Shade-tolerant species reestablished themselves in the understory. Stands harboring complements of both early and late successional species represented islands of high biological diversity. Fire suppression, on the other hand, increases uniformity in habitats as competition eliminates early successional species, leaving only shade-tolerant understory plants to reproduce. Burned landscapes included habitat types dominated by early successional pines, shrubs, or herbaceous species, whereas unburned landscapes were more uniform in their cover of later successional fir-dominated communities. 1948 Fire suppression has helped change the ecosystem dynamics of communities adapted to frequent, low-intensity wildfire.
Trees killed by drought, insects, or pathogens create abundant fuel that exacerbates fire hazard.
When fire occurs in such a system, it is often larger and more severe than one expected in areas with a natural fire regime. Forest composition differences between 1941 and 1991 in the Blue Mountains of Oregon and Washington. Paradoxically, while fires help maintain native biological diversity, they also create opportunities for invasive alien species to become established. Thus, restoring a more natural fire regime will have to be carefully considered to maximize ecosystem benefits while minimizing biological and social costs. Hypothetical stand development sequence.