(a) List five morphological features that are characteristic of plant found in each of the following habitats:-(i) tropical rainforest. (ii) savanna. In each case, state function of the features listed in (a) to the plant.
(b) Explain the term: ecological succession
(c) By means of a diagram only, outline the carbon cycle to show the relative importance of the cycle to life in general.
Explanation
(a)(i) Morphological features of Tropical rainforest plants:
- They are tall trees with unbranched trunks which taper very little.
- Usually their barks are thin and they have buttresses.
- The leaf buds lack protective covering while the matured leaves are oval in shape, having entire margins and an acumen or drip tip.
Functions of features listed:
- Tall unbranched trunks enable the plants to receive adequate sunlight .
- Thin bark allows the plant to lose water by transpiration and makes the trees a good source of timber.
- Buttress roots provide mechanical support against wind.
- Buds lack protective covering and this encourages easy breakage for the buds.
- Drip tip type of leaves allows water to drain easily from the leaves, hence transpiration is facilitated.
(ii) Morphological features of plants in the Savanna:
- They have long twisted roots and thick bark.
- Trunks are gnarled (covered with hard lumps) and twisted.
- Because of the underground stems, grasses are tuff and perennial.
Functions of features listed:
- Long twisted roots facilitate the absorption of water and mineral salts and also facilitate quick regeneration after fire attack.
- Thick bark enables the plants to withstand harsh conditions, e.g. fire.
- Gnarled and twisted trunk reduce excessive loss of water as well as resistance to fire attack .
- Underground stems enable the plants to survive during dry season and fire attack.
- Tuffs and perennial Grasses have inner parts which are highly protected by the outer tuffness against fire outbreak.
(b) Ecological succession can be referred to as a gradual, cumulative and predictable progressive change in the ecological communities in an area with a definite movement toward a position of equilibrium known as climax. It can be classified into primary and secondary succession. Primary succession is the colonization of borne vegetation or bare ground or rocks which have not previously been colonized, e.g. surfaces of fresh hardened molten magma and sand dunes. Secondary succession is the colonization of an area following the destruction or removal of the original vegetation. Barren habitat is gradually colonized by a series of plant and animal inhabitants until a final stable community is achieved.
