BEIJING (AP) - Springtime in Beijing usually brings out bustling crowds for rock concerts, food festivals and other outdoor revelry amid the smog and catkins. But this year, police in the Chinese capital have been canceling everything from an Earth Day event to a heavy metal concert, stoking worries that the authorities are cracking down on any large gathering deemed politically risky.

The cancellations have hit the city's music scene, with annual summer mainstays such as the Strawberry Music Festival going dark. Police also recently shut down the Gaymazing Poker Race, a mix of pub crawl and poker tournament that was set to raise funds last week for the Beijing LGBT Center, a gay and lesbian service and cultural group. The race's co-sponsor, the Great Leap Brewing pub, responded by pre-emptively canceling its own massive June craft beer festival for fear of a last-minute police shutdown.

Lucia Wang, of Great Leap, said city authorities cited concerns about excessive crowds, while John Shen, a program manager at the LGBT center, said he was given no explanation at all. Beijing police did not respond to a faxed request for an interview Thursday.

"This year it seems impossible to do large events like this," Wang said. "We have a high chance of being canceled in the last minute."

As for the reasons behind the cancellations, Wang said, "That's the question for all big event organizers now."

The cancellations in Beijing hit as the government tightens its grip nationwide on independent civic groups and activity, with non-governmental organizations and university professors saying they've been working under tighter scrutiny. Chinese officials also have been promising tighter crowd controls after a New Year's Eve stampede killed 36 people along Shanghai's famed Bund riverfront due to inadequate policing.

Archie Hamilton, who promotes music festivals and other events in China, said he believes the clampdown in Beijing reflects the overall political atmosphere, with Communist Party authorities trying to rein in what they see as a society too accepting of liberal and Western influences. He said a March 14 show by the Japanese rock band Boris was canceled with two days' warning, after the musicians had already arrived in Beijing.

Several events also have been scraped in central Beijing and in Chaoyang Park, and a music-filled show organized for this weekend by the U.S. Embassy and China's Ministry Culture was first canceled and then moved to a district in the city's east.

"My pocket view is that as far as the powers that be are concerned, society is a little out of control, with too much expression and frivolity and general chaos," Hamilton said. "And I feel that (President) Xi Jinping and the new administration have come in and gone, 'We need to focus on this a lot. We need to get this right and make sure this doesn't get too out of control.'"

Shi Shusi, an independent Beijing-based commentator, said the clampdown reflects the party's insecurities amid a slowing economy and an anti-corruption drive that has caught tens of thousands of officials.

"This instability all affects how the politicians view people outside the party's control," Shi said. "Whether it's music or other activities, in China, everything is political."

After the Shanghai stampede, Chinese officials scaled down some popular events during February's Spring Festival but are now targeting gatherings that would not appear to present a safety risk.

The craft beer event would have drawn an estimated 5,000 people to a downtown commercial center, Wang said. The Earth Day event plus a heavy metal music festival scheduled for May 28 would have drawn at least several hundred people.

Other large events have been allowed to continue, such as an April 18 boxing match and barbecue that drew hundreds to the city's artsy Shuangjing neighborhood as well as a concert by the U.S. pop group the Backstreet Boys that same night.

For the Earth Day event, police stepped in only after hundreds of environmental and other groups signed on to help run the festival, which would have included an environmental issues presentation, live music and question-and-answer session, said Eva Mei, a marketing specialist with co-organizer Gung Ho! Pizza.

"The event had been getting more visibility," Mei said.

For Hamilton and other promoters, the crackdown means a spring and summer drained of Beijing's usual sweaty fun.

"This put the fear into all of us," he said. "Everyone's afraid of getting it wrong and losing a lot of money. ... It's that harmless stuff, of people getting together and sharing and being creative, which is what China is about, but it's not really happening."