Ligustrum lucidum invasion alters the soil water dynamic in a seasonally multi-specific dry forest

Abstract

Plantinvasion is one of the major global environmental threats with the potential toalter the ecosystem stability and functioning. In water-limited ecosystems, theimpacts of non-native invasive trees on the water balance are particularlyrelevant since they can compromise the use of water by native taxa of theecosystem and water provision for humans. In this paper, we assessed thehydrological impacts of the Ligustrum lucidum (Chinese glossy privet) invasionon a mountain seasonally dry forest of the Chaco region (Central Argentina).More specifically, we determined volumetric soil water content, runoff, andactual evapotranspiration, and their relations to the size of rainfall eventsin native forest stands and its adjacent invaded stands. We combined three-yearsfield measurements and remote sensing data. L. lucidum stands showed less watercontent through the soil profiles than the native forest (0–70 cm depth; 19.6and 23.1 %, respectively), particularly during the dry conditions. The driercondition in the deeper soil layers compared to the upper ones in the invadedstands indicated less rainwater percolation throughout the soil profile overthe year, independently of the magnitude of the rainfall events. Dailyvariation of deep-water content (60–70 cm depth), only observed in L. lucidumstands, showed nightly increase and day-time decrease in dry conditions. Runoffwas similar and almost nil in both native and invaded forests, even after largerainfall events (>30 mm). L. lucidum stands showed ~ 18% higher annualactual evapotranspiration rates than native stands. Based on our results,relatively higher water consumption for mono-specific L. lucidum stands inperiods when photosynthetic activity of multi-specific native dry forest isstill low may represent a competitive advantage in terms of plant invasion, andat the same time it generates negative impacts on water resources, reducingsoil water content and limiting deep-water recharge in a water-limitedecosystem.