I am sorry, I seem to have missed where the family was listed in the Gudmundrå church-registers between 1889-98 and that the poor-house seems to have been established 1889. According to Gudmundrå AI:7b they are listed in Strömnäs ångsåg 1884-88, the poor-house in Frånö 1889-98 (Gudmundrå AI:8b), but after that according to Gudmundrå AIIa:2 in a house owned by Gabriel Johansson's widow in Frånö. There is no indication of why they lived in the poor-house, but I think your definition of Erik's occupation, vagabond laborer, probably is correct. Planks could be falling also on a stevedore, either ashore or on a ship. Or he could be working at one of the numerous saw-mills (lumber plant is the american expression) on the island Alnö.
Fattiggården seems to be the domicile of old workers, widows, and some orphans. Erik Nordlander's family is an exception, indicates that Erik mostly was absent. Brita Stina attended a communion 1891 alone.
in the except from the 1890 census Erik's profession was worker, though he was also listed as vagrant, location: På obekant ort (Unknown) and across the page: Intagna å församlingens fattiggård i Frånö (taken to the parish poor-house in Frånö).