Plant Species Diversity Creates Long-term Stability

Biological Strategy

Prairie ecosystem

AskNature Team

Image: Ryan Stone on Unsplash / CC BY - Creative Commons Attribution alone

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.

Search this Function

Maintain Biodiversity

The greater the amount of genetic and species variation in an ecosystem, the more resilient that ecosystem is to disturbances. Variation in ecosystems across the Earth also contributes to the Earth’s resilience to unpredictable changes. This variation is called biodiversity. Because living systems compete with each other for scarce resources, maintaining biodiversity involves creating conditions for a large variety of species to successfully co-occur and reproduce. For example, within a wetland, there are different vegetation types. This diversity results in a complex mosaic of microenvironments as the vegetation types alter air flows, light regimes, and water temperatures and chemistry. Because organisms vary in their ideal environmental conditions, these micro-environments increase the diversity of plants in the wetland. In turn, having a wetland in an otherwise dry area increases biodiversity at an even larger scale.

Search this Function

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.

Search this Living System

Diverse plant species in prairie grasslands support a long-term, stable ecosystem because they exhibit complementary functionality.

An ecosystem is a biological community of interacting organisms and their physical environment. A healthy ecosystem includes multiple species that serve similar functions or roles – for example, more than one species that fertilizes the soil and more than one that controls the population of a certain predator. This redundancy is crucial to supporting the long-term stability of the ecosystem because natural disturbances – such as fires, disease, or changing climate – can sometimes eliminate entire species unable to survive the change. With redundancy in environmental function, if one species dies off, another species that serves a similar role is more likely able to react and thrive after the disturbance. It can then take the place of the previously dominant species, thereby keeping the ecosystem resilient.

Image: Francesco Ungaro / CC BY - Creative Commons Attribution alone

Image: Ryan Stone on Unsplash / CC BY - Creative Commons Attribution alone

For example, consider a situation in which a prairie grassland ecosystem’s main food-producing plant is completely destroyed by a fire. A plant species that was previously less abundant may now be better suited to live in the new soil conditions, and therefore become the new dominant food-producing plant species serving the grassland. As long as the post-fire composition of plant species fills the same functional role as the pre-fire plant community, then the prairie will be able to survive the fire intact.

This summary was contributed by Ashley Meyers.

Image: Emily Harrington /

1) In a low diversity system a disturbance (red) could wipe out the entire population. 2) In a high diversity system, only some members of the population perish, leaving others to take their place and keeping the system functioning.

Last Updated June 18, 2020

References

Journal article

Biodiversity: Population Versus Ecosystem Stability

Ecology | 09/05/2006 | David Tilman

embedly preview

Reference

Journal article

Compensation and the Stability of Restored Grassland Communities

Ecological Applications | 02/10/2007 | Eric W. Seabloom

embedly preview

Reference

“More diverse communities have been shown to have higher and more temporally stable ecosystem functioning than less diverse ones, suggesting they should also have a consistently higher level of functioning over time. Diverse communities could maintain consistently high function because the species driving function change over time (functional turnover) or because they are more likely to contain key species with temporally stable functioning. Across 7 y in a large biodiversity experiment, we show that more diverse plant communities had consistently higher productivity, that is, a higher level of functioning over time. We identify the mechanism for this as turnover in the species driving biomass production; this was substantial, and species that were rare in some years became dominant and drove function in other years. Such high turnover allowed functionally more diverse communities to maintain high biomass over time and was associated with higher levels of complementarity effects in these communities. In contrast, turnover in communities composed of functionally similar species did not promote high biomass production over time. Thus, turnover in species promotes consistently high ecosystem function when it sustains functionally complementary interactions between species. Our results strongly reinforce the argument for conservation of high biodiversity.” (Allan et al. 2011:17034)

Journal article

More diverse plant communities have higher functioning over time due to turnover in complementary dominant species

Proceedings of the National Academy of Sciences | 27/09/2011 | E. Allan, W. Weisser, A. Weigelt, C. Roscher, M. Fischer, H. Hillebrand

embedly preview

AskNature