Leaf to canopy upscaling approach affects the estimation of canopy traits

Abstract:
In remote sensing applications, leaf traits are often upscaled to canopy level using sunlit leaf samples collected from the upper canopy. The implicit assumption is that the top of canopy foliage material dominates canopy reflectance and the variability in leaf traits across the canopy is very small. However, the effect of different approaches of upscaling leaf traits to canopy level on model performance and estimation accuracy remains poorly understood. This is especially important in short or sparse canopies where foliage material from the lower canopy potentially contributes to the canopy reflectance. The principal aim of this study is to examine the effect of different approaches when upscaling leaf traits to canopy level on model performance and estimation accuracy using spectral measurements (in-situ canopy hyperspectral and simulated Sentinel-2 data) in short woody vegetation. To achieve this, we measured foliar nitrogen (N), leaf mass per area (LMA), foliar chlorophyll and carbon together with leaf area index (LAI) at three vertical canopy layers (lower, middle and upper) along the plant stem in a controlled laboratory environment. We then upscaled the leaf traits to canopy level by multiplying leaf traits by LAI based on different combinations of the three canopy layers. Concurrently, in-situ canopy reflectance was measured using an ASD FieldSpec-3 Pro FR spectrometer, and the canopy traits were related to in-situ spectral measurements using partial least square regression (PLSR). The PLSR models were cross-validated based on repeated k-fold, and the normalized root mean square errors (nRMSEcv) obtained from each upscaling approach were compared using one-way analysis of variance (ANOVA) followed by Tukey’s post hoc test. Results of the study showed that leaf-to-canopy upscaling approaches that consider the contribution of leaf traits from the exposed upper canopy layer together with the shaded middle canopy layer yield significantly (p < 0.05) lower error (nRMSEcv < 0.2 for canopy N, LMA and carbon) as well as high explained variance (R2 > 0.71) for both in-situ hyperspectral and simulated Sentinel-2 data. The widely-used upscaling approach that considers only leaf traits from the upper illuminated canopy layer yielded a relatively high error (nRMSEcv>0.2) and lower explained variance (R2 < 0.71) for canopy N, LMA and carbon. In contrast, canopy chlorophyll upscaled based on leaf samples collected from the upper canopy and total canopy LAI exhibited a more accurate relationship with spectral measurements compared with other upscaling approaches. Results of this study demonstrate that leaf to canopy upscaling approaches have a profound effect on canopy traits estimation for both in-situ hyperspectral measurements and simulated Sentinel-2 data in short woody vegetation. These findings have implications for field sampling protocols of leaf traits measurement as well as upscaling leaf traits to canopy level especially in short and less foliated vegetation where leaves from the lower canopy contribute to the canopy reflectance.
Author Listing: Tawanda W. Gara;Andrew K. Skidmore;Roshanak Darvishzadeh;Tiejun Wang
Volume: 56
Pages: 554 - 575
DOI: 10.1080/15481603.2018.1540170
Language: English
Journal: GIScience & Remote Sensing

GIScience & Remote Sensing

GISCI REMOTE SENS

影响因子:6.0 是否综述期刊:否 是否OA:是 是否预警:不在预警名单内 发行时间:1962 ISSN:1548-1603 发刊频率:Bi-monthly 收录数据库:SCIE/Scopus收录 出版国家/地区:UNITED STATES 出版社:TAYLOR & FRANCIS LTD

期刊介绍

GIScience & Remote Sensing publishes original, peer-reviewed articles associated with geographic information systems (GIS), remote sensing of the environment (including digital image processing), geocomputation, spatial data mining, and geographic environmental modelling. Papers reflecting both basic and applied research are published.

GIScience & Remote Sensing出版与地理信息系统(GIS)、环境遥感(包括数字图像处理)、地理计算、空间数据挖掘和地理环境建模相关的原创、同行评审文章。发表了反映基础和应用研究的论文。

年发文量 104
国人发稿量 71
国人发文占比 68.27%
自引率 6.7%
平均录取率 18%18%
平均审稿周期 平均Submission to first decision: 5 days; Submission to first post-review decision: 52 days; Acceptance to online publication: 21 days;平均9.0个月
版面费 -
偏重研究方向 地学-遥感
期刊官网 https://www.tandfonline.com/journals/tgrs20
投稿链接 https://rp.tandfonline.com/submission/create?journalCode=tgrs

质量指标占比

研究类文章占比 OA被引用占比 撤稿占比 出版后修正文章占比
99.04% 74.74% 0.00% 0.00%

相关指数

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期刊预警不是论文评价,更不是否定预警期刊发表的每项成果。《国际期刊预警名单(试行)》旨在提醒科研人员审慎选择成果发表平台、提示出版机构强化期刊质量管理。

预警期刊的识别采用定性与定量相结合的方法。通过专家咨询确立分析维度及评价指标,而后基于指标客观数据产生具体名单。

具体而言,就是通过综合评判期刊载文量、作者国际化程度、拒稿率、论文处理费(APC)、期刊超越指数、自引率、撤稿信息等,找出那些具备风险特征、具有潜在质量问题的学术期刊。最后,依据各刊数据差异,将预警级别分为高、中、低三档,风险指数依次减弱。

《国际期刊预警名单(试行)》确定原则是客观、审慎、开放。期刊分区表团队期待与科研界、学术出版机构一起,夯实科学精神,打造气正风清的学术诚信环境!真诚欢迎各界就预警名单的分析维度、使用方案、值得关切的期刊等提出建议!

预警情况 查看说明

时间 预警情况
2024年02月发布的2024版 不在预警名单中
2023年01月发布的2023版 不在预警名单中
2021年12月发布的2021版 不在预警名单中
2020年12月发布的2020版 不在预警名单中

JCR分区 WOS分区等级:Q1区

版本 按学科 分区
WOS期刊SCI分区
WOS期刊SCI分区是指SCI官方(Web of Science)为每个学科内的期刊按照IF数值排 序,将期刊按照四等分的方法划分的Q1-Q4等级,Q1代表质量最高,即常说的1区期刊。
(2021-2022年最新版)
REMOTE SENSING Q1
GEOGRAPHY, PHYSICAL Q1

关于2019年中科院分区升级版(试行)

分区表升级版(试行)旨在解决期刊学科体系划分与学科发展以及融合趋势的不相容问题。由于学科交叉在当代科研活动的趋势愈发显著,学科体系构建容易引发争议。为了打破学科体系给期刊评价带来的桎梏,“升级版方案”首先构建了论文层级的主题体系,然后分别计算每篇论文在所属主题的影响力,最后汇总各期刊每篇论文分值,得到“期刊超越指数”,作为分区依据。

分区表升级版(试行)的优势:一是论文层级的主题体系既能体现学科交叉特点,又可以精准揭示期刊载文的多学科性;二是采用“期刊超越指数”替代影响因子指标,解决了影响因子数学性质缺陷对评价结果的干扰。整体而言,分区表升级版(试行)突破了期刊评价中学科体系构建、评价指标选择等瓶颈问题,能够更为全面地揭示学术期刊的影响力,为科研评价“去四唯”提供解决思路。相关研究成果经过国际同行的认可,已经发表在科学计量学领域国际重要期刊。

《2019年中国科学院文献情报中心期刊分区表升级版(试行)》首次将社会科学引文数据库(SSCI)期刊纳入到分区评估中。升级版分区表(试行)设置了包括自然科学和社会科学在内的18个大类学科。基础版和升级版(试行)将过渡共存三年时间,推测在此期间各大高校和科研院所仍可能会以基础版为考核参考标准。 提示:中科院分区官方微信公众号“fenqubiao”仅提供基础版数据查询,暂无升级版数据,请注意区分。

中科院分区 查看说明

版本 大类学科 小类学科 Top期刊 综述期刊
地球科学
2区
REMOTE SENSING
遥感
3区
GEOGRAPHY, PHYSICAL
自然地理
3区
2021年12月
基础版
地学
1区
REMOTE SENSING
遥感
2区
GEOGRAPHY, PHYSICAL
自然地理
2区
2021年12月
升级版
地球科学
2区
REMOTE SENSING
遥感
3区
GEOGRAPHY, PHYSICAL
自然地理
3区
2020年12月
旧的升级版
地球科学
1区
REMOTE SENSING
遥感
1区
GEOGRAPHY, PHYSICAL
自然地理
2区
2022年12月
最新升级版
地球科学
2区
REMOTE SENSING
遥感
3区
GEOGRAPHY, PHYSICAL
自然地理
2区