 What do human eyes have in common with a handheld camera or a camera mounted on a satellite in space? Well, human eyes and cameras can both capture the timing of when plants grow buds leaf out flower fruit and die back The science known as plant phenology But why do we need fancy cameras to study phenology if we can see it with our own eyes? Let's first talk about why we study phenology You see scientists have used their eyes to record when plants bud leaf out flower and fruit for centuries These annual plant life cycle events known as phenophases are often triggered by seasonal changes in rainfall temperature and day length Their timing is important to study because it's impacted by changes in climate and Impacts on phenophase timing by climate can impact humans plants than animals, too For example, scientists have observed that some plants are leafing out earlier in recent years This means that fruit trees and crops that we depend upon for food might bud and flower earlier in the season Leaving them at risk for damage during spring frosts Birds that depend upon those flowers and fruits are also impacted when they can't find those mid-migration snacks that they flew so far to eat The importance of phenology is why neon scientists and citizen scientists involved with project bud burst and nature's notebook Recording phenophase dates at locations across the country with lots of data collected by lots of people We can track changes in timing of specific phenophases for a plant each year However, our eyes can only observe so many plants How do we track the timing of phenophase events across a state a country or even the globe? To measure more plants over larger areas We need to view the forest above the trees at a different scale Imagine what our human eyes would see standing in a tree house looking across the top of a forest From this view we can see lots of trees, but maybe not each individual bud and leaf on a tree We can capture that tree house view using cameras designed for tracking phenology called phenocams phenocams are placed in fixed locations in our program to take pictures of specific areas every day This spares us humans from having to man the tree house day and night recording what we see Projects like neon and the phenocam network have these cameras set up at locations across the United States Pheno cams record whether a plant is green or brown just like our eyes do But a camera can take a picture of a whole lot of plants at one time This allows us to estimate phenophase events across huge areas including entire sections of forest and grasslands A camera records the amount of green or brown being reflected from those plants too Something our eyes can see but not assign a numeric value to So as plants turn green in the spring the amount of brightness of green in the image increases And when the plant turns brown in the fall the camera will record that too If we plot the amounts of green on every graph, we can tell when the trees began to turn green and when they are the most green We can also tell when they begin to turn brown and when they lose their leaves or die back for the winter Over time we can compare the dates of plants turning green in the spring And dying back and losing their leaves in the fall to see if the dates change significantly from year to year But what if we want to measure phenology across an entire state or country? Well, imagine what you'd see if you were sitting on a satellite looking down on the earth from space From space, we can't see individual buds or leaves or even individual trees However, we can measure the greenness and brownness of groups of plants Rather than send lots of humans to space to record this We use high powered scientific cameras mounted on satellites orbiting the earth Like many phenocams satellite cameras like landsat and modus can be used to measure greenness and brownness too And because they are further away from the earth they can take images of larger areas on the ground Recording the greening and browning of plants across entire states and countries across the world To sum this all up Phenology is the study of the timing of life cycle events like the opening of leaves or flowers on a plant The timing of plant phenophases helps us understand how changes in climate like temperature and precipitation Impact plants animals and as humans too We can measure the timing for individual plants and phenophases with our eyes and a notepad But we need cameras mounted on platforms above the force and satellites in space to estimate this timing across larger areas And that is how and why we measure phenology over large areas