| Abstrakt: |
In 250 20 m x 20 m permanent plots in the Craigieburn Range, Canterbury, New Zealand, 1970 stem density wa 2,191/ha, basal area was 52.4 m2/ha, and stem biomass was 179.1 Mg/ha. Net production ofstemwood (1974--1987) was 2.0 Mg/ha/yr; mortality was 3.5 Mg/ha/yr. By 1987 density had decreased by 30%, basal area by 12%, and stem biomass by 13%. Stands with many short trees of small mean dbh were common at high elevation, whereas stands with fewer, taller trees with large mean dbh were common at low elevation. Stemwood production and mortality rate were higher in tall stands. Mortality was well distributed among plots, indicating small, frequent canopy openings; stand turnover calculations were 66 year (based on 2.2% annual biomass loss) to 83 year (based on 1.2% annual stemwood production). Larger canopy openings were also evident, but were more infrequent, so stand turnover times due to 'catastrophic' disturbances were in the range of 350- -4000 yr. Consequently, the small, high-frequency disturbances blurred effects of larger disturbances on stand structure and also constrained the fluctuation in forest biomass. [ABSTRACT FROM AUTHOR] |
