Can Gio mangrove forest develops by the accumulation and aggradation of silt from Sai Gon – Dong Nai river to the lower section – Long Tau and Nga Bay river, Dong Tranh, Nha Be and Soai Rap river.
Can Gio mangrove forest’s environmental conditions are very special: an intermediary ecosystem (buffer system) between aquatic and on land ecosystems, fresh water and salt-water ecosystems. It is a by-the-sea area with many estuaries. Can Gio mangrove forest receives a great deal of silt and nutrients from the upper section and basins of rivers. Under the influence of the sea – the tide, Sac forest’s botanic system has been formed with an abundance of types and this is the supply of food and the sanctuary for aquatic organisms and on land vertebrates
Vam Sat salt-marsh alone has an abundant and assorted system of animals and plants: Rhizophora apiculata (Duoc tree), Nipa fruticans, Melaleuca cajeputy (Tram tree), Sonneretia alba, Sonneretia ovata, Sonneretia casseolaris (Ban tree), Aegiceras corniculatum (Su tree), Bruguiera cylindrica (Vet tree); 63 species of microorganisms, 140 species living at the bottom as shrimps, crabs, shell-fishes, 45 types of fishes, 8 types of reptiles, 37 species of birds and other species such as monkeys, deers, weasel. There are also some valuable and rare species listed in Red Book: Crocodile porosus, Spot-billed Pelican, Smooth Otter.
Can Gio previously had many animals such as: deer, weasel, monkey, wildcat, fox, pangolin, python, snake and big on-land animals as tiger, wild boar, bear; and water animals as crocodile, water varen, sea turtle, otter …
Recent researches about birds in Can Gio have totaled up about 15 species belonging to 47 families, 17 sets. Among which there are 15 species belonging to 3 families, 1 set. The studies reveal that there are 51 water bird species and 79 non-water bird species in different living environments. Among the water birds, 21 species are migrant birds (41.7% of water bird species) and among 79 non-water bird species, there is 1 migrating species. The number of Can Gio’s water birds account for 33.55% of that of the whole country (149 species).
Can Gio’s valuable and rare birds:
_ Spot-billed Pelican
_ Painted Stork
_ Lesser Adjutant
_ Milky Stork.
_ Spotted Greenshank.
After a survey, the bird sanctuary of Vam Sat, in particular, has 26 species, of which 11 species are water bird (09 natural and 02 domesticated: Painted Stork, Lesser Adjutant)
According to statistic figures at the end of 1998, Can Gio mangrove forest has a total land and forest area of 38,556 ha, of which 30,162 ha is protective forest consisting of natural forest and restored forest since 1978. This community can be divided into two small categories: planted forest & natural forest. Especially, the salt marsh and brackish plant system was originally scattered from Indonesia and Malaysia.
Natural forest community
In this system, there is a special type of forest: tropical mixed broad-leaf forest. Even with bamboo forest after so many years under the destruction of the war, there are still some remainder such as Tre-gai bamboo, Z. oenophia Mill … The rest are brackish and salt-marsh trees: phoenix paludosa(Cha La tree). Acrostichum aureum (Rang tree), excoecaria agallocha(Gia tree), Molothrus ater (Chia voi tree) usually grow on higher land that is less submerged in water.
Planted forest community
- Eucalyptus, Acacia auriculiformis are planted on land to to maintain soil and fight against landslide. It is suitable to the soil on which phoenix paludosa (Cha La tree), Acrostichum aureum (Rang tree) grow.
- Nypa fruticans live mainly in brackish area and sometimes in alkaline salt land.
- Rhizophora apiculata accounts for 75% of the salt-marsh forest and allocates in area with the height of about 0.7 – 0.9 m.