"Figure 5: pH levels in fen, marsh and swamp have increased by 17.5% between 1978 and 2007","" "Level of pH in soils, Great Britain, 1978, 1998 and 2007","" "","" "Notes","" "Unit","pH level" "","" "","Broadleaf, mixed and yew woodland","Acid grassland","Bracken","Dwarf shrub heath","Bog","Fen marsh and swamp","Neutral Grassland" "1978","5.09","4.44","4.14","4.19","4.29","4.64","5.52" "1998","5.47","4.72","4.47","4.50","4.49","5.35","5.99" "2007","5.75","4.78","4.64","4.55","4.51","5.45","6.14"