The Long-Term Effect of Timber Stand Improvement on Snag and Cavity Densities In the Central Appalachlans 1 2 (original) (raw)
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The effects of thinning intensity on snag and cavity tree abundance in an Appalachian hardwood stand
Canadian Journal of Forest Research-revue Canadienne De Recherche Forestiere, 2000
Traditional silvicultural practices focus on manipulating forest vegetation structure for commodity production. Structural features important to wildlife, such as snags, trees with decay, and cavity trees are also affected by forest management, but these effects are often not quantified. This study measured the effects of different thinning intensities (45, 60, and 75% residual relative densities and uncut controls), heartwood decay resistance (resistant, slight), and age (formed pre-or post-treatment) on the density and volume of snags and decayed wood in an Appalachian hardwood stand. Cavity trees considered useful to local woodpecker species were also measured. Results indicated that snags and decayed wood were two to four times more abundant in controls compared with heavily thinned (45% residual density) treatments. Most snags were small-diameter, decay-resistant sassafras (Sassafras albidurn (Nutt.) Nees) and black cherry (Prunus serotina Ehrh.) that died early in stand development. Large-diameter (230 cm diameter at breast height) snags and cavity trees were uncommon in both thinned treatments and controls.
Cavity trees, snags, and selection cutting: a northern hardwood case study
Northern Journal of Applied Forestry, 2007
Although traditional application of the selection system includes a focus on high-value trees that may reduce cavities and snags, few studies have quantified those habitat features in managed uneven-aged stands. We examined the effects of single-tree selection cutting on cavity trees and snags in a northern hardwood stand immediately prior to the second cutting. Marking followed guidelines proposed by Arbogast, C, Jr. (1957. Marking guides for northern hardwoods under selection system. US For. Servo Res. Pap.· 56, lake States Forest Experiment Station. 20 p.), with the objective of improving stand quality for timber production while maintaining a balanced diameter. distribution. The stand contained seven species of cavity trees and snags; sugar maple and American beech were most common, the latter comprising 20% of snags and 26% of cavity trees despite its relatively minor (7%) contribution to stand basal area. We found that 92% of cavity trees were live, underscoring the value of living trees as sources of cavities. Precut cavity tree density (25.2 live cavity trees per hectare) was more than twice tnat found in other studies of selection stands, although density of snags (11.0 snags per hectare) was comparable or lower. More than 50% of sampled cavity trees were designated for removal in the second selection cut, reducing projected postcut density to 11.0 live cavity trees per hectare, a density similar to that found in other studies. Postcut density of large cavity trees (3.3 live trees >45 cm dbh per hectare) exceeded published guidelines for northern hardwoods (0.25 to 2.5 live cavity trees >45 cm dbh per hectare). We speculate that the relatively high maximum diameter (61 cm dbh) and long cutting cycle (20 years) used to define the target stand structure may have contributed to the number of cavity trees observed. Nevertheless, selection cutting as applied in this study will likely reduce cavity abundance unless retention of trees with decay is explicitly incorporated into the management strategy.
Snag dynamics and cavity occurrence in the South Carolina Piedmont
Forest Ecology and Management, 1999
Standing dead trees, or snags, are natural components of forest stands and are important habitats for many wildlife species. We examined snag dynamics from 1982±1990 on 140 0.1 ha plots in the upper Piedmont of South Carolina. Plots were established in 10 stand type±age class combinations. Mean snag density was 28.4 snags/ha and mean snag diameter (DBH) and height were 20.3 cm and 9.9 m, respectively. Highest snag densities occurred in hardwood stand types; pine plantations had lower (p 0.05) snag density than all other types. Within a particular stand type, snag densities, recruitment rates, and loss rates generally were lowest in the oldest age classes. Intermediate age classes of all stand types had higher snag densities and snag turnover rates than younger or older stands within that type. Young pine plantations had the lowest recruitment rate (" x1.79 snags/ha/year) and old pine plantations had the lowest loss rate (" x1.59 snags/ha/year) of all the stand type±age class combinations. Although twenty species of snags were observed, ®ve species/species groups, shortleaf pine (Pinus echinata), red oaks (Quercus spp. ), white oaks (Quercus spp. ), loblolly pine (P. taeda), and yellow poplar (Liriodendron tulipifera), occurred most frequently. Snag DBH and cavities/snag were not signi®cantly correlated. Stage of decay for cavity and noncavity snags (r0.97 and 0.83, respectively; p 0.05) and number of cavities/snag (r0.78) increased with year since snag recruitment. Ten snag species contained cavities (" x0.1 cavities/snag), but shortleaf pine accounted for 56% of the cavity years observed (" x0.18 cavities/snag). Three other softwood species also contained equal to or above average numbers of cavities/snag. Approximately 30% of all snags fell within two years of recruitment, 55% within three years, and 95% within six years. Snag longevity was independent of diameter class (p0.67). Hardwood snags, especially those in upland hardwood stands, appeared to persist longer than pine snags. As pine plantations managed on short rotations (<25 years) and older-aged stands (>50 years) of all types may not provide abundant snags in the South Carolina Piedmont, the potential for wildlife habitat might be enhanced if older, larger diameter trees, especially softwood species, are retained or designated as snag replacements. #
Environments, 2021
In this study the influence of forest management on the characteristics of snags and tree cavities in the Hyrcanian forests of Iran was investigated. In particular, the effect of two sylvicultural treatments (shelter wood and single-tree selection) was assessed in comparison to protected stands. The abundance, diameter, height, and degree of decay of snag species, and the characteristics of birds excavated and natural cavities (number and height from the ground level) were measured by systematic plots in each stand. The results showed that the abundance, species diversity, and size of snags in both of the sylvicultural treatments were significantly lower than the protected stands. The number of birds excavated and natural cavities on thicker snags with moderate decay was significantly higher than other decay classes. Abundance, species diversity, size of snags, and number of tree cavities in the single-tree selection stands were significantly higher than sheltered-wood stands.
Distribution of cavity trees in midwestern old-growth and second-growth forests
Canadian Journal of Forest Research, 2003
We used classification and regression tree analysis to determine the primary variables associated with the occurrence of cavity trees and the hierarchical structure among those variables. We applied that information to develop logistic models predicting cavity tree probability as a function of diameter, species group, and decay class. Inventories of cavity abundance in old-growth hardwood forests in Missouri, Illinois, and Indiana found that 811% of snags had at least one visible cavity (as visually detected from the ground; smallest opening [Formula: see text]2 cm diameter), about twice the percentage for live trees. Five percent of live trees and snags had cavities on mature ([Formula: see text]110 years) second-growth plots on timberland in Missouri. Because snags accounted for typically no more than 10% of standing trees on any of these sites, 8085% of cavity trees are living trees. Within the subset of mature and old-growth forests, the presence of cavities was strongly relat...
Sustaining Cavity-Using Species: Patterns of Cavity Use and Implications to Forest Management
ISRN Forestry, 2013
Many bird and mammal species rely on cavities in trees to rear their young or roost. Favourable cavity sites are usually created by fungi, so they are more common in older, dying trees that are incompatible with intensive fiber production. Forestry has reduced amounts of such trees to the extent that many cavity-using vertebrates are now designated “at risk.” The simple model of cavity use presented helps unite research findings, explain patterns of use, and clarify trade-offs that can, or cannot, be made in snag management. Predictions generated are tested using data from over 300 studies. Implications to forest management are derived from the tests, including the following: ensure sustained provision of dying and dead trees, retain both conifers and hardwoods and a range of size and age classes, sustain a range of decay classes, ensure that some large trees or snags are retained, promote both aggregated and dispersed retention of dead and dying trees, meet dead wood requirements f...
Forest Ecology and Management, 2004
Snags provide an important resource for a rich assemblage of cavity-nesting birds in the southwestern United States. To expand our knowledge of snag use by cavity-nesting birds in this region, we documented characteristics of snags with and without excavated cavities in mixed-conifer and ponderosa pine (Pinus ponderosa Dougl. ex Laws) forest in north-central Arizona. Snags were sampled in 113 square plots (1 ha each) randomly located within a study area covering approximately 73,000 ha across two National Forests. Density of snags was three times greater in mixed-conifer forest (n ¼ 53 plots) than in ponderosa pine forest (n ¼ 60 plots), but density of snags containing cavities and overall cavity density did not differ between forest types. In both forest types, snags containing cavities were larger in diameter and retained less bark cover than snags without cavities. Most cavities were in ponderosa pine and Gambel oak (Quercus gambelii Nutt.) snags, and most were in snags in advanced decay classes with broken tops. Our results are largely consistent with previous results from ponderosa pine forest, but differ from previous studies that documented heavy use of quaking aspen (Populus tremuloides Michaux) by cavity nesters in mixed-conifer forest. These results support management to protect and recruit large snags well distributed across the landscape. The relatively high use of ponderosa pine and Gambel oak snags in both forest types suggests that recruitment of large pine and oak snags should be emphasized, and previous studies suggest emphasizing aspen recruitment as well. This may require special management efforts in mixed-conifer forest. These species are relatively shade-intolerant seral species in this forest type, and are apparently declining in this forest type due to fire-suppression efforts and resultant patterns of ecological succession. #
Canadian Journal of Forest Research, 1998
The effects of uneven-aged management on the availability of coarse woody debris habitat were examined in northern hardwood forests (with and without a hemlock component) in north-central Wisconsin and adjacent western Upper Michigan. Snags, cavity trees, fallen wood, and recent tip-up mounds in 15 managed uneven-aged (selection) stands were compared with levels in 10 old-growth stands and six unmanaged even-aged second-growth stands. Amounts of coarse woody debris in selection stands were generally intermediate between old-growth and even-aged stands. Density of snags >30 cm DBH in northern hardwood selection stands averaged 12/ha, approximately double that found in even-aged northern hardwoods, but only 54% of the level in old-growth northern hardwoods. Highest densities of snags >30 cm DBH occurred in old-growth hemlock-hardwood stands, averaging over 40 snags/ha. For combined forest types, the volume of fallen wood (>10 cm in diameter) was significantly lower in selecti...
Forests, 2020
Standing deadwood is an important attribute of old-growth boreal forests and it provides essential microhabitats for deadwood-associated species. In managed boreal forests, short rotations tend to limit the amount and diversity of standing deadwood. This study evaluates if the anthropogenic supply of deadwood attributes through tree girdling or by providing nest boxes may favor deadwood-associated species. We studied the short-term response of saproxylic beetles, foraging woodpeckers, and secondary cavity users to snag and cavity supply in 50 to 70-year-old black spruce stands. In spring 2015, we girdled 8000 black spruce according to two spatial distributions (uniform and clustered), and we also installed 450 nest boxes of six different sizes at three distances from the forest edge. Using trunk window traps, we captured significantly more beetles in sites with girdled trees than in control sites in both 2015 and 2016. We also recorded a trend of a greater abundance of beetles in clusters of girdled trees than within uniformly distributed girdled trees. Trypodendron lineatum (Oliver) dominated beetle assemblages, representing 88.5% of all species in 2015 and 74.6% in 2016. The number of beetles captured was 7× higher in 2015 than in 2016. In contrast, we observed greater amounts of woodpecker foraging marks in fall 2016 than in either fall 2015 or spring 2016. Woodpeckers foraged significantly more in clusters of girdled trees than within uniformly distributed girdled trees. Woodpeckers' foraging mark presence was positively associated with the proportion of recent cuts at 1 km around the study sites. Five Boreal Chickadee (Poecile hudsonicus Forster) pairs used nest boxes and occupied smaller box sizes that were located away from the forest edge. Our study showed that structural enrichment can be effective in rapidly attracting deadwood-associated species within managed forest stands.
Wildlife implications across snag treatment types in jack pine stands of Upper Michigan
Forest Ecology and Management, 2018
Standing dead trees, or snags, represent post-disturbance biological legacies in forest ecosystems, and intentional creation of new snags is increasingly common during forest treatments. The abundance, volume, size, and distribution of snags can affect wildlife communities and stand-level biological diversity. Characteristics such as the wood properties of different tree species, environmental conditions, and cause of tree death (e.g., insects, disease, senescence, wind, fire) can influence decomposition and subsequent use of snags by wildlife. The objectives of this study were to characterize decay patterns in jack pine (Pinus banksiana) snags that had been killed by prescribed fire, topping, and girdling and determine the effects of these treatments on subsequent snag use by subcortical insects and primary cavity-nesting birds. The prescribed fire, topping, and girdling treatments were implemented in 2003, 2004, and 2007, respectively; bird excavations were quantified in 2014 and insect activity was measured in 2016. One-way analysis of variance tests were used to examine any differences among treatments in snag characteristics, decay characteristics, past insect activity, and past use by birds. An information theoretic approach to model selection was then used to rank potential predictors of bird foraging activity and cavities. The topping treatment had unique decay characteristics relative to the other two treatments; topped snags had the highest levels of past insect colonization, were softer, and had higher proportions of loose bark remaining on the boles. Trees killed by prescribed fire had the greatest number of foraging excavations and cavities. Girdled snags had the lowest evidence of past insect colonization and showed different levels of decay and insect use at different vertical positions on the snag bole. Comparison of candidate models showed that a model containing treatment type alone was the highest ranked when predicting foraging by birds, while snag diameter was the highest ranked when predicting the presence of cavities. A model containing treatment and snag density was also a highly ranked for predicting cavity presence. Our findings suggest that different jack pine snag treatments result in unique decay trajectories that may influence snag use by an array of wildlife taxa. Our characterization of three snag creation treatments can also inform options for generating snags, depending on the desired outcome, when management for biological legacies and wildlife habitat is of interest within mixedpine forests of the Great Lakes region. 1. Introduction Dying trees, standing dead trees (snags), and downed woody material have numerous ecological functions and contribute to structural complexity and biodiversity within forests (Harmon et al., 1986, Franklin, 1988). For example, dying trees increase availability of resources such as light, nutrients, and water, and provide structure and food for a wide range of taxa (Franklin et al., 1987). A diversity of fungi, plants, and animals utilize snags and downed wood throughout their life cycles (