There are various studies in the US and other countries. I am most familiar with this one, and have visited the plots. https://www.fs.usda.gov/treesearch/pubs/737M. There may be other publications on this study, and this study addressed effects of burn frequency including annual burns in the SC coastal plain, long leaf and loblolly pine forest.

I would like to add the condition of the forest floor, vegetation, grasses and forbs fuels (dormant/growing) moisture) as well as weather affects the intensity and severity of the prescribed burning. Also how the forest floor is lighted, such as strips, aerial ping balls with fire accelerant, or just as one or multiple points can produce different effects. Consultation with trained prescribed burn specialists could help you achieve results with lowered effects. Smoke is another issue, especially in the urban interface to manage.

There could be many negative impact due to regular fire.

Like, Poor to very poor regeneration of vegetations in the forest plot.

Kind regards

Changes induced by fire may include alterations to soil properties (N, C, organic matter, pH, etc.), community shifts toward exotic and/or fire resistant and resilient species, tree regeneration failure, and in the most extreme cases an indefinite shift from forest cover to shrub or grassland. Certain forests are adapted to frequent fire, those of the southwestern United States for example. Trees like ponderosa pine, lodgepole pine, and western larch possess fire-adapted traits such as thick bark and serotinous cones. Still, even for high fire frequency adapted forests a one-year fire return interval over many years would be very stressful, unless the fire was very low intensity. Yearly high intensity fires would likely favor understory species that rely on fire to reproduce and preclude certain trees species. Such a fire regime might move an ecosystem away from forest cover toward grassland.

Thanks Matthew Joseph Ruggirello

Thanks to all

If forest fire occurs every year in a particular forest areas the negative impacts which can be observed are 1) degradation of the vegetation, 2) destruction of microflora and microfauna, 3) lost of biodiversity, 4) lost of the land nutriments, 5) lost of cultivation land, 6) reduction of the cereals production yields, or 7) réduction of grass yields or biomass.

Dear Sanjeet Kumar

Another study about shorter interval wildfire impacts on boreal forests:

https://www.nature.com/articles/s41598-019-55036-7

Dorian