Nutrient Cycle
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The document presents a model of the mineral nutrient cycle in different ecosystems. It uses circles of different sizes and thick arrows to represent the relative amounts of nutrients stored and transferred between biomass, litter, and soil. In taiga/coniferous forests, litter stores the largest amount of nutrients while biomass is low. Soil contains few nutrients due to leaching and slow decomposition of needle leaves. In tropical rainforests, biomass stores the most nutrients due to rapid growth, while litter storage is limited due to fast decomposition, and soil is nutrient-rich but prone to leaching.
Nutrient Cycle
- 2. Model of the mineral nutrient cycle Taiga: Temperate Coniferous Forest Selva: Tropical Rainforest
- 3. ??? What do the circles and letters represent? Why are they in different sizes? What do the arrows represent and why are they in different thickness? B ? S ? L ?
- 4. Model of the mineral nutrient cycle Developed by P.F. Gersmehl in 1976 Attempts to show the differences between ecosystems in terms of nutrients stored in, and transferred between three compartments (represented in circles): Litter Biomass Soil
- 5. Thickness of arrows represent the proportion of nutrient transfers between the components of biomass, litter and soil
- 6. The total amount of organic matter, including humus and leaf litter, in the soil Litter ‘ L’
- 7. Biomass ‘ B’ The total mass of living organisms, mainly plant tissue, per unit area.
- 8. naturally occurring, unconsolidated or loose covering on the Earth's surface. a mixture of mineral and organic constituents that are in solid, gaseous and aqueous states Soil ‘ S’
- 9. Taiga (Coniferous) Litter is the largest store of mineral nutrients in the coniferous forest. Biomass is relatively low in coniferous forest due to: only one layer of coniferous trees little undergrowth contains a limited variety of species needle-like leaves
- 10. Taiga (coniferous) Soil contains few nutrients because: lost through leaching and as surface runoff (after snowmelt when the ground is still frozen low temp restrict the rate of chemical weathering of parent rock and hence replacement rate is slow low temp + thick cuticles of needle-like leaves also discourage the action of decomposers and breakdown of litter into humus is thus very slow hence podsol soils of the taiga have low fertility potential
- 11. Selva (Equatorial Rainforest) Biomass is the largest store of mineral nutrients in the tropical rainforest due to high annual temp + very high and evenly distributed rainfall + year long growing season contributing to tall, dense and rapid growth of vegetation biomass composed of several layers of plants and countless different species
- 12. Selva (Equatorial Rainforest) Litter store is limited , despite the continuous fall of leaves, due to the rapid decomposition of dead vegetation. (Hot & wet climate provides ideal environment for bacterial action.)
- 13. Selva ( Equatorial Rainforest) Soil is rich in nutrients BUT is easily leached and washed away by surface runoff litter content is rapidly reduced so that the soil has to rely upon the replacement of nutrients from the chemical and biological weathering of the bedrock