This process is called photosynthesis.
The interesting thing that they mentioned was that at very low temperaturesthe rate of photosynthesis is so low that the relative level of light istherefore high (not being absorbed) in the cells and this excess light candamage the photosynthetic apparatus. This effect is known as"photoinhibition". They write that "Even if the temperature stays above thelimit of frost tolerance, the thylakoids may be damaged when cells in thefrozen state are exposed to high light. In conifer needles, suchphotoinhibition appears to be a major factor of winter damage but usually canbe repaired in the growing season."
Photosynthesis - an overview | ScienceDirect Topics
In the arctic tundra, snow cover persists into the spring after air temperatures and light increase to levels suitable for photosynthesis of vascular plants in the absence of snow cover.
Many people have alluded to the idea that evergreens continue tophotosynthesize in the winter. It would seem to many that this would be sosince the evergreens hold on to their leaves through the winter. The rate ofphotosynthesis is temperature dependent and I have always assumed that atvery low temperatures this rate would be so low as to be undetectable andbasically at an apparent standstill. However, in the book "Plants andTemperature" the authors discussed some research on the effects of lowtemperatures on the various photosynthetic activities, and on thephotosynthetic apparatus itself. It appears that at very low temperaturesphotosynthesis is still plodding along at a rate that can be measured.
Photosynthesis of Overwintering Evergreen Plants | …
Conditions in tropical rainforests are favorable in two respects: neither temperature nor moisture limits growth. In places where the growing season is not interrupted by cold winters, even angiosperms can photosynthesize all year round—and they don’t need tough needles and scales to do it. Neither do they need to conserve water, so leaf forms that limit surface area and evapotranspiration are not needed.
How do evergreen trees keep their greenness throughout …
This activity was facilitated by favorable conditions in the subnivean environment, where CO 2 concentrations are elevated, temperatures are often above freezing, and light levels are sufficient to drive photosynthesis.