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What finances are available and what are the costs of completing the survey?
Surveys are typically designed with limited resources. The need for cost-effectiveness influences many components of the survey, including
For each of these elements of your survey, each decision will involve a trade-off between the time and personnel you have available and the scope and detail of the data you collect. Ultimately these decisions should be guided by the research question you are addressing.
Sampling intensity
There is often a direct relationship between the intensity and the cost
of sampling. The more quadrats that are collected, the more time it will
take to sort samples and identify the biota. In some instances however,
the main cost may be in getting to a remote site and the time (and thus
cost) required to collect data may be small by comparison. Needless to
say, careful planning is required to optimise the intensity of sampling
with respect to the costs involved.
Taxonomic resolution
The skills required for species identification are expensive. This is
particularly true for aquatic and terrestrial invertebrate species. Therefore,
the finances available for a survey will be a determinant of the level
of taxonomic identification.
In the mid-1980's, the need for cost-effective invertebrate survey techniques was realised and it was also recognised that it was crucial to collect, compile, analyse, and interpret environmental data rapidly to facilitate management decisions. Therefore, methods of 'Rapid Biodiversity Assessment' were developed. As described by Oliver and Beattie (1996), these methods have fallen into five main categories:
- the use of surrogate, indicator taxa in place of all taxa. The surrogate taxa should have known relationships to the diversity of other taxa, and should respond in a predictable way to environmental parameters, or represent a range in some functional attribute.
- the use of restricted sampling, rather than intensive sampling.
- the use of morphospecies that can be identified by non-specialists.
- the use of taxonomic ranks (e.g. Genus, Family, Order) rather than species to assess biodiversity.
- extrapolation from species accumulation curves or other models.
Methodology
Methods that require specialist equipment may be limited by the project
budget. For instance the use of satellite imagery may be an efficient
way to determine vegetation types at a broad scale, however the cost of
acquiring and interpreting such imagery may be prohibitive.
Measures of abundance
Again, measures of abundance are of a level of accuracy that is determined
by the researcher, and can have a substantial influence on cost. For example,
a visual estimate of plant cover in a 20 m x 20 m plot is relatively rapid
and therefore inexpensive. However, a detailed determination of plant
species abundance by counting stems and mapping canopy area is time-consuming.
Each of these elements of your survey will involve a trade-off between the time and personel you have avaliable, and the scope and detail of the data you collect. Ultimately this decision should be guided by the research question you are addressing.
