Recruitment facilitation in expanding forests of Mediterranean juniper is sex-biased

•Sapling recruitment for J. thurifera varies along a gradient of forest expansion.•Recruitment for J. thurifera is facilitated by conspecifics at the expanding front.•Saplings are spatially associated to male adult trees at the expanding front.•Heterospecific woody cover positively influences sapling density of J. thurifera.•Areas recently colonised by J. thurifera are key targets for management actions.