Measurement and modelling ozone fluxes over a cut and fertilized grassland
Measurement and modelling ozone fluxes over a cut and fertilized grassland
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砍伐和施肥草地上臭氧通量的测量和建模
DOI：
10.5194/bg-6-1987-2009
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发表时间：
2009
期刊：
影响因子：
4.9
通讯作者：
B. Loubet
中科院分区：
文献类型：
--
作者：
R. Mészáros;L. Horváth;T. Weidinger;A. Neftel;E. Nemitz;U. Dämmgen;P. Cellier;B. Loubet
摘要。在2000年5月20日至6月15日的GRAMINAE综合试验期间，采用涡旋相关法测量了德国北部布伦瑞克集约管理草地上的臭氧通量。在测量活动期间，覆盖了三个不同阶段的植被：刈割前的高草冠层（2000年5月29日）、刈割后的矮草冠层和施肥后的重新生长的植被（2000年6月5日）。结果表明，除天气条件外，农业活动对O3通量有显著影响。切割后，白天平均沉积速度（vd）从0.44 cm s - 1下降到0.26 cm s - 1，在第三阶段再次上升到0.32 cm s - 1。进行了详细的模型计算，以估计沉积速度和臭氧通量。该模型捕获了沉积的一般日格局，在第一、第二和第三周期，vd的日值分别为0.52、0.24和0.35 cm s−1。因此，该模型预测的对切割的响应比测量的更强，但比基于叶面积变化的预期要小。结果表明，刈割和施肥对土壤通量有复杂的影响。采伐植被减少初期气孔通量减少幅度较大，但一周后气孔通量恢复到原来的80%。与此同时，非气孔通量似乎在切割后直接增加，该模型部分解释了沉积到土壤中的增加。刈割后缺失的汇可能是与刈割后暴露的植物衰老部位释放的生物源性挥发性有机物的化学相互作用，也可能是施肥后土壤NO排放的增加。冠层温度的升高也可能促进了叶片表面臭氧的破坏。这些结果说明了冠层结构和非气孔途径对O3通量的重要性。
Abstract. During the GRAMINAE Integrated Experiment between 20 May and 15 June 2000, the ozone flux was measured by the eddy covariance method above intensively managed grassland in Braunschweig, northern Germany. Three different phases of vegetation were covered during the measuring campaign: tall grass canopy before cut (29 May 2000), short grass after cut, and re-growing vegetation after fertilization (5 June 2000). Results show that beside weather conditions, the agricultural activities significantly influenced the O3 fluxes. After the cut the daytime average of the deposition velocity (vd) decreased from 0.44 cm s−1 to 0.26 cm s−1 and increased again to 0.32 cm s−1 during the third period. Detailed model calculations were carried out to estimate deposition velocity and ozone flux. The model captures the general diurnal patter of deposition, with vd daytime values of 0.52, 0.24, and 0.35 cm s−1 in the first, second and third period, respectively. Thus the model predicts a stronger response to the cut than the measurements, which is nevertheless smaller than expected on the basis of change in leaf area. The results show that both cut and fertilization have complex impacts on fluxes. Reduction of vegetation by cutting decreased the stomatal flux initially greatly, but the stomatal flux recovered to 80% of its original value within a week. At the same time, the non-stomatal flux appears to have increased directly after the cut, which the model partially explains by an increase in the deposition to the soil. A missing sink after the cut may be the chemical interaction with biogenic volatile organic compounds released after the cut and exposed senescent plant parts, or the increase in soil NO emissions after fertilization. Increased canopy temperatures may also have promoted ozone destruction on leaf surfaces. These results demonstrate the importance of canopy structure and non-stomatal pathways on O3 fluxes.