DST-NRF CENTRE OF EXCELLENCEFOR INVASION BIOLOGY

Ecology and Biodiversity

Energy and Food websWhat is biodiversity

The biodiversity crisisThe Convention for Biological Diversity

How to measure biodiversityLinks

WHAT IS ENERGY?

Energy is the property of a system that enables it to do work

Several forms of energy: kinetic, potential, heat, chemical, nuclear and radiant energy.

Common measures of energy: joules (SI Unit), calories and kilowatt-hours

SOURCES OF ENERGYSun: primary source of energy on earthFossil fuels: coal, oilNuclear energy

LAWS OF ENERGY1st law of energy: Energy cannot be created or

destroyed but can be transferred from one form to another

2nd law of energy: When one form of energy is transferred into another form, some useful energy is always lost as heat, therefore, energy cannot be recycled.

In nature systems go from order to chaos - Entropy is the amount of disorder in a physical system

Closed system: entropy remains constant or increases

In an open system: entropy can decrease, at a local scale - by using energy, this tendency can be “reversed” - Think of a teenager’s bedroom

FLOW OF ENERGY

HEAT ENERGY RETURNED TO THE ATMOSPHERE

Solar energy

plants

herbivores

carnivores

top carnivores

deat

h an

d de

cay

ENERGY & NUTRIENT FLOW IN A FOOD CHAIN

Solar energy

Plants Consumers (herbivores and carnivores)

DecomposersInorganic nutrient pool

Heat

Heat

HeatEnergy

Nutrients

EXAMPLES OF A FOOD CHAINT

ER

RE

ST

RIA

L F

OO

D C

HA

IN

MA

RIN

E F

OO

D C

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EXAMPLE OF A FOOD WEB

Definition of Biodiversity

“Biological Diversity or Biodiversity- The variety of life in all its forms, levels and combinations. Includes ecosystem diversity, species diversity, and genetic diversity.”

EcosystemsRiver, forest, high alpine, …

SpeciesFir, spruce, oak, …

Genetic diversityDifferent alleles ina population

More Definitions

Visualise the Earth as being made up of building blocks

We start with an INDIVIDUAL

A group of individuals from the same species together in an area is known as a POPULATION

An organism is an individual from any kingdom

More Definitions

Populations of different species are usually found living together making up a COMMUNITY

The grouping of both living communities and their non-living surroundings form an ECOSYSTEM

River, forest, high alpine, …

More Definitions

A BIOME consists of many different ecosystems together

Map taken from: http://www.environment.gov.za/enviro-info/nat/biome.htm

Species diversity

Many studies have focused on a few groups of organisms; mostly plants and vertebrates.

Ecologists should also investigate the effects of environmental change on invertebrates.

InsectsAfter Purvis & Hector 2000 Nature 405: 212-219

Chordates incl.vertebrates

Plants

Biodiversity in South Africa

South Africa is home to an unique selection of species. This even includes the worlds smallest floral kingdom.

South Africa is a signatory to the Convention for Biological Diversity that aims to reduce the loss of biodiversity.

Capensis The Cape Floral Kingdom

The smallest of the six floral kingdoms (the Western Cape province).

With a very rich flora including many endemic plant families.

Like Australis, Capensis is regarded as a segregated remnant of an ancient Antarctic Floral Kingdom (Gondwana).

Fynbos traditionally thought to be less rich in insects than other habitats.

Seeds of many fynbos plants are ant –dispersed (myrmechory)

Cape Floristic Biodiversity Hotspot

One of the world's five Mediterranean hotspotsCharacterised by evergreen fire-dependent

shrublands The greatest non-tropical concentration of

higher plant species in the world The only hotspot that encompasses an entire

floral kingdom, 5 of South Africa’s 12 endemic plant families and 160 endemic genera.

The Succulent Karoo Biodiversity Hotspot

Richest succulent flora on earth69% of plants are endemicReptiles show relatively high levels of

endemismOne of only two entirely arid ecosystems to earn

hotspot statusHome to the mysterious tree-like succulent, the

“halfmens”, as well as many unique species of lizards, tortoises and scorpionsThreats: Grazing, agriculture and mining, especially for diamonds and heavy metals

Maputaland-Pondoland-Albany Biodiversity Hotspot

Highest tree richness of any temperate forest on the planet (nearly 600 tree species)Important centre of plant endemismThe celebrated, bird-of-paradise flower is a

distinctive hotspot endemicRescue of the white rhino from extinction (took

place in this hotspot) one of the best-known success stories in African conservationThreats: industrial and local farming and the expansion of grazing lands

Why should we care about biodiversity?

Why we should worry about biodiversity is debated

Intrinsic value

Ethical value (e.g. god’s creation)

Economic value (e.g. medicines)

Ecosystem services (one of the most important reasons from a scientific perspective) The Earth’s organisms and ecosystems maintain our planet’s life support system

■ Increased stability

■ Increased adaptability

■ Increased productivity

Recreation

But …

Man only uses a small number of species directly for food, medicines, building materials, recreation, … (90% of human food sourced from plants comes from just 30 species)

Many species seem to fulfil similar functions.

Some monocultures are more productive than diverse systems (under ideal conditions).

However, healthy functioning ecosystems are vital to ensure that there essential resources (e.g. air and water) for life on Earth

What determines local biodiversity

Area

Connectivity

Productivity

Disturbance

History

…

Species-area relationship

Larger areas harbour more species. (MacArthur & Wilson 1967 Theory of Island Biogeography, Princeton Univ. Press)

■ less extinctions■ more immigrations■ more diverse habitats■ etc.

Same book also explain why more isolated areas are less diverse.

Diversity-productivity relationship

Overall areas with higher productivity seem to have larger diversity as well.However, some monocultures seem to be very productive (under ideal conditions).Highly productive systems may have reduced diversity through increased competition. The diversity-productivity relationship is scale-dependent.

Intermediate disturbance

Under stable conditions some species will out-compete others.Disturbance creates free space for establishment

by removing strong competitors. Thus disturbance creates a more patchy environment with different successional stages coexisting.However, in strongly disturbed habitats only a few

specialists can survive.Disturbance events can vary in frequency and

severity.

Cattle: cow pads, grazing, trampling

Fire: ash, removal of litter

Tractor: opening of bare Ground, aeration, …

INDICATORS OF BIODIVERSITY

Assumption: indicator is correlated with overall biodiversity.

Indicators can be taxa or abiotic variables

Cost effective

Time savings

Easy and accurate to measure

Biodiversity Indices

Problem how to decide what is a diverse site/ which site has a higher diversity

Simplest method: Species richness

Other Indices contain more information about the species composition than just richness

Equitability or evenness

Evenness

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5

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15

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Site dominated bysingle speciesSite with more evenspecies distribution

Site dominated by one speciesIf you select an individual at random it is likely to be a grasshopper

Site with even species distributionIf you select an individual at random it is equally likely to be any of the four species

Species

# In

div

idu

als

Biodiversity Indices

Shannon-Wiener Diversity: H Shannon-Wiener Equitability: EH

Simpson’s Diversity: D Simpson’s Equitability: ED

S total number of species in the community (richness)

pi proportion of S made up of the ith species

Useful for questions like: “Which site is the most diverse?”“Are school grounds impoverished?”

Biodiversity Indices

Renkonen index Sørensen index

p1i = Frequency of species i in site 1p2i = Frequency of species i in site 2a = Number of shared speciesb = Number of species only in site 1c = Number of species only in site 2

Useful for questions like: “Is ant species composition within a habitat type (e.g. fynbos) more similar than ant species composition between sites from different habitats?”“Are school grounds more similar to each other than nature reserves are to other nature reserves?”

Links (Biodiversity)

Convention on Biological Diversity Handbook (the 3rd Edition) http://www.biodiv.org/handbook/default.asp

IUCN Red lists http://www.redlist.org/

Biodiversity Hotspots http://www.biodiversityhotspots.org/Pages/default.aspx

Links (General)

Air photograps http://earth.google.com/

can be linked with antbase http://www.antweb.org/google_earth.jsp

Control sites: South Africa National Parks

http://www.sanparks.org/

Cape Nature Conservation managed reserves http://www.capenature.org.za