▁R ivers ▁in ▁the ▁north ▁and ▁D ib ru ▁river ▁in ▁the ▁south . ▁It ▁mainly ▁consists ▁of ▁mo ist ▁mixed ▁semi - ever green ▁for ests , ▁mo ist ▁mixed ▁decid uous ▁for ests , ▁can eb rak es ▁and ▁grass lands . ▁It ▁is ▁the ▁largest ▁sal ix ▁sw amp ▁forest ▁in ▁north - e astern ▁India , ▁with ▁a ▁tropical ▁mon so on ▁climate ▁with ▁a ▁hot ▁and ▁wet ▁summer ▁and ▁cool ▁and ▁usually ▁dry ▁winter . ▁Ann ual ▁ra inf all ▁ranges ▁from ▁. ▁It ▁is ▁a ▁haven ▁for ▁many ▁end anger ed ▁species ▁and ▁rich ▁in ▁fish ▁divers ity . ▁ ▁Conserv ation ▁The ▁area ▁was ▁declared ▁as ▁D ib ru ▁Res erved ▁Forest ▁in ▁ 1 8 9 0 . ▁In ▁ 1 9 2 0 , ▁additional ▁area ▁was ▁added ▁to ▁the ▁D ib ru ▁Reserve ▁Forest . ▁In ▁ 1 9 2 9 , ▁Sa ik how a ▁Reserve ▁Forest ▁was ▁declared . ▁In ▁ 1 9 3 3 , ▁more ▁area ▁was ▁added ▁to ▁the ▁D ib ru ▁R F . ▁In ▁ 1 9 8 6 , ▁an ▁area ▁of ▁ 6 5 0   km 2 ▁was ▁pre lim in arily ▁declared ▁as ▁a ▁wild life ▁san ctu ary ▁out ▁of ▁which ▁finally ▁ 3 4 0   km 2 ▁was ▁declared ▁as ▁wild life ▁san ctu ary ▁in ▁ 1 9 9 5 . ▁In ▁ 1 9 9 7 , ▁D ib ru - Sa ik how a ▁B ios