An examination of the grassland habitats surveyed using the Fossitt (2000) habitat classification shows that by far the most abundant habitat recorded during the ISGS was GS4 Wet grassland, covering over half of the surveyed area (Figure 5). The next most abundant habitat was GSi, semi- improved grassland (mapped as GA1), encompassing both wet and dry semi-improved grassland, which accounted for 16% of the surveyed grassland. GS1 Dry calcareous and neutral grassland was the third most abundant grassland habitat surveyed, while GS2 Dry meadows and grassy verges habitat was rare at just under 6%. GM1 Marsh was the rarest of all the grassland habitats: when taken together with grassland-associated swamp habitats such as tall-herb swamp communities, total coverage was just over 1% of the total surveyed area. GS1, GS2 and GS4 Wet grassland were recorded in all 26 counties. However, GS3 Dry-humid acid grassland was not recorded from three counties, Kilkenny, Longford and Wicklow, while GM1 was not recorded from seven counties: Carlow, Kilkenny, Laois, Louth, Meath, Wicklow and Wexford. It should be noted, however, that areas of these habitats probably exist within these counties in locations that were not surveyed for the ISGS. Wicklow in particular would be expected to have large areas of GS3 within the Wicklow Mountains SAC (002122), an area that was excluded from the ISGS survey area.
Figure 5: Proportion contributed by each Fossitt grassland habitat to the total area of grassland surveyed during ISGS 2007-2012. GM1 includes small areas of swamp and flush/fen habitats.
When the distribution of the grassland habitat types is examined on a regional rather than a national basis (Table 12), there are striking deviations from the national averages across almost all of the grassland categories. The greatest regional differences are found for GS4 Wet grassland, which varied from a high of 66% of the surveyed area in the Border region, down to just 18% of the surveyed area of the Mid-East & Dublin region. The South-East region had the next lowest proportion of GS4, with 31%. This trend would seem to confirm the expected correlation between wetter habitats and higher rainfall.
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Table 12: Summary Fossitt (2000) grassland habitat statistics of sites surveyed, differentiated by Teagasc region. PF is only included when associated with an Annex I grassland habitat. Percentage frequencies only include sites
where there was a mapped area of the Fossitt habitat.
GS1 GS2 GS3 GS4 GM1* GSi Overall
Border No. of sites 114 56 102 326 35 229 350
% frequency 32.6 16 29.1 93.1 10 65.4
Area (ha) 981.5 106.2 653.1 6366.4 60.7 1499.5 9667.4
% regional surv. area 10.2 1.1 6.8 65.9 0.6 15.5 100
Mid-East & No. of sites 23 32 10 39 12 27 68
Dublin % frequency 33.8 47.1 14.7 57.4 17.6 39.7
Area (ha) 122.9 517.4 558.6 306.5 31.3 202.6 1739.3
% regional surv. area 7.1 29.7 32.1 17.6 1.8 11.6 100
Midland No. of sites 41 37 5 94 18 69 116
% frequency 35.3 31.9 4.3 81 15.5 59.5
Area (ha) 204.4 203.9 55.1 1737 107.2 701.8 3009.3
% regional surv. area 6.8 6.8 1.8 57.7 3.6 23.3 100
Mid-West No. of sites 44 18 4 62 7 53 90
% frequency 48.9 20 4.4 68.9 7.8 58.9
Area (ha) 331.4 77.3 132.1 820.9 12.4 277.3 1651.5
% regional surv. area 20.1 4.7 8 49.7 0.8 16.8 100
South-East No. of sites 31 23 17 55 8 31 87
% frequency 35.6 26.4 19.5 63.2 9.2 35.6
Area (ha) 179 108.2 234.5 315.1 14 158.6 1009.4
% regional surv. area 17.7 10.7 23.2 31.2 1.4 15.7 100
South-West No. of sites 73 37 48 172 25 105 224
% frequency 32.6 16.5 21.4 76.8 11.2 46.9
Area (ha) 259.2 133.1 367.7 1170.2 49 457.7 2436.8
% regional surv. area 10.6 5.5 15.1 48 2 18.8 100
West No. of sites 153 46 52 186 17 124 257
% frequency 59.5 17.9 20.2 72.4 6.6 48.2
Area (ha) 769.4 173.8 175.5 2109.8 37.5 408.3 3674.4
% regional surv. area 20.9 4.7 4.8 57.4 1 11.1 100
Total in ISGS No. of sites 479 249 238 934 122 638 1192
% frequency 40.2 20.9 20 78.4 10.2 53.5
Area (ha) 2847.8 1320 2176.6 12825.9 312.1 3705.7 23188.1
% total surv. area 12.3 5.7 9.4 55.3 1.3 16 100
* Includes small areas of FS or PF habitats
The GS1 Dry calcareous and neutral grassland habitat also had an uneven regional distribution, with the highest proportion, 21%, found in the West region, followed closely by the Mid-West at 20%, the two regions which include the Burren National Park, an area with abundant limestone pavement and calcareous soils. The lowest proportion of GS1 was in the Mid-East & Dublin region and the Midland region, in both of which it comprised 7% of the surveyed area. However, the GS2 Dry meadows and grassy verges habitat was highest in the Mid-East & Dublin region, at 30%, while it comprised just 1% of the surveyed area of the Border region, presented graphically in Figure 6. Within the Mid-East & Dublin region in particular, there has been a recent trend in managing large, publicly owned areas of grassland as traditional hay meadows, with good examples at site 1324 Newbridge Demesne, Dublin, and site 1499 Castletown House, Kildare.
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GS3 Dry-humid acid grassland, though comprising a relatively small proportion (9%) of the surveyed grassland, constituted almost one-third (32%) of the surveyed area of the Mid-East & Dublin region, due to large areas of GS3 recorded in Kildare around the Curragh, but only 2% of the Midland region. GM1/FS Marsh/swamp had a low distribution throughout all regions, with the highest proportion, 3%, recorded in the Midland region.
Figure 6: Proportional distribution of grassland habitats throughout the Teagasc regions. GM1 includes small areas of swamp and fen/flush habitats.
Figure 7 shows the broad associations between grassland habitats, as classified under Fossitt (2000), and various geographical landscape features. It should be noted that these are not exact associations, as landscape features were recorded at a site level rather than at a relevé level, but they do give an indication of the landscape context in which the grassland habitats occur. Marsh/swamp habitats were more likely to occur on sites occurring on a floodplain or by a lake, and least likely to be present in sites associated with upland areas (hill or mountain). On eskers and on coastal or island sites, the most frequent grassland habitat was GS1 Dry calcareous and neutral grassland. However, GS3 Dry- humid acid grassland was rarely recorded in association with eskers or in lowland situations but was instead most frequent in sites that occurred in association with bogland or in an upland context.
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Figure 7: Proportional measure of association between Fossitt (2000) habitats and landscape features
Site size was analysed and the distribution of size classes was plotted using 10 ha interval classes. While site size is to some extent an artificial construct, partly depending on non-ecological factors such as land access, it may also depend on the quality of grassland in an area, with larger sites often signifying the presence of a complex of semi-natural grassland habitats. Figure 8 shows that a large proportion, 45%, of grassland sites were 10 ha or less, with only 5% of sites measuring over 60 ha in size.
An examination of site size on a regional basis (Figure 9) reveals that the region with the greatest proportion of larger sites is the Border region; this region also has the smallest proportion of sites in the smallest size class, while the region with the most sites in the smallest size class is the South-East.
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Figure 9: Proportions of sites in each Teagasc region within each size class.