Water manipulation by dam construction has resulted in stabilization of downstream soil bars with subsequent stable forestation, starting from grasses. Eragrostis curvula, one such dominative grass have been investigated in this study. Three transects (each approximately 50 m) were selected in the Arakawa river flood meadow, Kumagaya. Field investigations were carried out in late spring to early autumn (2007), part of the year which, relatively sever rainfalls with subsequent flooding as well as high temperatures taking place.

The colony parameters were tested with environmental parameters that include soil moisture content and its deviations, soil morphology and nutrient levels. For the relationship building CANOCO 4.5 and linear regression were used.

Substandard soil conditions with poor nutrient levels resulted in mono E. curvula colonies. However colonization of E. curvula reduced with the increase in soil water content, and large deviations to it proved to be a significant inhibitor. High nutrient levels coupled with high soil moisture and its associates gave a competitive disadvantage over other perennial plants. Irrespective of number of colonies it showed significant levels of adaptation to its micro environments by way of biomass allocation and root morphological plasticity.