Robotany: A portable, low-cost platform for precise automated aerial imaging of field plots

Abstract

The 1 m2 quadrat is a standard field survey tool in ecology. Traditionally, a researcher places a square frame on the ground and manually records data about organisms (typically plants) within that quadrat. Collecting data through this method can require a great deal of time on-site. For some studies, it would be more efficient to collect data as images in the field, and then extract desired data from the images later. Equipment currently available for precise aerial imaging of plants is most applicable to large-scale settings (e.g. entire fields) or controlled environments (e.g. greenhouses or growth chambers). There is a lack of technology suited to 1 × 1 m quadrat surveys of natural communities. To satisfy this need, we developed a portable, low-cost platform (‘Robotany’) that automatically takes a set of data samples to precisely cover a 1 m2 field plot. The current design is optimized for taking aerial photographs of short herbaceous plants in mowed or grazed habitats, at a spatial resolution of 24 non-overlapping photographs per 1 m2, using a digital single-lens reflex (DSLR) camera with the lens 55 cm above the ground. Novel attachment and actuation methods allow for fast, convenient assembly and disassembly, and the waterproof frame can be disinfected with ethanol. The device was reliable and precise in its initial two summers of field testing (ca. 200 plots imaged). These images were of sufficient resolution to identify common plant taxa, and to collect information on plant size, flowering status, and damage by foliar pathogens and herbivores. The apparatus was robust to frequent disassembly, transport and reassembly. The on-site time and labour of quadrat-based field surveys can be greatly reduced with this device. For some applications, images may replace on-site (manual) data collection from quadrats. For other applications, the images may complement on-site data collection, as a digital back-up and source of additional data (e.g. high-resolution spatial mapping of plant species or traits, or types of ground cover). The Robotany is modular and can be adapted to different research needs, including replacement of the camera with a different type of sampler.