228 J. Dover et al. Agriculture, Ecosystems and Environment 80 2000 227–242
habitat, in a re-analysis of data from the Butterfly Mon- itoring Scheme transect for Woodwalton Farm. This
followed from the suggestion of Dover 1996 that the shelter afforded by green lanes composed of a double
line of hedges would be superior to single hedgerows. The definition of what constitutes a green lane is a
difficult one Belsey, 1998, as the width of the track of a green lane may vary and be bounded by banks,
ditches, hedges, scrub or dry-stone walls. The track itself should be unmetalled, but that does not exclude
the addition of hard-core to improve traction for farm machinery. The variability of the boundary features
and the exact nature and disturbance regime includ- ing cutting of the track are likely to impinge on the
value of green lanes as wildlife habitat and hence the number, type and abundance of species within them.
This paper addresses the question of whether green lanes are superior, in terms of adult butterfly abun-
dance and species richness, to simpler linear features such as hedgerows, grass banks and drystone walls.
2. Methods
2.1. Study sites Data from three study areas are presented here,
varying in location and type from lowland arable farms in Hampshire Manydown in the south of England
Fig. 1. Map of the Warburton study site in Trafford used for butterfly transects in 1997. The green lanes and other field margins indicated by dots were divided up into 53 transect sections not shown. Map not to scale.
and the Traffordnorth-Cheshire border Warburton in the northwest, to upland farmland in the Yorkshire
Dales Ribble. The standard method of recording us- ing butterfly transects was used at all sites Pollard
et al., 1975; Hall, 1981.
2.1.1. Warburton The principal study area was in the Parish of War-
burton, Trafford Nevell, 1997 contained within a strip of land bounded by the Manchester Ship Canal
to the north, the River Bollin to the south, a metalled road to the east and contiguous farmland to the west.
The Warburton site Fig. 1 was principally arable land with the main crops being cereals, with some
carrots and one large field of rough wet grassland. Field boundaries in Warburton were grass banks and
hedgerows, with the green lanes bounded by a mix- ture of these habitats. In places the ‘hedgerows’ were
made principally of bramble, and some of the grass banks were clearly relict hedgerows. The majority of
the green lanes were at different levels from the fields, with some sunk to approximately 2 m below field level
in places Fig. 2. Many of the green lanes and field boundaries can be clearly seen on an estate map of
1751, with discontinuities in some fields showing the likely positions of the individual strips in the former
medieval Town Field Bayliss, 1996.
At Warburton the field boundaries and green lanes were divided up into 53 sections reflecting
J. Dover et al. Agriculture, Ecosystems and Environment 80 2000 227–242 229
Fig. 2. Cross-sections of green lanes used for butterfly transects at the Warburton site in 1997. a Green lane at the same level as
adjacent fields. b Green lane above adjacent field level on one side, but below on the other. c Green lane below adjacent field
level. Boundary vegetation varied from double hedges to grass banks with intermittent scrub.
obvious physical changes such as aspect, vegetation and boundary type. Butterflies were recorded in 1997
in the following four situations: along grass banks and hedgerows surrounding fields but not associated
with green lanes 12 and 16 sections, respectively, ‘outside’ green lanes, i.e. where green lanes were
the boundary habitats of fields 16 sections, and the ‘inside’ of green lanes, i.e. along the track bounded
by hedgerowsbanks making up the green lane nine sections Fig. 2.
2.1.2. Ribble A more limited study was carried out in the coun-
tryside surrounding the villages of Hellifield and Long Preston in the Ribble Valley of the Yorkshire Dales.
The Ribble site was mainly grassland but with one area backing on to household gardens. At the Ribble
site, field boundaries were typical for uplands in England, being either grass banks or stone walls, with
the green lanes being bounded by stone walls. At the Ribble site, the surveyed field boundaries
were less contiguous, and were deliberately selected in 1997 to provide four replicates each of stone walls,
grass banks and green lanes. The sites were dispersed over the countryside in a 4 km×2 km block of farm-
land.
2.1.3. Manydown The third study area was in north Hampshire and
was used by Dover et al. 1990 in their comparison of conventional field margin management and the tech-
nique known as ‘conservation headlands’. The farm was principally arable, but with grass produced mainly
for seed and for a small beef herd. The field boundary habitats were principally grass banks and hedgerows
but the study also included transects through two cop- piced woodlands and a single green lane.
Data from Manydown was abstracted from tran- sects carried out in 1987 and 1988. The data on field
margins has been taken from the experimental con- trols used in the conservation headland evaluations
in 1987 and 1988 Dover, 1991. The 1988 data was supplemented by additional field margin data from
areas of the farm subject to normal farm practice but previously unpublished. Butterfly records from field
margins were made for their entire length and, there- fore, vary in both length of sampling unit and location
between the 2 years. In addition, data also previ- ously unpublished was collected from a woodland
transect carried out over the same route in 1987 and 1988 which included the rides and open glades of two
deciduous woodlands together with the ‘inside’ of a green lane which abutted the larger of the two woods;
these woods were used for butterfly dispersal stud- ies by Dover et al. 1992. Butterflies were recorded
from this transect in 100 m length sections. The data from the two types of transect were integrated for
butterfly abundance analysis by correction for length. Comparisons of species richness have not been made
as they may not be reliable, because of the different collection methodologies employed.
2.2. Biotic and abiotic parameters At the Warburton site, in addition to the abundance
of butterflies, records were made of variables which
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
