The Douglas Tigers topped Carson in four games Thursday night to secure a spot in next week's Division I volleyball playoffs. After Douglas won the first two games, 25-20 and 25-19, Carson mounted a rally to win the third game, 25-19.The Tigers, now likely the third seed in the Sierra League behind Bishop Manogue and Galena, turned it around with a 25-18 win in the fourth game to grab the victory.The Tigers, 7-9 in league, built a 17-7 lead in the opening game on the strength of strong play at the net by Jenna Broussard and Katie McCollough. Carson fought …