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 variation of life forms within a given ecosystem, biome, or for the entire Earth. .
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What the syllabus says….. Explain the concept and importance of biodiversity in tropical rainforests
1. What is Biodiversity? Definitions….. Biodiversity is the variation of life forms within a given ecosystem, biome, or for the entire Earth. Biodiversity is the totality of genes, species and ecosystems in a given area 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. 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 Genetic diversity Species diversity Ecosystem diversity Species richness Endemics Range of species Abundance of species Total number 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.
Located within 60 -900 N of the equator Temperaturesare below freezing for most of the year Precipitationis in the form of snow and less than 120mm/year (it is technically a ‘cold desert’) Tundra Vegetationis low growing, wind and frost resistant lichens mosses and shrubs NPP: 140 gms/m2/year
Located mostly in the centre of continents within 40 -600 N & S of the equator Temperatures Winters are cold (-200C) summers are hot (+200C) Temperate Grasslands Precipitationis in the form of snow in winter and heavy showers in summer. Annual totals in the order of 400mm/year Vegetationis 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 coasts TemperaturesSummers are relatively cool, winters are mild Precipitationis mostly rain which falls in the winter months. It totals around 1000mm/year Vegetationis 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 equator Temperaturesare high all year Rainfallis over 2000mm and falls throughout the year Vegetationis 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 TRF Use 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
50% energy loss at each level by respiration and decay Trophic levels 4 - Tertiary Consumers 3 - Secondary Consumers 2 - Primary Consumers 1 - Primary Producers
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.
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.