The Blackhawks also parted with goalie Robin Lehner, who wound up with the Vegas Golden Knights.
"I think going into a period like this at the trade deadline, you have to try to manage your assets going forward," Bowman said. "When you have expiring assets and you talk around the League to teams and find out if there's interest in them, then you do your best to try and get the maximum return you can."
Selected by the Edmonton Oilers in the fourth round (No. 93) of the 2012 NHL Draft, Gustafsson has 116 points (28 goals, 88 assists) in 214 regular-season games and one assist in five Stanley Cup Playoff games.
Forbort has one assist in 13 games after the 27-year-old missed the first 43 games of the season with a back injury. He's in the final season of a two-year contract and can become an unrestricted free agent July 1.
Selected by the Kings with the No. 15 pick in the 2010 NHL Draft, Forbort has 53 points (six goals, 47 assists) in 268 games.
"He's a big, rangy defenseman," Treliving said. "He adds some weight. He adds some size (6-foot-4, 219 pounds). He adds some defending ability. He's very good on the penalty kill. So, we looked at that two ways, not only to address personnel that is out, but then when [Mark Giordano] comes back in, maybe there is a way to lessen his workload on both sides of special teams."
The Flames are without defensemen Mark Giordano, who won the Norris Trophy voted as the top defenseman in the NHL last season, and Travis Hamonic. Giordano has been out since Feb. 4 with a hamstring injury but is with the Flames on a five-game road trip that started with a 4-2 win against the Detroit Red Wings on Feb. 23. Calgary plays the Boston Bruins at TD Garden on Tuesday (7 p.m. ET; NESN, SNW, NHL.TV).
Hamonic has been out since Feb. 8 with an upper-body injury and is week to week.
"You come in here, you're either selling and trying to acquire assets, or you're trying to help your team," Treliving said. "Where we're at, right now, we wanted to see if we could push it. We wanted to go to the (dressing) room and say, 'Look, we're trying our best to help.'"
The Flames also traded defenseman Brandon Davidson to the San Jose Sharks for future considerations. The 28-year-old defenseman is without a point in seven NHL games this season.
Calgary (32-25-6) is tied with the Arizona Coyotes for the first wild card into the Stanley Cup Playoffs from the Western Conference and two points behind the Vancouver Canucks for third place in the Pacific Division.
"When you set your prices of what you're willing to pay, then you have to account for or put those towards your back end," Treliving said. "I didn't want to come out here after spending six or seven (draft) picks and maybe not improving your team. Adding people, but maybe not improving your team.
"You can always look outside, or you can say, 'OK, let's shore up, let's give ourselves some depth, let's put some confidence in the people you do have.' Our big bullets, in terms of draft picks, we saved in our holster.
"I'm excited. I'm excited that we addressed some areas of need, which was our blue line right now."
