Vegetation at Kushiro Wetland, Alder
Expansion of Alder Area

Alder is able to be observed at almost all of low moors in Japan, and is known as the rare vegetation to grow to be arboreal vegetation there. At Kushiro wetland, the alder area has been expanded rapidly recently, and reaches about 30% of wetland area in 1998.

Various reasons are considered for this expansion, such as wetland aridification cuased by the accumulation of sand and soil and/or the lower of groundwater level, and the changes of nutrition contents into the wetland which are nitrogena and phosphorous in general. There are in fact some studies to shows some relation of alder expansion and these causes, yet the relation is not able to be concluded to be based on sound science.

An important matter first is to make sure scientifically why the alder vegetation has been expanded rapidly. Based on the results from those studies, the management to this issue has to be considered carefully
Alder at Hirosato Area in 1993
Alder at Hirosato Area in 2000
Comparison of Alder Vegetation at Hirosato Area
At the Hirosato area, the alder vegetation has been expanded about 130m2 in 7 years.