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林业科学 ›› 2018, Vol. 54 ›› Issue (5): 177-184.doi: 10.11707/j.1001-7488.20180519

• 研究简报 • 上一篇    

阳生叶光能利用率与光化学反射植被指数关系

李师宇, 于颖, 范文义   

  1. 东北林业大学林学院 哈尔滨 150040
  • 收稿日期:2017-04-05 修回日期:2017-10-22 出版日期:2018-05-25 发布日期:2018-06-05
  • 基金资助:
    国家自然科学基金项目(31500518;31500519)。

Relationship between the Photochemical Reflectance Vegetation Index and Photosynthetic Light Use Efficiency for Sunlit Leaves

Li Shiyu, Yu Ying, Fan Wenyi   

  1. Forestry School, Northeast Forestry University Harbin 150040
  • Received:2017-04-05 Revised:2017-10-22 Online:2018-05-25 Published:2018-06-05

摘要: [目的]对帽儿山地区主要树种的实测光谱与植被光能利用率进行统计分析,从光化学植被指数定义出发,修正PRI指数,进而得到阳生叶PRI与LUE之间较稳定的定量关系,为碳循环模型准确估计植被初级生产力(GPP)和净初级生产力(NPP)提供基础。[方法]数据采集时间为2016年8月,测量时间为10:00—15:00。LUE测定采用Li-Cor6400光合仪,叶片反射率是通过SVC HR-1024i在实验室测量获得。对实测PRI指数与LUE分针阔树种进行相关性分析和回归分析;对多波段反射率与LUE进行逐步回归分析,提取与LUE高相关性波段,重新组合形成新的PRI指数;分针阔树种建立修正后PRI指数与LUE回归关系。[结果]1)传统PRI指数与LUE相关性分析:针阔树种阳生叶PRI与LUE的pearson相关系数为0.234(P=0.079);阔叶仅为0.121(P=0.389),相关性低;针叶相对较好为0.467(P=0.174),对针叶进一步进行回归拟合,其R2较低(R2=0.218 2;P=0.174),传统PRI指数在此次研究中适用性较差。2)对多个波段反射率逐步回归分析,筛选后得到5个波段反射率组成的多元回归模型,其相关性有所提高(R2=0.402 2,P=0.04);波段518 nm处反射率对LUE的贡献率最大,偏回归平方和R2=0.133 4。基于传统PRI定义,对PRI指数进行修正,用518 nm反射率替换531 nm处反射率,用修正PRI指数与LUE建立新的一元回归模型。3)用修正PRI指数与LUE分树种分别建立一元回归模型,其回归结果:对于针阔树种阳生叶叶片两者之间R2为0.496 9(P<0.001),RMSE为0.024 7;对于阔叶树种阳生叶叶片两者之间R2为0.404 5(P<0.001),RMSE为0.023 6;对于针叶树种阳生叶叶片两者之间R2为0.538 5(P<0.001),RMSE为0.018 9。结果与传统PRI指数构建的一元回归模型及逐步回归构建的多元模型相比,显著性有明显提高。[结论]建立帽儿山地区针阔叶树种上层阳生叶叶片修正后PRI指数与LUE的关系。相比较传统PRI指数,修正后的PRI指数与LUE有着更高的相关性;所构建的一元回归模型不管是对针叶树种还是阔叶树种都有良好适用性。

关键词: 阳生叶, 改进光化学植被指数, 植被光能利用率, 逐步回归法

Abstract: [Objective] The purpose of this study is to analyze the relationship between measured spectrum and photosynthetic light utilization efficiency (LUE) of the sunlit leaves of the main tree species in the Maoershan Forest Farm. The definition of photochemical reflectance index (PRI) is modified to obtain a stable relationship between the PRI and LUE of the sunlit leaves, which provides an important basis for accurately estimating gross primary productivity (GPP) and net primary productivity (NPP) by the carbon cycling model. [Method] The data were collected from 10: 00-15: 00 AM in August 2016. LUE was measured by Li-Cor6400 photosynthetic apparatus, and leaf reflectance was measured in laboratory by the SVC HR-1024i. The correlation and regression analysis of PRI and LUE were carried out by SAS software. The relations between multi-band reflectivity and LUE were analyzed by stepwise regression analysis. The higher correlation bands with LUE were selected to modify PRI, and the relationship between modified PRI and LUE was established in coniferous and broadleaved species. [Result] 1) The correlation coefficient between traditional PRI and LUE was low. The Pearson correlation coefficient was 0.234 (P=0.079) for all sunlit leaves of coniferous and broadleaved species, among which 0.121 (P=0.389) for broadleaved species and 0.467 (P=0.174) for coniferous species. Further regression fitting for conifers showed a lower correlation (R2=0.218 2; P=0.174), and poor applicability of traditional PRI for this study. 2) By stepwise regression analysis of multiple-band reflectivity, the multiple regression models of the reflectivity of five bands were obtained after screening, and the correlation was improved (R2=0.402 2, P=0.04). The contribution of reflectance at 518 nm to the LUE was the largest with R2=0.133 4. Based on the definition of traditional PRI, the PRI index was modified by replacing the reflectivity at 531 nm with the reflectivity at 518 nm, and a new regression model was established between modified PRI and LUE. 3) For all sunlit leaves of coniferous and broadleaved species, the modified PRI was well related to LUE (R2=0.496 9, P<0.001; RMSE=0.024 7); for sunlit leaves of broadleaved species, R2 and RMSE were 0.4045(P<0.001) and 0.0236, respectively; for sunlit leaves of coniferous species, R2 and RMSE were 0.5385(P<0.001) and 0.018 9, respectively. The results derived from the new model were significantly improved compared with the results of using the multiple regression model constructed by the traditional PRI and LUE. [Conclusion] Compared to the traditional PRI, the modified PRI index can improve the relationship between the PRI and LUE of all sunlit leaves of coniferous and broadleaved species in Maoershan region.

Key words: sunlit leaves, modified photochemical reflectance index, photosynthetic light use efficiency, stepwise regression

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