Data containing information on a study of the impact of Storm Arwen on biodiversity and forest structure of Kielder Forest (Northumberland), May-July 2022. The following are included: (i) fallen timber found along 100 m transects (species, tree circumference, and whether it was flat on the ground); (ii) trees found inside 10x10-m plots (species; diameter at breast height [DAP]; status [alive vs dead]; and whether the tree was still standing); (iii) plant cover and richness in 2x2 m quadrats (Braun-Blanquet cover and plant species present); (iv) spatial data (GIS layers and buffers around survey and sampling sites); and (v) bird point counts (species detected and distances to each individual recorded) Surveys were conducted at twelve control-impact pairs (24 sites in total), whereby impact sites were those severely affected by Storm Arwen. Within each site, we carried out one 100 m transect, three 10x10 m plots, three 2x2 m quadrats, and two to four bird point counts depending on the size of the site