Introduction to Biodiversity

What the syllabus says…..

Explain the concept and importance of

biodiversity in tropical rainforests

1. What is Biodiversity?

Definitions…..

Biodiversity is the variability among living organisms from all sources..... Terrestrial, marine and aquatic ecosystems and the ecological complexes of which they are a part: this includes diversity within species, between species and of ecosystems.

Biodiversity is the totality of genes, species and ecosystems in a given area

Biodiversity is the variation of life forms within a given ecosystem, biome, or for the entire Earth.

A clear, concise definition …… p.38 IB Study Guide

Species diversity- the number of species in a given area.

Genetic diversity- The genetic variation within species. This can be in populations that have been separated geographically, but also amongst individuals within single populations.

Ecosystem diversity- this looks at the variety of different ecosystems or habitats that occur within an area and takes into account the biotic and abiotic components.

Biodiversity

Range of species

Total number of species

Genetic diversity Ecosystem diversity

Species diversity

Endemics Species richness

Abundance of species

Measuring biodiversity Large-scale global ecosystems (biomes) differ in their biodiversity. The following are examples of biomes (global ecosystems) ordered from higher to lower latitudes. There are clear differences in

climate (temperature and precipitation) and therefore biodiversity.

A key concept is NET PRIMARY PRODUCTIVITY. This is the amount of new

biomass that is produced each year (biomass = Total amount of living matter present at any given moment in an

ecosystem. Expressed as dry weight of tissue per unit area)NPP is given in grammes per m2 per year.

Biomes of the World

Tundra

Located within 60 -900 N of the equator

Temperatures are below freezing for most of the year

Precipitation is in the form of snow and less than 120mm/year (it is technically a ‘cold desert’)Vegetation is low growing, wind and frost resistant lichens mosses and shrubs NPP: 140 gms/m2/year

Temperate GrasslandsLocated mostly in the centre of continents within 40 -600 N & S of the equator

Temperatures Winters are cold (-200C) summers are hot (+200C)

Precipitation is in the form of snow in winter and heavy showers in summer. Annual totals in the order of 400mm/year

Vegetation is almost entirely grassland. The wetter the area the taller the prairie grasses. Human use of these areas is dominated by wheat and cattle farming.

NPP: 600 gms/m2/year

Temperate Deciduous Forest

Located 40 -600 N & S of the equator, nearer the coastsTemperatures Summers are relatively cool, winters are mildPrecipitation is mostly rain which falls in the winter months. It totals around 1000mm/year

Vegetation is deciduous woodland (oak, ash, elm and beech) which lies dormant in the winter when light levels are low

NPP: 1200 gms/m2/year

Rainforest

Located within 100 N or S of the equatorTemperatures are

high all year

Rainfall is over 2000mm and falls throughout the year

Vegetation is dense and mostly trees often found in 3 layers – shrub layer, canopy and ‘emergents’ (forest giants)

NPP: 2200 gms/m2/year

Main reasons for differences in biodiversity

• Climate (precipiation and temperature)

Precipitation (total, variations over time, intensity) Temperature Temperature range (range from min to max) Length of growing season

• Nutrient cycles• Amount of sunlight for photosynthesis

Biodiversity and climate

• Planet Geography p.311 for summary of climate types and biomes

• Advanced Geography p.212 for brief notes on characteristics of TRF climate.

Nutrient cycling• Nutrient cycling occurs within an ecosystem.• Nutrients are the chemical elements and

compounds organisms need to grow and function.

Nutrient cycling in the TRFUse the following text to make brief notes…• Advanced Geograpy p.206

You need to understand how nutrient cycling works and the characteristics of nutrient cycling in the TRF

If you are new to ecosystems and haven’t much of an idea about nutrient flows, trophic levels and food chains, a read through the following texts will give you a brief introduction. Whilst these concepts are not specified in the syllabus, it is important to understand the processes so that you can then see how reduction of biodiversity in the TRF has important environmental consequences.

Planet Geography p.303-307

Advanced Geography p.204-206

Trophic levels

1 - Primary Producers

2 - Primary Consumers

3 - Secondary Consumers

4 - Tertiary Consumers

50% energy loss at each level by respiration and decay

2. The importance of biodiversity An ecosystem is a complex set of relationships among the living resources, habitats and residents of an area, including plants, birds, trees, fish and microorganisms, soils, water and people.

Ecosystem services

Extra reading

‘The Guardian’ environment section has a part dedicated to the

issue of biodiversity (link on our website). There is a wealth of

information on this topic and it is well worth a visit.