A computer based study of the flora of highly acidic environments
An account is given of the use of a computerised database approach to the study of the chemistry and botany of streams with a pH at and below 4.0. the SIEUR (Stream Information Entry, Update and Retrieval) system was designed and implemented on the Northumbrian Universities IBM System 370 computer running under the M.T.S. operating system. SIEUR has been used to store approximately 2500 water chemistry and 2700 biological records. Of these, 269 chemistries and 125 biologies were collected from 10 m reaches from four countries where the pH was at or below 4.0 on the day of sampling. Principal component and cluster analyses of the acid chemistries suggested that they may be grouped together, based on the level of the various cations measured. This grouping follows closely a geographical breakdown of the sites and is probably a reflection of the mining associations of the majority of the sites. There was no similar grouping of the biological samples. Detailed examination of the distribution of 30 photosynthetic species which occurred live suggested that four patterns of reaction to low pH existed. In the design and practical application of the SIEUR system to the investigation of the acid datasets several problems and some solutions were identified. The need to date, time and location stamp all data at all stages of the analyses was apparent. SIEUR provides an "expansion facility" to overcome the problem of chemical and biological sampling not necessarily occurring together on the same day. By the use of this facility the user can specify the leeway by which chemical and biological samples from the same site are linked to each other in terms of date of sampling. A major design consideration was the need to identify structure in the data and to be able to store and retrieve this as data. During the use of the system the need for comprehensive statistical and graphical facilities was apparent. The decision to provide interfaces to existing packages to do this, rather than provide integral facilities was fully justified in terms of the flexibility obained.