Why is the productivity of Douglas-fir higher in New Zealand than in its native range in the Pacific Northwest, USA?

Title data

Waring, Richard ; Nordmeyer, Alan ; Whitehead, David ; Hunt, John ; Newton, Michael ; Thomas, Christoph ; Irvine, James:
Why is the productivity of Douglas-fir higher in New Zealand than in its native range in the Pacific Northwest, USA?
In: Forest Ecology and Management. Vol. 255 (2008) Issue 12 . - pp. 4040-4046.
ISSN 0378-1127
DOI: https://doi.org/10.1016/j.foreco.2008.03.049