Priority Habitats Inventory (England)

The Priority Habitat Inventory is a spatial dataset that maps priority habitats identified in the UK Biodiversity Action Plan and listed as being of principal importance for the purpose of conserving or enhancing biodiversity, under Section 41 of the Natural Environment and Rural Communities Act (2006).

The PHI is updated twice a year and where possible habitats are mapped to polygons in OS Mastermap. These polygons are merged or split where necessary to create resulting habitat patches.

The PHI currently maps 27 terrestrial and freshwater priority habitats across England. These being: Blanket bog (BLBOG), Calaminarian grassland (CALAM), Coastal & floodplain grazing marsh (CFPGM), Coastal saltmarsh (SALTM), Coastal sand dunes (CSDUN), Coastal vegetated shingle (CVSHI), Deciduous woodland (DWOOD), Limestone pavements (LPAVE), Lowland calcareous grassland (LCGRA), Lowland dry acid grassland (LDAGR), Lowland Fens (LFENS), Lowland heathland (LHEAT), Lowland meadows (LMEAD), Lowland raised bog (LRBOG), Maritime cliff & slope (MCSLP), Mountain heath & willow scrub (MHWSC), Mudflats (MUDFL), Purple moor grass & rush pastures (PMGRP), Reedbeds (RBEDS), Saline lagoons (SLAGO), Traditional orchards (TORCH), Upland calcareous grassland (UCGRA), Upland hay meadows (UHMEA), Upland heathland (UHEAT), Upland flushes, fens & swamps (UFFSW), Lakes (LAKES), Ponds (PONDS).

The PHI also includes four habitat classes which are not priority habitats, but which hold potential importance for conservation of biodiversity in England. These can indicate a mosaic of habitat which may contain priority habitats, have restoration potential and/or contribute to ecological networks. Where evidence indicates the presence of unmapped or fragmented priority habitats within such polygons, these are attributed as additional habitats. These being: Fragmented heath (FHEAT), Grass moorland (GMOOR), Good quality semi-improved grassland (GQSIG), No main habitat (NMHAB).

For some polygons the PHI contains additional information about the main habitats in the form of feature descriptions and corresponding feature codes. These being: Priority Ponds and lakes - Oligotrophic lakes (OLIGO), Dystrophic lakes (DYSTR), Mesotrophic lakes (MESOT), Eutrophic standing waters (EUTRO), Ice age pond (ICEAG), Pond with floating mats (PWFLM) Deciduous woodland – Upland Oakwood (UPOWD), Lowland beech and yew woodland (LBYWD), Upland mixed ashwoods (UMAWD), Wet Woodland (WETWD), Lowland mixed deciduous woodland (ASNWD), Plantations on ancient woodland (PAWDS) Grassland – Countryside Stewardship Option (CSOPT), Waxcap grassland (WAXCP) Heathland – Dry Heathland (DRYHL), Wet heathland (WETHL) Coastal sand dunes – Dunes under coniferous woodland (CWDUN), Dunes under deciduous woodland (DWDUN) General – Degraded (DEGRD)