There have been many!
Whilst I had initially been determined that soil moisture levels were the over-riding factor in the biogeographical distribution of pteridophytes, it quickly became clear to me that to utilise that data in isolation (at least within this piece of research) would be counter-productive. Having initially been interested in pteridophytes’ ability to reproduce in a variety of circumstances, I began to realise the following points:
a) Their presence does not appear to be restricted to soil moisture, therefore one must also consider light levels, soil pH, prevailing weather conditions and ambient temperature.
b) Their ability to reproduce sexually or clonally, or indeed apogamously in some cases, could have a significant bearing upon results.
c) How their presence (particularly in the case of Pteridium aquilinum) might impact upon the biodiversity of other botanical species. Which also raised eventual questions regarding Dryopteris spp. proving to be of a similar ilk albeit in a quite different environment. Therefore, raising the question of which pteridophyte genera is where? And thus forth what other botanical species are (or should be) there?
d) As alluded to above and in previous posts, it became clear that my initial thoughts of comparing Dryopteris filix-mas with Pteridium aquilinum were compounded by my education in fern identification. Having found that at various points Dryopteris affinis and Dryopteris dilatata were also present.
e) D. filix-mas appears to be present in areas where one might not usually expect it.
All of this led me to alter my initial Research Proposal, and the resulting final proposal submitted in November 2016 was subsequently titled “Comparison of the ecologies of Dryopteris agg. and Pteridium aquilinum”.
I undertook this change with direct reference to the points noted above, and also with the dawning realisation (and literary research) of the propensity for P. aquilinum to definitely impact upon biodiversity in Britain due to humankind’s land management practices allowing it to reproduce clonally in essence upon open grasslands. And furthermore, from the realisation that D. filix-mas (and possibly similar family members) has a similar potential to form, where conditions are favourable, a ‘green desert’ upon woodland floors.
In this way my research began to develop a two-pronged approach: Firstly, and foremostly as a study in how pteridophytes are able to adapt to changing ecosystems given their reproductive restrictions, and secondly if they could be a potential threat to biodiversity through their adaptable nature.