Joint hierarchical models for sparsely sampled high-dimensional LiDAR and forest variables

TL;DR

This paper introduces a Bayesian hierarchical model for jointly analyzing sparse, high-dimensional LiDAR data and forest variables, enabling detailed inference on forest biomass and addressing data misalignment and high dimensionality.

Contribution

The paper presents a novel process-based Bayesian hierarchical framework for joint modeling of LiDAR signals and forest variables, handling misalignment and high-dimensional data.

Findings

Effective in simulation experiments

Applied successfully to Penobscot Experimental Forest data

Provides uncertainty measures for biomass estimates

Abstract

Recent advancements in remote sensing technology, specifically Light Detection and Ranging (LiDAR) sensors, provide the data needed to quantify forest characteristics at a fine spatial resolution over large geographic domains. From an inferential standpoint, there is interest in prediction and interpolation of the often sparsely sampled and spatially misaligned LiDAR signals and forest variables. We propose a fully process-based Bayesian hierarchical model for above ground biomass (AGB) and LiDAR signals. The process-based framework offers richness in inferential capabilities, e.g., inference on the entire underlying processes instead of estimates only at pre-specified points. Key challenges we obviate include misalignment between the AGB observations and LiDAR signals and the high-dimensionality in the model emerging from LiDAR signals in conjunction with the large number of spatial locations. We offer simulation experiments to evaluate our proposed models and also apply them to a challenging dataset comprising LiDAR and spatially coinciding forest inventory variables collected on the Penobscot Experimental Forest (PEF), Maine. Our key substantive contributions include AGB data products with associated measures of uncertainty for the PEF and, more broadly, a methodology that should find use in a variety of current and upcoming forest variable mapping efforts using sparsely sampled remotely sensed high-dimensional data.