Plant-Environment
Relationship
HO Pui-sing
Contents
Development of Plants
Equatorial / Tropical Rain Forest
Tropical Desert Vegetation
Local Plant-Environment Relationship
The Relationship of Biomes to Ecolines
Development of Plants
Classification of Plants
Factors affecting plants development
Classification of Plants
Life form of plants
Trees
Shrubs
Lianas
Herbs
Vegetation structure
Forest
Woodland
Lichens
Factors affecting development
Plant habitats
Water availability
Temperature
Time
Human
Plant habitats
Plants affect landform and soil (Env.)
Different conditions of slopes, drainage
and soil type will create different plant
environment = plant habitats
Water availability
Types of plants
Xerophytes
Hygrophytes
Mesophytes
Tropophytes
Deciduous plants
Evergreen plants
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.
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)
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.
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.
Process of succession
Pioneers
Grasses & Shrub
Pine seedings
Deciduous forest (Climax)
Process of succession
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)
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…….
Tropical Rain Forest
Congo Basin
Amazon Basin
South-east Asia
http://www.radford.edu/~swoodwar/CLASSES/GEOG235/biomes/
rainforest/rainfrst.html
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
Characteristics of TRF Vegetation
Evergreen forest
Vegetation Layers
Leaves
Drip-tips
Roots
Cauliflory
Evergreen
No Seasonal variation
Leaf-growth, flowering, fruiting, leaffall…….go on continuously
Trees can live to a great age
Vegetation layers
Emergents Layer
Canopy Layer
Middle Layer
Shrub Layer and
Understorey
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
Leaves
Uniform, dark green, glossy, leathery,
oval and broad-leaved
Strong insolation and transpiration
a heavy cuticle
leathery.
Waxy Leaves and Drip-tips
Buttress Roots
Caulifory
Types of vegetation
Tree species
Epiphytes
Parasites
Tree Ferns
Undergrowth
Saprophytes
Mangrove swamps (riverine)
Trees and Climbers
Epiphytes and Parasites
Undergrowth
Mangrove
Mangrove swamps
Prop-roots
Radicle
Tropical Desert Vegetation
Natural Environment
Among the driest places on earth (<250mm)
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 < half the annual
potential evapotranspiration
Tropical Desert Vegetation
Characteristics of the vegetation
Types of vegetation
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 (1:3.5 to 1:6)
Special leaves (small, roll, spiny and shed
foliage) for reduce transpiration and preserve
water.
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
Characteristics - others
Sparsely distribution for not enough
water supply
Low biomass, few species, lack of
competition
Types of vegetation
Ephemeral annuals
Succulent perennials
Non-succulent perennials
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
Ephemeral annual
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
Succulent perennials
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
Non-succulent perennials
Local Plant-Environment Relationship
Altitude zones of vegetation
The local variation of vegetation in TRF
The local variation of vegetation in
desert
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
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
Altitude zones of vegetation
Altitude zones of vegetation
Tropical Mountains
Tropical Mountains
Hot country <1000m
Temperate country 1000-1800m
Cold country 1800-3500m
Snow country or frost country >3300m
Mid-latitude Mountains
Mid-latitude Mountains
Montane Zone (<2000m)
Submontane, montane, high montane
Subalpine Zone (2000-2700m)
Alpine Zone (2700-3700m)
The Local variation in TFR
Poor drainge (Swamp)
Various kinds of stilt roots
Peat soil
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
Biomes to Ecoclines
Biomes are “the world’s 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.
The main biomes
Tropical rain forest
Savanna or tropical grassland
Desert
Temperate forest (evergreen / deciduous)
Temperate grassland
Coniferous forest
Tundra
Ecocline
Temperature change and water availability
are the most important factors affecting
ecocline pattern.
Ecocline (Equator to North Pole)