Modelling Individual Tree Diameter Growth of <i>Quercus mongolica</i> Secondary Forest in the Northeast of China

• Main Authors: Xuefan Hu, Guangshuang Duan, Huiru Zhang
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Sustainability
• Subjects: <i>Quercus mongolica</i> secondary forest; diameter growth model; two level mixed-effects model; random effects
• Online Access: https://www.mdpi.com/2071-1050/13/8/4533

<i>Quercus mongolica</i> secondary forest is widely distributed in the northeast of China, but it usually has low productivity, unstable structure, poor health, and low biodiversity. Diameter is a tree variable that is commonly used for forest growth measurement, to provide the basis for forest management decision. Two level generalized linear mixed effects individual diameter growth model were developed using data from two times surveys of 12 <i>Q. mongolica</i> secondary forest permanent plots that were distributed among Wangqing forest farms. Random effects of 14 tree species and 12 plots were introduced into the basic model consisting of three factors: tree size, competition of surrounding trees, and site quality. The results showed that initial diameter at breast height(DBH) was the most important variable affecting diameter growth, followed by competition, while the effect of site quality on diameter growth was not significant. Compared with the basic model, the prediction accuracy of the mixed effect model was improved by 17.69 %, where R² reached to 0.6805, indicating that it is suitable for the individual-tree diameter growth prediction of the secondary forest of <i>Q. mongolica</i>.