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

Sajad Ghanbari, Kiomars Sefidi and Matthew M. Aghai
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Sajad Ghanbari: Department of Forestry, Ahar Faculty of Agriculture and Natural Resources, University of Tabriz, Iran
Kiomars Sefidi: Department of of Natural Resources, Faculty of Agriculture and Natural Resources Technology, University of Mohaghegh Ardabili, Ardabil, Iran
Matthew M. Aghai: Center for Sustainable Forestry at Pack Forest, School of Environmental and Forest Science, University of Washington, United States

Journal of Forest Science, 2019, vol. 65, issue 7, 272-282

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.

Keywords: conservation-based management; diameter differentiation; forest structure; nearest neighbour (search for similar items in EconPapers)
Date: 2019
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Persistent link: https://EconPapers.repec.org/RePEc:caa:jnljfs:v:65:y:2019:i:7:id:45-2019-jfs

DOI: 10.17221/45/2019-JFS

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