PS 5-48 - CANCELLED - 100 years is not enough for old growth status: Re-sampling woody debris and live trees in a chronosequence of 16 northern hardwood forests

Background/Question/Methods

Woody debris is an important asset to forest ecosystems as a C pool, habitat for wildlife, and a germination site for trees.
The woody debris in a stand is driven by the mortality of overstory trees throughout the stand’s development. Forest development, however, takes place over long periods of time and thus is difficult to study directly. One approach is to substitute space for time, by studying stands of different ages that have developed under similar climatic and edaphic conditions, and interpreting them as a chronosequence. We re-sampled a chronosequence of fourteen northern hardwood stands after 16 years to describe how stand level characteristics (volume, biomass, species contribution, and decay class) of woody debris vary with stand development and in comparison to live trees. All stands are located in the White Mountains of New Hampshire and were clear-cut in the last 150 years. Two true old-growth forests were also sampled to enable comparisons with the oldest stands in the chronosequence.

Results/Conclusions

The oldest chronosequence sites were unlike true old-growth stands due to a lack of large live and downed trees. These results suggest that steady state conditions for coarse woody debris and live trees may not be reached until after 150 years. In contrast, fine woody debris peaked at 30-50 years, during the self-thinning of early-successional species. Re-sampling of the chronosequence revealed dramatic increases in woody debris volume from infrequent disturbances.