They need moisture to grow into grass first and such moisture, if it comes in too big a deluge, may simply wash the seeds away. In dry weather, the seeds might not grow at all. Although rehabilitation teams usually attempt to use native seeds, the simple process of dumping loads of seed from the air can change the makeup of vegetation normally controlled by the terrain. If grasses take hold too quickly, Beyers said, they can hamper the regrowth of forests. The researchers recommended that rehabilitation teams include ecologists and other specialists who can help determine whether the roots of native vegetation survived a fire and are likely to restore the natural landscape on their own.
Most areas do return pretty well on their own.
A vital message emerging from the research is that regardless of how much money agencies spend on rehabilitation, there is no quick fix for hillsides stripped by fire, the scientists said. Most of the West has evolved with periodic fires, and just as time inevitably will bring such fires, as it did this summer, it also will mend the burns they leave behind. The problem is that it's hard to just sit by and let that happen. If you seed and a flood comes and someone's back yard fills with mud, it's an act of God. If you don't seed and a flood comes and someone's back yard fills with mud, it's the agency's fault.