A fundamental law of biology: the number of species is proportional to roughly the third root of area. This is true for animals and plants.
It makes sense! More area allows more species to exist. The number of species cannot increase as fast as the area, since some species in the smaller area will be found in the larger area.
Thus the rule of thumb: if you consider an area ten times larger, you will find twice as many species.
Example just outside of the SRPER: common tidy-tips, Layia platyglossa
http://tchester.org/srp/plants/communities/7.html
Comments and feedback: Tom Chester
Last update: 6 November 2005.