What are the top issues confronting the National Park System? A slew of answers could be tacked onto that question, ranging from sprawl outside park boundaries and habitat fragmentation to pollution.

The other day someone pointed out a list on National Geographic's website, and while it's certainly a good list of candidates, there's no apparent date to which you can attach the list. The fact that the story mentions "392" units of the system somewhat dates the list, as there currently are 394. Still, the authors came up with a nice Top 10:

* "Untold Stories" stemming from the vast archival resources of the National Park Service that are collecting mothballs somewhere due to a lack of space to display them and curatorial staff to catalog them and tell their stories.

* "Crumbling infrastructure." This is in reference to the Park Service's estimated $9.5 billion backlog of maintenance. Still, the infusion of more than $750 million through the American Recovery and Reinvestment Act has made some inroads into this backlog.

* "Wildlife Management." This is certainly a key issue in light of fragmenting habitats and human pressures through development that are impacting wildlife from Everglades to Denali.

* "Foreign invaders." Exotic species -- plants, animals, insects, fish -- all are creating problems in various corners of the park system.

* "Adjacent development." See "wildlife management" above.

* "Climate change." Impacts of an altering climate already are being noticed in the parks, from the melting glaciers in Glacier National Park to bug infestations in Rocky Mountain, Grand Teton, Yellowstone, and other western parks made possible by warmer weather.

* "Water issues." There perhaps is no better example of what happens when natural water flows are replumbed by humans than the struggling "river of grass" in Everglades National Park.

* "Air pollution." The National Geographic article mentions Great Smoky Mountains National Park, but you could easily add Acadia, Sequoia, Grand Canyon, and Mesa Verde to the list of parks impacted by air pollution, whether it arrives in the form of high ground-level ozone levels, particulates, or acid rain.

* "Transportation Troubles." The article links this to poor roads in the parks but much progress has been made, and is continuing, in parks such as Yellowstone, Sequoia, and Great Smoky.

* "Visitor Experience." This entry hinges on how people enjoy the parks. Debate continues to swirl over how appropriate different uses -- snowmobiles, ORVs, overflights, mountain bikes -- are in the parks, and yet these forms of recreation are popular with many visitors.

There certainly are other strong candidates that could be added to this list. For instance...

* Diversity in the Parks. If overall visitation is weighted towards any one demographic, such as Baby Boomers, who will advocate for the parks when the Baby Boomers fade away? Strides are being made in this area as evidenced, for instance, in efforts being made by Yosemite National Park staff to interest more visitors of Hispanic descent in the park.

* Overall funding. This perhaps should be at the top of the list, for as long as Congress fails to adequately provide for the parks the maintenance backlog will continue to grow, stories will go untold, species will suffer, natural, cultural and historic resources will be impacted, and visitor services will decline.

* Under-staffing. It can be argued that there are not enough full-time, professionally trained staff in the parks, whether they be interpreters, law enforcement rangers, or curatorial staff. Volunteers are great, but they should complement, not supplement, full-time staff.

* Employee recruitment. Surveys have shown that NPS staffing, overall, is tilted toward white males. If visitor diversity efforts are to succeed, it would seem that diversity in staffing is important, too.

* Political interference. Under this you could list politicians who try to legislate management of the parks and require the Park Service to spend incredible amounts of time and dollars studying prospective park units that on first blush probably don't deserve to be added to the system.

* Illegal immigrants. Whether the source is drug runners or illegal aliens traveling through Southwestern parks such as Organ Pipe Cactus National Monument or Saguaro National Park or Mexican drug cartels setting up marijuana groves in Sequoia, Yosemite and even North Cascades National Park, these are serious problems that are threatening park visitors and staff and impacting park resources.

Any other threats you would place on this list?