Synthesis: disturbance, management, and policy Tenets of disturbance patch dynamics Principles for applying disturbance in management and policy Case study: wildfire policy in rapidly changing North American forests Summary of how wildfires and the thinking of the US Forest Service has changed: Fire size and fire season are unprecedented. Most experienced, big-fire team leaders saying every year ‘I’ve never seen that before,’” There are longer summers, drier landscapes and more beetle-killed tree stands. The Forest Service is challenged to get to its year-round land-management duties of forest thinning and controlled burns met when the agency’s budget has been drained by firefighting costs. The tension among letter fires burn or putting them out to protect property necessitates more nuanced assessment of what risks are worth taking, whose interests are at stake, and what actions are even possible in terms of budget and manpower. In addition, the information about what areas to protect from fire is not always available or up to date. If everything is wildland-urban interface on a map, suppression decisions can’t be strategically made without more input from the community, the county commissioners, and the sheriff regarding what should be protected and what can be let go. There should not be unnecessary exposure (of firefighters) that won’t get the results best for the property owners as well as the forest. Then, putting out fires when conditions are prime for wildfire, i.e., fire suppression, may be less costly than letting them burn and potentially destroying property. Plans can be made about how we want the landscape to look before a fire season, and they can all be for naught once the fire season starts and the wildfires begin. If it is very hot, dry and windy conditions, we can’t risk direct action and expose our fire fighters.

Tenets of disturbance patch dynamics Disturbance is common in nature and may even be necessary for some species to flourish Fire scars in longleaf pine growth rings indicating regular, natural fire interval. It is a fire-dependent species. In the absence of fire, this species declines in abundance. There are many fire-dependent pine species across North American forests.

Adaptations to fire in longleaf pine Cone serotiny Grassy stage Fire-resistant morphology (left) and punctuated growth in longleaf pine (right): adaptations to frequent surface fire Remains 10 years in grass stage at left before shooting above flame front. Stores photosynthate in root for burst of growth. In fire-resistant morphology, growth tissue protected by needles. Rapid growth over 3-4 years extends growth tissue above fire front Cone serotiny: seeds will not be released from cone until heated above a threshold temperature Punctuated growth

Sandhills with natural fire regime

Fire-suppressed longleaf pine habitat results in replacement of longleaf pine by oaks. Increased stem density of hardwoods that have invaded in the absence of frequent surface fires.

Tenets of disturbance patch dynamics Disturbance and diversity are intertwined.

Intermediate Disturbance Hypothesis Connell, J. H. 1978. Diversity in tropical rain forests and coral reefs. Science

Tenets of disturbance patch dynamics Aspen trees amid pine in Rocky Mountain National Park, Colorado Fire in southern California in chaparral vegetation (right) Removal of natural disturbances can have a negative impacts in natural and in coupled human-natural systems. Disturbance in this sense becomes the absence of the historic disturbance regime.

For decades, forest managers have called attention to "aspen decline," a long-term reduction in area of aspen forests. It turns out it is related to the lack of disturbance.

Lodgepole pine replace aspen in the absence of intense stand-clearing fire With intense fire, aspen will sprout from root stock and increase in abundance. No fire is a disturbance for aspen and it will decline when fire’s are suppressed Alternative arguments: heavy browsing by large ungulates may be responsible for decline, which prevents the regeneration of aspen.  Other researchers say that the decline today is an artifact of past land use. Aspen increased in abundance due to widespread disturbance caused by timber harvesting and fires in the late 1800s and early 1900s – this is what may have enabled aspen to become abundant in the Rocky Mountains. Then, natural processes of succession should result in a reduction of aspen as that cohort matures and dies.

A dam has changed the flow regime of the Apalachicola River A dam has changed the flow regime of the Apalachicola River. The floodplain no longer floods as regularly due to alteration of the river channel induced by the dam. Drought in the southeastern US has also limited the amount of water that enters the river.

Tenets of disturbance patch dynamics 4. The extent to which a disturbance has been historically prevalent for an area determines species responses, abundance, and evolution. Volcanic eruptions Natural fire regime

Seasonal inundation in the Pantanal The Pantanal, the lowland region of SW Mato Grosso state, Brazil, bordering the Paraguay River and extending to the western edge of the Brazilian Plateau. Parts of the pantanal extend into Bolivia and Paraguay. It is the world's largest wetland area, c.77,000 sq mi (200,000 sq km). It is subject to annual flooding, it is not a marshland; the water is not stagnant but flowing across a very wide area. The pantanal completely dries out at the end of the six-month rainy season. Seasonal inundation in the Pantanal

Lava flow, Hawaii

Tenets of disturbance patch dynamics Natural disturbance is not necessarily a disaster Yellowstone Fires of 1988

Tenets of disturbance patch dynamics Resource extraction practices began to mimic natural disturbances. Selective logging and limiting the size of clear cuts are an attempt to mimic natural disturbances

Selective logging

Insert image of “classic” Yellowstone Because disturbance is common, unrealistic to manage land with the intent of keeping it the same. It is not possible to preserve wilderness if by definition it must change.

Tenets of disturbance patch dynamics Disturbance can act in synergism with each other

Coupled fire-geomorphic disturbance in chaparral Chaparral vegetation is fire-adapted Fuels accumulate and result in fire Some water-repellant oils translocate to subsurface of soil This layer acts like wax-paper; water will not infiltrate soil Runoff and erosion increases in a positive feedback Mudflows more extensive in El Nino years that follow an active wildfire season.

Anthropogenic climate change: background disturbance Anthropogenic warming contributing to drought and wildfire in west Not just fuel-build up from fire suppression policies Last decade warmest on record and corresponds to larger area of forest burned Describe the evidence for and impacts of anthropogenic climate change on wildfire in US western forests Describe the evidence for and impacts of anthropogenic climate change on wildfire in US western forests

Sudden aspect decline syndrome In addition to altered fire regime: Drought in western US (approximately half is attributed to human climate change versus natural fluctuation in temperatures and rainfall) Aspen is a clonal organism, and with drought stress, many individual trees become weakened at once More susceptible to pests: bronze poplar borer, aspen bark beetles

Megadisturbance Co-occurrence of multiple disturbance events If threshold of severity or frequency crossed, transition to new vegetation states Integration of many disturbance factors that result in catastrophic disturbance, one that shifts forests to new state

Describe how boreal forests of the north are changing

Case study: current wildfire policy in rapidly changing North American forests Describe the evidence for and impacts of anthropogenic climate change on wildfire in US western forests Describe how boreal forests of the north are changing Describe the reasons why forest management policy needs reform and what these new recommendations are Explain why we need to view wildfire governance as a socio-ecological problem and state some of the goals and characteristics of this view