GIS are effectively spatial database systems that hold attribute data like conventional databases but additionally they provide means of creating, displaying and querying spatial objects. The main spatial data objects are:

• Points – have a position in space but no area
• Lines – have a vector in space but no area
• Regions - have positions/boundaries in space and areas
• Grids - hold arrays of values in a spatial framework with a third 'z' value (e.g. elevation or soil pH)
• Geo-referenced rasters - ‘bitmap picture’ located in space

In a GIS attribute data can be attached to or overlaid with these spatial objects to enable geographic display and analysis.

How do GIS help us ?

Most environmental records have spatial attributes. For conservation assessment, reporting & monitoring we need to know what, when and where. GIS can help us by providing tools for spatial data management including:

• Data capture - from a variety of sources - maps, satellite and airborne remote sensing, radar, aerial photography, direct-keying, automatic logging, GPS
• Data integration and comparison - species, landcover and vegetation data; ecological and administrative units, re-classification
• Data storage and maintenance - digital map management, version control, editing control, added security, ease of dissemination
• Data quality - error tracing, edge matching, georeferencing.

Applications of GIS

Much of the original development of GIS technology was for environmental applications and consequently GIS are used in a vast range of applications. Four examples are outlined below.

Data integration and mapping – One of the most useful features of GIS are their ability to help integrate different data. Various datasets can be brought together by using layers in the GIS. Each layer representing different information. In the case of management planning we have used GIS to analyse information gathered from site surveys and produce series of related site maps in common formats. Aerial photographs can be geo-referenced (positioned in space by use of ground control points) and viewed in the GIS. These can be used to accurately map features visible on the air photo but which are not present on topographic maps. Air photos can also be used as a backdrop to overlay other information such as site boundaries. Other data such as vegetation type, position of quadrats or dip-wells etc. can also be added in different layers. Once data re-captured in the GIS the software can be used to measure characteristics such as position, length and area. Such statistics are useful for calculating management inputs or survey effort. In the GIS they can be measured quickly and are reproducible.

Figure 1: Reclassifying NVC map to habitat map[a]

Data capture and management – As mentioned above, data can be captured from the sources such as air photos. Other ways of capturing data include any mapped records and remote-sensing data. GIS provide powerful tools for record checking. Because they allow the exploration of spatial relationships, point distribution data, for example, can be cross-checked with other data for positional accuracy. Many environmental records have errors in map references and GIS can be used to check they fall within the correct geographic areas. In the case of line-based or area-based mapped data, for example field survey maps, GIS can be used to check for edge areas and logical consistency. Because GIS are powerful database systems they also provide means for managing data.^[ii] Maps held within GIS are more secure than paper-based ones and it is possible for system managers to keep map-bases accurate and up to date. Maps and their associated data can be easily archived, for example onto CD. GIS can also save time, it can be much quicker to find and access a map on a computer terminal than in a map cabinet in another building – particularly if someone else has borrowed the map!^[iii]

Mapping and reporting change – Because GIS provide tools for measuring spatial data they are valuable aids to monitoring projects. The National Parks have used air-photo-based data to monitor and record vegetation change.^[iv] Maps were prepared for different points in time and GIS used to measure the change in habitat areas. The GIS thereby provided illustrative maps and measures of change derived from statistical analysis. GIS were also used in this way for analysing and measuring changes recorded by the Countryside Survey.^[v] By using a common map-base GIS-generated maps can provide a common format for reporting change and thus reduce variation introduced by using different mapping bases.

Data manipulation and reporting – Because data within a GIS can be combined by means of a common spatial framework (a co-ordinate system and a projection) they can be analysed and reported within different spatial units. For example, species observation data may be recorded with a ‘random’ area based upon the ranges of recorders rather than political or administrative boundaries. Within a GIS these data could be recorded in terms of counts within parishes, districts, counties or biogeographic regions according to need. In a similar fashion data can be re-classified by re-naming categories, aggregating them or dividing them. Using the example of vegetation mapping (see Figure 1) an NVC vegetation map can be converted into a habitat map by reclassifying NVC polygons into habitat types. The GIS can then be used to thematically map these habitats to provide a more easily recognisable and understandable map. If this needs to be refined or colours or lines styles changed GIS provides the ease of electronic editing in the same way that a word processor provides for writing reports.

Pros and cons of using GIS

Because they offer such powerful tools GIS provide challenges as well as solutions.

• Offer a vast range of tools for spatial data creation, management, analysis and reporting
• Can help organisations work more efficiently and effectively
• Can enable organisations to do new things
• Can improve productivity – particularly in map access and automation
• Provide possible cost savings - map copies, staff time, cost sharing
• Improve data security - reduce risk of loss, make backup easy, improve control over copyright/confidentiality
• Improve communication - make data more readily accessible, provide higher quality maps, offer standardisation and electronic communication.

• Hardware and software purchase can be costly
• Data acquisition, map-bases and data can be up to 80% of total costs
• Additional staff training can be needed, more highly trained staff may require higher salaries
• Can cause/initiate change in the organisations adopting them. This may mean changing roles and working practice for staff.

Some wider impacts of using GIS, they:

• Generate the need for systematic georeferencing of data
• Encourage awareness about the need for data standards
• Can facilitate data sharing
• Often increase transparency in working
• Give staff more analytical capability
• Enable organisations to add value to their services and/or provide new functions.

Conclusions

Environmental and biological records have spatial characteristics, it is therefore vital to record and understand their geographic characteristics. GIS can help us by providing a wide range of tools for managing spatial data and discovering trends and relationships in our data. GIS implementation may be a single desktop license or a large corporate system, with every level in-between. Careful thought is needed before adoption across whole departments or organisations and many organisations have therefore been reluctant to adopt GIS. However, GIS are also software tools, like conventional spreadsheets or databases, and they can be usefully adopted by individuals or small departments without ‘corporate’ adoption. On this basis it is best just to get stuck in and start using GIS.

Like all information systems GIS rely upon the quality and availability of data within them. Quality spatial and spatially-related environmental data should be our goals. If we get that right then it will be possible to develop useful and effective geographical information systems.

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