林分结构变化对杉木人工林土壤水分影响的模拟

Simulation on Effect of Stand Structure Change on Soil Moisture Dynamics in Chinese Fir Plantation

为了分析林分结构调控影响林地土壤水文动态过程,以浙西钱江源上游地区开化县林场城关分场施业区为研究对象,应用2010—2014年杉木纯林实测土壤水分数据对基于物理基础的一维水热耦合(SHAW)模型进行参数测定和验证,并分析杉木复层异龄林土壤水分变化和水量平衡特征。结果表明:杉木纯林土壤水分模拟值略高于实测值,两者的均方根误差、平均偏差和相对平均绝对误差分别为0.041、0.009和15.4%,模型总体上模拟精度较高。杉木复层异龄林比纯林年均土壤储水量(0~60 cm)增加9.4 mm,年均蒸散量增加36.4 mm,土壤水分深层渗漏量减少115.6 mm;纯林和复层林土壤水分的年变化量与地表径流量差异较小,分别为0.7、0.2 mm。因此,构建杉木复层异龄林可以增加土壤水库容量,更好地发挥森林水源涵养功能。

Simultaneous Heat and Water （SHAW） model, a one-dimensional process-based numerical model of water and heat transfer, was used to simulate the dynamics of soil moisture and water balance in Chinese fir （ Cunninghamia lanceolata ） plantation. SHAW model was calibrated and validated using the measured data of soil moisture in monoculture Chinese fir plantations from 2010 to 2014. The soil moisture and water balance characteristics were analyzed in multi-storied Chinese fir plantation. During simulated period （2010-2014）, the simulated values of soil moisture were higher than the measured ones in the monoculture plantation. The root mean square error （RMSE）, mean bias error （MBE） and relatively mean absolutely error （RMAE） between simulated and measured soil moisture values were 0.041 m^3·m^-3 , 0.009 m^3·m^-3 and 15.4%, respectively. Overall, SHAW model could accurately estimate the dynamics of soil water in the Chinese fir plantation. Compared to the monoculture stand, the average annual soil water storage （0-60 cm） of the multi-storied stand was increased by 9.4 mm, the average annual evapotranspiration was increased by 36.4 mm, the deep leakage of soil moisture reduced by 115.6 mm, the change of soil moisture was increased by 0.7 mm, and surface runoff was reduced by 0.2 mm. Therefore, the construction of multi-storied Chinese fir plantation will be beneficial to enhance the capacity of soil reservoirs and better effect of water conservation.