The hydrological response of Pteronia incana‐ invaded areas in the Eastern Cape Province, South Africa

The impact of vegetation invasion on hillslope soil moisture dynamics was investigated by comparing three surface cover conditions. Soil moisture variations under grass, bare areas and Pteronia incana , a patchy invader shrub, were monitored fortnightly between 01 November 2007 and 01 May 2008 in an experimental setup where high frequency ECH 2 O EC‐20 soil moisture probes connected to a 5‐channel Em50 datalogger were calibrated and installed in the field. Grass cover had consistently high moisture readings during the three major rainfall episodes identified. Soil moisture retention was also greatest under grass cover. The difference in post‐rainfall moisture retention between grass and P. incana surfaces was significant up to about 6 days; thereafter, a parallel trend in soil moisture change was noted. Grass cover experienced the highest moisture loss after each rainfall episode. The constrained soil moisture budget under P. incana and bare areas has implications for runoff conditions and landscape functionality. Despite this, P. incana's resource capture capability, as demonstrated by persistent, albeit limited soil moisture retention, must be taken cognizance of when developing strategies to rehabilitate rangelands with P. incana –bare surface mosaics.