age range between 35 to 355 years since last major fire, and in which fertility declined with stand age. Litters from three early successional dominant species (Betula pendula, Pinus sylvestris, Vaccinium myrtillus), two late successional dominant species (Picea abies, Empetrum hermaphroditum), and one intermediate species (Vaccinium vitis-idaea) were collected from each stand. Their litters were extracted and protein complexation capacities measured. The data demonstrated high complexation capacities for the two early successional species (V. myrtillus and B. pendula), which was inconsistent with the first hypothesis. No species demonstrated a significant correlation between their complexation capacity and stand age (i.e. fertility) across the 10 stands, which did not support my second hypothesis. Finally, litter extracts were added to a soil with and without a protein source, in order to evaluate whether litter extracts with high protein complexation capacities would demonstrate low N mineralizaiton rates. This experiment revealed that extracts from three species (B. pendula, P. abies, and ...