Anatomy of Branch Wood of Amygdalus orientalis Mill.: Responses to Livestock Browsing in the Zagros Semi-Arid Forest (Ilam)

Mousa, Z; Soheili, F; Oladi, R; Naji, H.R

doi:10.22034/ijf.2025.506013.2044

Anatomy of Branch Wood of Amygdalus orientalis Mill.: Responses to Livestock Browsing in the Zagros Semi-Arid Forest (Ilam)

Document Type : Research Paper

Authors

Z Mousa ¹

F Soheili ²

R Oladi ³

H.R Naji ⁴

¹ MSc. in Forest Ecology, Dept. of Forest Sciences, Ilam University, Ilam, I. R. Iran.

² Ph.D. in Forest Biological Sciences, Dept. of Forest Sciences, Ilam University, Ilam, I. R. Iran.

³ Associate Prof., Deptartment of Wood Science and Technology, Faculty of Natural Resources, University of Tehran, Karaj, I. R. Iran.

⁴ 4Associate Prof., Dept. of Forest Sciences, Ilam University, Ilam, I. R. Iran.

10.22034/ijf.2025.506013.2044

Abstract

Introduction: Forests represent the most valuable form of vegetation, playing a crucial role in maintaining ecological balance and driving economic, social, and environmental processes. The Zagros forests have faced persistent degradation over decades. This ongoing process of destruction continues to escalate. One of the primary drivers of this degradation is overbrowsing by livestock, which not only inhibits forest regeneration but also leads to soil compaction, reduced biodiversity, and diminished production capacity of these forests. Given the critical role of livestock as a major contributor to the deterioration of the Zagros forests, understanding the intricate relationships between ecosystem components—particularly the dynamic interactions between livestock and plant communities—is essential for developing effective management strategies. In this context, investigating changes in wood anatomy provides insights into the defense mechanisms employed by trees against damaging factors . This study focuses on the impact of livestock browsing stress on the anatomical characteristics of the wood of Amygdalus orientalis (mountain almond), in the forests of Ilam province, Iran. By examining alterations in wood cell elements under grazing pressure, this research aims to enhance our fundamental understanding of cellular-level structural changes and elucidate the adaptive strategies utilized by trees to withstand such stressors.
Materials and Methods: In this study, two forested areas surrounding the city of Ilam, which are continuously subjected to browsing by livestock from nearby villages, were selected for sampling. Sampling was conducted on both accessible lower branches that had been browsed by animals and higher, out-of-reach branches that remained unbrowsed. Six randomly selected almond shrubs were used as sampling units. All samples of browsed and unbrowsed twigs were collected from one side of each shrub to minimize variability. The branches were then cut into small 5 × 5 mm fragments for cellular structure analysis. Laboratory procedures were maceration of the samples, preparation of thin microscopic sections, and staining of the wood specimens. Subsequently, the samples were photographed using a camera equipped with imaging software. Various anatomical features of the wood were measured using a light microscope, including fiber length, fiber wall thickness, vessel density, early vessel diameter, early vessel area, number of axial parenchyma cells, number of wood rays, crystal frequency, tyloses frequency, and annual ring width. These measurements were conducted systematically to ensure accuracy and repeatability.
Results: The results a significant of livestock on the most wood anatomical characteristics. Specifically, the length of fibers, early vessel diameter, early vessel area, number of axial parenchyma cells, and number of wood rays were observed to decrease. The highest decrease was in vessel and paranchyma characteristics. Fiber wall thickness, number of vessel, crystal frequency, and tyloses frequency showed an increase. The time series over the past five years revealed a reduction in the width of annual growth rings in browsed trees compared to unbrowsed ones. The width of annual growth rings in browed wood samples was about 37% less than in unbrowsed samples, so that the average width of annual rings in the last five years in browsed samples was 354 microns and in unbrowsed samples was 568 microns. These findings highlight the profound impact of browsing on the anatomical structure.
Conclusion: It can be concluded that livestock browsing induces structural changes during wood formation, leading to alterations in plant form and architecture, ultimately resulting in reduced health, performance, and productivity of trees. Furthermore, these findings can inform practical solutions aimed at mitigating the impacts of browsing on trees in economic silviculture practices. Such insights can also support the development of appropriate strategies for the protection and conservation of forest ecosystems, ensuring their sustainability and resilience.

Keywords

Almond shrub

Forest conservation

Livestock browsing Stress

Wood cellular characteristics

Zagros forests

Subjects

Biology and Physiology

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