Age-independent diameter increment models for mixed mountain forests

编号 030037602

推送时间 20230102

研究领域 森林经理 

年份 2022 

类型 期刊 

语种 英语

标题 Age-independent diameter increment models for mixed mountain forests

来源期刊 EUROPEAN JOURNAL OF?FOREST?RESEARCH

期 第376期

发表时间 20220823

关键词 Age-independent growth equations;  Algebraic difference approach;  Mixed effects models;  Uneven-aged forest;  Mixed species forests;  Growth index; 

摘要 Mixed mountain forests with an uneven-aged structure are characterized by a high tree-growth?variability making traditional age-dependent?growth?models inapplicable. Estimating site productivity is yet another impediment for?modelling?tree?growth?in such forests. Uneven-aged mixed-stand forests are known for their high resilience, resistance and productivity, and are being promoted as a suitable alternative to even-aged, pure plantations for climate change adaptation and mitigation. However, their?growth?must be accurately measured and predicted, but diameter at the breast height (dbh) increment models specifically designed for uneven-aged mixed mountain forests are still rare. Using permanent sampling network data and 465 increment cores, we built two age-independent dbh increment (i(d)) models for the main species of the study area, namely Norway spruce (Picea abies (L.) Karst.), silver fir (Abies alba Mill.) and European beech (Fagus sylvatica L.). Mixed effects models and the algebraic difference approach were employed to develop i(d) models based on empirical and commonly used theoretical?growth?functions. A past?growth?index was further developed and introduced in the model in order to explain the i(d) variability. Several mixed effects calibration strategies were assessed in order to obtain the most accurate localized curve for new plots. Tree size, competition and biogeoclimatic variables were found to explain the i(d) through the empirical?growth?function, while the?growth?index significantly improved the theoretical?growth?function for Norway spruce. The optimization of the calibration strategy for the mixed effects?modelling?framework enables the?growth?index implementation in?forest?practice as an accurate method for estimating site productivity. The accuracy of the two i(d) models was similar: the root mean squared error of the empirical?growth?function varied between 0.940 and 1.042 cm for spruce, beech and fir, while the root mean squared error obtained through the theoretical?growth?function for spruce only was 1.105 cm. The basal area increment prediction at the plot level based on the theoretical?growth?function reached a root mean squared error of 0.043 m(2) while using the empirical?growth?function the root mean squared error is 0.047 m(2). The high accuracy obtained using age-independent models underlines their suitability for predicting?growth?in mixed uneven-aged forests. The developed models can be easily integrated into?forest?practice to accurately obtain i(d) estimates.

服务人员 付贺龙

服务院士 唐守正

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