Geography – Nutrient cycling in rainforests and savannas | e-Consult

Gerschmel Diagram for a Grassland Ecosystem:

The diagram illustrates the decreasing amount of energy available at each successive trophic level. Energy is transferred from producers to primary consumers, then to secondary consumers, and so on. At each transfer, a significant portion of the energy is lost as heat.

Impact of Human Activities:

• Pesticides: Pesticides can reduce the population size of primary consumers (e.g., grasshoppers). This leads to less energy available for secondary consumers, potentially causing a decline in their populations. The disruption of the food chain can have cascading effects throughout the ecosystem.
• Fertilisers: Fertilisers can increase the growth rate and biomass of producers (grasses). This can lead to an initial increase in the population of primary consumers, but it can also alter the species composition of the grassland, potentially favouring species that are more tolerant of the fertilisers. However, excessive fertiliser use can lead to nutrient runoff, causing eutrophication and harming aquatic ecosystems.
• Habitat Loss: The destruction of grassland habitats reduces the overall biomass available to support the ecosystem. This can lead to a decline in the populations of all trophic levels, disrupting energy flow and reducing ecosystem stability.

Overall Health of the Ecosystem: Human activities can significantly reduce the efficiency of energy transfer within the grassland ecosystem. This can lead to a decline in biodiversity, reduced ecosystem resilience, and ultimately, a less healthy and productive ecosystem. Sustainable land management practices, such as integrated pest management and reduced fertiliser use, are crucial for mitigating these negative impacts.