Nitrogen fixation and net primary production in a young Sitka alder stand

Biomass, net primary production and nitrogen fixation rates were measured in a 5-year-old Sitka alder (Alnus sinuata (Regel) Rydb.) stand. Acetylene reduction assays yielded a nitrogen fixation estimate of 35 kg N ha−1 year−1. The biomass of leaves, stems, roots, and nodules was 13 720 kg ha−1 and aboveground net primary production was 6000 kg ha−1 year−1.