Productivity in Ecosystems

A grass field in England receives 3.4x1010 kJ/Ha of solar radiation each year.

Each year 8x107 kJ/Ha of this solar radiation is stored as biomass. A further2x107 kJ/Ha is released in respiration.

10% of the grass is consumed by cattle. These cattle have respiratory losses of 2.5x106 kJ per year, and excretory losses of 5.1x106 kJ per year.

Using the information above, answer the following questions by filling the values in the text boxes.

The total amount of energy trapped by a plant during photosynthesis is called it's .Some of this energy is lost as .The rest is stored as tissue or , and is called .

The grass field has a GPP of x108 kJ/Ha per year. x107 kJ/Ha per year is released in respiration, so the NPP of the field is x 107 kJ/Ha per year.

10% of the grass is consumed by cattle so the GPP of the cattle in the field is x106 kJ/Ha per year . These cattle have respiratory losses of 2.5x106 kJ/Ha per year, and excretory losses of 5.1x106 kJ/Ha per year. The NPP of the cattle is x105 kJ/Ha per year

The productivity of the whole ecosystem is called the Gross Ecosystem Productivity (GEP). The Net Ecosystem Productivity (NEP) is the GEP minus .


What natural factors other than the amount of sunlight can affect the productivity of the field?

Humans can influence the productivity of the field. Describe two ways that they can do this.

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