UAV-based thermography reveals spatial and temporal variability of evapotranspiration from a tropical rainforest

Frontiers in Forests and Global Change

Forests and Global Change

Christian Stiegler¹  Isa Marques²  Hendrayanto Hendrayanto³  Medha Bulusu⁴  Alexander Röll⁴  Dirk Hölscher⁵  Florian Ellsäßer⁶  Joyson Ahongshangbam⁷ 

[1] Bioclimatology, University of Göttingen, Göttingen, Germany;Chairs of Statistics and Econometrics, University of Göttingen, Göttingen, Germany;Forest Management, Bogor Agricultural University (IPB), Bogor City, Indonesia;Tropical Silviculture and Forest Ecology, University of Göttingen, Göttingen, Germany;Tropical Silviculture and Forest Ecology, University of Göttingen, Göttingen, Germany;Centre of Biodiversity and Sustainable Land Use, University of Göttingen, Göttingen, Germany;Tropical Silviculture and Forest Ecology, University of Göttingen, Göttingen, Germany;Department of Natural Resources, ITC, University of Twente, Enschede, Netherlands;Tropical Silviculture and Forest Ecology, University of Göttingen, Göttingen, Germany;Institute for Atmospheric and Earth System Research, University of Helsinki, Helsinki, Finland;

关键词: close-range sensing;    DATTUTDUT;    heterogeneity;    land surface temperature;    seasonality;    site conditions;   

DOI  :  10.3389/ffgc.2023.1232410

 received in 2023-05-31, accepted in 2023-08-11,  发布年份 2023

来源: Frontiers

【 摘 要 】

Evapotranspiration (ET) from tropical forests plays a significant role in regulating the climate system. Forests are diverse ecosystems, encompass heterogeneous site conditions and experience seasonal fluctuations of rainfall. Our objectives were to quantify ET from a tropical rainforest using high-resolution thermal images and a simple modeling framework. In lowland Sumatra, thermal infrared (TIR) images were taken from an uncrewed aerial vehicle (UAV) of upland and riparian sites during both dry and wet seasons. We predicted ET from land surface temperature data retrieved from the TIR images by applying the DATTUTDUT energy balance model. We further compared the ET estimates to ground-based sap flux measurements for selected trees and assessed the plot-level spatial and temporal variability of ET across sites and seasons. Average ET across sites and seasons was 0.48 mm h–1, which is comparable to ET from a nearby commercial oil palm plantation where this method has been validated against eddy covariance measurements. For given trees, a positive correlation was found between UAV-based ET and tree transpiration derived from ground-based sap flux measurements, thereby corroborating the observed spatial patterns. Evapotranspiration at upland sites was 11% higher than at riparian sites across all seasons. The heterogeneity of ET was lower at upland sites than at riparian sites, and increased from the dry season to the wet season. This seasonally enhanced ET variability can be an effect of local site conditions including partial flooding and diverse responses of tree species to moisture conditions. These results improve our understanding of forest-water interactions in tropical forests and can aid the further development of vegetation-atmosphere models. Further, we found that UAV-based thermography using a simple, energy balance modeling scheme is a promising method for ET assessments of natural (forest) ecosystems, notably in data scarce regions of the world.

【 授权许可】

Unknown   
Copyright © 2023 Bulusu, Ellsäßer, Stiegler, Ahongshangbam, Marques, Hendrayanto, Röll and Hölscher.