BLANCO RIVER RIPARIAN FOREST REGENERATION FOLLOWING A RECORD FLOOD IN CENTRAL TEXAS

Abstract

A record flood in 2015 resulted in widespread disturbance of the Blanco River riparian corridor with extensive loss of vegetation through floodplain stripping. The riparian forest along the Blanco River is slowly recovering via two primary pathways—natural regeneration from the seedbank and through resprouting of damaged trees. We conducted a study of woody riparian vegetation along the Blanco River to quantify the composition of the recovering forest community and the proportion of trees that are regenerating by resprouting vs. seedbank colonizers. The study captured overall compositional and density patterns as well as comparisons among three geomorphic settings including instream channel bars, the riverbank and near-channel lower elevation floodplain, and the higher-elevation floodplain to upland terraces. Seedlings represented 90% of the density and only 2% of the biomass; in contrast, resprouted trees represented 10% of the density and 98% of the biomass. Fast-growing pioneer species such as sycamore (Platanus occidentalis) and black willow (Salix nigra) were dominant nearest the river channel while facultative and upland species such as pecan (Carya illinoiensis) and hackberry (Celtis spp.) dominated plots higher on the floodplain. Seedlings were far more numerous than resprouts, and seedling density was highest in plots along the riverbank and closest to the channel.