Snags and Down Wood in Missouri Old-Growth and Mature Second-Growth Forests

Abstract

As forest managers in the Midwest focus more attention toward understanding and maintaining ecosystem processes, greater emphasis is being placed on the role of snags and down wood in providing wildlife habitat, cycling nutrients, and maintaining continuity in forest structure following harvest. We measured five remnant old-growth hardwood tracts and six mature, second-growth, hardwood tracts in Missouri and compared findings concerning (1) the volume of down wood and (2) the number and size distribution of snags (i.e., standing dead trees). Volume of down wood ≥ 10 cm in diameter averaged 36 m³/ha on the old-growth tracts, double the 18 m³/ha mean volume for the second-growth sites. This difference in volume was concentrated in pieces of down wood with diameters larger than 20 cm; below diameters of 20 cm the number of pieces of down wood by diameter class was similar for the old-growth and second-growth sites. On the old-growth sites, the mean basal area of snags ≥ 10 cm dbh was 1.9 m²/ha. This was approximately 1.5 times greater than the mean basal area of snags on the second-growth sites. The number of snags ≥ 10 cm dbh on the old growth sites was approximately 9% pf the number of live trees on those sites. The corresponding value for second-growth sites was 8%. On both the old-growth and second-growth sites, the number of snags and the number of live trees by dbh class followed a negative exponential (reverse-J) form. Frequency distributions for the number of snags by dbh class closely followed those for live trees on the same sites. These results provide managers with general guidelines for the quantity of down wood likely to be found in mature second-growth forests and old-growth forests. We also provide some provisional rules of thumb for estimating the density and size distribution of snags from values observed for live trees in the same stand. North. J. Appl. For. 14(4):165-172.

Dynamics of coarse woody debris following gap harvesting in the Acadian forest of central Maine, U.S.A.

“…The projected area of CWD (an estimate of log surface area potentially available for seedling establishment) of 252.2 m 2 /ha (2.52% of ground surface) found in this study is similar to that reported from forests of the central or eastern North America (MacMillan 1981;Shifley et al 1997), yet is substantially lower than that reported from northwestern North America, where CWD can cover from 10 to 25% of the forest floor (see Harmon and Sexton 1995;Clark et al 1998).…”

Effects of timber harvest on carbon pools in Ozark forests

“…The primary goal of our study was to evaluate the impacts of harvest on sizes and allocation of C pools within forests of the Missouri Ozarks. Indeed, the stem density (401-1761 individualsÁha -1 ) and basal area (8.9-27.0 m 2 Áha -1 ) fell within the ranges of values reported by other studies of similar forests in this region (Weaver and Ashby 1971;Muller 1982;Shifley et al 1997). Unfortunately, comparisons of our C pool components to other studies were hampered because C pool estimates are differently influenced by sitespecific disturbance regimes and the definitions of some major C pools vary, especially for dead organic matter (Grier and Logan 1977;Matthews 1997;Schlesinger 1977).…”

Comparison of snag densities among regeneration treatments in mixed pine–hardwood forests

“…Various natural processes and forest-management activities can affect snag abundance and size distribution. In the absence of large-scale mortality events such as ice storms, disease outbreaks, or wildfire, the diameter distribution of snags in the southeastern US may resemble that of live trees in mature forests, with most snags being in the smaller size classes in unthinned stands (McComb and Muller 1983;Shifley et al 1997;Moorman et al 1999). However, snags may represent only 5%-14% of the total number of stems (McComb and Muller 1983;Shifley et al 1997).…”