Rural Regeneration Act Article 35

To the dilapidated area within rural community extensively retarding community landscape, sanitation and land use, the competent authorities at the municipal and the city/county levels may directly carry out environmental greening and building maintenance or modification when the residential address and whereabouts of landowner or building-owner is unknown, and there is no disputation raised during 3-month period of declaration bulletined by the competent authorities at the municipal and the city/county levels.
中文原文 農村再生條例第35條
直轄市或縣(市)主管機關對農村社區內有妨礙整體景觀、衛生或土地利用之窳陋地區,其土地所有權人或建築物所有權人有住所不詳或行蹤不明,經直轄市或縣(市)主管機關於村(里)辦公處所及其他適當處所公告三個月,期滿無人異議者,得逕為實施環境綠美化、建築物之維護或修繕。

English translation for reference only; the Chinese text prevails. Not legal advice.