Effect of topography on tree species composition and volume of coarse woody debris in an Oriental beech (Fagus orientalis Lipsky) old growth forests, northern Iran

Abstract

There is an emerging interest in the relationships between forest structure and topographic aspects. Still, such patterns have been scarcely studied in undisturbed mixed beech forests in northern Iran. We investigated the influence of topographical factors including aspect, slope degree, and landform index (LI) on the distribution of dominant tree species and coarse woody debris (CWD). Tree density and basal area were not significantly correlated with any of the measured parameters, except a moderate relation between basal area and LI (r = -0.376; P = 0.029). Redundancy analysis (RDA) of the tree layer revealed a significant relationship between the measured environmental variables and species distributions. CWD volume showed significant negative correlation with percent canopy coverage and was highly correlated with slope. Density of CWD in decay class IV was significantly correlated with aspect and percent of canopy cover. Analyses of CWD distributions in relation to both living vegetation and topographic gradients showed a highly complex interplay of factors driving the distribution of CWD across the forest stands.

Heterospecific Tree Density and Environmental Factors Affect Afzelia africana Sm. Population Structure in the Pendjari Biosphere Reserve, West Africa: Implications for Management and Restoration

“…Typically, steeper slopes and gravity-driven processes would challenge tree mechanical stability and growth. Thus, a negative correlation between basal area and slope is expected (Mensah, Salako, et al, 2018;Mensah, Veldtman, Assogbadjo, Gle`le`Kakaı¨, & Seifert, 2016;Sefidi, Esfandiary Darabad, & Azarian, 2016). Interestingly, we observed an opposite pattern, that is, higher basal area on increasing slope, which could have resulted from a shift in plant resource use strategies by the species to match the harsh environmental conditions on higher slopes (e.g., lower waterretention capacity and increased soil erosion).…”

Differential Responses of Taxonomic, Structural, and Functional Diversity to Local-Scale Environmental Variation in Afromontane Forests in South Africa

“…For instance, in a lowland rain forest of southern Taiwan, Tsui et al (2004) observed higher organic carbon, available N and K, extractable Fe and exchangeable Na at upper slope position, and highest pH, available P, exchangeable Ca and Mg on the footslope. Further, a negative correlation between basal area and the percent of slope is expected because of the stability of trees that grow on steeper slopes and gravity-driven processes (Sefidi et al, 2016). Thus, water exigent species would likely be more abundant and dominant on flat and gentle slope sites, while steeper slopes (with limited water availability and soil nutrients) would tend to challenge tree growth and size.…”

“…There are insights that forest structure and community assembly relate with local environmental variables such as altitude and slope (Gallardo-Cruz, Pérez-García, & Meave, 2009). For instance, basal area and forest biomass are typically reported to be highest at lower slope sites (Sefidi, Esfandiary Darabad, & Azarian, 2016; Takyu, Aiba, & Kitayama, 2003; Vilà et al., 2007). The influence of slope or topographical variables can be mediated by light radiation, temperature, moisture, runoff, infiltration, soil properties, and resources availability (Tsui, Chen, & Hsieh, 2004; Yirdaw, Starr, Negash, & Yimer, 2015).…”

Assessing selected microhabitat types on living trees in Oriental beech (Fagus orientalis L.) dominated forests in Iran

“…Temperate-mixed forests in the Hyrcanian region in northern Iran are one of the most important natural ecosystems with the highest economic value and a key role in the conservation of forest biodiversity in Iran. These forests are characterized by a heterogeneous stand structure, either horizontal or vertical (Sefedi et al 2016). The most abundant characteristic tree species is Fagus orientalis L. Today, major shares of these Hyrcanian forests are managed with individual tree selection systems with interventions every 10 years intending to mimic natural gap dynamics processes.…”