Colorado’s wildfire-stricken forests showing limited recovery


 Colorado’s wildfire-stricken forests showing limited recovery

 
30 January 2017

published byhttp://www.colorado.edu


USA —   Colorado forests stricken by wildfire are not regenerating as well as expected and may partially transform into grasslands and shrublands in coming decades, according to a new University of Colorado Boulder study.

The paper, published in the journal Ecosphere by former doctoral student Monica Rother and geography professor Thomas Veblen, examined the sites of six low-elevation ponderosa pine forest fires which collectively burned 162,000 acres along the Colorado Front Range between 1996 and 2003. Eight to 15 years after the fires, the researchers expected – based on historical patterns – to see young trees cropping up across the landscape. Instead, 59 percent of plots surveyed showed no conifer seedlings at all and 83 percent showed a very low density of seedlings. Although it is possible that more seedlings will appear in upcoming years, future warming and associated drought may hinder significant further recovery.

“It is alarming, but we were not surprised by the results given what you see when you hike through these areas,” said Rother, who earned her doctorate from CU Boulder in 2015 and works as a fire ecologist at Tall Timbers Research Station in Tallahassee, Florida.

Among the most barren sites were those of the 2000 Walker Ranch fire in Boulder County and the 2000 Bobcat Gulch fire in Larimer County, where approximately 80 percent of plots surveyed contained no new young trees.

While more severe fires may be partly to blame, the study suggests that increasing Colorado temperatures, too, are hampering forests’ ability to regenerate after a fire and moving the treeline of ponderosa pine forests upward, as a result.

“This should be a wake-up call, that under the warming trends associated with human-caused climate change, significant shifts in forest extent and vegetation types are already occurring,” said Veblen. “We are seeing the initiation of a retreat of forests to higher elevations.”

In addition to the Walker Ranch and Bobcat Gulch fires, the researchers assessed the Buffalo Creek fire of 1996; the Hayman fire of 2002; the High Meadows fire of 2000; and the Overland fire of 2003. They collected data from 2-by-50-meter plots at various elevations and fire severities, sampling a total of 302 plots.

Only 2 to 38 percent of plots surveyed, depending on the fire site, were considered “stocked,” or on their way to recovery.

The Hayman fire area, the largest fire in Colorado history, fared the best, with 40 percent of sites showing abundant regeneration. This could be due to its exposure to more summer monsoonal rains.

Previous research has suggested that hotter, more severe fires make it harder for the forest to bounce back by killing mature trees and reducing seed stock. But the study found that even after lower-intensity fires, presumed to have had less effect on mature trees and seed stock, seedlings were still scarce. Hotter, drier areas at lower elevations or on south-facing slopes had the fewest seedlings.

“Fire severity is definitely relevant, but climate appeared to play the greatest role,” in limiting forest recovery, said Rother.

For a companion study, published in 2015, the authors planted ponderosa pine and Douglas fir seedlings at Heil Valley Ranch in Boulder County, placing half of them under warming chambers to raise the temperature by 2.7 degrees F. The warmer temperatures alone severely limited seedling survival and growth.

Statewide annual average temperatures have risen about 2 degrees F in 30 years and are expected to rise another 2.5 to 6.5 by 2050.

Veblen notes that similar studies in the Western states have also shown a lack of forest resilience post-fire.

Helping fire management, a transition from forest to grassland could be desirable in certain highly populated environments, he said. But such shifts could also have negative implications for some species of wildlife and for watershed management.

“I don’t want to present this as being entirely negative,” said Veblen. “For me, the negative aspect is what it indicates about the future.”

For now, the authors hope their research can help forest managers determine where to plant seedlings after a fire to give them the best chance of survival. The study was funded by the National Science Foundation and Boulder County Open Space.

El capitán del primer batallón de la Unidad Militar de Emergencias (UME), Emilio Arias, ha descrito como “dantescos” los efectos del incendio forestal en el paraje natural de la Sierra de Gata (Cáceres), aunque ha sido optimista en cuanto a su extinción al darse una situación “bastante favorable” en estos momentos. Fotogalería ALCALDE 11 Fotos La Sierra de Gata, tras el incendio “El incendio se dio por estabilizado y ahora mismo sólo hay pequeños focos que se reactivan por lo que la situación es bastante adecuada para intentar extinguir el fuego”, ha explicado Arias en una entrevista en COPE. Arias ha descrito como “dantesco” el efecto del fuego en una zona “donde el terreno era precioso”. El mando único del Plan Director del Infoex decidía este lunes mantener activo el Nivel 2 de peligrosidad en el incendio de Sierra de Gata ante las previsiones de viento y altas temperaturas. Las mismas predicciones indican que habrá una mejoría a partir de las primeras horas de la noche del lunes, según ha informado la Junta de Extremadura. Más de 200 efectivos se mantienen en la zona. Intentar llegar a la normalidad es “un tanto difícil”, y que ahora hay que hacer valoraciones de los daños El incendio declarado el pasado jueves ha arrasado unas 7.500 hectáreas de alto valor agrícola, ambiental y paisajístico, de ahí que el Gobierno regional haya iniciado ya la evaluación de los daños y comenzado a preparar la recuperación de la zona. El director general de Medio Ambiente, Pedro Muñoz, ha afirmado que el incendio ha causado un “desastre” desde el punto de vista medioambiental ya que ha arrasado miles de hectáreas de pinar, olivar y pastos, además de haber producido cuantiosos daños materiales en algunas poblaciones. La asociación conservacionista SEO/Birdlife ha denunciado que el incendio afectó gravemente a especies amenazadas y a espacios protegidos de la Red Natura 2000, incluidos robledales, madroñales y castañares centenarios. Todo el área afectada es una zona ornitólogica de interés mundial. Por su parte, el alcalde de la localidad cacereña de Hoyos, Óscar Antúnez, ha alabado la participación ciudadana en el municipio para ayudar a los operarios del plan Infoex como “lo bonito dentro de la tragedia” y ha añadido que el “sentir general” de los ciudadanos de Sierra de Gata es de “frustración e indignación” tras el incendio forestal. El alcalde ha señalado que ha podido hablar con los vecinos de la localidad y que los “más afectados” son los que han perdido fincas o casas de campo, sobre todo una familia que ha perdido su domicilio de vacaciones habitual, que era una casa “recién reformada”. Asimismo, Óscar Antúnez ha indicado que intentar llegar a la normalidad es “un tanto difícil”, y que ahora hay que hacer valoraciones de los daños, tanto la Mancomunidad de Municipios de Sierra de Gata como la Junta de Extremadura, para ver qué ayudas se pueden proporcionar y de qué modo, además de cuáles serán los medios disponibles. Por último, el primer edil de Hoyos ha explicado que los vecinos, “más allá de la lamentación”, deben intentar hacer “una vida normal”, aunque ha considerado que es muy difícil “dado el paisaje que tenemos”, ya que casi el 90% del término municipal está calcinado, ha indicado.

Ver más en:http://www.20minutos.es/noticia/2532392/0/fuego/gata/dantesco/#xtor=AD-15&xts=467263


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