Since hydrogen is light I think for the most part these hydrogen burns are going to be high in the sky and burn harmlessly. With about as much effect minus radiation as this nuke exploding high in the sky did.
However occasionally the burns would be close to the ground because of the weather phenomenon of inversion layers. Almost all areas of the world get inversion layers but the inversion layers are of differing strength and frequency. Some inversions just last a few hours in the morning at certain times of the year, some inversions last for days weeks or months. For example here on earth every decade or so we are treated to a scene like this at The Grand Canyon.
In the north west part of Utah roughly in the old lake bed of Bonneville Lake, most winters a large and persistent inversion layer develops, that might last from December until sometime in march. Some years it does not develop for long some years it comes and locks in a low layer of cold air for months.
Frequency and size of the burns would vary depending on topography and weather. Weather always varies.
Taking the premise that natural disasters are basic to evolution I think you would find that the plant and animal life on this planet would be much more diverse then it is here on earth. Evolution is about survival of the fittest. All living things would have all the variables that we have here on earth to evolve plus the added variable of the hydrogen burns.
There are lots of plants that survive large disruptive events like explosions, avalanche, flood and fire. Some ecosystems depend on these events, especially in the case of wild fires, to thrive.
Consider Aspen trees.
Ecological Adaptations:
Quaking aspen occurs on a wide variety of sites. It grows on moist
uplands, dry mountainsides, high plateaus, mesas, avalanche chutes,
talus, parklands, gentle slopes near valley bottoms, alluvial
terraces, and along watercourses. It is most common at elevations
between 6,000 and 10,000 feet. Most of the reproduction of Aspen is by
root-sprouting, many trees in a grove being connected together by a
common root system in what are referred to as "clones." Because the
trees are in clones, they are genetically identical. This species is
not shade tolerant, and entire clones can be lost due to the
encroachment of spruce and fir into this type of ecosystem. Aspen
is dependent on fire, clear cutting, or other "clearing" disturbance
to keep stands open, free of conifers, and reproducing from
suckers.
Aspen trees would thrive and dominate an eco system that was blown away every few years or decades.
Consider the Yellowstone fires and the adaptation of the lodgepole pine tree.
The predominant tree in Yellowstone, the lodgepole pine, fared poorly
from the fires, except in areas where the heat and flames were very
mild. The lodgepole pine is serotinous and often produces pine cones
that remain closed and will not disperse seeds unless subjected to
fire.
The Mysterious Tunguska Explosion, 1908, huge event that was a giant explosion that leveled 80 million trees. Described as a giant fireball in the sky.
Look at this picture and you will see the plant life that will dominate, the decedents of the large tree on the right of the picture may inherit what ever traits helped this tree remain standing. There are bushes in the picture that appear to have survived the event unscathed. You can imagine that there are grasses and smaller plants that also survived but not really visible in the picture. There is an ecosystem here and the plants that survived will pass on the traits in there genetic that helped them survive. If you repeat the event every few decades or so a whole diverse eco system will develop that needs the explosion like the lodgepole pine, or thrives on the devastation of the explosion like the quaking aspen. Species that were stifled by the shade of the larger trees will also thrive in the new ecosystem.
