قاب (نمونه‌برداری)

thumb|A quadrat used to measure the percentage cover of certain species A quadrat is a frame used in ecology, geography, and biology to isolate a standard unit of area for study of the distribution of an item over a large area. Quadrats typically occupy an area of 0.25 m2 and are traditionally square, but modern quadrats can be rectangular, circular, or irregular. A quadrat is suitable for sampling or observing plants, slow-moving animals, and some aquatic organisms.