For some time I have been developing a simplified version of the gcn habitat suitability indices (HSI) that were developed by Rob Oldham and colleagues at De Montfort University. The simplified HSI guidelines attempt to predict presence of newts (rather than number of newts) and were presented at the 2006 Herp Workers Meeting, with a workshop organised the following year. The guidelines were eventually published by ARG UK in 2010.
The current HSI guidelines include some descriptions that are not as clear as I would like and could lead to increased risk of error when users attempt to calculate scores. For example I've seen some reports where ecological consultants report water quality as 'bad', even when the pond supports aquatic plants such as water mint and mammals such as water shrew.
I am therefore now soliciting feedback from anybody who uses the methodology. All feedback that will be taken into consideration when I update the text. If you would like to offer comments please do let me know. Most planned changes are quite minor and are intended to help ensure a high standard of data collection and scoring. It is intended that any new revisions will remain compatible with older versions and no changes to the overall range of variables is planned.
As a reminder, here is a list of the 10 habitat variables that form the basis of the HSI:
1. Geographic Area
2. Pond Area
3. Pond Permanence
4. Water Quality
5. Shade
6. Waterfowl
7. Fish
8. Pond Count
9. Terrestrial Habitat
10. Macrophytes
Comments on one or all of these variables will be gratefully received. Other observations on the general application of the methodology or situations where even accurate results result in difficulties in interpretation are also welcome.
Whilst there is no immediate urgency to submit comments, the revision is planned for 2011 so that it will be available on the ARG UK website in advance of the 2012 survey season. Please be aware that comments received late may not be fully considered this time around and may have to wait for inclusion in a future revision.
Comments should be emailed to [email protected] with the subject: GCN HSI Comments
Comments