Science notes 3.1 p 1

Biodiversity: The variety of organisms found in a specific region, calculated by dividing the number of species by the number of individuals.

Examples:

• Classroom: 2 species (human, bearded dragon), 21 individuals (20 humans + 1 IBb) → Very low biodiversity (0.09)

• San Diego: 680 species, 12,000 individuals → Very low biodiversity (0.05)

• Home: 2 species (dog), 4 individuals → High biodiversity (0.5)

• Biodiversity index closer to 1 indicates greater biodiversity.

Types of Biodiversity:

• Genetic: Variety of genes in a population

• Species: Number of species in a community

• Ecosystems: Number of ecosystems in the biosphere

Measuring Biodiversity:

• Canopy Fogging: Insecticide is sprayed into trees to collect insects on screens for identification.

• Transect Sampling: Area gridded with transect lines; examined at intervals for various species.

• Mist Netting: Fine nets are used to entangle animals like birds and bats.

• Aerial Photos: Photos taken from above for studying migrating animals.

• Surveys: Public reports of sightings in nature.

• Quadrat Sampling: Areas of equal size are sampled for representation (e.g., ripples, insects).

1. Importance of Biodiversity: Higher biodiversity indicates a healthier ecosystem, enabling better responses to changes and disruptions. Stable ecosystems are dynamic and can be affected by natural events (e.g., storms, floods) and human actions (e.g., droughts). These disruptions can change nutrient and food availability, plant productivity, and species numbers. Some ecosystems may not recover from severe disruptions and can transform into entirely different ecosystems (e.g., the change from forest to desert).