Chapter 4 (Part 2): Plant Succession

Primary Seres, Secondary Dynamics, Climax Theories and Silvicultural Applications

1. Riverain Succession on Gangetic Alluvium

Primary succession on new alluvial deposits in Northern India progresses through six stages.

Stage 1 — Pioneer community
Saccharum spontaneum + Tamarix dioica

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Stage 2
Acacia catechu + Dalbergia sissoo

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Stage 3
Acacia catechu + Holoptelea + Adina cordifolia + Albizia procera

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Stage 4
Holoptelea + Adina + Lagerstroemia parviflora + Bombax ceiba + Terminalia bellirica

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Stage 5
Adina + Lagerstroemia parviflora + Terminalia spp. + Shorea robusta

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Stage 6 — Climax
Shorea robusta + Lagerstroemia + Terminalia spp. + Adina

Moist variant: Trewia nudiflora and Toona ciliata appear in Stage 4 in damp sites. Syzygium cumini forms the undercanopy in Stage 6.

Stage-wise reference table

Stage	Characteristic species
1	Saccharum spontaneum, Tamarix dioica
2	Acacia catechu, Dalbergia sissoo
3	Acacia catechu, Holoptelea, Adina cordifolia, Albizia procera
4	Holoptelea, Adina, Lagerstroemia parviflora, Bombax ceiba, Terminalia bellirica
5	Adina, Lagerstroemia parviflora, Terminalia spp., Shorea robusta
6	Shorea robusta, Lagerstroemia, Terminalia spp., Adina

2. Coniferous Succession in Temperate Himalayas

Succession on new mountain soils progresses through four stages.

Stage 1 — Shrub associations

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Stage 2 — Pioneer forest: Blue pine / Kail (Pinus wallichiana)

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Stage 3 — Mixed forest: Deodar (Cedrus deodara), Spruce (Picea smithiana) and Blue pine (Pinus wallichiana)

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Stage 4 — Climax: Spruce (Picea smithiana), Fir (Abies pindrow) and Deodar (Cedrus deodara)

Sequence: Shrubs → Kail → Deodar + Spruce + Kail → Spruce + Fir + Deodar.

3. Estuarine Succession on Tidal Mudflats

Estuarine succession occurs on tidal mudflats and deltaic deposits.

Stage 1 — Mangrove scrub: Ceriops, Avicennia

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Stage 2 — Mangrove trees: Rhizophora, Bruguiera

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Stage 3 — Slow-growing salt-water Heritiera forest

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Stage 4 — Finer brackish-water Heritiera forest

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Stage 5 — Fresh-water swamp forest without Heritiera

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Stage 6 — Climax: Tropical Evergreen or Semi-evergreen forest

4. Retrogression and Secondary Succession

Retrogression (Regression)

Reversion of vegetation to an earlier successional stage following the introduction of an adverse factor such as fire, clearing, overgrazing or severe drought.

Retrogressive stages are generally lower in height and more xerophytic in character.

Secondary pioneers after disturbance

Habitat / Site	Characteristic secondary pioneers
Moist tropical evergreen clearings	Macaranga spp., Trema orientalis, Acrocarpus fraxinifolius, Callicarpa
Himalayan secondary hill clearings	Woodfordia fruticosa, Indigofera pulchella, Berberis lycium
General colonizers	Pinus wallichiana, Trema, Anthocephalus cadamba

Key idea: When the causes of retrogression are removed, secondary succession can begin through the establishment of characteristic pioneer species.

5. Theories of Climax

Mono-climax Theory — Clements (1916)

Climate is the sole master factor governing vegetation. Given sufficient time without disturbance, all seral communities in a region ultimately converge towards one climatic climax.

Poly-climax Theory

Permanent differences in soil, relief and drainage prevent complete convergence, producing multiple stable edaphic or topographic climaxes within a climatic region.

Aubreville's Mosaic Theory

Tropical climax forests are dynamic mosaics of small constituent units undergoing cyclic alternations of species replacement.

Whittaker's Climax Pattern Theory

Rejects fixed absolute climaxes and views climax as a continuous steady state adapted along multi-variable environmental gradients.

Comparison of climax theories

Theory	Main proposition	Key emphasis
Mono-climax	One regional climatic climax.	Climate as master factor.
Poly-climax	Multiple stable climaxes.	Soil, relief and drainage.
Mosaic	Dynamic patchwork of forest units.	Cyclic species replacement.
Climax pattern	Climax varies continuously along environmental gradients.	Multiple environmental variables.

6. Categories of Climax Formations

Climax category	Definition / ecological status	Indian forestry examples
Climatic climax	Governed by regional climate and natural biotic interactions.	Southern Tropical Wet Evergreen (Type 1A/C1); Moist Sal Forest (Type 3C/C2); Western Mixed Coniferous (Type 12/C1d).
Edaphic climax	Stable community differing from regional climatic climax due to soil peculiarities.	Cane brakes (Type 1B/E1); Wet bamboo brakes (Type 1A/E2); Terminalia tomentosa on heavy clay; Anogeissus pendula (5B/E1); Boswellia serrata (5B/E2); Babul (5B/E3); Hardwickia (5B/E4).
Pre-climax	Community preceding regional climatic climax, occurring under drier conditions.	Pinus roxburghii on dry ridges within Subtropical Broad-leaved Forest; very moist Teak adjoining Evergreen forest at Mt. Stuart.
Post-climax	Community more exacting than climatic climax on exceptionally moist microsites.	Evergreen / Semi-evergreen patches such as Golatappar, Dehradun, within Moist Deciduous Sal forest.
Biotic sub-climax / Disclimax	Stable community held short of climatic climax by persistent biotic interference.	Grassy riverain subclimax; Chir pine where Quercus incana is climatic climax; Sal, Teak and Deodar maintained by periodic controlled fire.

7. Important Differences Between Climax Categories

Climatic climax

Determined by regional climate.

Edaphic climax

Determined by persistent soil conditions.

Pre-climax

Associated with relatively drier conditions than the regional climatic climax.

Post-climax

Associated with exceptionally moist microsites and more exacting vegetation.

Disclimax

Maintained by persistent disturbance or biotic interference such as fire and grazing.

Memory trick: Climatic = Climate; Edaphic = Earth/soil; Pre = Drier; Post = Wetter; Dis = Disturbance.

8. Importance of Plant Succession in Silviculture

Forest classification

Provides the ecological foundation for classifying forests into climatic, edaphic and seral forest types.

Choice of plantation species

Helps avoid planting exacting climax species on raw, immature seral soils where they may fail to establish.

Management of economic sub-climaxes

Guides the use of controlled disturbance, such as periodic burning or grazing, to maintain economically valuable species as stable sub-climaxes.

Examples: Shorea robusta, Tectona grandis and Cedrus deodara are mentioned in relation to management of commercial biotic sub-climaxes.

9. Important Species and Succession Associations

Species	Successional association
Saccharum spontaneum	Riverain pioneer on Gangetic alluvium.
Tamarix dioica	Riverain pioneer on Gangetic alluvium.
Pinus wallichiana	Pioneer forest in temperate Himalayan succession.
Shorea robusta	Gangetic alluvial climax community; also cited as an economic sub-climax.
Macaranga spp.	Secondary pioneer in moist tropical evergreen clearings.
Trema orientalis	Secondary pioneer in moist tropical evergreen clearings.
Woodfordia fruticosa	Secondary pioneer in Himalayan hill clearings.
Acacia catechu	Early and intermediate riverain stages.
Heritiera	Intermediate stages of estuarine succession.

10. Quick Revision Box — Chapter 4 Complete

• Thoreau (1863): Coined "forest succession".
• Clements (1916): Mono-climax theory and six-step succession mechanism.
• Ecesis: Establishment from germination to reproduction.
• Reaction: Vegetation modifies its own habitat.
• Riverain pioneers: Saccharum spontaneum and Tamarix dioica.
• Conifer pioneer: Pinus wallichiana (Kail).
• Secondary pioneers: Macaranga and Trema in tropical evergreen clearings; Woodfordia in hill clearings.
• Mono-climax: One climatic climax.
• Poly-climax: Multiple climaxes due to soil, relief and drainage.
• Mosaic theory: Dynamic forest patches.
• Whittaker: Climax pattern along environmental gradients.
• Disclimax: Maintained by persistent biotic interference.
• Commercial sub-climaxes: Sal, Teak and Deodar are cited in relation to disturbance management.

11. Interactive MCQ Quiz

15 questions. Tap an option to see the correct answer and explanation straight away, then go to the next question.

Chapter 4 (Part 2) | Plant Succession

Silviculture notesAll quick revision notes →

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