sietokäyrä

A sietokäyrä, or tolerance curve, is a graphical representation used in ecology and toxicology to illustrate the relationship between the intensity of a stimulus and the organism's response or tolerance to it. Typically, the stimulus is plotted on the x-axis, and the organism's response (such as survival rate, growth, or reproductive success) is plotted on the y-axis. The curve shows how the response changes as the stimulus increases.

In ecological contexts, a sietokäyrä might depict how a species' population size or health varies with environmental factors like temperature, pH, or nutrient levels. For instance, a species might thrive within a specific temperature range, showing a peak in its tolerance curve, but its survival or reproduction would decline sharply at temperatures outside this optimal zone. This decline represents a decrease in tolerance.

In toxicology, sietokäyrät are used to assess the impact of chemical substances. They can show the dose-response relationship, indicating the level of exposure at which adverse effects begin to appear, become more severe, or reach a point of maximum effect. Different species or even different individuals within a species can exhibit different sietokäyrät, highlighting variations in sensitivity. The shape of the curve can reveal whether the response is linear, threshold-based, or saturating. Understanding these curves is crucial for setting environmental standards, managing ecosystems, and evaluating the safety of chemicals.