Impact of long and short-term conservation periods on structure of English yew (Taxus baccata L.) in Arasbaran forests, Iran

Abstract

Yew (Taxus baccata L.) is one of the most important and threatened tree species in the Arasbaran region of northwestern Iran. To understand the natural stand structure of yew forests to inform forest management, we assessed the structural characteristics and composition of yew communities using the nearest neighbour and full callipering method at three sites with different conservation histories. Within a one-hectare sampling area, tree species identity, diameter, height, and crown diameter were measured. In each of these sampling areas, 56 sample points were surveyed in a 25 m × 25 m grid for tree species identity, diameter, height, and distance from reference to neighbour trees. To quantify the structural characteristics in areas of different conservation status, some indices were calculated including mingling, distance between reference tree and its nearest neighbouring trees, diameter and height differentiation, uniform angle, and Clark-Evans index. Results revealed that four species – hornbeam (68%), maple (8%), yew (7%), and oak (5.2%) – composed 88% of the tree species. The majority of trees had a short distance (2–3 m) between neighbours. The mean diameter differentiation index for long-term and short-term conservation areas was 0.59 and 0.06, respectively. The uniform angle index showed that there was no class value = “1” at all three sites. In the long-term enclosed area, Clark-Evans index was 1.18. In short-term enclosed areas, it was less than 1 (0.82). At all sites, yew trees were in the least vital class. We conclude that enclosing affects the yew stand structure, specifically in long-term periods of enclosure.

REDD implementation for greenhouse gas reduction and climate change mitigation in Hyrcanian forests: a case study of the Kojoor Watershed, Northern Iran

“…To combat this, it is vital to accurately and systematically monitor deforestation and forest degradation to gain essential data on the extent, causes, and patterns of forest loss. This information serves as a foundation for informed decision-making and the development of targeted strategies to mitigate the adverse impacts of climate change (Ghanbari et al, 2018;Leon et al, 2022). The reducing emissions from deforestation and forest degradation (REDD) strategy is one such targeted approach that aims to address deforestation and forest degradation to mitigate climate change (Muttaqin et al, 2019).…”

Patterns of density and structure of natural populations ofTaxus baccatain the Hyrcanian forests of Iran

“…Thus, the interdependencies of multiple structural attributes across many stands of different forest management types and developmental stages have not yet been explored. The variation of habitat conditions has led to differences in various structural indices such as diameter, basal area and height of trees (Ghanbari et al ).…”

“…To date, some studies of the stand structure of yew have been conducted in different regions of the world, and these all demonstrating the importance of the structure of natural stands (Iszkuło and Boratyński , Iszkulo et al , Dobrowolska et al , Casals et al , Vessella et al , Ghanbari et al ). Most of these studies, however, have used measures that quantify forest structures at very local scales.…”

“…Most of these studies, however, have used measures that quantify forest structures at very local scales. For example, in Arasbaran forests in Iran, Ghanbari et al () studied the impact of long and short‐term conservation periods on structure of European yew. In the Hyrcanian forests, Golabian et al () found that the diameter distribution curve of yew trees indicated even‐aged stand with a two‐layered structure.…”