5.1. VEGETATION SECTION
5.1.1. SPECIES RICHNESS, DIVERSITY AND DOMINANCE INDEX
The most species rich field was South Field at Reeds Farm. Thirty-two species were recorded; 5 annuals, 4 biennials and 23 perennials, which included 11 grass species. Twenty-five species were recorded at Woodham Lodge Farm. The least species rich fields were at Chaplefield and the North Field at Reeds Farm, with thirteen and fifteen species respectively (Table 5.1).
Woodham Lodge Farm had the highest species diversity with an average of 3.74 species occurring in each quadrat cell. The South Field at Reeds Farm had an average of 3.69 species occurring per quadrat. Front Field at White House Farm has the lowest diversity, only an average of 2.11 species occurring per quadrat (Table 5.1).
Table 5.1: Species richness, diversity index and dominance index.
The South Field at Reeds Farm has the highest dominance index, with 10 species reaching dominance. At Lodge Farm, only creeping thistle and slender foxtail dominated any one area.
Table 5.2: Species reaching dominance in at least one quadrat
5.1.2 ANNUALS, BIENNIALS AND PERENNIALS
All fields surveyed are dominated by perennial species. The two most species rich fields are South Field at Reeds Farm, and Woodham Lodge Farm, both of which were left to naturally regenerate. The two least species rich fields are Chaplefield, Birkett Hall, and North Field at Reeds Farm. Chaplefield is dominated by Lolium perenne, and North Field by Festuca spp. (Figure 5.1).
Comparison of Borders and Cores
Core areas have a lower species richness generally, although on South Field there is little difference between the two areas. For Front Field, Back Field and Spring Field, no biennials occur in the core of the field (Figure 5.5).
5.1.3. COVER AND ABUNDANCE
Cover of Problem Grasses
There are notable variations in the grass species which dominate a farm. On North Field, Reeds Farm, and at White House, Festuca spp. dominate. At Woodham Lodge Alopercurus myosuroides dominates, and on the South Field, Reeds Farm, Arrhenatherum elatius dominates. At Birtkett Hall Lolium perenne dominates, however Elymus repens is abundant on Cowbridge (Figure 5.2).
Cover of Problem Weeds
Cirsium arvense has produced the greatest cover for all the problem weeds, although it was not very widespread on North Field and Chaplefield. Senecio jacobaea is a problem on both fields at Reeds Farm, Front Field at White House and Chaplefield at Birkett Hall (Figure 5.3), although generally produced less cover than Cirsium arvense orRumex obtusifolius.
Abundance of Problem Weeds
Elymus repens is the most abundant species overall. Cirsium arvense is the most abundant of the broad-leaved weed species. Rumex obtusifolius is present in large numbers on Springfield and Woodham Lodge (Figure 5.4).
Table 5.4 shows the frequency data for all the species recorded in each of the nine fields. Grasses, clover, problem weeds and the woody perennials will be discussed in turn.
Lolium Perenne (Perennial rye-grass)
On the fields at Birkett Hall, where perennial rye grass was sown, the relative frequency of occurrence is over 90% for each field, with a maximum of 100% for Chaplefield. On Chaplefield a majority of quadrats had a cover entirely consisting of perennial rye grass.
Festuca spp. (Fescues)
Festuca spp. are frequently spread over both the Back Field and Front Field at White House Farm, where they were planted as part of the Countryside Access Scheme, and also at Reeds Farm on the North Field where they have started to dominate by means of natural regeneration.
Elymus repens (Couch)
Couch grasses are of a higher frequency on Cowbridge at Birkett Hall, and also on the naturally regenerated fields of Reeds Farm. They are not, however, very frequent at Woodham Lodge, although they do occur in some dispersed patches, especially in close proximity to large oaks.
Arrhenatherum elatius (False oat grass)
False oat grass is only very frequent at Reeds Farm in the South Field where it occurs in 47.8 % of quadrat cells. It does not occur in any quadrat cell in the North Field at Reeds Farm. The second highest frequencies recorded for false oat grass are at Woodham Lodge Farm (11%).
Bromus sterilis (Barren brome)
Barren brome is not a great problem generally, although it is quite frequent on the South Field at Reeds and also on Saunders at Birkett Hall, although it occurs mainly in marginal areas of a field and not core areas.
Alopercurus myosuroids (Slender foxtail)
Slender foxtail is only frequent at Woodham Lodge Farm (75.8%). It is present on the other set-aside fields but only in scattered areas.
Holcus lanatus (Yorkshire fog)
Yorkshire fog occurs in the South Field of Reeds in 21.3% of quadrat cells, and also occurs at Woodham Lodge Farm, and Front Field at White House. It is not recorded on any of the other fields studied.
TRIFOLIUM REPENS (WHITE CLOVER)
With the exception of Woodham Lodge the only fields where clover was present in significant numbers was at Birkett Hall where it was sown. At Woodham Lodge it tended to occur in small but frequent patches. The largest cover and frequency occur on Springfield. Cowbridge is adjacent to Springfield and was also sown with clover, but the cover is very small in comparison.
Table 5.3: Cover and frequency of White Clover
|Mean % Cover||Frequency|
Cirsium arvense (Creeping Thistle)
Creeping thistle is very common to all fields, especially on the backfield at White House and at Woodham Lodge where it occurs in over 50% of quadrat cells. Only in the North Field at Reeds Farm is it less frequent, where it only occurs in 2.8% of quadrat cells.
Cirsium vulgare (Spear Thistle)
Spear thistle is present at Reeds Farm and Birkett Hall, but only in low numbers. It was present at White House, but did not occur in any of the quadrat cells. The highest frequency in 5.6% in Saunders at Birkett Hall.
Rumex obtusifolius (Broad-leaved docks)
Broad-leaved docks occur in quadrat cells on all fields. The only area which had a very high abundance of broad-leaved docks was Springfield ‘top end’ (frequency for total field 18%). There were also a large population of docks present on Bell Meadow at Birkett Hall where the old allotments were located.
Senecio jacobaea (Common ragwort)
Common ragwort is most frequent on the North Field at Reeds Farm, occurring in 16.7% of quadrat cells (Plate 3). It was recorded on all fields except the Back Field at White House (where it was present amongst the thistles, but not within a quadrat), and Cowbridge at Birkett Hall. Hoary ragwort is also present on the Front Field at White House in 4.4% of quadrat cells.
Heracleum sphondylium (Hogweed)
Hogweed is generally present close to the field margins and not in the core areas. The highest frequencies occur on the South Field at Reeds Farm and at Woodham Lodge Farm (6.6% and 5.6% respectively). The only recording of hogweed at Birkett Hall was on Cowbridge, occurring in 1.5% of quadrat cells. It was however present in most hedges.
Galium aparine (Cleavers)
Cleavers were only recorded on the Front Field at White House, and occurred in 6.7% of quadrat cells.
Convulvulus arvensis (Lesser Bindweed)
Lesser bindweed was recorded on all fields except at Woodham Lodge. The highest frequency was on the South Field at Reeds Farm where it occurred in 29.5% of quadrats (Plate 3).
Quercus petraea (Sessile oak)
On the Back Field at White House sessile oak occurred in 7.3% of quadrats, most of which were on the margins of the field.
Prunus spinosa (Blackthorn)
On Back Field at White House blackthorn occurred in 14.6% of quadrats, and had a high cover in the marginal areas alongside the blackthorn hedges. Blackthorn was also present in the South Field at Reeds Farm in 3.3% of quadrat cells.
Crataegus monogyna (Hawthorn)
Hawthorn was present only in the Front Field of White House at 4.4% of quadrat cells.
Populus alba (White poplar)
White poplar was recorded in 1.2% of quadrat cells on the Back Field at White House, and in 1.4% of quadrat cells in the South Field at Reeds. It was also present in the margins of the North Field at Reeds, and the Front Field at White House.
Highest species richness and diversity occurs on naturally regenerated fields. Perennial species dominate all fields, including the cores of fields. The margins are more diverse. For each farm studied, different grass species dominated the sward. The main problem weed is Cirsium arvense. Senecio jacobaea is a problem at Reeds Farm. Bromus sterilis is not a problem on any of the farms. Woody perennials are generally only present on field margins. On Woodham Lodge Farm, the trees planted as part of the Woodland Premium Scheme had failed to grow. Almost all the trees had died (Plate 4). Most tree species recorded occurred on Back Field at White House Farm.
Table 5.4 cont.