As well as substantial areas of agriculturally improved grassland used for silage, semi improved grassland habitats include permanent pasture and hay meadows at higher altitudes over sandstone and gritstone, a small area of semi improved mostly neutral grassland associated with carboniferous limestone in Upper Nidderdale and grassland influenced by the underlying magnesian limestone in the north eastern corner of the AONB. 

The area surrounding the village of Greenhow, one of the highest villages in Yorkshire and associated with lead mining since the Roman occupation, supports fragments of calaminarian grassland associated with spoil heaps that were the by-product of the lead mining industry. Here, plants like mountain pansy, spring sandwort, alpine penny cress and moonwort form species-rich swards over thin scree soils containing flourspar, calcite and barytes.  The heavy metal concentration in these soils prevents encroachment by more competitive plants and maintains a high diversity of species.

The semi improved grasslands, especially those close to the edges of the heather moorland blocks, often waterlogged and with areas of rushes, are notable for their complement of  breeding and wintering waders such as curlew,  lapwing, redshank and snipe. 

There are regionally important concentrations of these birds in the AONB. Many farmers in the AONB are developing grassland conservation plans in conjunction with the Department of the Environment, Food and Rural Affairs under a scheme called Environmental Stewardship.