Vegetation restoration and plant roots improve soil infiltration capacity after a severe forest fire in Daxing’anling, northeast China

Abstract

Soil infiltration plays an important role in the transformation of precipitation into surface water, soil water, and groundwater. Forest fires significantly alter soil quality and hydrological processes. Identifying a method to accelerate the restoration of soil infiltration capacity after forest fires is of major interest. Vegetation restoration may greatly influence soil infiltration capacity by altering soil and vegetation properties. However, little is known about the relationships among root biomass, soil properties, and infiltration capacity after severe forest fires. The objectives of this research were to assess soil infiltration capacity during vegetation restoration and to identify the strongest predictors of infiltration among various soil properties and the biomass of roots of different diameter classes. The influences of vegetation restoration approaches (planted regeneration and natural regeneration [NR]) on root biomass, soil properties, and infiltration rates in burnt areas were observed. Total root biomass increased each year following the burn (3.808 to 56.690 t hm^–2). The soil physical and chemical properties improved more after 24 years of restoration than after other restoration durations. The initial infiltration rate (IIR), steady infiltration rate (SIR), and average infiltration rate (AIR) of the soils increased as vegetation restoration progressed. The IIR, SIR, and AIR after 24 years of restoration were higher than those under NR. Correlation analysis showed that IIR, SIR, and AIR correlated significantly and positively with coarse root biomass (biomass of >2 cm diameter roots, RD_coarse), total root biomass (RD_total), and soil organic matter (SOM). The conceptual path model demonstrated that among the studied properties, RD_coarse and SOM most strongly affected soil infiltration, which increased as vegetation restoration progressed. Coarse roots (>2 cm diameter) played a more important role in improving soil infiltration than other root types. Planted regeneration is more conducive to accelerating the restoration of soil infiltration than NR in Daxing’anling, northeast China.