Disturbance (ecology)

Introduction

Disturbance in the context of ecology refers to a temporary change in environmental conditions that causes a pronounced change in an ecosystem. Disturbances can have profound immediate effects on ecosystems and can, consequently, greatly alter the natural community. These changes can either be physical (such as an earthquake or fire) or biological (such as an infestation of insects or the introduction of a new species).

A forest fire, one of the most common forms of ecological disturbance.

Types of Disturbances

Disturbances can be categorized into several types based on their causes, effects, and durations.

Natural Disturbances

Natural disturbances are those that occur as a result of natural processes. These include events such as earthquakes, volcanic eruptions, tsunamis, hurricanes, tornadoes, floods, droughts, wildfires, and landslides. These disturbances can drastically alter the physical environment and can have significant impacts on the biological communities within the affected ecosystems.

Anthropogenic Disturbances

Anthropogenic disturbances are those that are caused by human activities. These include events such as deforestation, urbanization, pollution, climate change, and overfishing. These disturbances can lead to the degradation of ecosystems and loss of biodiversity.

Biological Disturbances

Biological disturbances are those that are caused by the activities of organisms. These include events such as pest infestations, invasive species, diseases, and overpopulation. These disturbances can alter the composition and structure of biological communities and can lead to changes in ecosystem function.

Effects of Disturbances

The effects of disturbances on ecosystems can be varied and complex. They can lead to changes in species diversity, community structure, and ecosystem function. These changes can be either positive or negative, depending on the nature of the disturbance and the characteristics of the affected ecosystem.

Changes in Species Diversity

Disturbances can lead to changes in species diversity. This can occur through the elimination of sensitive species, the proliferation of resistant species, or the introduction of new species. The net effect on species diversity can be either positive or negative, depending on the nature of the disturbance and the resilience of the affected ecosystem.

Changes in Community Structure

Disturbances can lead to changes in community structure. This can occur through the alteration of species interactions, the disruption of food webs, or the modification of physical habitats. The net effect on community structure can be either positive or negative, depending on the nature of the disturbance and the resilience of the affected ecosystem.

Changes in Ecosystem Function

Disturbances can lead to changes in ecosystem function. This can occur through the alteration of nutrient cycling, the disruption of energy flow, or the modification of ecosystem services. The net effect on ecosystem function can be either positive or negative, depending on the nature of the disturbance and the resilience of the affected ecosystem.

Disturbance Regime

A disturbance regime refers to the pattern of disturbances that a particular ecosystem undergoes over time. It is characterized by the type, frequency, severity, and spatial distribution of disturbances. Disturbance regimes play a crucial role in shaping the structure and function of ecosystems.

Disturbance and Succession

Ecological succession is the process by which the structure of a biological community evolves over time. Disturbances play a key role in this process by creating opportunities for new species to establish and grow. The nature and intensity of disturbances can influence the rate and trajectory of succession.