The elastic strain build-up and damage induced by 50 keV He implantation at RT and 550°C into (0001)AlN were studied using a combination of XRD experiments, XRD simulation, and TEM experiments. Evidence for strong dynamic annealing with efficient point defect recombination is reported at RT. The point defect recombination is found to be enhanced with increasing implantation temperature where He concentration is low, indicating increased mobility of interstitial-type defects and resulting in low strain. A reversed effect is observed for He concentration exceeding 5 at.% (3 at.%) at RT (550°C) : thermally activated mechanisms related to the nucleation and growth of He-V complexes overcome the point defect recombination and promote the strain and damage build-up. At 1x10 17 cm-2 , only clusters of interstitials are observed at RT, whilst bubbles and basal stacking faults are additionally formed at 550°C for a critical He concentration estimated to be close to 4-6 at.%.