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Looking for age-related growth decline in natural forests: unexpected biomass patterns from tree rings and simulated mortality

Oecologia

By:
, ,
DOI: 10.1007/s00442-014-2881-2

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Abstract

Forest biomass growth is almost universally assumed to peak early in stand development, near canopy closure, after which it will plateau or decline. The chronosequence and plot remeasurement approaches used to establish the decline pattern suffer from limitations and coarse temporal detail. We combined annual tree ring measurements and mortality models to address two questions: first, how do assumptions about tree growth and mortality influence reconstructions of biomass growth? Second, under what circumstances does biomass production follow the model that peaks early, then declines? We integrated three stochastic mortality models with a census tree-ring data set from eight temperate forest types to reconstruct stand-level biomass increments (in Minnesota, USA). We compared growth patterns among mortality models, forest types and stands. Timing of peak biomass growth varied significantly among mortality models, peaking 20–30 years earlier when mortality was random with respect to tree growth and size, than when mortality favored slow-growing individuals. Random or u-shaped mortality (highest in small or large trees) produced peak growth 25–30 % higher than the surviving tree sample alone. Growth trends for even-aged, monospecific Pinus banksiana or Acer saccharum forests were similar to the early peak and decline expectation. However, we observed continually increasing biomass growth in older, low-productivity forests of Quercus rubra, Fraxinus nigra, and Thuja occidentalis. Tree-ring reconstructions estimated annual changes in live biomass growth and identified more diverse development patterns than previous methods. These detailed, long-term patterns of biomass development are crucial for detecting recent growth responses to global change and modeling future forest dynamics.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Looking for age-related growth decline in natural forests: unexpected biomass patterns from tree rings and simulated mortality
Series title:
Oecologia
DOI:
10.1007/s00442-014-2881-2
Volume
175
Issue:
1
Year Published:
2014
Language:
English
Publisher:
Springer
Contributing office(s):
Southwest Biological Science Center
Description:
12 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Oecologia
First page:
363
Last page:
374
Number of Pages:
12
Country:
United States
State:
Minnesota
Other Geospatial:
Superior National Forest