Sunflecks are brief increases in solar irradiance that occur in understories of an ecosystem when sunlight is able to directly reach the ground.
Although each sunfleck only last for seconds or minutes at a time, they can be responsible more than 80% of the photons that reach plants in the understory, and up to 35% of carbon fixation.
The amount of energy that a sunfleck provides depends on their duration, size and shape and the intensity of photosynthetically active radiation (PAR), which itself depends on the arrangement of vegetation in the canopy and the position of the sun in the sky.
[1] The abundance of sunflecks varies greatly both within and between ecosystems, generally the frequency and intensity of sunflecks decreases as tree {i.e., plant or canopy} height and the leaf area index increase.
[1] There is no clear distinction between sunflecks and sunpatches, although the latter tend to last for at least an hour and the intensity of PAR reaches the full level of sunlight, whereas the intensity of PAR in sunflecks rarely reaches this.