Photosynthesis is one of the fundamental processes that plant undergoes in order to sustain life. It is a process that involves capturing CO2 from the atmosphere by green pigments or also known as chlorophyll. The CO2 captured is then converted to chemical energy by plants. Gross Primary Production (GPP) is the total production of chemical energy produced from photosynthesis. It is one of the methods that allow scientists to measure the CO2 that a system is taking in.
During winter, it is not only the animals like bears that hibernates but also the forest. During this time, forest conserves energy, thus, shutting down photosynthesis. The process is important in tracking carbon levels globally. Scientists have been using satellites in keeping track of the forest GPP. It was observed that during fall and winter that the leaves turn brown and drop while in spring and summer the leaves turn green which means chlorophyll is once again present. Given this observation, researchers have difficulties in detecting the GPP in the evergreen trees since they retain their chlorophyll.
A new study found out a way of addressing the said problem in monitoring GPP. When plants undergo photosynthesis, chlorophyll becomes excited in the exposure to sun. The chlorophyll will then return to its normal state and will emit photon, thus, producing a glow that is invisible to the naked eye. The glow produced is called a solar-induced fluorescence (SIF). The SIF which occurs during photosynthesis is traceable by certain satellites.
In their study, the researchers were able to monitor the daily and seasonal SIF pattern that matches the GPP magnitude. To keep track, they used a scanning spectrometer on a tower measuring the glow through the evergreen forest in Colorado, according to study published on Proceedings of the National Academny of Science.
Moreover, they found out that plants apply a certain protective pigments or sunscreen during winter. When the sunscreen was applied by plants, both photosynthesis and fluorescence activity decrease, which make scientists confident in the collection of SIF signals as a proxy in monitoring the CO2 uptake of the forest. The new development also serves as an alternative way in observing the response of the forest in climate change.
"We are trying to develop technique to be able to see photosynthesis at large scales, so we know just how much CO2 the biosphere is consuming keeping a finger on the pulse of the biosphere," explained Troy Magney, research scientist of the NASA Jet propulsion laboratory and the California Institute of Technology.
Based on the data collected between June 2017 and June 2018 from spectrometer system in sulbapne conifer forest at Nivot Ridge, Colorado, the team discovered that the pigments are the reason for the SIF seasonal cycles. The conifers produced high level of pigments that are part of xanthophyll cycle which shields plant tissues from excess light.
"You and I can get sunburned. Too much ultraviolet radiation will damage our cells. Some people can protect themselves because their skin produces more melanin pigment to adjust to high-light environment," explained David Bowling, biology professor at the University of Utah and co-author of the study.
"Ultimately, measuring the small fluorescence glow from plants will allow us to see exactly the timing and magnitude of carbon uptake from the terrestrial biosphere. This will help us understand how forests are responding to climate change and suggest how they might respond to future climate change," expressed Magney.
