Ok, lets start from the big picture and work our way down.
Loss of habitat. A forest is naturally a place with a variety of niches for species. When the forest burns, not all habitat may burn equally, but you many species will have their habitat damaged or destroyed.
Loss of food sources:
A change in abiotic conditions: those species who thrive in shade will be exposed to more sunlight. The temperature of the soil will change. The amount of soil runoff will change.
