Live Crown Ratio as an Indicator for Tree Vigor and Stability of Turkey Oak ( Quercus cerris L.): A Case Study

Stăncioiu, Petru Tudor, Șerbescu, Alexandru Alin and Dutcă, Ioan (2021) Live Crown Ratio as an Indicator for Tree Vigor and Stability of Turkey Oak ( Quercus cerris L.): A Case Study. Forests, 12 (12). ISSN 1999-4907

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Stability of forests represents a significant objective for climate change mitigation. As stand stability is influenced by the stability of individual trees, promoting stable trees is vital for a sustainable forest management. However, inside stands, trees experience intense competition. As a result, the crown recedes and diameter growth is affected, the trees becoming slender and more susceptible to biotic and abiotic disturbances. Finding effective indicators for tree vigor and stability is therefore important. This study aimed to assess the performance of the live crown ratio as an indicator in deciding the timing of tending operations for obtaining and maintaining vigorous Turkey oak trees. Live crown ratio (LCR) and height to diameter ratio (HDR) were determined for 80 sampled Turkey oak trees. A threshold of 100 for HDR was chosen to classify trees as slender or not slender. Next, conditional inference tree and logistic regression were used to determine the LCR threshold value where trees become slender. As the sample included small trees, using breast height to measure diameter may have affected the results. Therefore, small and large trees were also analyzed separately. For the entire dataset, the methods reached quite different results (LCR threshold of 0.371 for conditional inference tree and of 0.434 for the logistic regression), and relatively high values compared to the literature. For tall trees (height > 12.5 m), the methods reached similar results: 0.386 for the conditional inference tree and 0.382 for the logistic regression. For small trees (height 12.5 m), the conditional inference tree method could not calculate any LCR threshold estimate, while the one from the logistic regression was unrealistically large (0.628). This confirms that using DBH for small trees to compute slenderness brings systematic errors. The live crown ratio was a good indicator of growth vigor for Turkey oak trees. Therefore, for stable trees (HDR 100), a LCR of 0.36−0.39 must be maintained and could be used to decide the timing for thinning in Turkey oak stands.

Item Type: Article
Additional Information: ** From MDPI via Jisc Publications Router ** History: accepted 10-12-2021; pub-electronic 13-12-2021. ** Licence for this article:
Keywords: height to diameter ratio, slenderness, forest stability, climate-smart-forestry
SWORD Depositor: JISC Router
Depositing User: JISC Router
Date Deposited: 28 Jan 2022 10:10
Last Modified: 28 Jan 2022 10:10

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