STUDIES O N TRE INSECT FAUNA ON SCOTCH BROOM
95
and Ulex europaewr L. Under the older bushes there is an accumulation
of characteristic broom litter. From ring counts made by Mr J. Levy,
some of the plants in this area started gi.owth in 1944 or 1945; these
are now dead. About 8074 of broom in this area died by 1960-61, but
i t is now regenerating and there are several dense stands of young
bushes.
Area 2 called the Cheapside plot is roughly rectangular and measures
about 410 m2. The naturally occurring bushes are of all ages and some
die each year.
Area 3 was another small plot of 120 naturally growing bushes by
Ashurst Lodge. When B. D. Smith studied a population of aphids
(1955-57) the bushes were 4 and 10 years old and 1-2.5 m high. One
side of this rectangular area was bordered by woodland and the remaining three sides by grassland. A11 the bushes in this area are now dead
(1967).
Area 4 is a 1-hectare plantation. In March 1957, 1623 broom seedlings
were planted out in 24 rows. Originally 10-15 cm high they reached
1.8 m by September 1959 and this height has remained more or less
constant. The plantation is bordered by woodland on its west and south
sides and by open grassland on the north and east. The plants are now
(1967) 10 years old and only half of the bushes are alive (see Table 111).
Area 5 is a plot of 138 bushes on the Rookery slope, planted in 1958
and 1959. The bushes grow singly or in groups of 2 to 8, forming 36
separate units. They occupy 8223 m2 and the area actually under broom
bushes is 4376 m2. This area is surrounded by grassland.
Area 6 consists of two small plots of broom seedlings planted out in
March 1966. Plots (A and B) are 100 m apart and each consists of 8
rows 93 m long, each with 30 seedlings. There are 480 plants in two
plots of 240. In 1966,O. M ' . Richards and myself started an experiment
in thiR area. Plot A has been sprayed with insecticides and plot B
remains untreated. Periodically the fauna on broom is sampled in both
areas and it is hoped that in 5-6 years comparison of the two groups
will provide an aseeasment of the effects of insect damage.
Irr. INSECTS LIVING WITHIN THE BROOM PoDs
The undehisced broom pod is a temporary microhabitat which occurs
in the field from May to September. At Silwood Park the complex of
insects within the pods is a microcosm of twenty-three species. These
were studied for a period of 3 years by Parnell (1962, 1963, 1964a,
1964b, 1966) in Area 1 (old broom) and in Area 4 (young bushes).
During this period a catastrophic change in the numbers of pods was
caused by frosts in late May in 1961.
95
and Ulex europaewr L. Under the older bushes there is an accumulation
of characteristic broom litter. From ring counts made by Mr J. Levy,
some of the plants in this area started gi.owth in 1944 or 1945; these
are now dead. About 8074 of broom in this area died by 1960-61, but
i t is now regenerating and there are several dense stands of young
bushes.
Area 2 called the Cheapside plot is roughly rectangular and measures
about 410 m2. The naturally occurring bushes are of all ages and some
die each year.
Area 3 was another small plot of 120 naturally growing bushes by
Ashurst Lodge. When B. D. Smith studied a population of aphids
(1955-57) the bushes were 4 and 10 years old and 1-2.5 m high. One
side of this rectangular area was bordered by woodland and the remaining three sides by grassland. A11 the bushes in this area are now dead
(1967).
Area 4 is a 1-hectare plantation. In March 1957, 1623 broom seedlings
were planted out in 24 rows. Originally 10-15 cm high they reached
1.8 m by September 1959 and this height has remained more or less
constant. The plantation is bordered by woodland on its west and south
sides and by open grassland on the north and east. The plants are now
(1967) 10 years old and only half of the bushes are alive (see Table 111).
Area 5 is a plot of 138 bushes on the Rookery slope, planted in 1958
and 1959. The bushes grow singly or in groups of 2 to 8, forming 36
separate units. They occupy 8223 m2 and the area actually under broom
bushes is 4376 m2. This area is surrounded by grassland.
Area 6 consists of two small plots of broom seedlings planted out in
March 1966. Plots (A and B) are 100 m apart and each consists of 8
rows 93 m long, each with 30 seedlings. There are 480 plants in two
plots of 240. In 1966,O. M ' . Richards and myself started an experiment
in thiR area. Plot A has been sprayed with insecticides and plot B
remains untreated. Periodically the fauna on broom is sampled in both
areas and it is hoped that in 5-6 years comparison of the two groups
will provide an aseeasment of the effects of insect damage.
Irr. INSECTS LIVING WITHIN THE BROOM PoDs
The undehisced broom pod is a temporary microhabitat which occurs
in the field from May to September. At Silwood Park the complex of
insects within the pods is a microcosm of twenty-three species. These
were studied for a period of 3 years by Parnell (1962, 1963, 1964a,
1964b, 1966) in Area 1 (old broom) and in Area 4 (young bushes).
During this period a catastrophic change in the numbers of pods was
caused by frosts in late May in 1961.