Hyper-temporal LiDAR for tracking fine-scale changes in vegetation structure, phenology, and physiology

Abstract:

Vegetation three-dimensional (3-D) structure is inherently dynamic - plants alter both the allocation of resources within the canopy and branch/shoot morphology at short time-steps to acclimate to local environmental conditions and maximize photosynthetic potential. However, 3-D structure is often ignored in ecological studies because it is difficult to characterize using traditional field methods. Terrestrial laser scanning (TLS) is a rapidly maturing technique to complement and enhance traditional field methods for quantifying 3-D geometric properties of ecosystems. Two major limitations of TLS include the low temporal resolution that often exists between each data acquisition, and the relatively high cost of such systems (entry level systems cost >$40,000 USD) that puts this method out of reach for many potential users. Consequently, TLS is currently limited as a mainstream method for capturing 3-D geometric ecosystem dynamics. Over the last several years, we have been developing a field-ready autonomously operating terrestrial laser scanner (ATLS) capable of monitoring fine-scale changes in vegetation structure on a daily time-step. We will present an overview of recent findings using the ATLS to track changes in vegetation structure in low-stature ecosystems – from cropping system dynamics to Arctic tundra phenology. Further, we will discuss the potential for laser intensity return information from both an ATLS and TLS to track changes in plant phenology and physiology (Chlorophyll content, photoprotective mechanisms, moisture) that occur simultaneously – or prior to – changes in vegetation structure. Our results suggest that fine-scale mapping of plant structure, phenology, and physiology using information from TLS and ATLS could provide new insights into vegetation dynamics in space and time.