A judge has ordered a group of tree-sitting protesters occupying a University of California oak grove to relinquish their perches or trade them for a jail cell.

The university plans to post notices on Tuesday warning protesters of the court order and its consequences.

On Monday, Superior Court Judge Richard Keller said the university has the right to protest its property and granted the school's request to evict the protesters, who object to the school's plan to remove some of the oaks to make way for an athletic center.

The university had argued the tree sitters posed a safety and health hazard with their makeshift community above Memorial Stadium.

"There are limitations to free speech, and one of them is time, place and circumstance," Alameda County Superior Court Judge Richard Keller said. "It's not an absolute right."

Those caught "lodging in, scaling, climbing or hanging or sitting or standing" in tree-houses, hammocks or platforms in the stand of trees could be fined $1,000 and sentenced to up to five days in jail, according to the judge's order.

Several tree-sitters said they would not comply.

"They're saying we're endangering the trees when they're planning to chop them down," said Zachary Running Wolf, a former Berkeley mayoral candidate who's been on the forefront of the 9-month-old protest. "It's a big joke."

Several lawsuits are seeking to block the athletic center project. On Tuesday, a different Superior Court judge is scheduled to continue hearing testimony. One suit was initiated by the city of Berkeley, which says the proposed sports complex would not be safe because the stadium sits atop an active earthquake fault.