Parks Canada offering free annual passes to the country's national parks.

Parks Canada is preparing for more visitors this year as people request free annual passes to explore the nation's natural treasures as part of Canada's 150th anniversary celebration.

Conservationists say it's important for people to connect with nature, but there are concerns about how more tourists might affect the ecological integrity of some of the more popular parks.

Ben Gadd, author of "Handbook of the Canadian Rockies'', says he's worried about increased vehicle traffic killing more wildlife in mountain parks.

He's also concerned about crowded attractions, trash and people putting themselves and others in danger by feeding or getting too close to wildlife.

He hopes there are enough staff to properly maintain the parks and to explain and enforce the rules to visitors.

So far more than 900-thousand people have ordered a free pass since they became available last month.

Ed Jager, director of visitor experience for Parks Canada, says they know they're in for a busy year.

He says the number of maintenance crews have been increased to ensure facilities will be kept in top shape.

Parks Canada is also trying to take some heat off of more popular parks by promoting other, less-visited destinations.