A Static Pulling Test Is a Suitable Method for Comparison of the Loading Resistance of Silver Birch (Betula pendula Roth.) between Urban and Peri-Urban Forests

Oskars Krišāns,Steffen Rust,Linda Čakša,Āris Jansons,Roberts Matisons,Didzis Elferts,Andris Seipulis

doi:10.3390/f13010127

Abstract

In urbanized areas, wind disturbances can be intensified by anthropogenic stresses under which trees may become hazardous, creating serious threats and damages to nearby targets. Therefore, species with notably lower both wood mechanical properties and compartmentalization, such as pioneers, are considered to have higher wind damage risk if subjected to unfavorable growing conditions. Eurasian aspen (Populus tremula L.) and silver birch (Betula pendula Roth.), are frequently found in both urban and peri-urban forests in Northeastern and Central parts of Europe, which strengthen the necessity for the evaluation of mechanical stability of such species. Therefore, static pulling tests were performed to compare the mechanical stability of the studied species in both urban and peri-urban forests. The loading resistance of the studied species differed, with birch being more stable than aspen, indicating aspen to be more prone to wind damage. Additionally, the mechanical stability of birch did not differ between trees growing in urban and peri-urban forests, suggesting static pulling tests are a suitable method for comparing trees from completely different growing conditions.

Highlights

Tendencies in urbanization indicate the spread of urban areas in both size and populations [1,2]
In Latvia, urban areas are relatively small and situated close to forests, the tree species found in forests are successfully acclimated in urban environment and the opposite [41]
The results of this study indicated silver birch was more resistant against static loading compared with Eurasian aspen

Summary

Introduction

Tendencies in urbanization indicate the spread of urban areas in both size and populations [1,2] Both urban and peri-urban forests are highly important in facilitating the quality of life in urban areas as they provide functions such as mitigation of urban heat islands [3], regulation of rainwater runoff [4], reduction of air pollution [5], and recreational services [6]. Trees in urbanized environments are subjected to unfavorable growing conditions with limited growing space that primarily limits nutrient and water supply [8]. Natural disturbances, such as storms, temperature stress, and droughts are potential threats for forests directly surrounding highly urbanized areas, especially as they are intensified by climate change [9,10,11]. The evaluation of mechanical stability of trees is a significant part of management of urban green areas [14]

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Conclusion