I cannot create a summary of the requested article because the search results provided do not include the article titled "Higher carbon storage in primary than secondary boreal forests in Sweden" from the journal Science, Volume 391, Number 6791, March 2026. The search results include articles on other topics related to boreal forests in Sweden - specifically, the impact of increasing CO₂ concentration on forest nitrogen availability and carbon emissions during forest fires – but not on the comparison of carbon storage in primary and secondary forests. In order to create an accurate and factual summary as per your requirements, I need to have the content of the specific article you have provided.