Derksen doesn’t actually say outright what vowel notation he’s using, but he does specify what stage of Proto-Slavic he reconstructs (my emphasis):
The reconstructed etyma represent a late stage of Proto-Slavic, posterior to the loss of glottalization under the stress and Stang’s law. Quantity, tone and stresse[s] are marked accordingly (see 3.5) The most recent development that I have taken into account is the shortening of the falling tone in word-forms of more than two syllables, e.g. *sь̏rdьce.
Based on this, you’d expect him to use the Slavicist style of representing vowels, and looking at his reconstructions, it’s clear that this is indeed what he does. That means that in Derksen’s reconstructions, the following applies:
| IPA |
Derksen |
| /ɪ̯/ |
ь |
| /ʊ̯/ |
ъ |
| /e/ |
e |
| /o/ |
o |
| /iː/ |
i |
| /ɨː/ |
y |
| /(j)eː/ |
ě |
| /aː/ |
a |
| /uː/ |
u |
For the lexeme *bùŗa, then, the Late-Proto-Slavic pronunciation reconstructed by Derksen is /bura ~ burʲa/.
I’m no Slavicist, but it seems to me that you are conflating two different stages of reconstruction when you write this (my emphases):
As far as I know, Proto-Slavic /u:/ (known as "jeri" in Croatian literature, "sharp i", usually denoted as *y) changed to /i/ in Croatian, whereas Proto-Slavic /u/ (also known as "back yer" or, in Croatian literature "jor", usually denoted as *ъ) changed either to /a/ in Croatian or disappeared due to the Havlik's Law.
Importantly, the Proto-Slavic vowel denoted by *y (aka jeri or sharp i) is not /uː/, but /ɨː/. It does come from Proto-Balto-Slavic /uː/, but it was unrounded (and probably fronted) in Slavic.
After that happened, Proto-Balto-Slavic diphthongs were monophthongised, with *au/*ou and *eu becoming a long /uː/ which kept its quality, as distinct from /ɨ/; this is easily seen in the Wikipedia chart of Proto-Slavic vowels, which has *i /iː/, *y /ɨː/ and *u /uː/ right next to each other. By Late Proto-Slavic (the stage reconstructed by Derksen), of course, these had all lost their length distinctions, but they remained qualitatively distinct as /i ɨ u/.
If you look at Derksen’s reconstruction, he gives the Proto-Balto-Slavic (“BSl”) form *bouʔr-, which contains precisely the diphthong *ou that we would expect to yield the Proto-Slavic u /u/ he reconstructs for *bùŗa.
As far as I know (but again, I’m no Slavicist, so correct me if I’m wrong), Late Proto-Slavic /u/ has remained /u/ fairly consistently in the Slavosphere – in the Wiktionary entry on Proto-Slavic *buřa, Modern Czech bouře is the only descendant that doesn’t have /u/ anymore, and that’s a much later inner-Czech development.
A note on toponyms
In comments and in the related question, some Balkan loans from other languages (Latin and Illyrian) are mentioned:
Latin 'o' usually gets borrowed in Croatian as 'i' (from Proto-Slavic *y), as in the placenames "Albona"-"Labin", "Salona"-"Solin", "Scardona"-"Skradin", "Narona"-"Norin", and "Flanona"-"Plomin"
… and there are a few toponyms where 'o' (presumably long 'o') gets reflected as 'u': Sulet (the name of Šolta in the local dialect) < Solenta, Pula < Pola... And in the river name Kupa, from the ancient name Colapis
At first blush, this looks very unexpected. Slavic has had /o/ for a long time, and that would surely be the most obvious candidate to use for /o/ when borrowing words from other languages – but not a single one of these borrowings have /o/. One reason for this may that the Slavic /o/ has historically been a phonetically open-mid vowel [ɔ], whereas at least (Vulgar) Latin /o/ and especially /oː/ was close-mid [o]. This is right in between [ɔ] and [u], and Slavic speakers may have felt that it was acoustically closer to their [u] and so used that value; there are parallels for this in Germanic loans from Latin.
Even so, /i/ (from earlier /ɨ/) is definitely not an obvious choice for /o/.
But if we look at the actual chronology of both sound changes and migrations, it may be possible after all to offer a conjecture that could just work:
- According to the Wikipedia article on Slavic migrations to the Balkans, Slavs started settling en masse in the Balkans in the 6th century
- According to the article on monophthongisation in Proto-Slavic, the PBS diphthong *au was monophthongised to *u in the 5th–7th century
- The original short *u and long *ū must have been unrounded/fronted to *ъ and *y before monophthongisation
- The merger of *o and *a is much earlier, so at this time, Slavic did not have short *a or long *o at all; but since Slavic *o was open /ɔ/, it was not an unexpected choice for /a/
If we make the assumption that these toponyms were encountered by Slavs very early on after they first arrived in the Balkans, and we assume that monophthongisation took place closer to the 7th than to the 5th century, we can set up a timeline that works (ignoring the exact chronology of when final vowels were lost):
| Time |
Occurrence |
Example |
| ~520–550 |
Slavs start arriving in the Balkans, encountering and borrowing some local toponyms in Latin and Illyrian |
Lat./Ill. Salōna, Poetovio /poiˈtoujo/ → PS *solūn(V), *paitauj(V) |
| ~550–575 |
High back vowels are fronted/unrounded |
*solūn > *solɨːn |
| ~600 |
Diphthongs are monophthongised |
*paitauj > *pitūj |
| ~575–600 |
Slavic settlement increases, additional toponyms borrowed |
Lat./Ill. Pola → *pūla |
| later |
Loss of length distinction, jers and some unstressed vowels |
*solɨːn > *solɨn, *pituj > Ptuj, *pūla > Pula |
| Post-Slavic |
ɨ > i |
*solɨn > Solin |
This obviously leaves out quite a lot of detail, and it’s not unlikely that there are further complications to various parts, but as a base chronology, it is a possibility.
