Crossdating Dead Trees: Does Sampling Height Influence Results?

In trees experiencing stress prior to death, growth may be partially or totally suppressed, or may occur only in the upper part of the boles. This may induce inaccuracies when retrospectively crossdating dead trees. In this study, we investigated the occurrence and range of time lags between year of last ring production (YOLRP) in crossdated discs collected at the base, at breast height (BrH), and in the upper part (UP) of the boles of 145 snags and logs of four boreal species. We also assessed the influence of tree age and growth prior to death. When comparing YOLRP in the upper and lower part of trees, more than half the time lags departed from zero. Mean lags ranged from 0.6 to 4.6 years according to species, with lags up to 14 years. Negative time lags, i.e. ring production occurring in the lower part of boles while it has stopped in the upper part, were also observed in up to 26% of cases. We suggest that when reconstructing fine patterns of mortality where accuracy must be optimized, sampling entire discs at BrH should be considered, as well as sampling a disc in the UP when sampling old or slowly declining trees. © 2017 by The Tree-Ring Society.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]

From management to stewardship: Viewing forests as complex adaptive systems in an uncertain world

The world's forests and forestry sector are facing unprecedented biological, political, social, and climatic challenges. The development of appropriate, novel forest management and restoration approaches that adequately consider uncertainty and adaptability are hampered by a continuing focus on production of a few goods or objectives, strong control of forest structure and composition, and most importantly the absence of a global scientific framework and long-term vision. Ecosystem-based approaches represent a step in the right direction, but are limited in their ability to deal with the rapid pace of social, climatic, and environmental changes. We argue here that viewing forest ecosystems as complex adaptive system provides a better alternative for both production- and conservation-oriented forests and forestry. We propose a set of broad principles and changes to increase the adaptive capacity of forests in the face of future uncertainties. These span from expanding the sustained-yield, single-good paradigm to developing policy incentives and interventions that promote self-organization and integrated social-ecological adaptation