The number of different species in a community is measured through two parameters. These parameters are species richness and species diversity.

Species richness measures the number of different species living in a community or area. For instance, if we found an area with 200 species and 20 species in another, the first community will have higher species richness than the second.
Species diversity is a measure of community complexity. It is a function of species richness and the abundance of species (species evenness) in the community. Higher species diversity is found in the community with many species and an abundance of even species.
For instance, a forest community with 30 different types of trees in even abundance will have higher species diversity than another forest community with 30 different types of trees but in an uneven abundance.
In general, ecologists believe that more diverse ecological communities are stable, which means they can recover after a disturbance. However, the diversity-stability relationship is not a universal rule. But, it is important for a biological community of organisms and their environment to evolve over time for survival.
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Communities evolve to have greater biomass and species richness in a process called
Communities evolve to have greater biomass and species richness in a process called succession. Succession is the term used to describe the process of community progression from lower species diversity to higher species diversity that is more stable.

Several different species make up a community in an ecosystem that may experience succession. Succession is sometimes avoidable and unavoidable. There are two types of successions:
- Primary Succession: The primary succession occurs when a new land, area, or community is exposed for the first time for habitat. For instance, a volcanic eruption can lead to primary succession as lava flows from the volcano, forming new habitation rocks.
- Secondary Succession: A secondary succession occurs when re-colonization occurs in a vast geographic area sharing a similar ecosystem. For instance, secondary succession occurs in forests disturbed by a wildfire burning most trees, vegetables, plants, and grass.
Succession is predictable and non-predictable. Wildfire in forests and volcano eruptions is a perfect examples of predictable succession. Accidental fire or damage to the environment is not predictable. Succession takes place in the ecosystem irrespective of its location. However, the most important factor that determines where major ecosystems are located on the globe is climate.
During the succession, the plants air and water around us experience a change that either degenerates or re-colonises an ecosystem. It is vital to note that succession primarily occurs with living things.
It is interesting to see how the number of species that live in an area evolves. Some ecosystems, for instance, may experience disturbances that may prevent communities from evolving. But not all communities go through the same disturbance that may encourage the progression of species.
Identify two factors that account for the diversity of species
The two factors that account for the diversity of species include:

- The number of species within the community or species richness.
- The number of individuals per species or species abundance.
Species richness is determined through census or simply counting the number of species living in an area. Species abundance is determined by dividing the number of species from one group by the total number of species from all groups.
In a population of bats living in a certain region
In a population of bats living in a certain region, there might be some free-tailed, silver-haired, and big-sized bats. The population living things such as bats largely depend on environmental factors. For instance, the big brown bats are found in the North American region. But how organisms interact with the environment cycle within an ecosystem also plays a crucial role in determining their population.
Species a and b are found in the same ecosystem
Species a and b found in the same ecosystem qualify for species diversity in the area. Species diversity is the measure of community complexity. Species diversity is calculated considering species richness and species evenness. A high number of species with more species evenness leads to higher species diversity.
Which of the following correctly describes a biological community?
All living things in an environment describe a biological community. A biological community or ecosystem is a place where species interact in a group.

The place could be a jungle inhabited by wild animals, soil containing fungi and bacteria, trees inhabited by birds and more. All ecosystems taken together make up a biome, a large area of lands, ponds, forests, reefs, and more.
Which of the following describes the number of different species in the community?
A different set of trees in a forest describes the number of different species in the community. Species can be anything living, such as a different set of microorganisms living in the soil. Species play a critical role in maintaining the balance of the ecosystem. Most species depend on each other directly or indirectly for survival.
Which term describes the number of different species in a community?
The term that describes the number of different species in a community is called biodiversity. Biodiversity considers all the living things, including fungi, animals, microorganisms, plants, bacteria, and others that work together to stabilize and support life in the ecosystem.
Biodiversity is the term that describes the number of different species living in an area.
Biodiversity is the term used to describe the enormous types of life on Earth. Several different species make up a community or ecosystem. A study of how living things on earth hints that more than 8.7 million species of animals and plants exist. But, only 1.2 million species have been identified so far.
Over time, the species have evolved with new traits that make them different from other species. The role of a species in an ecosystem is more than generating a life circle. These species ensure that life in the ecosystem is balanced and stabilized.