Study of vegetation in the Pheasant Pen, Old Sulehay Forest

Pam Low, Norman Low, Nick Owens

Introduction

One of the arguments for acquisition of Old Sulehay Forest by the Wildlife Trust was the inappropriate management by the previous owners of this SSSI. The estate was managed for pheasant shooting and this entailed the placement of a pheasant rearing pen at TL 062 988, to the north west of the cross-rides by the chestnut trees (Fig. 1). The effects of pheasant rearing on wildlife have not been well studied, though there is some evidence that pheasants remove a large number of lepidoptera pupae from the leaf litter. This study focused on the after effects of pheasants on the ground vegetation inside the pen. The last birds are thought to have been reared in 1997 or 1998. An earlier study of the effects of pheasant release pens was carried out by the Game Conservancy Trust on 56 pens in south and east England (Ludolf et al. 1989). They showed that annual plants (often considered weeds) and perennials requiring high soil fertility increased in pheasant release pens at the expense of characteristic woodland perennials. However, the effects were confined to the enclosure itself and the immediate area around the pen.

Methods

A 10m x 10m square was selected inside the pen as a representative area. A second 10m x 10m square west of the pen (beyond the area affected by vehicles and human trampling near the pen) was selected as a control. The control area had similar canopy cover and woody plant species to the pen area, mostly consisting of sallow (Salix sp), field maple (Acer campestre), hawthorne (Cretaegus monogyna) and crab apple (Malus sylvestris).

Within the experimental and control areas, ten 1m² quadrats were chosen using random coordinates, the same coordinates being used for the experimental and control areas.

Six recording visits were made, in March, April, May, June, July and September 2002. For each quadrat, percentage cover was estimated by eye for dog’s mercury (Mercurialis perennis), moss, bare ground, and leaf litter. The number of individual herbaceous plants of other species was recorded in each square, as well as the number of newly germinated seedlings which were identified when possible.

Results

Table 1 summarises the results for the pheasant pen and the control area. There were clear differences between the two areas. The pheasant pen contained less than half the cover of dog’s mercury (22% compared with 55%), but more than twice the cover of moss - either on the ground or on fallen wood – 21% compared with 9%. Bare earth inside the pen averaged 23% of the ground surface, covering about three times the area outside the pen where it averaged 8%. Leaf litter was generally more abundant inside the pen though this may have been partly a reflection of its being obscured by plants in the control area. Herbaceous plants were much less common inside the pen, averaging 0.5 plants per m² inside and 4 plants per m² outside.

The number of herbaceous plant species, excluding grasses, averaged about 3 species per m² inside and 8 species outside. A total of 5 herbaceous plant species was recorded inside the pen and 15 species outside. Grasses were very scarce with only a few plants to be seen in either area. The number of this year’s germinated seedlings inside the pen was generally greater than outside, perhaps as a result of the greater area of bare ground inside. The seedlings did not generally mature into adult plants in the pen or in the control area, many of them dying off in mid summer, especially the non-woody species. The herbaceous plant and seedling species identified in each area are shown in Table 2.

Conclusion and plans for future studies

This study shows that there are clear differences between the pheasant pen and nearby comparable areas of woodland 4-5 years after the cessation of pheasant rearing. The area inside the pen was poorer in terms of percentage cover by dog’s mercury, the dominant plant in the field layer in the forest, and was also impoverished in terms of herbaceous plant numbers and species, with more bare ground and more moss inside the pen. The reasons for these differences are likely to be the impacting of the ground by birds and humans with perhaps some influence by nutrient enrichment (nitrates and phosphates from bird droppings). The pheasant release pen near the offices on the Ring Haw site is dominated by nettles and may have more nutrient enrichment and deeper soil than the Old Sulehay site. Follow up studies should include:

· A repeat of the above study every 5 years to discover the speed of recovery of the pen area.

· An interrupted belt transect through the pheasant pen extending 100 metres each side to investigate the extent of pheasant damage beyond the immediate pen area.

· An investigation of the flora of the pheasant release pens on the Ring Haw site.

References

Ludolf,C. Payne, S. and Robertson P. 1989. The effects of pheasant release pens and strawed rides on ancient woodland ground flora. Game Conservancy Trust Review 1988. Fordingbridge.

Fig 1. Map showing pheasant pen area, and location of control areas.

Table 1. Vegetation in Pheasant Pen and Control Area 2002
		March	April	May	June	July	Sept.	Mean
Dog's mercury (% cover)	Pen	9	23	24	25	25	25	21.8
	Control	10	58	65	67	66	66	55.3
Moss (% cover)	Pen	14	16	16	23	29	31	21.5
	Control	10	8	7	7	9	13	9.0
Bare earth (% cover)	Pen	30	27	25	18	15	23	23.0
	Control	14	12	6	6	6	4	8.0
Leaf litter (% cover)	Pen	40	40	37	33	29	21	33.3
	Control	49	4	18	20	18	21	21.7
Herbaceous plants (excl. grass) (no./m^2)	Pen	0.3	0.6	0.6	0.5	0.5	0.3	0.5
	Control	1.3	5.1	5.1	3.9	4.5	3.3	3.9
Herbaceous plant species (total number all quadrats)	Pen	2	4	4	2	3	1	2.7
	Control	7	7	10	11	9	7	8.5
Seedlings (no./m^2)	Pen	0.8	5.5	11.6	9.7	3.4	2.1	5.5
	Control	0.5	4	3.6	6.7	3.7	2.6	3.5

Table 2. Herbaceous plant species identified in the Pheasant Pen and Control area.
Species	Pen	Control
* = species present
Adult plants
Lords and ladies (Arum maculatum)	*	*
Stinging Nettle (Urtica dioica)	*	*
Violet (Viola sp)	*	*
Forget-me-not (Myosotis sp.)	*
St. John's Wort (Hypericum sp)	*	*
Bluebell (Endymion non-scriptus)		*
Thistle (Cirsium sp)		*
Lesser celandine (Ranunculus ficaria)		*
Herb bennet (Geum urbanum)		*
Enchanter's nightshade (Circaea lutetiana)		*
Fern (Dryopteris?)		*
Speedwell (Veronica sp)		*
Cleavers (Geum aparine)		*
Wild strawberry (Fragaria fesca)		*
Creeping jenny (Lysimachia nummularia)		*
Woodrush (Luzula sp)		*
Seedlings
Willow herb (Epilobium sp)	*	*
Hawthorne (Crategus monogyna)	*	*
Dog rose (Rosa canina)	*	*
Elder (Sambucus nigra)	*	*
Sycamore (Acer pseudoplatanus)		*