Mapping global leaf inclination angle (LIA) based on field measurement data
<p>Leaf inclination angle (LIA), the angle between the leaf surface normal and zenith directions, is a vital trait in radiative transfer, rainfall interception, evapotranspiration, photosynthesis, and hydrological processes. Due to the difficulty of obtaining large-scale field measurement data...
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Copernicus Publications
2025-04-01
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| Series: | Earth System Science Data |
| Online Access: | https://essd.copernicus.org/articles/17/1347/2025/essd-17-1347-2025.pdf |
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| author | S. Li S. Li S. Li H. Fang H. Fang |
| author_facet | S. Li S. Li S. Li H. Fang H. Fang |
| author_sort | S. Li |
| collection | DOAJ |
| description | <p>Leaf inclination angle (LIA), the angle between the leaf surface normal and zenith directions, is a vital trait in radiative transfer, rainfall interception, evapotranspiration, photosynthesis, and hydrological processes. Due to the difficulty of obtaining large-scale field measurement data, LIA is typically assumed to follow the spherical leaf distribution or simply considered to be constant for different plant types. However, the appropriateness of these simplifications and the global LIA distribution are still unknown. This study compiled global LIA measurements and generated the first global 500 m mean LIA (MLA) product by gap-filling the LIA measurement data using a random forest regressor. Different generation strategies were employed for noncrops and crops. The MLA product was evaluated by validating the nadir leaf projection function (<span class="inline-formula"><i>G</i>(0)</span>) derived from the MLA product with high-resolution reference data. The global MLA is <span class="inline-formula">41.47<i>°</i>±9.55<i>°</i></span>, and the value increases with latitude. The MLAs for different vegetation types follow the order of cereal crops (54.65°) <span class="inline-formula">></span> broadleaf crops (52.35°) <span class="inline-formula">></span> deciduous needleleaf forest (50.05°) <span class="inline-formula">></span> shrubland (49.23°) <span class="inline-formula">></span> evergreen needleleaf forest (47.13°) <span class="inline-formula">≈</span> grassland (47.12°) <span class="inline-formula">></span> deciduous broadleaf forest (41.23°) <span class="inline-formula">></span> evergreen broadleaf forest (34.40°). Cross-validation shows that the predicted MLA presents a medium consistency (<span class="inline-formula"><i>r</i>=0.75</span>, RMSE <span class="inline-formula">=</span> 7.15°) with the validation samples for noncrops, whereas crops show relatively lower correspondence (<span class="inline-formula"><i>r</i>=0.48</span> and 0.60 for broadleaf crops and cereal crops, respectively) because of the limited LIA measurements and strong seasonality. The global mean <span class="inline-formula"><i>G</i>(0)</span> is <span class="inline-formula">0.68±0.11</span>. The global <span class="inline-formula"><i>G</i>(0)</span> distribution is out of phase with that of the MLA and agrees moderately with the reference data (<span class="inline-formula"><i>r</i>=0.62</span>, RMSE <span class="inline-formula">=</span> 0.15). This study shows that the common spherical and constant LIA assumptions may underestimate the interception of most vegetation types. The MLA and <span class="inline-formula"><i>G</i>(0)</span> products derived in this study could enhance our knowledge of global LIA and should greatly facilitate remote sensing retrieval and land surface modeling studies.</p>
<p>The global MLA and <span class="inline-formula"><i>G</i>(0)</span> products can be accessed at <a href="https://doi.org/10.5281/zenodo.12739662">https://doi.org/10.5281/zenodo.12739662</a> (Li and Fang, 2025).</p> |
| format | Article |
| id | doaj-art-69d424e7bd264bb2944a68e8a6b1f92c |
| institution | DOAJ |
| issn | 1866-3508 1866-3516 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Earth System Science Data |
| spelling | doaj-art-69d424e7bd264bb2944a68e8a6b1f92c2025-08-20T03:09:28ZengCopernicus PublicationsEarth System Science Data1866-35081866-35162025-04-01171347136610.5194/essd-17-1347-2025Mapping global leaf inclination angle (LIA) based on field measurement dataS. Li0S. Li1S. Li2H. Fang3H. Fang4National-Local Joint Engineering Laboratory of Geo-Spatial Information Technology, Hunan University of Science and Technology, Xiangtan 411201, ChinaLREIS, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, ChinaCollege of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, ChinaLREIS, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, ChinaCollege of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China<p>Leaf inclination angle (LIA), the angle between the leaf surface normal and zenith directions, is a vital trait in radiative transfer, rainfall interception, evapotranspiration, photosynthesis, and hydrological processes. Due to the difficulty of obtaining large-scale field measurement data, LIA is typically assumed to follow the spherical leaf distribution or simply considered to be constant for different plant types. However, the appropriateness of these simplifications and the global LIA distribution are still unknown. This study compiled global LIA measurements and generated the first global 500 m mean LIA (MLA) product by gap-filling the LIA measurement data using a random forest regressor. Different generation strategies were employed for noncrops and crops. The MLA product was evaluated by validating the nadir leaf projection function (<span class="inline-formula"><i>G</i>(0)</span>) derived from the MLA product with high-resolution reference data. The global MLA is <span class="inline-formula">41.47<i>°</i>±9.55<i>°</i></span>, and the value increases with latitude. The MLAs for different vegetation types follow the order of cereal crops (54.65°) <span class="inline-formula">></span> broadleaf crops (52.35°) <span class="inline-formula">></span> deciduous needleleaf forest (50.05°) <span class="inline-formula">></span> shrubland (49.23°) <span class="inline-formula">></span> evergreen needleleaf forest (47.13°) <span class="inline-formula">≈</span> grassland (47.12°) <span class="inline-formula">></span> deciduous broadleaf forest (41.23°) <span class="inline-formula">></span> evergreen broadleaf forest (34.40°). Cross-validation shows that the predicted MLA presents a medium consistency (<span class="inline-formula"><i>r</i>=0.75</span>, RMSE <span class="inline-formula">=</span> 7.15°) with the validation samples for noncrops, whereas crops show relatively lower correspondence (<span class="inline-formula"><i>r</i>=0.48</span> and 0.60 for broadleaf crops and cereal crops, respectively) because of the limited LIA measurements and strong seasonality. The global mean <span class="inline-formula"><i>G</i>(0)</span> is <span class="inline-formula">0.68±0.11</span>. The global <span class="inline-formula"><i>G</i>(0)</span> distribution is out of phase with that of the MLA and agrees moderately with the reference data (<span class="inline-formula"><i>r</i>=0.62</span>, RMSE <span class="inline-formula">=</span> 0.15). This study shows that the common spherical and constant LIA assumptions may underestimate the interception of most vegetation types. The MLA and <span class="inline-formula"><i>G</i>(0)</span> products derived in this study could enhance our knowledge of global LIA and should greatly facilitate remote sensing retrieval and land surface modeling studies.</p> <p>The global MLA and <span class="inline-formula"><i>G</i>(0)</span> products can be accessed at <a href="https://doi.org/10.5281/zenodo.12739662">https://doi.org/10.5281/zenodo.12739662</a> (Li and Fang, 2025).</p>https://essd.copernicus.org/articles/17/1347/2025/essd-17-1347-2025.pdf |
| spellingShingle | S. Li S. Li S. Li H. Fang H. Fang Mapping global leaf inclination angle (LIA) based on field measurement data Earth System Science Data |
| title | Mapping global leaf inclination angle (LIA) based on field measurement data |
| title_full | Mapping global leaf inclination angle (LIA) based on field measurement data |
| title_fullStr | Mapping global leaf inclination angle (LIA) based on field measurement data |
| title_full_unstemmed | Mapping global leaf inclination angle (LIA) based on field measurement data |
| title_short | Mapping global leaf inclination angle (LIA) based on field measurement data |
| title_sort | mapping global leaf inclination angle lia based on field measurement data |
| url | https://essd.copernicus.org/articles/17/1347/2025/essd-17-1347-2025.pdf |
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