Climate and ungulate browsing impair regeneration dynamics in spruce-fir-beech forests in the French Alps

Abstract Key message Different components of water balance and temperature reduce density height growth saplings Picea abies (L.) H. Karst (Norway spruce), Abies alba Mill. (silver fir) Fagus sylvatica L. (European beech) in mixed uneven-aged forests the French Alps Jura mountains. Ungulate browsing is an additional pressure on fir beech that could jeopardise renewal these species future. Context The uncertainty tree recruitment rates raises questions about factors affecting regeneration processes forests. Factors such as climate, light, competition ungulate may play important role determining regeneration, forest structures thus future composition. Aims objective this study was to quantify sapling densities increments spruce, identify dominant environmental variables influencing them Methods Sapling increment were recorded 152 plots, non-linear models obtained establish relations between known affect namely altitude, slope, aspect, canopy openness, soil characteristics, temperature, precipitation browsing. Results Regeneration density, varying from 0 7 per m 2 , decreased with also negatively affected for spruce by PET, but positively mean annual content. Height reached up 50 cm annually, increasing openness decreasing under high maximum summer temperatures beech. statistical effect different varied slightly among trends quite similar. Additionally, high, being most intensely browsed, followed closely beech, while rarely browsed. Conclusions All results suggest more warming a decrease availability impact three species, possible reduction fluxes. observed increase populations leading increased be particularly detrimental saplings.