Species numbers, area, and habitat diversity on the habitat‐islands of Mizorogaike pond, Japan

Species‐area relationships of flowering plants were analyzed on the habitat‐islands (hummocks on a floating bog) of Mizorogaike Pond, Japan. Three habitat units ( Sphagnum cuspidatum unit, Sphagnum palustre unit, and fallen leaves unit) in which habitat conditions were homogeneous and a group of habitat‐specific species occurred were recognized on the hummocks. Six hummock types were determined according to various combinations of the three habitat units. The most fundamental species‐area relationships in which size itself affects the number of species were shown by hummocks with only one habitat unit. The species‐area relationships for hummocks with two or three habitat units included the effects of habitat diversity in addition to size. The speciesarea curve for all hummocks was an average of these relationships. It is concluded that area in species‐area relationships affects species numbers in two ways: number of habitat units and size of each habitat unit.