Airborne Tree Crown Detection for Predicting Spatial Heterogeneity of Canopy Transpiration in a Tropical Rainforest

Remote Sensing

Hendrayanto¹  Alexander Röll²  Joyson Ahongshangbam²  Dirk Hölscher²  Florian Ellsäßer² 

[1] Forest Management, campus Darmaga Bogor Jawa Barat, Bogor Agricultural University, Bogor 16680,Indonesia;Tropical Silviculture and Forest Ecology, University of Goettingen, Buesgenweg 1, 37077 Goettingen, Germany;

关键词: ams3d;    3d structure;    drone;    photogrammetry;    riparian sites;    sap flux;    scaling;    structure from motion;    sumatra;    unmanned aerial vehicle (uav);    upland sites;    water use;   

DOI  :  10.3390/rs12040651

来源: DOAJ

【 摘 要 】

Tropical rainforests comprise complex 3D structures and encompass heterogeneous site conditions; their transpiration contributes to climate regulation. The objectives of our study were to test the relationship between tree water use and crown metrics and to predict spatial variability of canopy transpiration across sites. In a lowland rainforest of Sumatra, we measured tree water use with sap flux techniques and simultaneously assessed crown metrics with drone-based photogrammetry. We observed a close linear relationship between individual tree water use and crown surface area (R² = 0.76, n = 42 trees). Uncertainties in predicting stand-level canopy transpiration were much lower using tree crown metrics than the more conventionally used stem diameter. 3D canopy segmentation analyses in combination with the tree crown−water use relationship predict substantial spatial heterogeneity in canopy transpiration. Among our eight study plots, there was a more than two-fold difference, with lower transpiration at riparian than at upland sites. In conclusion, we regard drone-based canopy segmentation and crown metrics to be very useful tools for the scaling of transpiration from tree- to stand-level. Our results indicate substantial spatial variation in crown packing and thus canopy transpiration of tropical rainforests.

【 授权许可】

Unknown