寒温带雨季降雨变化下白桦树干液流速率对环境因子的响应差异
Differential Responses of Sap Flow to Environmental Fact ors under Contrasting Rainfall Amounts during the Rainy Season in a Boreal Birch Forest
[目的]本研究旨在探究寒温带雨季降雨变化下不同分化等级白桦树干液流速率对环境因子的响应差异，以期为深入理解白桦次生林生态水文过程和气候变化下的次生林经营管理提供科学依据。[方法]基于径阶分布，我们选择了 3 株优势木、中等木和被压木作为样本树，在 2021-2023 年雨季(6-8 月)期间，使用Granier热扩散探针技术(TDP)连续观测树干液流，并分析了光合有效辐射(PAR)、水气压亏缺(VPD)、土壤含水量(SWC)等环境因子的相关性。[结果]PAR和VPD是影响不同分化等级白桦树干液流速率(Fdi)的主要因素。Fdi随PAR增加而增加，随VPD增加先增加后稳定。当SWC低于0.1 8 cm3/cm3时，Fdi 显著下降(p<0.01)。Fdi 表现为优势木(Fdd)>中等木(Fdm)>被压木(Fds)，且对PAR、VPD、SWC的响应各异。随着雨季降雨量的减少，PAR对Fds和Fdm的驱动作用减弱，而VPD的影响增强，Fdd则呈相反趋势。在干旱的雨季，Fdd主要受PAR驱动，同时受VPD和SWC影响;Fds主要受VPD控制，受PAR影响较小，SWC的影响最小。Fdm对SWC的响应与Fdd相近，而对PAR和VPD的响应与Fds相近。[结论]PAR和VPD是寒温带白桦次生林的主要影响因子。在干旱雨季，SWC的降低显著限制了树干液流速率，并且优势木和中等木对SWC的降低响应更积极。
[Objective]This study aimed to investigate the differences in the response of sap flow rates in birch trees of varying differentiation levels to environmental factors under the changing rainfall conditions of the boreal temperate rainy season.The goal was to provide a scientific basis for a deeper understanding of the eco-hydrological processes of birch secondary forests and the management of these forests under climate change.[Methods]Based on diameter class distribution,three sample trees representing dominant,intermediate,and suppressed trees were selected.During the rainy seasons of 2021 to 2023(June to August),sap flow was continuously monitored using the Granier heat dissipation probe technique(TDP).Correlations with environmental factors such as photosynthetically active radiation(PAR),vapor pressure deficit(VPD),and soil water content(SWC)were analyzed.[Result]PAR and VPD were identified as the main factors influencing the sap flow rates(Fdi)of birch trees of different differentiation levels.Fdi increased with the increase in PAR and initially with VPD,stabilizing at higher levels of VPD due to saturation.Significant decrease in Fdi was observed when SWC fell below 0.18 cm3/cm3(p<0.01).The hierarchy of Fdi was dominant trees(Fdd)>intermediate trees(Fdm)>suppressed trees(Fds),with varying responses to PAR,VPD,and SWC.As rainfall decreased during the rainy season,the driving effect of PAR on Fds and Fdm weakened,while the influence of VPD strengthened,showing an opposite trend for Fdd.During the dry rainy season,Fdd was primarily driven by PAR and jointly influenced by VPD and SWC;Fds was mainly controlled by VPD with minimal influence from PAR and SWC.Fdm lay intermediate,responding to SWC similarly to Fdd,while its response to PAR and VPD was akin to that of Fds.[Conclusion]Our results showed PAR and VPD are the primary influencing factors of the birch secondary forest in the boreal temperate zone.During the dry rainy season,the decrease in SWC significantly limited the sap flow rates,with a more active response from dominant and intermediate trees.
田野宏;满秀玲;徐志鹏;蔡体久;
东北林业大学林学院 哈尔滨 150040##东北林业大学森林生态系统可持续经营教育部重点实验室 哈尔滨 150040;东北林业大学林学院 哈尔滨 150040##东北林业大学森林生态系统可持续经营教育部重点实验室 哈尔滨 150040;东北林业大学林学院 哈尔滨 150040##东北林业大学森林生态系统可持续经营教育部重点实验室 哈尔滨 150040;东北林业大学林学院 哈尔滨 150040##东北林业大学森林生态系统可持续经营教育部重点实验室 哈尔滨 150040;
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