Effects of moss restoration on topsoil water dynamics in a temperate vineyard

Abstract. Climate change is intensifying pressure on vineyard soil and water management, particularly under-vine, where vegetation is commonly suppressed to minimize competition with grapevines. Bryophytes represent a promising but little-tested alternative to bare soil or cover crops. We evaluated moss restoration as an under-vine ground cover in a temperate, rainfed vineyard in southwestern Germany, comparing it with bare soil and cover crop (grass) over a 22-month field experiment. Continuous topsoil moisture measurements using time-domain transmission sensors were used to analyse the initial response time (the time between the onset of precipitation and the first increase in topsoil moisture) and the peak response time (the time between the onset of precipitation and the maximum topsoil moisture). We additionally quantified mean topsoil moisture and drying rates and monitored treatment development during and after maintenance.

Moss restoration did not significantly delay topsoil moisture response times following precipitation compared to grass or bare soil. Initial response times followed the pattern grass > moss > bare soil; differences between treatments were most pronounced under light and moderate precipitation and declined with increasing intensity, with moss and bare soil converging under heavy events. Peak response times followed a similar pattern (grass > moss ≈ bare soil), with significant differences restricted to light and heavy precipitation events: grass exhibited longer peak response times than bare soil under light rainfall and longer times than both bare soil and moss under heavy rainfall. Mean topsoil moisture did not differ significantly among treatments, whereas drying rates were higher under moss and bare soil than under grass. Moss plots initially suppressed grass establishment and consistently exhibited the lowest variability in topsoil moisture response, although vegetation cover and functional differences between treatments gradually converged after maintenance ceased.

Overall, moss restoration maintained topsoil moisture dynamics comparable to bare soil while avoiding the delayed infiltration and higher variability associated with grass cover. These results suggest that mosses may provide a low-maintenance under-vine ground cover with stable hydrological functioning, warranting further investigation into their long-term persistence and performance under future climate and management scenarios.