Home▸Articles▸Ecology & Conservation Biology

Species Accumulation Curve: Understanding Biodiversity in Sampling

A powerful tool for ecologists to estimate biodiversity from limited samples.

mysimulator teamUpdated June 2026≈ 3 min read▶ Open the simulation

What is a Species Accumulation Curve?

A species accumulation curve (SAC) plots the number of unique species discovered against the total number of samples collected. It helps ecologists understand how biodiversity changes as more samples are taken from an environment.

The curve typically starts steep, indicating rapid discovery of new species, and levels off as more samples are added, suggesting that most species have already been identified.

How Does Sampling Affect the Curve?

Sampling methods significantly influence the shape of the SAC. Random sampling tends to provide a smoother curve with less variability compared to systematic or clustered sampling, which can lead to more erratic patterns due to spatial clustering of species.

The true richness of an environment is often estimated using statistical models like Chao2, which accounts for rare species that may not be detected in initial samples.

live demo · related simulation● LIVE

Why Use the Species Accumulation Curve?

Understanding SACs helps ecologists design more effective sampling strategies and estimate the total number of species present in a given area. This information is crucial for biodiversity conservation, ecosystem management, and understanding ecological processes.

By analyzing the curve, researchers can determine when additional samples are needed to achieve a reliable estimate of species richness.

Real-World Applications

Species accumulation curves are used in various fields such as environmental monitoring, biodiversity hotspots identification, and ecological impact assessments. They help in making informed decisions about conservation efforts and resource allocation.

In practical scenarios, SACs can guide the design of protected areas or inform policies aimed at preserving endangered species.

Frequently asked questions

What does a steep curve indicate?

A steep curve indicates high biodiversity, suggesting that many new species are being discovered with each additional sample.

How can the Chao2 estimator improve species richness estimation?

Chao2 estimator corrects for underestimation by accounting for rare species in initial samples, providing a more accurate estimate of total species richness.

Why is sampling order important?

Sampling order can affect the shape and reliability of the SAC. Randomized sampling tends to provide more consistent results compared to systematic or clustered approaches.

How does spatial clustering impact species richness estimation?

Spatial clustering can lead to overestimation of species diversity because it may not capture the true distribution of species across the landscape, especially if species are patchily distributed.

Try it live

Everything above runs in your browser — open Species Accumulation Curve — Ecological Sampling Simulator and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.

▶ Open Species Accumulation Curve — Ecological Sampling Simulator simulation

What did you find?

Add reproduction steps (optional)