SAMPLING

Vegetation sampling will be conducted using a range of protocols according to client requirements. For routine survey and mapping our preferred methodology is to use estimates of % cover determined at sample sites located using unbiased systematic methods to allow the extraction of statistically valid assessments of plant density. Alternatively, for survey and monitoring of rare species, we will locate individual specimens to allow accurate assay.

 

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Whatever sampling method used, CS routinely spatially locate all such samples, which is essential for accurate determination of vegetation/habitat distribution together with the use of geostatistical methods for density mapping.

This also allows re-visits to sample sites if required for confirmation of observations, especially useful with scarce species. Using post-sampling phase correction we typically expect to achieve sub-metre accuracy during this process.

 

 

Boundaries for Phase 1 and Phase 2 NVC survey mapping are likewise determined as GPS located linear features in the field, as opposed to post-survey digitisation of field sketches. This again has the advantage of repeatability, together with re-visit potential if required to assess change.

Where greater accuracy is required, or if the habitat is unsuitable for the direct use of GPS methods we combine the use of optical ‘total station’ surveying referenced to fixed GPS locations. This allows survey into, for example, woodland where GPS alone is unusable, and can allow us to locate with an accuracy of a few centimetres.

 

 

The use of GPS boundary mapping allows direct data entry into a GIS for analysis, display and map production. This allows for display over existing map products or ortho-corrected aerial imagery.

 

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