Effects of small rock check dams on channel bed, vegetation diversity, and soil properties 10 years after a severe wildfire in forest micro-catchments of central eastern Spain

Abstract

One of the most common post-fire management techniques is the construction of check dams in catchments. However, little research has explored how small check dams impact on bed profile, vegetation diversity and soil properties several years after their construction in Mediterranean ephemeral channels draining micro-catchments burned by severe wildfires. To fill this gap, this study has evaluated the effects of rock check dams installed about 10 years ago in small catchments after a wildfire in Castilla La Mancha (Central Eastern Spain). The changes in channel morphology, plant diversity as well as a large dataset of soil properties have been analysed close to the check dams in comparison to burned but non-regulated channels. Neither the channel slope nor bed sediment size significantly changed downstream and upstream of the structures in comparison to the non-regulated channels. Thanks to the unexploited retention capacity, the studied control works are still able to store the mobilised sediments on occasion of the most intense floods. Higher species richness in both upstream and downstream sections (+64%) was detected, while the plant evenness was not altered compared to the non-regulated channels. Regarding the soil properties, increases in organic matter (over 200%), nutrients (+72% for N and +152% for P) and some cations (+29% for Ca and +86% for Mg) were measured. Overall, the presence of the rock check dams in the burned micro-catchments, although improving many key plant and soil characteristics, did not sharply change the hydrological, geomorphological and ecological conditions compared with those of the non-regulated catchments.