Ecosystem profile assessment of biodiversity: sampling protocols and procedures
Mahan C, Sullivan K, Kim KC, Yahner R, Abrams M, Snyder C, Lemarie D, Young J, Smith D, Ross R, Bennett R. 1998. Ecosystem profile assessment of biodiversity: sampling protocols and procedures. ER9806. Pennsylvania State University. University Park, PA
Ecosystems are a mosaic of interacting organisms occupying an area, and include the physical environment.