人工同龄纯林冠层辐射场模拟模型 II.应用与验证

A CANOPY RADIATION MODEL FOR EVEN-AGED PLANTATION II. APPLICATION AND VALIDATION

应用建立的人工同龄林辐射场模型对杉木 (Cunninghamialanceolata)人工林冠层辐射场进行了模拟 ,以实测的冠层辐射数据对模型进行了验证 ,对模型的不确定性以及叶面积密度和叶片散射的影响进行了计算和分析。结果表明 ,模拟和实测辐射场及日总量无显著差异 ,所建模型适于对杉木人工林冠层辐射的模拟。模型可能的误差来源包括树冠形状的不规则性、树冠大小和高低的不一致性、叶片在小范围内的簇生性等。考虑二维叶面积密度 (LAD)分布的模拟结果优于平均LAD。叶片的散射辐射约占总辐射的 3%～ 11%,且越靠近树冠里层和下部 ,散射作用越大。

Measured radiation within the canopy of a Chinese fir plantation was used to validate an established canopy radiation model for even_aged plantations. Uncertainties and the impacts of leaf area density (LAD) distribution and scattered radiation were also calculated and analyzed with the model. Results show that there was no significant difference between measured and modeled instantaneous and daily radiation within canopy. Errors of simulations may result from irregular crown shape and crown size, grouped needles on shoots, etc. 2_D LAD distributions may improve the radiation simulation compared to averaged LAD. Simulated scattered radiation accounted for 3%-11% of total radiation, while low crown position and increased depth within the crown increased the relative proportion of scattered radiation.