I just come back from it.
I have encountered more sphagnum patches than I expected, though some are rather stressed, especially those on the south-facing slopes. Perhaps it is because of more sunlight and less moisture. Besides, there are very few sphagnum patches larger than 5 metres in any dimension, except some in SK0993 in those gullies.
Besides, I just found that many sphagnum patches can be found in these ESA vegetation types: cottongrass moorland, dry bog heather or non-heather dominated. I'll do a chi-square test to see if the hypothesis is true: that land use type is related to sphagnum presence.
A possible spectral signature can be found using about 20 sphagnum patches I found this time. The problem is the difference between aerial photographs made large-scale classification complicated: you have to identify sphagnum patches one square km by another. This could mean extensive fieldwork next phase.
The validation of these signatures is another problem. I can guess they are pretty good predictions, but this must be verified using more fieldwork data.
I may need to do more study on sphagnum habitats considering elevation and hydrology. I also need to talk with Jack in the coming weeks. For the next period, the main focus will be on hydrology models.
The data were organised into a 2x2 contingency table.
回复删除Dry bogs and cottongrass moorlands are defined as suitable habitats, the rest are unsuitable.
The result of the chi-square test:
Using pure Pearson's chi-square test, chi-square = 7.04, p = 0.008 . Using Pearson's chi-square test with Yates' Continuity Correction, chi-square= 5.88, p = 0.0153. Thus the null hypothesis is rejected on a 0.05 credibility level. Sphagnum observed depend on vegetation types.