Understorey plant contribution in water balance along a gradient of oak stand density
Résumé
In the context of climate change, water resources of temperate forest ecosystems may become limiting with risk of stand decline. Forest managers advice to reduce stand density to limit stand water consumption, but this often leads to the development of monopolistic understorey plants. Our objective was to quantify the relative water uptake of two common understorey plants (Molinia cerulea Moench and Pteridium aquilinum Kuhn) in mature Quercus petraea Liebl. stands close to Orléans (47°49’29”N, 2°29’02”E), France. Twenty plots (10 plots per species) were established in spring 2012 along a gradient of stand basal area (from 10 to 30 m².ha-1). On each plot, two circular areas (40 m-diameter) were set up, one weeded and the other untouched. Soil water content (SWC) and tree growth were monitored every two weeks. Understorey had a significant impact on stand water balance in 2012. The SWC minimal values were higher in weeded plots, and under stand with bracken SWC decreased faster than with purple moor-grass. In 2013 we will pay attention to the phenology of both species and consequences on the water balance dynamic. These results will be discussed in relation forest management in the perspective of increasing droughts in the next decades.