This study aimed to evaluate the current status of the Mongolian steppe region using a modified stand quality index (mSQI). The mSQI was calculated by summing the multiplied value of the extended summed dominance ratio (ESn) and indicator species scores (s-score). ESn was calculated as a relative value using the maximum values in all of the communities surveyed or study periods. The s-score was derived from an octave transformation (base-2 logarithmic transformation) of the ESn, and calculated from the ratio of ESn value between grazed and ungrazed stands. For example, s-scores >1.0 indicate that a species is decreased by grazing, and s-scores <1.0 indicate that a species is increased by grazing. In addition, the palatability of plants to livestock was reflected in the indicator s-scores. Species known to be unpalatable were evaluated as having a low s-score in this study. Conventional evaluation methods indicated that the deteriorated land was improved by an increase in the plant biomass even if the abundance of plants of low utility value increased. The mSQI is a new evaluation method that can determine qualitative species characteristics and can be used to identify steppe with high utility value for local nomads.
2015 The Society of Vegetation Science