Nutrient Cycles

• There is limited availability of nutrient ions in a usable form. It is important that elements such as carbon, nitrogen and phosphorous are recycled.
• Every nutrient cycle follows one simple sequence. This begins when the nutrient is take up by producers as simple, inorganic molecules, which are then incorporated into organic molecules. When the producer is eaten, the nutrient passes into consumers. It then passes along the rest of the food chain.
• When producers and consumers die, their complex molecules are broken down by saprobiontic microorganisms (decomposers) that release nutrients in the original simple form. This concludes the nutrient cycle.
• Saprobionts are highly important in nutrient cycles - without them, nutrients would remain locked up as part of complex molecules that cannot be taken up and used by plants.
• Mycorrrhizae are associations between certain types of fungi and the roots of the vast majority of plants. The fungi act as extensions of the plants root system and vastly increase the total surface area for the absorption of water and mineral ions.
• The mycorrhizae acts like a sponge, and can hold water and mineral ions in the region around the roots. This adaptation enables the plant to better resist drought and to take up inorganic ions more readily.
• The mycorrhizal relationship between plants and fungi is a mutualistic one. The plant benefits from improved water and inorganic ion uptake, whilst the fungus receives organic compounds, such as sugars and amino acids from the plant.