Water content distribution characteristics and species-specific water content prediction model for tree species in Jiaohe, Jilin Province

Objective This study analyses the distribution characteristics of the water content of 12 tree species in Northeast China. Species-specific allometric equations of the 12 tree species were established, in order to explore the differences in water content characteristics among different tree species as forests develop, as well as provide model reference for the estimation of water content in this area.

Method One-way ANOVA and multiple comparison methods were used to contrast differences in water content and its proportion among organs across the 12 tree species. Utilizing Kendall’s rank correlation analysis to identify diameter at breast height (D), tree height (H), and (D²H) as predictor variables in water content prediction models with whole-tree and organ-specific water contents serving as response variables. Different forms of water content prediction models were constructed based on these relationships. Optimal models were selected through evaluation using the coefficient of determination, parameter significance level, and Akaike’s information criterion. Integrating stand information, this approach was employed to calculate the water content of trees across different developmental stages.

Result (1) Overall, average water content was highest in leaves, followed by roots, branches, and stems. Except for Carpinus cordata, all other species showed a consistent pattern in water allocation across organs: stem > root > branch > leaf. As D increases, the proportion of branch water content increases, while the proportion of stem and leaf water content decreases, with no significant change in root water content. (2) The water content prediction models for all 12 tree species were best represented by logarithmic functions. The optimal independent variables for different tree species organ water content models are different. (3) With forest succession, both water content and biomass per unit area increase.

Conclusion The study highlighted significant differences in water content and distribution among organs and species, with species-specific relationships between water content and D/H. The percentage of water content of different organs shows different trends with the increase of breast diameter. The water content prediction models for all 12 tree species were best represented by logarithmic functions. The single-species models had higher fitting accuracy, while the multi-species model had broader application. This research elucidates the spatiotemporal dynamics of water status in temperate-boreal tree species, contributing to a deeper understanding of ecosystem dynamics. It provides a scientific basis for accurate estimation of tree water content in the forest region of Jiaohe, Jilin Province, China.