GE1101E BIOSPHERE

BIOGEOGRAPHY

Features and processes

How soils and vegetation are generated

Anthropogenic impacts to the biosphere

BIOMES

inland tropical forests and mangroves

How are they managed in a singaporean context?

BIOSPHERE

Sum of all soils, biomes, flora and fauna

Interactions with other components of the Earth

Plants and animal distribution and patterns

ECOLOGY = relationships between organisms and their environments

Ecosystems = complex of many variables

complicated flows of energy and matter

an open system

biotic and abiotic components

Habitats = physical environments where species live

climate and topography

Ecological niches = specific functions for an organism in that ecosystem

COMPETITIVE EXCLUSION PRINCIPLE

Apex predator concept

TRANSFER OF ENERGY IS CRITICAL in ecosystems

NPP: total photosyn - total respir FOR A PLANT COMMUNITY

Photosyn, respir, transpir

Elemental processes through C, O, N, H20

PROCESSES

BIOTIC

ABIOTIC

Food chains and trophic levels

energy is transferred through consumption and decomposition

Loss of energy between trophic levels

Possible push towards vegan/vegetarianism

Energy flows can go both ways = TROPHIC CASCADE

Pri --> tertiary or VICE VERSA

Can affect phy geo in profound ways

Elements recycled in biosphere through gaseous or sedimentary cycles

C and O cycles linked by Photosyn and Respir

Mobile reservoir of C and O in atmosphere

Nitrogen cycle

Needed for protein makeup in plants

Lightning fuses N to soils

Bacteria fixes N to N03s and NH4s

Natural N vs human fertilizers

SOILS AND VEGETATION

Soils = unconsolidated regolith

50% mineral and solid matter

other half

1/4 air

1/4 humerus

1/4 water

Dynamic zone of interaction between rock and atmosphere

Medium for vegetation growth

Develop into horizons from interactions with air, organic matter, water, minerals

distinguished by colour

Different horizons = diff soil profiles

O horizon = ORGANIC MATERIAL

A horizon = Minerals + dark-coloured organic material, seed germination

Elluviation --> downward gravitational movement of material through soil layers

B horizon = Where material from A is ILLUVIATED

C horizon = unconsolidated regolith

R horizon = bedrock

Texture

Clay <0.02mm

silt <0.2mm

Sands <2mm

Used to classify soils

Can affect porosity and permeability

Structure

bulk density (mass/vol)

Platey, blocky, prismatic

Chemical structure

pH?

mineral structure

How does Geography affect soil formation

Climate

T affects chemistry and organic matter

P affects E and I height

relief/topography

Parent material

impacts vegetation growth on soil

Organic activity and matter

Affect decomposition and recycling of O layer via earthworms, bacteria

Time

Affects horizon development

GEOGRAPHY OF SOILS

Pedogenesis and pedogenic regimes

Distinct soil processes lead to soil orders

Tropical = iron rich, highly weathered from strong leaching and clay-rich B layer

Most nutrients stored in vegetation, not soil

Why care?

SUSTAINABLE SOIL MANAGEMENT FOR AGRICULTURE

Mismanagement causes land degradation

Lucrative business

Carbon sinks

Absorb a lot of CO2, possible mitigation to global warming

bad farming and land clearance

affects yields

VEGETATION

Combination of plant and floral species and the land they cover

Primary producers

base of the ecosystem

Adapt according to bgeog of the area

Plant succession

Evolution of pioneer communities to climax communities

Increased complexity

Stable system at climax = MICROCLIMATES FORM

ECOTONES

Where 2 distinct ecosystems meet

can be gradual or sharp

occurs along elevation changes

BIOMES

large scale communities of plants and animals

Determined by principle of limiting factors

factor least in supply determines growth

5 Major types

Forest

Savanna

grassland

Desert

Tundra

Different ways of adaptation

ANTHROPOCENE and human impacts

New geological era, epoch of humans

Impacts

Env pollution

Habitat removal and damage

Changing structure of soils and ecosystems

Altering species composition

Overexploiting resources

introducing exotic organisms

elimination of biological pests

Improper waste disposal

Large ecological footprints

DISTURBING EQUILIBRIUM

Annoying other biotic species

enroachment, fragmentation and destruction

implications at all scales

feedback from micro to macro scales

Primarily tropical rainforests

Affect processes in spheres

Biodiversity loss

-ve impacts on atmosphere

humans destroy habitats --> impacts env --> impacts humans

EXTINCTION

Permanent loss of species from an area

Reduces biodiversity and drives evolution

Caused via human habitat destruction, over-harvesting, species INTRODUCTION

SINGAPORE'S BIOMES

Coastal and lowland dipterocarp

Trees <50m

Evergreen w/ buttress roots

10k plus fauna species

Nutrient-poor soils

Primary (old growth) + Secondary (succession from abandoned/disturbed land

Left with 0.2% primary at BoGa and Bukit Timah nat res

signs of enroachment and fragmentation

role as green lungs

Land loss due to increased urbanisation

need for habitat preservation

Park spaces, recreation and education

ultimately how sustainable is it?

MANGROVES

Salt-tolerant vegetation

Salt exclusion via leaves and roots

BRA --> breathing and anchorage via pneumatopores

PROVIDE HABITAT FOR ESTUARINE SPECIES

TIDAL PROTECTION DUE TO REDUCTION OF WAVE ENERGY

Carbon sink

Government conservation

Mangrove engineering

combining human knowledge with natural ecosystems