Biodiversity within a community

Measuring biodiversity

To assess biodiversity, samples must be taken from a community (all the organisms of all species that live in the same area). When collecting samples, it is essential to ensure they are:

• Random: Sampling should avoid bias, such as selecting only the tallest or most visible individuals. For example:

  • In human studies, each individual can be assigned a number, and random numbers are used to select participants.

  • In studies of animals, random sampling methods can include choosing random locations.

  • For plants or stationary organisms, quadrats can be placed randomly by using coordinates generated from random numbers.

• Representative: A sufficiently large sample size (generally between 10 and 1000) reduces the chances of skewed results and allows for errors or anomalies in measurements.

Species Richness and the Index of Diversity

Species richness is a simple measure of the number of different species in a community, but it doesn’t account for the number of individuals within each species. To provide a more accurate measure of biodiversity, the index of diversity (denoted as d) is often used. The formula for the index of diversity is:

where:

• N = total number of organisms of all species

• n = total number of organisms of each species

• ∑ = sum of the calculated values for each species

A higher index of diversity indicates a greater level of biodiversity, reflecting both the variety of species and the balance of individuals within each species.

Impact of farming on biodiversity

Human activities, particularly farming practices, have significantly reduced biodiversity. Some of the main ways farming impacts biodiversity include:

1. Deforestation and Habitat Loss: The clearance of woodlands and hedgerows to create farmland destroys habitats, removes food sources, and eliminates ecological niches for many species.

2. Monoculture: Growing a single type of crop reduces biodiversity, as it limits the variety of plants and animals that can thrive in that environment.

3. Use of Pesticides: Pesticides kill pests but can also eliminate non-target species, disrupting food chains by removing both predators and prey.

4. Herbicides: Herbicides reduce plant diversity by killing non-crop plants, which in turn reduces food sources for herbivores and other animals reliant on those plants.

5. Fertilisers and Eutrophication: Runoff from fertilisers can lead to nutrient overload in water bodies (eutrophication), causing algae blooms that deplete oxygen and disrupt aquatic ecosystems.

Conservation efforts

To balance conservation with farming, various strategies are employed to maintain or enhance biodiversity:

• Protected Areas: Certain areas are set aside to limit human activity, allowing ecosystems to function with minimal disturbance.

• Agri-environment Schemes: These offer financial incentives to farmers who adopt wildlife-friendly practices, such as maintaining hedgerows and creating wildlife corridors.

• Education and Ecotourism: Raising awareness about biodiversity and promoting ecotourism encourages sustainable use of natural resources.

Biodiversity conservation is crucial not only for ecosystem health but also for potential future resources, such as new medicines. The decline in biodiversity threatens ecosystem stability, and active conservation efforts are essential to preserve the diversity of life on Earth for future generations.

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