Lecture 6 Secondary Vegetation Flashcards
Secondary Vegetation
Secondary vegetation = Vegetation that has re-grown after the destruction of the original vegetation (primary vegetation), by natural or, more commonly, by human impacts
Eological Succession
= Process of continuous, uni-directional change in the vegetation
In Singapore, typical succession scenarios, if undisturbed for several decades or centuries =
Primary forest Cleared ground or big gap in forest canopy Trema belukar (if soil is undegraded) Tall secondary forest (if seed sources are available) Primary forest (if seed sources are available)
Primary forest Cleared ground Agriculture (soil is degraded) Adinandra belukar Tall secondary forest (if seed sources available) Primary forest (if seed sources are available)
Secondary Vegetation in Singapore
Spontaneous (arising without human intervention) Herbaceous vegetation (soft, juicy,small, non-woody plants, i.e., weeds like lalang) leaves have silica- razor blades Secondary forest (explained later) Other secondary vegetation (explained later) Managed (with periodic human intervention) (the ridge) *When you burn Lalang, they don’t get killed as the bottom part still stays
Herbs
Herbs are soft juicy plants
Lalang is soft but they also have silica on both sides of the leaves
Managed Secondary Vegetation
Succession prevented by periodic human disturbance, e.g., mowing or pruning
Once intervention stops, succession to forest can proceed
Secondary Forest
Forest = Large area covered by trees
Tree = Large, woody plant with single main stem or trunk
Secondary forest = Forest in the state of secondary vegetation
Secondary Forests in Singapore
Most common forest type About 4% of Singapore’s area now Originally = about 0% Large continuous patches Mostly in Western reservoirs Pulau Ubin Pulau Tekong BTNR and CCNR*
Secondary Forests in BTNR and CCNR
Most common forest type
Indicative of past human activities even in nature reserves
Agricultural Crops of Old Singapore
Gambier Rubber Pineapple Pepper Tapioca
Black pepper from unripe fruit, boiled for a short while and dried under sun or machine. Some are just dried without boiling under the sun.
White pepper is from the ripe fruit, soaked in water and fruit skin removed and just the seeds are dried under sun
Gambier
Tanin – treat leather otherwise animal skin will rot
Vitex pinnata Hevea brasiliensis (rubber)
Vitex – no leaf stalk and has 2 smaller leaflets
Secondary Forest Types in Singapore
Low secondary forest and scrub - Trema belukar - Adinandra belukar Tall secondary forest Other secondary forest types
Trema Belukar 1
Trema belukar = Secondary forest that grows up on undegraded soil, dominated by Trema species Origin of this name Malay, belukar = secondary forest Trema, from the two species lesser trema (Trema cannabina) rough trema (Trema tomentosa)
Canopy Strata of Forest
Stratum A: Emergent trees Stratum B: Main canopy trees Stratum C: Sub-canopy trees Stratum D: Treelet or shrub layer Stratum E: Forest floor herbs and seedlings
Trema Belukar 2
Tends to be found in nature reserves where soil is undisturbed
A natural type of secondary forest
Occurs when large gaps form in the canopy from natural (e.g., tree fall) or human disturbance
Adinandra Belukar 1
Adinandra belukar = Species-poor, anthropogenic, heath forest (secondary forest) that grows up on degraded soil, dominated by tiup tiup (Adinandra dumosa)
Adinandra Belukar 2
Origin of this name
Malay, belukar = secondary forest
Adinandra, from the dominant species
tiup tiup (Adinandra dumosa)
Named by Holttum
Soil
Low nutrients (low nitrogen and phosphorus)
Acidic (pH 3.3 to 3.9)
Few plant species can grow
First Head of Dept of Biological Sciences, NUS)
First to describe adinandra belukar in 1954
became President of Singapore Gardening Society when it was established in 1936.
Adinandra Belukar Plants
Very low species diversity in plants, fewer animals and microbes than in primary forest Dominated by medium-sized to short trees tiup tiup simpoh air tembusu tropical pitcher plants common acacia others
