Plant-Environment Relationship

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Plant-Environment Relationship

• HO Pui-sing

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Contents

• Development of Plants
• Equatorial / Tropical Rain Forest
• Tropical Desert Vegetation
• Local Plant-Environment Relationship
• The Relationship of Biomes to Ecolines

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Development of Plants

• Classification of Plants
• Factors affecting plants development

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Classification of Plants

• Life form of plants
• Trees
• Shrubs
• Lianas
• Herbs
• Vegetation structure
• Forest
• Woodland
• Lichens

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Factors affecting development

• Plant habitats
• Water availability
• Temperature
• Time
• Human

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Plant habitats

• Plants affect landform and soil (Env.)
• Different conditions of slopes, drainage and soil
  type will create different plant environment
  plant habitats

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Water availability

• Types of plants
• Xerophytes
• Hygrophytes
• Mesophytes
• Tropophytes
• Deciduous plants
• Evergreen plants

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Temperature

• Plant growth photosynthesis, flowering, fruiting
  and seed germination
• Water availability rate of transpiration and
  evaporation
• Damage damage the cell tissues for too cold
• Frontier a boundary which a plant species cannot
  survive.

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Time

• Plant and animal communities succeed one another
  on the way to a stable endpoint, making up an
  ecological succession
• Climax vegetation (climatic control)
• Subclimax vegetation (non-climatic control)

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Reason for succession

• Results of species competition in a given
  environment.
• Populations of well-adapted species replace
  earlier ones now less well equipped to compete in
  the altered conditions.
• There is a gradual change in the community.

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Process of succession

• Pioneers (annual herbs, weeds)
• Grasses and shrubs
• Pine seedlings
• Pine forest
• Broad-leaved deciduous trees (oak forest) Climax
  forest
• Climax community balance between Vegetation and
  physical environment.

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Process of succession
Deciduous forest (Climax)
Pine seedings
Grasses Shrub
Pioneers
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Process of succession
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Patterns in successional processes

• Development of soil mature
• Height of plants increases and strata clear
  developed
• Biomass (productivity) increase
• Species increases
• Create new micro-climates
• Species replace one another (succession)
• Climax community forms (stable, balance)

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Human impact on vegetation

• Clearing forest disturbs the climax vegetation
• Introduce new plant disease
• Extinction of a original plant species
• Changing soil structure and properties
• Reasons farming, mining, urbanization and
  industrialization.

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Tropical Rain Forest
Congo Basin
Amazon Basin
South-east Asia
http//www.radford.edu/swoodwar/CLASSES/GEOG235/b
iomes/rainforest/rainfrst.html
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Natural Environment

• High insolation
• Monthly temperature between 26oC and 27oC
• Annual rainfall usually more than 2000mm
• Convection Rain is common
• Hot and wet throughout the year

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Characteristics of TRF Vegetation

• Evergreen forest
• Vegetation Layers
• Leaves
• Drip-tips
• Roots
• Cauliflory

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Evergreen

• No Seasonal variation
• Leaf-growth, flowering, fruiting, leaf-fall.go
  on continuously
• Trees can live to a great age

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Vegetation layers
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Vegetation Layers

• Emergent layer
• very tall tree with broad crown (30-40m)
• few in number
• Canopy layer
• a continuous cover (20m)
• Middle layer
• younger trees (5-15m)
• Shrub layer and undergrowth
• little growth because of shade

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Leaves

• Uniform, dark green, glossy, leathery, oval and
  broad-leaved
• Strong insolation and transpiration a
  heavy cuticle leathery.

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Waxy Leaves and Drip-tips
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Buttress Roots
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Caulifory
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Types of vegetation

• Tree species
• Epiphytes
• Parasites
• Tree Ferns
• Undergrowth
• Saprophytes
• Mangrove swamps (riverine)

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Trees and Climbers
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Epiphytes and Parasites
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Undergrowth
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Mangrove
Mangrove swamps Prop-roots Radicle
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Tropical Desert Vegetation
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Natural Environment

• Among the driest places on earth (lt250mm)
• Mean annual temperature above 18oC
• Low relative humidity
• Irregular and unreliable rainfall
• Highest percentage of sunshine of any climate
• Large diurnal temperature range
• Highest daytime temperature of any climate
• Annual precipitation lt half the annual potential
  evapotranspiration

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Tropical Desert Vegetation

• Characteristics of the vegetation
• Types of vegetation

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Characteristics - Morphological

• Extensive root systems (vertical or horizontal)
• Deeply penetrating roots reach permanently wet
  soil or ground water store
• Horizontal roots may extend for 5-20m
• Low shoot-to-root ratio (13.5 to 16)
• Special leaves (small, roll, spiny and shed
  foliage) for reduce transpiration and preserve
  water.

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Characteristics - Anatomical

• Cuticularisation produces a watertight and
  waxy-like surface
• Lignification provides mechanical support
• Low, rounded shapes can reduce damage by strong
  wind
• Many hairs

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Characteristics - others

• Sparsely distribution for not enough water supply
• Low biomass, few species, lack of competition

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Types of vegetation

• Ephemeral annuals
• Succulent perennials
• Non-succulent perennials

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Ephemeral annual

• 50-60 of desert plants
• Complete its full life cycle within 6-8 weeks
  (short life cycle)
• Small size, shallow roots
• Fast germinating, growing, flowering and seeding
• Extensive germination immediately after
  precipitation
• Eg. Desert plantains, desert fescue

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Ephemeral annual
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Succulent perennials

• Enlarge the parenchyma tissues with the addition
  of water
• Stems and leaves allow store water during rainy
  season
• Stomata are closed during day and open at night
• Eg. Catus

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Succulent perennials
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Non-succulent perennials

• Can be divided into three types
• Evergreens
• Drought-deciduous
• Cold-deciduous
• Commonly found where a little water is available.
  (wadis, oases, perennial rivers)
• Eg. Tamarisks, acacias, grasses, palms

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Non-succulent perennials
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Local Plant-Environment Relationship

• Altitude zones of vegetation
• The local variation of vegetation in TRF
• The local variation of vegetation in desert

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Altitude zones of vegetation

• Vegetation changes with an increase in elevation
  because the following reasons
• Temperature drops
• Relative Humidity increase
• Precipitation increase
• Orographic rain in windward slope
• Rain shadow in leeward slope

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continues

• Light intensive and day time increase
• Outgoing radiation at night increase
• Large diurnal range of temperature
• Permanent snowcaps exist on very high Mts.
• Faster wind speed
• Aspects South facing slope vs. North facing
  slope

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Altitude zones of vegetation
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Altitude zones of vegetation
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Tropical Mountains
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Tropical Mountains

• Hot country lt1000m
• Temperate country 1000-1800m
• Cold country 1800-3500m
• Snow country or frost country gt3300m

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Mid-latitude Mountains
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Mid-latitude Mountains

• Montane Zone (lt2000m)
• Submontane, montane, high montane
• Subalpine Zone (2000-2700m)
• Alpine Zone (2700-3700m)

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The Local variation in TFR

• Poor drainge (Swamp)
• Various kinds of stilt roots
• Peat soil

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The local variation in Desert

• Near Water courses more vegetation
• Plant can be established in stable sand dunes
• Ephemerals grow in thin soil
• Succulent and non-succulent need a thick soil

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Biomes to Ecoclines

• Biomes are the worlds major communities,
  classified according to predominant vegetation
  (Climax) and characterized by adaptations of
  organisms to that particular environment.
• Ecocline is a gradient along which communities
  and environments change.
• Ecotone is a transition zone between two
  ecosystems.

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The main biomes

• Tropical rain forest
• Savanna or tropical grassland
• Desert
• Temperate forest (evergreen / deciduous)
• Temperate grassland
• Coniferous forest
• Tundra

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Ecocline

• Temperature change and water availability are the
  most important factors affecting ecocline pattern.

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Ecocline (Equator to North Pole)