CTAP Sampling Design

• Spatially balanced, random sampling
  
• Sampling units are based on 36 square mile townships, there are 1765 within Illinois
• Each 'habitat type' in a township is given random numbers and sites are sampled sequentially until a suitable site, based on protocol parameters, is found.
• Initial selection was prior to the 1997 field season.
• Site sampling is on a 5 year rotation.

Sampled to date

• Forests: 156
• Grasslands: 185
• Wetlands: 180