BRITISH BRYOLOGICAL SOCIETY
Survey of the
Bryophytes of Arable Land
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General Instructions
Sample design
The main national survey comprises three classes of field, for which data will be collected together using the same methodology.
Class 1 Fields located in a random selection of tetrads (2-km squares) distributed in the main arable areas of Britain. The location of these squares and the method of their selection are set out in an attached table.
Class 2 Fields located anywhere in Britain, selected because they are in a suitable condition for bryophyte recording.Class 3 Fields selected for specific attributes, such as having wet hollows or being used for special crops or organic farming.
Sampling methodology in the field
Suitable condition. A field is in suitable condition
when it is:-
1. Arable or in set-aside following arable use
2. Either the bryophytes are large enough for most of them be identified
or (a rare case) there are none but you judge from the time of year that
they ought to be identifiable if they were there. Do not reject a
field merely because it has few bryophytes; we want to know if there is
little or nothing there.
Class 1 fields. The aim is to visit at least 2 fields per chosen tetrad. It is also possible to revisit fields on subsequent occasions, which may be in subsequent years. A revisit does not count as a 2nd field. Go to the tetrad and search for fields in suitable condition. If none can be found in the chosen tetrad, then any of the 9 adjacent tetrads can be visited for this purpose. If this takes you into another 10-km square, do not worry. Provided that the field is a Class 1 field, this fact entered on the card will be sufficient for checking on completeness.
Permission. Having found a suitable field, get permission to search it. We accept that permissions may not always be required, for example for an unfenced field by a public footpath where it is clear that a few people straying onto the arable area after harvest will not disturb game, damage crops or cause offence. You should use common sense and show sensitivity and respect for farmers in this matter.
Time spent searching for bryophytes. In most fields, you should aim to spend about 30 minutes, but it partly depends on how many of you there are. If it turns out that a field has almost no bryophytes, you may be able to leave after 10 minutes, but this is unusual. (We have once seen a stubble field in suitable condition with no bryophytes at all, and on another occasion with only one plant of Tortula acaulon (Phascum cuspidatum) in the whole area.). If the field has a very rich flora you may need to spend longer. The basic rule is to go on searching until you are not finding anything new.
How to search for bryophytes. What is needed is a ‘random walk’, stopping at intervals and getting down on your hands and knees to examine what is there. Identify what you can in the field. You should accept that several common tuberous species normally have to be checked microscopically.
How to collect and identify bryophytes. Each specimen to be examined should be kept separate from the others. An easy method of achieving this is to wrap specimens in small bits of newspaper and put them in a tin. Back at home, the specimens should be checked microscopically in the usual way, washing out tubers where necessary. We will provide an identification pack. Most tuberous species can be readily identified, but we have found difficult plants on calcareous soils that appear to be intermediate between Bryum radiculosum and B. ruderale, and on acid soils that appear to be intermediate between B. rubens and B. subapiculatum (microerythrocarpum). You should be prepared in some cases to write Bryum sp.
How to recognize soil types. The menu allows 6 primary soil types, between which are various intermediates. Each soil can be described by a primary and a secondary soil type if there is an intermediate (this is explained in more detail in the instructions for filling in the recording sheet). The following explanations may be found helpful. We do not in practice expect you to do a detailed textural analysis, but we do want to have a broad indication of texture, and in particular to separate sandy and clayey soils.
1 chalk Enter this if chalk is visible in the soil. A soil is rated as mainly a chalk soil if it is generally whitish; chalk is the secondary attribute if there are lumps of chalk but not so many as to make the appearance white.
2 sand Sand particles are defined as bigger than silt particles and smaller than gravel, i.e. in the range 0.05-2.0 mm. A sandy soil feels gritty.
3 clay Clay particles are the smallest, defined as <2µm. A clayey soil feels smooth and sticky when wet, and can be rolled into a sausage, which coheres.
4 silt Silt particles are intermediate between sand and clay, 2-50µm. They cannot be seen with the naked eye and do not feel gritty. Silty soils lack the smoothness and coherence of clay soils.
5 loam Loamy soils are ones that contain a mixture of sand, silt and clay. They are generally the most easily workable, adequately drained arable soils.
6 peat Almost all peaty arable soils are on fen peat. Peat is easily recognizable because it is light and black.
Soil pH. Soil samples need be no bigger than a medium-sized clod of moss, enough to occupy when crumbled about 3 cm in the bottom of a plastic cup. We recommend taking 3 separate mossy clods from a field, measuring the pH of the 3 samples separately then recording the mean as the pH value on the card and noting the values for the 3 samples in the 'Comments' box. To measure the pH, mix the soil with water to form a slurry over which there is about 25% supernatant. Leave for a few minutes and stir again. Dip the electrode of the pH meter into the slurry and obtain a reading. One of the pH meters that we have tested takes a few minutes to settle down. You will have to learn the idiosyncrasies of your instrument. Alternatively, samples can be dried and stored for later re-wetting. We can measure pH for you if you do not have a meter.
Habitat and crop. These are easy if there is no setaside. Crop 1 is the first crop sown after tillage. Crop 2 is the second crop. If you have pure wheat stubble, Crop 1 is wheat; if you have rape sown into wheat stubble, then Crop 1 is wheat and Crop 2 is rape. The complication is that setaside is deemed to be a habitat after the April following harvest, but before April, setaside is Crop 2. The reason for this is that before April, the presence of setaside depends on the farmer’s intentions (i.e. it is a mental concept) and cannot be recognized by field observation. Unless you interview the farmer, you could not recognize it as setaside.
Filling in the recording sheet. Detailed instructions on how to fill in the recording sheet are given in the third worksheet of the electronic recording form.
Data entry and analysis
Data entry. We shall use a special data entry program
modified from BRCinputter, a data entry program written by Mark Telfer
for the Biological Records Centre. With BRCinputter, data are entered
directly into a relational database in Microsoft Access.
Data analysis. It is not possible to specify all the
analyses that will be required. The following are envisaged.
• Species richness; what are the trends in relation to environmental
factors such as time of year, soil texture, soil pH, part of the country,
previous crop?
• What is the relation between vascular cover, bryophyte cover and
the species present?
• Which species tend to occur together and can the associations
simply be explained by their environmental preferences?
• Which species are commonest in different parts of the country?
• Do species from arable fields in predominantly non-arable areas
differ from those in the main arable areas?
• What are the habitat requirements of particular rare species?
• Can we understand the results in terms of life cycles and likely
means of immigration or persistence?
Supplementary biological work
We have poor information on the life cycles of many species, on how quickly
they develop etc. If you can make observations or experiments that can
advance our understanding, it would be good to fit them in with this survey.
Records over time of growth and development in a single field would be
useful.
Acknowledgements
David Roy (CEH Monks Wood) provided us data for the random allocation
of tetrads and mapped them. David Holyoak encouraged us to go ahead and
has helped to elucidate (though not yet solve) the problem of smooth-tubered
Bryum species. Mark Telfer developed BRCinputter.
References
Fuller, R. M., Groom, G. B. & Jones, A. R. (1994). The Land Cover
Map of Great Britain: an automated classification of Landsat Thematic
Mapper data. Photogrammetric Engineering and Remote Sensing 60, 553-562.
Porley, R. D. (2000). The conservation ecology of arable plants: What
role for research? In Fields of vision: a future for Britain's arable
plants (ed. P. Wilson and M. King), pp. 8-19. Plantlife, London.
Porley, R. D. (2001a). Recording Matters 19. Bulletin of the British Bryological
Society 76, 45-47.
Porley, R. D. (2001b). Recording Matters 20. Bulletin of the British Bryological
Society 77, 30-32.