NEON Prototype Digital Hemispheric Photos of plot vegetation, multiple domains, collected 2013-2015

Digital Hemispheric Photos (DHPs) of plot vegetation were collected once for a subset of sites from twenty randomly selected Distributed Plots (eventIDs containing '00'); collection from these plots was timed such that DHPs were acquired within a one month window that also included a NEON AOP remote-sensing flight over the site. DHPs were also collected from n=3 Tower Plots, typically on a 2 week interval, from leaf-out to senescence. Within each plot, photo points are arranged according to the shape of a square cross, oriented in alignment with the cardinal axes, and with points spaced every 4 meters. At each photo point within the plot, photos of understory vegetation were acquired, with 'understory' defined as vegetation typically less than 2 meters height. In grasslands and scrublands, the understory was therefore the only vegetation photographed. When an overstory was present, i.e. vegetation greater than 2 m height, photographs of overstory were also acquired at each photo point. Overstory images were typically collected in the crepuscular hours of the day, when direct sunlight was not illuminating the foliage. Overstory images were sometimes collected under overcast conditions, such that the sun does not cast a shadow. Understory images were typically collected during daylight hours.