Applicable for A-Level, IB, DSE, AP-Level Exams
In land-based and aquatic ecosystems, plants synthesise organic compounds from atmospheric/aquatic CO2 during photosynthesis. Biomass can be measured in terms of mass of carbon or dry mass of tissue per given area. GPP is the chemical energy store in plant biomass whereas NPP is the chemical energy store in plant biomass after respiratory losses to the environent has been taken into account.
To improve efficiency of biomass transfer within farming, farmers can simply food webs to reduce energy losses to non-human food chains. In addition, they can reduce respiratory losses within a human food chain by restricting movement in pens for example.
Nutrients are recycled through ecoystems as they do not have an extraterrestrial source. Saprobionts help in decomposition via extracellular digestion. Mycoorhizae are associations between certain type of fungi and the roots of majority of plants.
Nitrogen cycle occurs in a couple stages: Nitrogen Fixation, Ammonification, Nitrification and Denitrification.
Within the phosphorus cycle, phosphate ions are released into the soil from rocks by weathering. These phosphate ions, with the assistance of mycoohizae, are assimilated into plant DNA and organic molecules. Phosphate ions are then passed along the food chain and are returned via faeces. Phosphate ions can also be passed into aquatic life and food chains and are mainly passed back into the soil via guano.
Organic fertilisers are from the remains of animals and helps the soil structure. Inroganic fertilisers contain a distinct amount of ions required for the growth of crops. Excessive fertiliser use can cause leaching and eventually fertilisers will be washed to rivers and lakes and cause eutrophication: Growth of algae on the surface of the water blocks sunlight and kills aquatic plants; saptrobiotic bacteria decompose the plants and use up oxygen in aerobic respiration. Oyxgen is used up and fishes die as a result.