Influence of Forest Management and Sylvicultural Treatments on Abundance of Snags and Tree Cavities in Mountain Mixed Beech Forests

Abstract

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.

Evaluation of Deadwood Characteristics and Carbon Storage under Different Silvicultural Treatments in a Mixed Broadleaves Mountain Forest

“…The results of this study showed that the frequency and volume of live trees were significantly lower in the harvested stands (Sh and Sc) than the protected stands (Pr), especially the frequency of large diameter trees. Other studies have also concluded that the frequency and volume of trees in the harvested stands were lower than in the protected stands [16,52,[58][59][60][61][62][63].…”

“…The Hyrcanian forests have been managed by different silvicultural treatments [16,47,57], as follows: shelterwood cutting from 1970 to 2000 (Sh stands), selection cutting from 2000 to 2014, and restricted cutting to damaged and fallen trees from 2016 to the present (Sc stands). The main natural disturbance in the Hyrcanian mountain forests in northern Iran is the wind that blows over and damages some trees every year.…”

“…These are as follows: sustaining biodiversity [3,4], providing a wide range of habitats for saprotrophic and heterotrophic organisms [5], regulation of nutrient cycling [6,7], regulation of hydrologic processes [8], as well as the provision of habitat for a wide diversity of organisms [9,10], including tree seedlings [11,12]. DW provides a habitat for wildlife such as wood-feeding termites [13,14], cavity-nesting birds [15,16], saproxylic beetles [17] and bats [18]. It facilitates tree regeneration by providing 'nurse logs' [19].…”

“…These changes depend on the productivity of forest ecosystems, mortality caused by succession processes and disturbances [29], and the decomposition rate [29]. In addition to the geographic region, forest structure and stand composition, forest management methods can also affect the amount and dynamics of DW and the rate of its decomposition in forest ecosystems [16,30,31]. The management regime models applied, as well as the disturbance, affect the quantity and characteristics of dead wood [4] and, to some extent, the stand age [32].…”

“…Volume, spatial distribution and characteristics of dead wood in forests, such as dimensions and degree of decay, also depend on the timber harvest [16,33], logging system used [34], level of mechanization [35], density and pattern of forest roads [36], stand distance from adjacent villages [37], human accessibility level [2,33], fuel wood market [38], the presence of pests and diseases [39,40], and succession level of forest stand [41].…”