Species Richness Helps System Respond to Disturbance

golden light pours over a wetland ecosystem with cat tails, wild flowers and trees

Biological Strategy

Ecosystems

AskNature Team

Image: Mateusz Liberra / Shutterstock / Some rights reserved

Protect From Animals

Animals–organisms that range from microscopic to larger than a bus–embody a wide variety of harms to living systems, including other animals. They threaten through predation, herbivory, defense, and parasitism, and they compete for resources such as water, nutrients, and space. Any given living organism commonly faces threats from a variety of animals, requiring strategies that effectively defend from each. Trout and other bony fish, for example, escape predators by having scales made of very thin, flake-like pieces of bone covered with slippery mucus. They also have behavioral strategies such as camouflage, fast swimming, and twisting and turning to achieve release from a predator’s grip.

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Manage Disturbance in a Community

When environmental conditions change, they can disrupt an ecosystem’s equilibrium. Excessive rain can cause flooding and drought can cause forest fires. An ecosystem must be resilient to such disturbances. Disturbances are unpredictable in location, size, and intensity, so ecosystems must be able to regrow and must have a variety of duplicate forms, processes, or systems that are dispersed in location. For example, a forest ecosystem can recover from fire because diverse organisms play different roles in different ways and in different locations. Many organisms can resprout or grow from seeds triggered by fire, and their dispersed distribution ensures that an entire population isn’t decimated. Though the recovered ecosystem may look totally different from the pre-fire one, the ecosystem as a whole remains healthy.

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a mountain with snow is in the background of a landscape with trees and shrubbery

Ecosystems

Eco- ("household"), system ("organized whole")

An ecosystem consists of all the biological and nonbiological elements that make up a defined area. That definition might seem vague, but that means it’s flexible: We can apply the word across different scales and times. Ecosystems can be small, like a single tide pool, or large, like coastal wetlands. Ecosystems can include plants, animals, bacteria, fungi, rocks, temperature, light, soil, and climate—all linked through the flow of energy and cycle of nutrients. Each part of an ecosystem interacts with, and is influenced by, other members of the system. These interactions are dynamic, leading to changes to any ecosystem over time.

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Ecosystems survive biotic and abiotic disturbances by having multiple species that respond in different ways.

“Woodward (1993) in his discussion of how many species are required for a functional ecosystem concludes that there is some evidence that if the individual species in an ecosystem exhibit a range of different frequency responses (i.e. where the resource requirements for optimal growth vary), then the more species, the greater the frequency richness and ecosystem stability. This implies that the greater the number of crop species the more assured one would be of achieving a harvest. This is consistent with the practices of subsistence farmers. A more assured income is also a prerequisite for a commitment to expenditure associated with maintaining landscape level ecosystem services. From this discussion it is possible to conclude that in an agricultural ecosystem diversity is advantageous, however, it must be planned to meet specified design criteria such as yield, insurance against crop failure or supply ecosystem services which contribute to an avoidance of the harmful effects of rising water tables, salinity, soil erosion and changes in soil structure.” (Main 1999:31)