Coarse Woody Debris Missouri Ozark Forest Ecosystem Project. Randy G. Jensen Stephen R. Shifley Brian L. Brookshire David R. Larsen Laura A. Herbeck. Wildlife habitat Birds.......... 36 Species Mammals...11 Species Reptiles........8 Species Nutrient cycling
Coarse Woody Debris
Missouri Ozark Forest Ecosystem Project
Randy G. Jensen
Stephen R. Shifley
Brian L. Brookshire
David R. Larsen
Laura A. Herbeck
Birds.......... 36 Species
Substrate for fungi and vascular plants
Slow release of nutrients back into the system
0.5 acre plots
70+ per site; 648 total
(Snags, DDW% cover)
0.25 acre plots
11 per site, overlaid
(all DDW characteristics)
Percent of Ground Covered
Number per acre
Percent of Live Trees
No pre-treatment effects
Mean = 241
Gradual increase in the amount of dead wood
Perhaps double the current volume
Harvested Stands (EAM or UAM)
Dramatic increase in the amount of down wood
Regeneration harvesting (substantial)
Because boles are removed increase % cover faster than volume
Down wood should increase on all sites
Snags eventually become down wood
Short term increase in snags = long term increase in down wood
Down coarse woody debris (CWD) is an important but little-studied indicator of forest structure, fire risk, habitat quality, nutrient cycling, and carbon storage.
Snags (standing dead trees) are closely linked to CWD because snags ultimately add to the pool of CWD.
CWD was inventoried in 1990-1991, 1994-1995 and 1999-2000 (post-treatment) using line transects .
Total combined length of transects was 27.75 miles of which about 1 mile of transect (total) passed through clearcuts. The 8,855 pieces of measured down wood covered about 1 mile of transect length or roughly 3.6 percent of the ground area (all MOFEP sites combined).
Down wood volume associated with individual silvicultural treatments sorted out in a logical order with total CWD for clearcut plots > group selection > single tree > intermediate thinning > no harvest.
Prior to the 1997 harvest treatments there were no significant differences among treatment groups . The volume and percent coverage of CWD approximately doubled before and after harvest treatments, even on the control plots.
Prior to harvest treatments, snags comprised about 5 sq.ft. basal area/ac with roughly 1 snag for every 10 to 12 live trees by dbh class.
Snags and CWD should continue to be periodically measured, particularly before and after harvest treatments. This will allow scientists to better quantify the magnitude and variability of the accumulation of snags and CWD in untreated stands.
Little is known about rates of decomposition for snags and down wood.
Periodic harvesting, particularly uneven-aged management with periodic thinning treatments, may eliminate trees that are prone to die and thus over time reduce the number of snags relative to untreated stands.
The volume of coarse woody debris of various sizes is indicative of fuel loading and ultimately of fire intensity if ignited. The MOFEP results could be used to support fire research and modeling efforts in the Ozarks.
The Forest Service Forest Inventory and Analysis (FIA) program is now collecting CWD data on a small proportion of plots as part of their on-going state-wide inventories. The FIA CWD sampling is just beginning, and results from the periodic MOFEP CWD inventories can serve as a reference point from which to evaluate the early FIA results.
Inventories of snags and CWD present sampling challenges because they are highly variable at small spatial scales. Moreover, snags are relatively rare events. Recent work related to cavity tree estimation indicates that appropriate spatial scales can be determined for estimating current and predicted levels of cavity trees. A similar approach would likely be productive if applied to estimation and prediction of snag density or CWD at stand and landscape scales.
Importance of Snags and Down Wood.
Initial Pre-treatment Conditions at MOFEP Sites.
Comparison of MOFEP sites to other locations.
Likely Changes Following Treatment.
(Jenkins and Parker)
No change in ratio of snags to live trees.
Modest increase in mean snag size.
Thinning (EAM or UAM)
Reduce number of snags in long run.
Girdling nonmerchantable stems will increase snags in the short run.
Regeneration harvesting (EAM or UAM)
Felling snags during harvesting will greatly decrease snags...BUT
Girdling nonmerchantable stems could greatly increase snags in short term
Any harvesting will alter the ratio of snags to live trees
No pre-treatment differences in snags or down wood.
Blocking probably not very helpful in grouping treatment areas for these characteristics.
Too bad, but not a big deal.
Dead wood flows from overstory to understory.
Snags and down wood volumes vary with stand age/condition
Management allows opportunity to control rates of snag accumulation and movement of wood from overstory to forest floor.
Any harvesting will rapidly increase the amount of down wood in the short term, but in the long term harvested sites will probably have less down wood than the No Harvest treatment.
Felling nonmerchantable stems will decrease the number of snags and increase the relative amount of down wood on the forest floor.
Girdling nonmerchantable stems will increase snags and delay input of some down wood.
Any harvesting will alter the ratio of snags to live trees.
Surface Area (sq.ft/ac)
Ground covered (%)
Snag Basal Area (sq.ft/ac)
Big Spring (30)
Snag Ratio (%)
Down Wood Volume (cu.ft/ac)
Snags per Acre