the public utilities board-maintained central catchment nature reserve is singapore's largest biosphere reserve. the sungei buloh wetland reserve aids in the conservation of both bird species and mangrove plants. the bukit timah nature reserve, albeit small-sized at , hosts myriad plant and animal lifeforms. chek jawa is situated in eastern pulau ubin. teeming with various kinds of marine life, chek jawa was "discovered" (much publicised) in 2001. the labrador nature reserve is located by the sea. described as "an oasis of tranquility and natural wonders", it teems with vast animal life, as well as plant life by the cliff. the large sungei buloh wetland reserve comprises mostly wetland and a few bird species, most notably the shorebird, can be spotted there. it is cited as the "first wetlands reserve to be gazetted in singapore".