Litter addition as a tool for restoring hydrological processes and controlling erosion in riparian forests disturbed by fine sediment deposition

Abstract

Riverscape aggradation due to the deposition of fine particles above natural forest litter can change the soil, sediment, and water properties, damage riparian vegetation, and reduce environmental integrity, especially in headwater streams. Litter addition techniques that enhance surface roughness and permeability can decrease the interference of fine particles on the ecosystem, representing a low-tech alternative to recover disturbed riparian areas. We aimed to evaluate run-off, percolation, storage coefficients, run-off volume, and sediment yield using a rainfall simulator and the mitigation potential provided by the addition of forest litter to limnological variables-turbidity, total suspended solids (TSS), electrical conductivity, pH, nitrogen-which are indicators of integrity that can reflect streams' aggradation. Fifteen soil samples from a disturbed area (silt and clay deposits aboveground), five from an undisturbed area (sandy soil), and superficial forest litter were obtained from riparian areas adjacent to two small streams in Caraj as National Forest, Brazil. The addition of litter showed great potential to mitigate erosive processes and to reestablish hydrological processes in the disturbed soil. The run-off volume and sediment yield were 2-4 times lower in litter addition treatments compared to non-litter addition. Litter addition also improved run-off water quality, especially turbidity and TSS, which were 12-16 times and 3-13 times lower, respectively. The experimental addition of litter has shown encouraging results to be applied in situ as a sustainable, low-cost, and simplified nature-based solution to contribute to the restoration of degraded riparian forests and reduce in-stream silt and clay aggradation.

The effects of leaf traits on litter rainfall interception with consequences for runoff and soil conservation

“…Finally, we recommend research on possible relationships between the canopy branch and leaf traits of different tree species, as possible agents of throughfall properties, and their leaf litter traits as determinants of the subsequent fate of throughfall water. A better understanding of the effects of leaf litter traits on hydrological processes at the vegetation level will enable us to propose management and restoration strategies with functional targets (Felix et al., 2023; Laughlin, 2014); and to select species composition that maximizes desirable processes, such as soil infiltration and resulting services (e.g. groundwater recharge and soil conservation).…”