230 J. Dover et al. Agriculture, Ecosystems and Environment 80 2000 227–242
Table 1 Non-butterfly data recorded from the green lanes, hedgerows and grass banks in the Warburton study area 1997
Parameter Data type
Physical and associated features Habitat type
Location of records: inside green lane, outside green lane, single hedgerow, grass bank presenceabsence
Length of section In metres
Windspeed Mean of startfinish records for each transect section m s
− 1
Crop Type in adjacent field presenceabsence: grassland, cereals, carrots
Nectar plants Ragwort Senecio spp.
No. of flowering stemstransect section Bramble Rubus fruticosus agg.
No. of metrestransect section Thistle-like compositae principally Cirsium spp.
No. of flowering stemstransect section
may have had an influence on butterfly distribution in- cluding, boundary type, crop, nectar plant abundance,
etc. Table 1.
2.3. Analysis Kruskal–Wallis one-way analysis of variance
ANOVA, followed by multiple comparisons us- ing procedures in UNISTAT Anon., 1995 where
appropriate, was used to compare butterfly abun- dance, species richness, nectar plant abundance, and
windspeed among the field margins, outside- and inside-components of green lanes, and woodland
rides. As no non-linear effects were expected from the abundance data it was standardised to numbers100 m
before analysis. However, as species richness is known to exhibit non-linear effects with increasing
transect length Sparks et al., 1997 data was stan- dardised to species richnesslog transect length before
analysis. Warburton butterfly and habitat data were also analysed using stepwise multiple regression.
3. Results
3.1. Warburton Butterflies were recorded in the 53 transect sections
on five occasions in July and August 1997: 1062 in- dividuals of 15 species were found Table 2.
3.1.1. Abundance Overall, the outsides and insides of green lanes had
significantly more butterflies than either grass banks or hedgerows, which did not themselves significantly dif-
fer in butterfly abundance Fig. 3a. When butterflies were divided into ‘closed’ or ‘open’ population strat-
egy groups there were differences evident between the outside and the inside of green lanes for closed popula-
tion species, with significantly more butterflies found inside green lanes than outside; this difference was not
evident for open population species Fig. 3a. ‘Open’ population species do not live in discrete colonies but
disperse continually from their natal patch, whereas ‘closed’ population species live in discrete colonies
Thomas, 1984.
At the individual species level, the seven most abundant species showed significant differences
among habitat types: Meadow Brown Maniola ju- rtina L. P0.01, Gatekeeper Pyronia tithonus
L. P0.001, Wall Lassiommata megera L. P0.001, Speckled Wood Pararge aegeria L.
P0.01, Small Tortoiseshell Aglais urticae L. P0.05, Peacock Inachis io L. P0.05 and
the Green-veined White Pieris napi L. P0.001. Multiple comparisons Fig. 4 showed several com-
mon features. Hedgerows and grass banks were not shown to be significantly different from one another
and the inside and outside of green lanes were not significantly different from one another except for
the Gatekeeper, where there were significantly more butterflies inside the green lane. In every case, sig-
nificantly more butterflies were found inside green lanes than were associated with hedgerows or grass
banks. Some species differences did, however, occur in respect of other habitat comparisons. Thus, signifi-
cantly more Meadow Brown, Small Tortoiseshell and Green-veined White butterflies were associated with
J. Dover et al. Agriculture, Ecosystems and Environment 80 2000 227–242 231
232 J. Dover et al. Agriculture, Ecosystems and Environment 80 2000 227–242
Fig. 3. a Mean numbers of butterflies ±1 S.E. in the four habitats studied at Warburton, Trafford in 1997 by population structure: all species: abundance of all butterfly species observed, closed species: species considered to have a closed population structure, open species:
species considered to have an open population structure. Multiple comparison information following significant P0.05 Kruskal–Wallis one-way ANOVA given above bar charts as a matrix; G: grass banks, H: hedgerows, OGL: outside green lane, IGL: inside green lanes;
n.s.: P0.05, : P0.05; n.b.: additional shading categories given refer to later figures. b Mean butterfly species richnesslog transect length ±1 S.E. Sparks et al., 1997 in the four habitats studied at Warburton, Trafford in 1997 by population structure.
J. Dover et al. Agriculture, Ecosystems and Environment 80 2000 227–242 233
Fig. 4. Mean numbers ±1 S.E. of seven butterfly species in the four habitats studied at Warburton, Trafford in 1997. See also Fig. 3.
the outsides of green lanes compared with grass banks and significantly more Wall, Speckled Wood and
Small Tortoiseshell butterflies were associated with the outsides of green lanes compared with hedgerows.
3.1.2. Species richness Total butterfly species richness did not differ be-
tween grass banks and hedgerows, but both had significantly fewer species than the outside or inside
of green lanes. The inside of green lanes had signif- icantly more species than the outside. This pattern
of significant differences was repeated when species were classified into ‘closed’ population species,
but ‘open’ population species did not differ signifi- cantly between the inside and outside of green lanes
Fig. 3b.
234 J. Dover et al. Agriculture, Ecosystems and Environment 80 2000 227–242
Fig. 5. Mean butterfly nectar plant richness ±1 S.E. in the four habitats studied at Warburton, Trafford in 1997. Bramble: metres of bramble100 m; thistle: number of flowering stems of thistles and thistle like Compositae100 m; ragwort: number of ragwort plants100 m.
See also Fig. 3.
3.1.3. Nectar plants The three main nectar plant groupings at the study
site were bramble Rubus fruticosus agg., ragwort Senecio spp. and thistle-like Compositae Dover,
1996. Ragwort abundance did not differ among the habitat areas P0.05, but both bramble P0.001
and thistle-like Compositae P0.05 did. In multiple comparisons, bramble differed significantly in every
combination except between hedgerows and grass banks with most associated with the insides of green
lanes. Thistles only differed significantly between banks or hedgerows and the insides of green lanes
Fig. 5.
3.1.4. Windspeed Data was collected on four out of the five sample
dates. Data show some consistent trends, with wind- speed being lowest in the insides of green lanes and
highest in grass banks with hedgerows, and the outside of green lanes intermediate in exposure Fig. 6. Blus-
tery conditions and differing windspeeds during the survey dates have contributed to data variability such
that consistent significance levels have not been main- tained. Although it was not expected that there would
be separation of the hedgerows and outside of green lanes, in 3 out of 4 days, windspeed appears slightly
higher outside green lanes. This probably results from the variation in habitat structure from grass bank to
scrub or hedgerow associated with this category.
3.1.5. Stepwise multiple regression Regression analyses were carried out to examine
the importance of biotic and abiotic factors on the raw butterfly data, as there were differences in adjacent
crop type, density of nectar sources, etc. Length was kept as a variable, rather than standardising the data to
unit length. As expected this is a significant factor in the majority of, but not all, analyses. Species richness
was analysed using the total richness of butterflies at the site, and also the data divided into open and closed
species groupings. The results Table 3 show the ex- pected dominance of the inside and outside of green
lanes, the importance of ragwort and also the positive effect of the rough grassland habitat. The poor habitat
quality of grass banks and hedgerows are highlighted in the analysis by population structure.
The importance of the rough grassland habitat is reinforced in the analysis of total butterfly abundance
Table 4 along with the favourability of the inside of green lanes and nectar sources. Individual analysis of
J. Dover et al. Agriculture, Ecosystems and Environment 80 2000 227–242 235
Fig. 6. Windspeeds ±1 S.E., recorded on four of the five sample days, in the four habitats studied at Warburton, Trafford in 1997. See also Fig. 3.
the most abundant butterfly species Tables 5–7 high- light different factors for each species, but consistent
factors include the inside of green lanes, rough grass- land, and nectar sources.
3.2. Ribble valley Butterflies were recorded in the 12 transect sections
on 10 occasions between late July and mid-September 1997. A total of 151 individuals of eight species were
Table 3 Factors affecting the number of species of butterfly in the field margins and green lanes of the Warburton study area 1997
a ,b
All species Open population species
Closed population species Variable
Regression r
2
F-value
c
Variable Regression r
2
F-value
c
Variable Regression r
2
F-value
c
name coefficient
at end name
coefficient at end
name coefficient
at end Constant
− 0.8230
Constant 3.7016
Constant −
1.3913 Inside GL
3.5226 25.25 33.25 c
Ragwort stems 4.6767
17.23 6.28 a
Inside GL 1.2873
31.83 12.84 c Outside GL
1.9430 49.23 14.54 c
Grass bank −
1.6339 29.57 18.57 c
Rough grass 2.5679
48.24 18.89 c Ragwort stems
6.8031 57.07
5.27 a Single hedge
− 1.2059
42.97 11.51 b Ragwort stems
3.8841 59.05
6.35 a Rough grass
2.8669 61.62
6.17 a Grass bank
− 0.6167
63.92 4.97 a
Log length 1.6975
64.88 4.37 a
Log length 0.9772
67.13 5.27 a
Bramble 0.8464
69.72 3.93 n
a
Length of transect section transformed by log x+1 prior to analysis.
b
n=P0.05; a=P0.05, b=P0.01, c=P0.001. Entry into equation set at 3.84; r
2
values cumulative.
c
Residual ms from final model used as denominator.
recorded Table 2; six species had open population strategies and made up 75 of records. Because of the
small number of butterfly records, abundance compar- isons were made only at the population structure level
Fig. 7.
3.2.1. Abundance Total abundance of butterflies for the insides of
green lanes was significantly higher than for single stone walls which, in turn, had significantly more
236 J. Dover et al. Agriculture, Ecosystems and Environment 80 2000 227–242
Table 4 Factors affecting the abundance of butterflies in the field margins and green lanes of the Warburton study area 1997; data grouped into
abundance of all species, open population species and closed population species
a
All butterflies Open population species
Closed population species Variable
Regression r
2
F-value
b
Variable Regression r
2
F-value
b
Variable Regression r
2
F-value
b
name coefficient
at end name
coefficient at end
name coefficient
at end Constant
− 12.3327
Constant −
5.5741 Constant
− 3.0352
Rough grass 64.8287
32.17 17.05 c Length
0.0944 28.33 13.18 c
Rough grass 28.7101
46.83 72.16 c Length
0.1550 55.01 32.94 c
Rough grass 44.4257
50.41 12.49 c Length
0.0275 59.34 14.73 c
Inside GL 25.6141
65.31 15.82 c Inside GL
16.9957 60.43 10.60 b
Inside GL 6.3094
68.05 13.36 c Thistle stems
3.2352 69.69
6.93 a Thistle stems
2.4461 65.47
6.25 a Ragwort stems
61.3534 68.47
4.47 a
a
a=P0.05, b=P0.01, c=P0.001. Entry into equation set at 3.84; r
2
values cumulative.
b
Residual ms from final model used as denominator.
butterflies than grass banks Fig. 7. Open population subdivision of the data followed the same pattern as
for total abundance. However, in the closed popula- tion subdivision grass banks and stone walls were
not significantly different, probably because of low butterfly incidence Fig. 7.
3.2.2. Species richness Only eight species were recorded at the Ribble Val-
ley site, reflecting the harsher upland grassland cli- mate compared with the more diverse lowland sites
of Warburton and Manydown, and no significant dif- ferences in species richnesslog length Sparks et al.,
1997 were detected for any of the population strategy groupings, or for the overall data set P0.05.
3.3. Manydown Butterflies were recorded in three grass banks and
four hedgerows around cereal fields in 1987 and four
Table 5 Factors affecting the abundance of three species of Satyrid butterfly in the field margins and green lanes of the Warburton study area 1997
a
Meadow Brown Gatekeeper
Wall Variable
Regression r
2
F-value
b
Variable Regression r
2
F-value
b
Variable Regression r
2
F-value
b
name coefficient
at end name
coefficient at end
name coefficient
at end Constant
− 1.3445
Constant 0.0000
Constant −
0.1796 Rough grass
21.0968 61.83 89.20 c
Inside GL 2.5393
25.19 12.37 c Ragwort stems
4.3526 36.89 10.52 b
Length 0.0128
66.74 7.38 b
Ragwort stems 11.6032 39.96 12.30 c
Bramble 1.0605
48.84 13.44 c Length
0.0028 54.00
5.49 a
a
a=P0.05, b=P0.01, c=P0.001. Entry into equation set at 3.84, r
2
values cumulative.
b
Residual ms from final model used as denominator.
grass banks and eight hedgerows in 1988; there were 15 woodland rideglade sections and six in the green
lane in both years. Records, taken at comparable times between May and September for the arable and wood-
land transect types, were made on 13 occasions in 1987 and 10 in 1988; 776 individuals of 18 species
were found in 1987 and 818 individuals of 17 species in 1988 Table 2.
3.3.1. Abundance In 1987, the total abundance data showed that the in-
terior of the green lane and woodland ridesglades had significantly more butterflies than hedgerows or grass
banks; that woodland ridesglades did not differ sig- nificantly from the green lane; and that hedgerows did
not differ significantly from grass banks. There were differences in abundance pattern between the closed
and open population groupings. The closed population grouping showed exactly the same pattern as the total
abundance data. The open population grouping failed
J. Dover et al. Agriculture, Ecosystems and Environment 80 2000 227–242 237
Table 6 Factors affecting the abundance of two species of Nymphalid butterfly in the field margins and green lanes of the Warburton study area 1997
a
Small Tortoiseshell Peacock
Variable name Regression coefficient
r
2
F-value
b
at end Variable name
Regression coefficient r
2
F-value
b
at end Constant
− 2.1262
Constant −
2.1719 Ragwort stems
62.8399 29.60
12.14 b Length
0.0276 37.85
42.54 c Rough grass
21.6347 52.93
7.67 b Rough grass
6.2154 51.32
6.38 a Thistle stems
1.5233 56.45
6.28 a Inside GL
3.7367 61.69
13.72 c Length
0.0365 60.31
5.11 a Thistle stems
0.3828 64.61
3.95 a Inside GL
6.7522 63.66
4.33 a
a
a=P0.05, b=P0.01, c=P0.001. Entry into equation set at 3.84; r
2
values cumulative.
b
Residual ms from final model used as denominator.
Table 7 Factors affecting the abundance of two species of Pierid butterfly in the field margins and green lanes of the Warburton study area 1997
a
Small White Green-veined White
Variable name Regression coefficient
r
2
F-value
b
at end Variable name
Regression coefficient r
2
F-value
b
at end Constant
− 0.3016
Constant −
0.3469 Length
0.0135 30.38
21.56 c Rough grass
19.1048 47.03
62.93 c Inside GL
2.0996 41.07
9.07 b Inside GL
4.1509 57.78
11.39 b Length
0.0128 62.57
6.27 a
a
a=P0.05, b=P0.01, c=P0.001. Entry into equation set at 3.84; r
2
values cumulative.
b
Residual ms from final model used as denominator.
Fig. 7. Mean numbers of butterflies ±1 S.E. in the three habitats studied at the Ribble site, Yorkshire in 1997 by population structure; G: grass banks, SW: stone wall, ISGL: inside stone walled green lane. See also Fig. 3.
238 J. Dover et al. Agriculture, Ecosystems and Environment 80 2000 227–242
Fig. 8. Mean numbers of butterflies ±1 S.E. by population structure in the four habitats studied at Manydown, Hampshire: a in 1987; b in 1988; G: grass banks; H: hedgerow; IGL: inside green lane; WR: woodland rideglade. See also Fig. 3.
to show significant differences between hedgerows and grass banks, or woodland rides and either the grass
banks or the hedgerows. There were, however, signif- icantly more butterflies associated with the inside of
the green lane compared with the woodland rides, the hedgerows and the grass banks Fig. 8a.
In 1988, few significant differences were evident in the total abundance data; although there were
J. Dover et al. Agriculture, Ecosystems and Environment 80 2000 227–242 239
significantly more butterflies associated with wood- land rides and the inside of the green lane than with
grass banks Fig. 8b. Further analysis showed no significant differences in the open population data
P0.05, whereas the closed population data exactly mirrored those for 1987.
3.3.2. Species richness In both years, the species richness trend fol-
lowed the same pattern data in parentheses for 1987 and 1988, respectively Woodland ridesglades 15,
14green lane 15, 12hedgerows 13, 11grass banks 7, 9.
4. Discussion
