西北旱区葡萄园水碳通量耦合模拟

Water and carbon coupled modeling of a vineyard in arid areas in Northwest China

对旱区葡萄园采用MAESTRA模型进行参数化并对其气孔导度子模型进行筛选,模拟了冠层辐射传输和碳同化量积累过程。结果表明PARp最大值集中在冠层顶0.4m深度以上及南侧0.1m深度以外,冠层北侧和中心部位的光强迅速减小。以液流测定结果为基准,检验了Jarvis系列气孔导度模型的效果。考虑土壤水分影响和引入参考冠层导度的J-Ref子模型使单株蒸腾量的模拟结果(18.34mol·vine-1·h-1)与测定值(17.74mol·vine-1·h-1)之间没有显著偏差。摸清了西北旱区葡萄园的干物质积累过程。干物质积累量模拟值为1 441.0g,仅比实测值高3.8%。模拟值积累曲线斜率滞后于实测值说明当年初葡萄萌芽消耗的碳水化合物并非来自当年光合产物,而是源于上年储存量,该储存量约占当年干物质总积累量的15%。本研究为西北旱区葡萄园冠层辐射传输和水碳通量研究提供了一套简单易行的模拟方法和参数化方案。

Modeling of water and carbon fluxes is essential for optimizing irrigation programs and improvingwater use efficiency. Parameters for the MAESTRA model applied in vineyards in arid region were deter-mined and canopy radiation transmission and carbon accumulation were simulated. The absorption of PARis higher in the first 0.4m layer from the top and 0.1m layer from the south side of the canopy. The de-crease of radiation is dramatically in the lower and north part of the canopy. With sap flow measurementsas a benchmark,different stomatal conductance sub-models were compared when modeling the transpirationrate. J-Ref sub-model,with the term of soil moisture limitation and the substitute of reference canopy con-ductance,could give the best simulation of water use(18.34mol·vine-1·h-1)comparing to the measurements(17.74mol·vine- 1·h- 1) when it was nested to MAESTRA. Modeled carbon assimilation accumulation(1441.0g) is higher than measurements by only 3.8%. There is a lag between the two accumulation lines,which suggested that the carbohydrates for the sprouting in spring are supplied not by the carbon assimila-tion of current year but by that of last year. And this storage accounted about 15% of the whole carbon as-similation accumulation. The parameterization of the MAESTRA model in this study would supply an optionof the canopy radiation transfer and water and carbon coupled modeling of vineyards in arid regions ofNorthwest China.