植物生态学报 ›› 2016, Vol. 40 ›› Issue (6): 574-584.DOI: 10.17521/cjpe.2015.0467

• 研究论文 • 上一篇    下一篇

利用3种校正方案提高间接法测定兴安落叶松人工林叶面积指数的精度

周明1,2, 刘志理1, 金光泽1,,A;*()   

  1. 1东北林业大学生态研究中心, 哈尔滨 150040
    2佳木斯市林业局, 黑龙江佳木斯 154007
  • 收稿日期:2015-12-21 接受日期:2016-05-09 出版日期:2016-06-10 发布日期:2016-06-15
  • 通讯作者: 金光泽
  • 基金资助:
    中央高校基本科研业务费专项(DL13E- A05)和黑龙江省留学归国基金项目(LC2016006)

Improving the accuracy of indirect methods in estimating leaf area index using three correction schemes in a Larix gmelinii plantation

Ming ZHOU1,2, Zhi-Li LIU1, Guang-Ze JIN1,*()   

  1. 1Center for Ecological Research, Northeast Forestry University, Harbin 150040, China
    and
    2Forestry Bureau of Jiamusi, Jiamusi, Heilongjiang 154007, China
  • Received:2015-12-21 Accepted:2016-05-09 Online:2016-06-10 Published:2016-06-15
  • Contact: Guang-Ze JIN

摘要:

木质部和集聚效应是影响间接法测定叶面积指数(LAI)精度的主要因素, 尤其是木质部的校正一直存在争议。针对这一问题, 该研究首先利用半球摄影法(DHP)和LAI-2000植物冠层分析仪法(LAI-2000法) 2种间接法测定了小兴安岭兴安落叶松(Larix gmelinii)人工林叶面积最大时期的有效LAI (Le), 然后提出了A、B、C 3种校正方案来提高间接法的测定精度。同时, 利用凋落物法和异速生长方程法2种直接法测定LAI, 以凋落物法测定值为标准来评估3种校正方案的校正效果, 并检验天顶角范围对校正结果是否存在显著影响。结果表明: 在0-45° (1-3环)、0-60° (1-4环)、45°-60° (4环)及0-75° (1-5环) 4种不同天顶角范围内, DHP测定的Le比凋落物法、异速生长方程法测定值分别低估19%-32%和8%-29%; 而LAI-2000法也得到相似的结论, 分别低估9%-30%和8%-28%。虽然校正方案A高估了木质部对LAI的贡献, 但在45º-60º天顶角范围内, 能有效地校正DHP测定的Le, 在1-3环和1-4环天顶角范围内, 能有效地校正LAI-2000法测定的Le。4种天顶角范围内, 校正方案B均能有效地校正DHP测定的Le。整体来看, 4种天顶角范围内, 校正方案C对DHP和LAI-2000法测定值的校正效果均优于其他2种方案。研究结果表明除木质部和集聚效应外, 天顶角范围的选择也是决定间接法测定LAI精度的重要因素。

关键词: 叶面积指数, 凋落物法, 异速生长方程法, 半球摄影法, LAI-2000植物冠层分析仪法, 天顶角

Abstract:

Aims Woody materials and clumping effects are key error sources in estimating leaf area index (LAI) by optical methods. However, how to correct the error caused by woody materials has not reached consensus. The aims of this study are (1) to evaluate the accuracy of optical methods for estimating effective LAI (Le) in a deciduous needle leaf forest stand, and (2) to develop a practical correction scheme to improve the accuracy of optical methods in estimating LAI.Methods Lewas estimated by two indirect methods (i.e., digital hemispherical photography (DHP) and LAI-2000 plant canopy analyzer method (LAI-2000 method) in an annual maximum leaf area period in a Larix gmelinii plantation. Then, we developed three correction schemes to improve the accuracy of indirect methods in estimating LAI. Meanwhile, two direct methods (i.e., litter collection and allometry methods) were used to estimate LAI. Taking LAI from litter collection as a reference, we evaluated the effectiveness of three correction schemes and tested the influence of zenith angle ranges on the correction results.Important findings With zenith angle ranges of 0-45° (rings 1-3), 0-60° (rings 1-4), 45°-60° (ring 4) and 0-75° (rings 1-5), Leobtained from DHP underestimated LAI from both litter collection and allometry by 19%-32% and 18%-29%, respectively. Lefrom LAI-2000 method with four zenith angles also underestimated LAI from both litter collection and allometry by 9%-30% and 8%-28%, respectively. Although the contribution of woody materials to LAI was overestimated in correction scheme A, it was effective in correcting Lefrom DHP with zenith angles of 45º-60º (ring 4), and also effective for Lefrom LAI-2000 method with zenith angles of rings both 1-3 and 1-4. Correction scheme B was all effective in correcting Lefrom DHP with four zenith angle ranges. Generally, correction scheme C was more effective than other two schemes in correcting Lefrom both DHP and LAI-2000 method with four zenith angle ranges. These results indicate that the zenith angle range is a key factor for determining the accuracy of optical methods in estimating LAI besides woody materials and clumping effects.

Key words: leaf area index, litter collection, allometry, digital hemispherical photography, LAI-2000 plant canopy analyzer method, zenith angle