KMS Chongqing Institute of Green and Intelligent Technology, CAS
| Simulation of maximum light coversion efficiency for a Phragmites salt marsh in the Liaohe river estuarine wetland | |
| Chen, Ji Long1,2; Li, Guo Sheng2,3; Liao, Hua Jun2; Wang, Bing Liang2; Cui, Lin Lin2 | |
| 2017 | |
| 摘要 | Maximum light conversion efficiency (MLE) is a critical parameter for the Carnegie Ames Stanford Approach (CASA) model, which is widely used for modeling net primary productivity (NPP) globally. However, it is difficult to parameterize MLE using experiments and field observation. MLE is fundamental in ecological studies, therefore, modeling MLE is of vital importance and significance. The present study determined the MLE of a Phragmites salt marsh in the Liaohe River estuarine wetland in China. The main objectives of this study were to: (1) determine the MLE of a Phragmites salt marsh; and (2) investigate the sensibility of MLE to environmental factors. Factors included in the CASA model comprised the Absorbed Photosynthetically Active Radiation (APAR) using sunshine duration, which was obtained from the National Meteorological Information Center; Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), calculated using the Normalized Difference Vegetation Index (NDVI) determined from 16-day Moderate Resolution Imaging Spectroradiometer (MODIS) data; temperature and water stress coefficients, calculated using MODIS reflectance data; and meteorological variables including air temperature, precipitation, sunshine duration, air pressure, water vapor pressure, wind velocity, and relative humidity. Field observations of the NPP of the Phragmites salt marsh were conducted at 54 sampling areas with a size of 250 m × 250 m, of which 27 sites were used for modeling, and the remaining for validation. The results showed that the Phragmites salt marsh had a relatively high carbon conversion efficiency, with an average MLE of 1.667 gC/ MJ, varying between 1.112 and 2.611 g C/ MJ, which was much higher than the proposed value of 0.389 g C/ MJ by Potter. It was even higher than that of broad?leaved, coniferous, and theropencedrymion forests. The simulated MLE was sensitive to global solar radiation and NDVI, decreasing with their increase, which was more pronounced at lower values. This indicated that it is important to check data quality and increase the data accuracy of global solar radiation. In the present study, global solar radiation was estimated using sunshine duration, with an accuracy of 95%. The relative range of MLE affected by the error of global solar radiation was from -4.14% to 4.56%. MLE became less sensitive as NDVI increased, whereas the simulated values still fell into the MLE range, but the NDVI error increased by 30%. In practical applications, the differences in MODIS NDVI data were much smaller, suggesting that our results are universal and could be used for other satellite images with different spatial resolutions. The air temperature and precipitation errors had little effect on the simulated results, as MLE was not sensitive to them. The results of the sensitivity analysis increased the reliability and confidence of the simulated MLE for the Phragmites salt marsh, which is of great significance when studying the carbon sink and sequestration potential of Phragmites wetlands in China and other regions globally. © 2017, Ecological Society of China. All rights reserved. |
| DOI | 10.5846/stxb201512162511 |
| 发表期刊 | Shengtai Xuebao/ Acta Ecologica Sinica
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| ISSN | 10000933 |
| 卷号 | 37期号:7页码:2263-2273 |
| 语种 | 中文 |
| EISSN | 18722032 |
