Plant-Environment Relationship
HO Pui-sing
Contents
Development of PlantsEquatorial / Tropical Rain ForestTropical Desert VegetationLocal Plant-Environment RelationshipThe Relationship of Biomes to Ecolines
Development of Plants
Classification of PlantsFactors affecting plants development
Classification of Plants
Life form of plantsTreesShrubsLianasHerbs
Vegetation structureForestWoodlandLichens
Factors affecting development
Plant habitatsWater availabilityTemperatureTimeHuman
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 plantsXerophytesHygrophytesMesophytesTropophytesDeciduous plantsEvergreen plants
TemperaturePlant growth: photosynthesis, flowering, fruiting and seed germinationWater availability: rate of transpiration and evaporationDamage: damage the cell tissues for too coldFrontier: 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 successionClimax 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 shrubsPine seedlingsPine forestBroad-leaved deciduous trees (oak forest) Climax forestClimax community = balance between Vegetation and physical environment.
Process of succession
Deciduous forest (Climax)Pine seedingsGrasses & ShrubPioneers
Process of succession
Patterns in successional processesDevelopment of soil matureHeight of plants increases and strata clear developedBiomass (productivity) increaseSpecies increasesCreate new micro-climatesSpecies replace one another (succession)Climax community forms (stable, balance)
Human impact on vegetation
Clearing forest disturbs the climax vegetationIntroduce new plant diseaseExtinction of a original plant speciesChanging soil structure and propertiesReasons: farming, mining, urbanization and industrialization…….
Tropical Rain Forest
http://www.radford.edu/~swoodwar/CLASSES/GEOG235/biomes/rainforest/rainfrst.html
Amazon Basin
Congo Basin
South-east Asia
Natural EnvironmentHigh insolationMonthly temperature between 26oC and 27oCAnnual rainfall usually more than 2000mmConvection Rain is commonHot and wet throughout the year
Characteristics of TRF Vegetation
Evergreen forestVegetation LayersLeavesDrip-tipsRootsCauliflory
Evergreen
No Seasonal variationLeaf-growth, flowering, fruiting, leaf-fall…….go on continuouslyTrees can live to a great age
Vegetation layers
Middle Layer
Emergents Layer
Canopy Layer
Shrub Layer andUnderstorey
Vegetation LayersEmergent layer
very tall tree with broad crown (30-40m)few in number
Canopy layera continuous cover (20m)
Middle layeryounger trees (5-15m)
Shrub layer and undergrowthlittle growth because of shade
Leaves
Uniform, dark green, glossy, leathery, oval and broad-leavedStrong insolation and transpiration a heavy cuticle leathery.
Waxy Leaves and Drip-tips
Buttress Roots
Caulifory
Types of vegetationTree speciesEpiphytesParasitesTree FernsUndergrowthSaprophytesMangrove swamps (riverine)
Trees and Climbers
Epiphytes and Parasites
Undergrowth
Mangrove
Mangrove swamps Prop-roots
Radicle
Tropical Desert Vegetation
Natural EnvironmentAmong 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 - MorphologicalExtensive root systems (vertical or horizontal)Deeply penetrating roots reach permanently wet soil or ground water storeHorizontal roots may extend for 5-20mLow 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 surfaceLignification provides mechanical supportLow, rounded shapes can reduce damage by strong windMany hairs
Characteristics - others
Sparsely distribution for not enough water supplyLow biomass, few species, lack of competition
Types of vegetation
Ephemeral annualsSucculent perennialsNon-succulent perennials
Ephemeral annual50-60% of desert plantsComplete its full life cycle within 6-8 weeks (short life cycle)Small size, shallow rootsFast germinating, growing, flowering and seedingExtensive germination immediately after precipitationEg. Desert plantains, desert fescue
Ephemeral annual
Succulent perennials
Enlarge the parenchyma tissues with the addition of waterStems and leaves allow store water during rainy seasonStomata are closed during day and open at nightEg. Catus
Succulent perennials
Non-succulent perennials
Can be divided into three typesEvergreensDrought-deciduousCold-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 vegetationThe local variation of vegetation in TRFThe local variation of vegetation in desert
Altitude zones of vegetationVegetation changes with an increase in elevation because the following reasonsTemperature dropsRelative Humidity increasePrecipitation increase Orographic rain in windward slopeRain shadow in leeward slope
continuesLight intensive and day time increaseOutgoing radiation at night increaseLarge diurnal range of temperaturePermanent snowcaps exist on very high Mts.Faster wind speedAspects – 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 TFRPoor drainge (Swamp)
Various kinds of stilt rootsPeat soil
The local variation in Desert
Near Water courses more vegetationPlant can be established in stable sand dunesEphemerals grow in thin soilSucculent and non-succulent need a thick soil
Biomes to EcoclinesBiomes 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 forestSavanna or tropical grasslandDesertTemperate forest (evergreen / deciduous)Temperate grasslandConiferous forestTundra
EcoclineTemperature change and water availability
are the most important factors affecting ecocline pattern.
Ecocline (Equator to North Pole)