Symbolic regression-based allometric model development of a mangrove forest LAI using structural variables and digital hemispherical photography

The leaf area index (LAI) serves as a proxy to understand the dynamics of plant productivity, energy balance, and gas exchange. Cost-effective and accurate estimation of LAI is essential for under-assessed carbon-rich tropical forests, e.g., mangroves. Here, we developed allometric equations to estimate LAI using a combination of non-destructive, optical measurements through digital hemispherical photographs (DHP), and genetic programming-based Symbolic Regression (SR). We used three structural variables: diameter at breast height (DBH), tree density (TD), and canopy height (Ht) for a mangrove forest in the BhitarKanika Wildlife Sanctuary (BWS), located along the Eastern coast of India. Triplet combination using SR provided the best equation (R2 = 0.51) than any singlet or duplet combination of the variables, and even it was better than Partial Least Square (PLS) based regression (R2 = 0.42). To the best of our knowledge, the current study is the maiden attempt to develop an allometric model to estimate LAI for a mangrove ecosystem in India. In-situ measurements of structural variables such as DBH, Ht, and TD can be used for LAI estimates, as shown here. LAI estimates using cost-effective methods would greatly enhance our understanding of the spatial and temporal dynamics of mangrove ecosystems

Allometric equation, BhitarKanika wildlife sanctuary, Canopy height, Diameter at breast height, Symbolic regression, Tree density

10.1016/j.apgeog.2022.102649

0143-6228

Paramanik, Somnath

8fb0a9ec-ddf2-4ceb-a749-131a401c3753

Behera, M.D.

927bb995-072a-4e42-90e8-4e26bb8ce3d0

Dash, Jadunandan

51468afb-3d56-4d3a-aace-736b63e9fac8

29 January 2022

Paramanik, Somnath

8fb0a9ec-ddf2-4ceb-a749-131a401c3753

Behera, M.D.

927bb995-072a-4e42-90e8-4e26bb8ce3d0

Dash, Jadunandan

51468afb-3d56-4d3a-aace-736b63e9fac8

Paramanik, Somnath, Behera, M.D. and Dash, Jadunandan (2022) Symbolic regression-based allometric model development of a mangrove forest LAI using structural variables and digital hemispherical photography. Applied Geography, 139, [102649]. (doi:10.1016/j.apgeog.2022.102649).

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Accepted/In Press date: 19 January 2022

e-pub ahead of print date: 29 January 2022

Published date: 29 January 2022

Additional Information: Funding Information: The Authors acknowledge the authorities of IIT Kharagpur for faciliting the study. SP thanks the Ministry of Education , Government of India for grant of a PhD Research Fellowship. The support of Odisha State Forest department during Field inventory is thankfully acknowledged. We thank the two anonymous Reviewers, who have given very valuable feedback to its earlier version that has improved the manuscript to a great extent. Funding Information: The Authors acknowledge the authorities of IIT Kharagpur for faciliting the study. SP thanks the Ministry of Education, Government of India for grant of a PhD Research Fellowship. The support of Odisha State Forest department during Field inventory is thankfully acknowledged. We thank the two anonymous Reviewers, who have given very valuable feedback to its earlier version that has improved the manuscript to a great extent.

Keywords: Allometric equation, BhitarKanika wildlife sanctuary, Canopy height, Diameter at breast height, Symbolic regression, Tree density