CANOPY ARCHITECTURE

Canopy architecture

" The overall profile of the tree top is known as canopy architecture".

Vegetation canopy structure describes the three-dimensional arrangement of leaves and includes such canopy attributes as canopy architecture, leaf angle distribution, ground cover fraction, leaf morphology, vegetation spatial heterogeneity, and shadows.

Canopy architectures in plants:-

Canopy architecture is the overall profile of tree the  tops. The trees gets grouped together leading to the formation of canopy and reduces the amount of light beneath them.

Factors controlling the canopy architecture:-

1. Pattern of growth in plant axis.

2. Arrangements and distribution of branches on main shoot.

3. Angle of branches on shoot.

4. Direction of branches.

5. Size, arrangement, distribution and shapes of leaves.

6. Genetic, environmental and nutritional factors.

Heliophytes or shade-introlerant plants- those plants which grows in full sunlight. eg. Sunflower, poplars, pines etc.

Sciophytes or shade-tolerant plants- certain plants which survive only under shade. eg. Fir, spruce etc.

However some plants can be facultative sciophytes as well as facultative heliophytes.

fig : Heliophytes and Sciophytes

The forest is made up of some individual tall plants which protrudes above normal level of canopy and are called as emergents.

The process of stratification i.e. arrangements of different plants or animals in different layer of substratum takes place in canopy.

Eg. Stratification in a tropical rain forest.

Based upon branching a tree, it may classified as:-

1. Culm- The stem is unbranched showing distinct nodes and internodes imparting a jointed apperance. Eg. Bambusa arundinacea (Bamboo).

2. Columnar (caudex)- In such case trunk is unbranched and bears a crown of leaves at its apex. Eg. Fan plam, areca catechu (supari) , Cocos nucifera (coconut) etc.

3. Excurrent- In such case lateral branches do not complete with the growth of main stem. Branches appear in acropetal succession. Thus, tree gives cone-like apperance. Eg. Pinus, Eucalyptus etc.

4. Decurrent or Deliquescent- When some of the lateral branches grows vigorously, the trunk Disappears after some distance due to the suppression of growth of terminal bud, the form called Decurrent. Eg. Magnifera indica (mango), Dalbergia(Shisham), Ficus benghalensis etc.

SHAPE OF CANOPY ARCHITECTURE

a. Round canopy- Trees which shows Decurrent or Deliquescent branching shows round canopy. Branch appears in alternate pattern. Branches present on upper side grows towards upper and outer sides. However, lower branches spread  out. Minimum overlapping of leaves in such cases. Eg. Magnifera indica , lagerstromia, Dalbergia, Ficus etc.

b. Conical canopy- In such case lateral branches do not complete with the growth of main stem. Branches appears acropetally (Monopodial/Racemose).

Branches appear either horizontally (eg. Araucaria) or ascent at a particular angle (eg. Thuja). Shape of tree is conical.

Eg. Pinus, Eucalyptus etc.

c. Oblong or cylindrical canopy- Branching in these trees can be Racemose (Gnetum) or cymose type (peltophorum). Main trunk remains upright. Lateral branches are short and grows towards upper side providing cylindrical shape to trees. 

Eg. Artocorpus (jack fruit).

d. Flat topped canopy- Growth of apical bud on main trunk stops after attaining a certain height. It bends on upper side, a twig appears which further give rise to Obliquely rising branches. Thus, tree imparts umbrella shape. Eg. Cassia, Terminalia (imli), Thespesia actifolia, Enterolobium saman (rain tree) etc.

e. Weeping tree- Due to weak branching or due to drooping branching pattern, trees impact weeping appearance.

Stem is Monopodial (Polyalthia) or stem is sympodial (Zizyphus jujuba).

Eg. Salix (weeping willow), Acacia arabica (Kikar).

f. Pagoda trees- Trees bear spirally arranged compacts, simple or palmate type of leaves. The branches on trunk arises in wholed fashion. The pagoda shape is very distinct when the tree is young. As the whorls ascent from the base to tip, length internode shortens and gives a typical pagoda shape to trees. Eg. Salmalia, Achras sapota (Chiku), Terminalis etc.

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