UAS for Forest Inventory Traits: A Review

Traits are notoriously challenging to measure at a desirably large spatial extent with traditional field methods, which limits the discoveries that forest ecologists can make with these data. There is a ripe opportunity for uncrewed aerial systems (UAS) to contribute to ecology through forest inventory trait mapping. UAS can help overcome the challenge of scale by collecting data at a larger spatial extent with comparable resolution. With the proliferation of large-scale spatially explicit analyses, using UAS for forest trait mapping is synergistic with the direction that the field of forest ecology is headed, and thus an essential method for forest ecology toolkits. Here we provide evidence that forest traits are increasingly used as the metrics of focus in forest ecology, review what forest inventory traits and attributes can be derived from UAS-based data, and dive into a case example of how researchers derive a particular trait, carbon stock, from UAS-based data. Our results highlight the underutilization and infancy of UAS in forest ecology. From our review of the carbon stock literature, we found a different method of calculating carbon stock from UAS data in every paper, each with their own hurdles and caveats in estimating plant-based carbon stock. UAS can push forest ecology and the concomitant field of spatial ecology into a future with better temporal and spatial resolution of data collected on an evermore affordable budget.