<\/p>\n
From 2000 to 2003, a series of wildfires ripped through Mesa Verde National Park, burning about 24,000-acres \u2013 nearly half of the park\u2019s old growth forest.<\/p>\n
Now, almost two decades later, park managers and biologists are concerned that the pi\u00f1on-juniper woodland is showing virtually no signs of growing back, posing the tough question: Will Mesa Verde\u2019s iconic forests ever be the same?<\/p>\n
\u201cWe\u2019re very concerned about the park\u2019s woodlands,\u201d said George San Miguel, Mesa Verde\u2019s natural resource manager. \u201cBecause if we lose the park\u2019s forests entirely, or if we have only scattered remnants, it won\u2019t tell the same story.\u201d<\/p>\n
Mesa Verde is both a national park and World Heritage site, home to more than 4,300 archaeological sites of the ancestral Puebloan people, and most notably known for the 600 cliff dwellings within the park\u2019s 52,485-acre boundary.<\/p>\n
Settlement of the Mesa Verde region, which spans parts of Colorado, New Mexico and Utah, dates back to 9,500 B.C. But the height of Mesa Verde\u2019s civilization is considered to have occurred from about 900 to 1280 A.D., with an estimated 5,000 to 8,000 people living in the area \u2013 more than today\u2019s population.<\/p>\n
However, by 1285 A.D., the last inhabitants left Mesa Verde, probably because of a period of prolonged drought, for other locations in Arizona and New Mexico, where their descendants live today.<\/p>\n
Yet as researchers rediscovered Mesa Verde in the late 19th century, leading to a national park designation in 1906, it became abundantly clear the original inhabitants of the area used the pi\u00f1on-juniper woodland in ingenious ways.<\/p>\n
\u201cThe people that lived here learned to be part of the ecosystem, part of woodland,\u201d San Miguel said.<\/p>\n
Ancestral Puebloans not only harvested wood to endure harsh winters, build structures and make tools, they also relied heavily on the protein-rich pi\u00f1on nuts as a staple of their diet.<\/p>\n
\u201cThey had art, they built cities, they did really well here for a long time,\u201d San Miguel said. \u201cAnd that\u2019s the story we tell: what they did to survive and thrive.\u201d<\/p>\n
In the mid-to-late 1990s, the invasive Ips beetle found its way into Mesa Verde and wiped out the old-growth pi\u00f1on in its path, the oldest of which ranged from 500 to 1,000 years old.<\/p>\n
Then, a severe drought in the 1990s caused perfect fire conditions \u2013 dead, dry trees \u2013 so when a lightning strike hit private property near the entrance of Mesa Verde at about 1:30 p.m. July 20, 2000, it wasn\u2019t long before a fire spread, ultimately consuming 19,607 acres within the park.<\/p>\n
Though this fire, called the Bircher Fire, consumed the greatest amount of forest, several other fires in the ensuing years, notably the Pony and Long Mesa fires, also took their toll in the park. Both were also caused by lightning strikes.<\/p>\n
\u201cIf you fly over, there\u2019s fire scars everywhere,\u201d said Steve Underwood, park fire-management officer. \u201cYou\u2019re seeing these forests change, and it\u2019s very startling. And it\u2019s happened not just over the course of my lifetime, but my career.\u201d<\/p>\n
Pi\u00f1on and juniper woodlands thrive in high-elevation deserts, usually between 4,500 to 7,500 feet. And while the hardy plants can survive a mere 7 to 25 inches of rain a year, they are terribly ill equipped to deal with wildfire.<\/p>\n
\u201cThese trees evolved not to deal with fire,\u201d said Renee Rondeau, a conservation biologist with Colorado Natural Heritage Program. \u201cThey can go without fire and it would not affect them, which tells you the places they grow did not, historically, have a lot of fires.\u201d<\/p>\n
Yet with the introduction of Western civilization in the American Southwest, and the impacts associated with climate change, such as drier years and an increased risk of wildfire, the new reality is that pi\u00f1on-juniper woodlands may not be adapted for future survival.<\/p>\n
Even in perfect natural conditions, pi\u00f1on and junipers take a long, long time to grow.<\/p>\n
Pi\u00f1on, for instance, don\u2019t produce germinating seeds until they reach 75 years in age. And even then, the plants only produce seeds every seven to eight years, requiring non-drought conditions and proper dispersing by animals.<\/p>\n
According to National Park Service data, pi\u00f1on-juniper woodlands cover as much as 15 percent of land in Arizona, Colorado, Nevada, New Mexico and Utah.<\/p>\n
\u201cHow can something that\u2019s that picky be that common?\u201d Rondeau said. \u201cThat just tells you the climate has been fairly stable for quite a while.\u201d<\/p>\n
Yet now a multitude of factors seem to be inhibiting pi\u00f1on-juniper regeneration in the burned areas of Mesa Verde.<\/p>\n
Warmer and drier conditions, associated with the impacts of climate change, and therefore increased fire risk, seem to be directly affecting the woodland\u2019s regrowth, researchers said.<\/p>\n
And then enter issues with more competitive Gambel oak and invasive species, such as cheat grass, and the question surfaces whether the pi\u00f1on-junipers can ever gain a stronghold again.<\/p>\n
The issue is not specific to Mesa Verde.<\/p>\n
At Bandelier National Monument, another ancestral Puebloan site in New Mexico, a series of high-severity wildfires consumed the predominately ponderosa forests, which are now overtaken by a variety of shrubs.<\/p>\n
\u201cWe\u2019re researching that question right now: Why aren\u2019t we getting pine regeneration?\u201d said chief of resource management Jeremy Sweat. \u201cAnd we may have to redefine recovery, because we\u2019re not sure some of these forest types will ever return.\u201d<\/p>\n
Last year, the Los Alamos National Laboratory released a study that suggested pi\u00f1on-junipers could be wiped out of the American Southwest by the end of this century as a result of climate change.<\/p>\n
Rondeau said models of different scenarios of pi\u00f1on-juniper habitat in 2035 and 2065 found that while there may be some refuges for the woodland, suitable habitat will significantly diminish over time.<\/p>\n
\u201cIf we can get our carbon emissions down and \u2026 keep (these forests) from burning, maybe our grandkids will be able to have pi\u00f1on here,\u201d Rondeau said.<\/p>\n
\u201cOne of the most common questions we get is when and why was there a burn,\u201d Underwood said of Mesa Verde\u2019s visitors, which hit 583,527 last year. \u201cWe\u2019ve added signs around the park, delineating each fire.\u201d<\/p>\n
San Miguel said there are indications in the park that pi\u00f1on-junipers can grow back. A 200-acre area known as the Glades that burned around 1700 or so does have a patch of young pi\u00f1on-juniper trees, about 200 years old.<\/p>\n
\u201cThat\u2019s our reference,\u201d San Miguel said. \u201cThat\u2019s what happens with fire and natural regeneration under good conditions.\u201d<\/p>\n
But if global temperatures continue to rise at their current pace and increase 5 to 7 degrees by the end of this century as scientists predict, San Miguel said, and fires continue to plague the arid desert landscape, it may be time to rethink what Mesa Verde will look like.<\/p>\n
Carbon dating conducted a few years ago in the park of sediment deposits went back tens of thousands of years, finding that Mesa Verde at one time supported ponderosa and Douglas fir in wetter years, and was absent of pi\u00f1on-juniper in drier years.<\/p>\n
These are indications that Mesa Verde\u2019s forests have changed over time, San Miguel said. But human impacts are creating a complication of unknowns in the process.<\/p>\n
\u201cWhat we\u2019re heading for now is not necessarily unprecedented,\u201d San Miguel said, \u201cbut you throw in invasive plants and fires, and then you have a wild card that throws everything into question.\u201d<\/p>\n