. British journal of entomology and natural history. Natural history; Entomology. BR. J. ENT. NAT. 3: 1990. Fig. 1. Seed harvester in action. i* •'.y i ?j-'i5(#1/lfh'-i'^"'«4«t suction heads and suction is applied to the sward mostly after it has been pushed over. Once the machine has passed, the sward springs up to a greater or lesser extent but does not return to the undisturbed condition, at least not on the same day, and this and the tyre tracks show which areas the machine has covered (Figure 2). To collect the full variety of seed it is necessary for the machine to make sever
. British journal of entomology and natural history. Natural history; Entomology. BR. J. ENT. NAT. 3: 1990. Fig. 1. Seed harvester in action. i* •'.y i ?j-'i5(#1/lfh'-i'^"'«4«t suction heads and suction is applied to the sward mostly after it has been pushed over. Once the machine has passed, the sward springs up to a greater or lesser extent but does not return to the undisturbed condition, at least not on the same day, and this and the tyre tracks show which areas the machine has covered (Figure 2). To collect the full variety of seed it is necessary for the machine to make several visits spread throughout late June and July (six visits in 1987). The sward must be dry to the touch before harvesting and sunny calm conditions are preferred. Effects on the invertebrates Both Dr Gibson and I concentrated on the invertebrates that were collected up by the machine on the day and were not able to investigate the longer-term effects of additional soil compaction and changes in the composition or structure of the vegetation that may or may not result from seed harvesting. Also, we were unable to sample the invertebrates that remained within the sward after the seed harvester had passed. Dr Gibson observed that the suction of the machine at normal power was low compared with standard insect vacuum samplers such as the 'D-vac' and Burkhard 'Univac'. On the basis of his experience with the D-vac he estimates that the catch of insects which he observed was equivalent to 1-3% of the likely fauna present in the area covered by the machine. In 1988 the machine made three visits between July 15 and early August and I was present on the first of these. The operation was 3 weeks late due to bad weather and most of the buttercup seed was missed. The forester moth had finished flying a fortnight previously (A Saunders pers. comm.) and did not appear in the catch. Composition of the catch The catch of seeds and insects was not simply closed up and removed from the site
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Keywords: ., bookcentury1900, booksubjectentomology, booksubjectnaturalhistor
