Microbial　resource　limitation　is　critical　to　ecosystem　function　and　processes.　However,　knowledge　about　the　patterns　and　mechanisms　of　microbial　resource　limitation　in　karst　fragmented　habitats　is　still　lacking.　In　this　study,　the　karst　negative　topography　fragmented　habitat—Zhanyi　Tiankeng　Group　was　taken　as　a　model　system,　and　the　microbial　resource　limitations　of　the　tiankeng　ecosystem　were　studied.　Tiankeng　soil　microbes　were　co-limited　by　C　and　P.　Compared　to　outside　the　tiankeng　sites,　the　tiankeng　provides　a　refuge　for　the　survival　of　microbes　and　alleviates　microbial　resource　limitations.　Habitat　fragmentation　has　altered　microbial　resource　limitations.　Lower　microbial　C　limitation　on　larger　tiankengs,　suggested　that　larger　fragment　habitats　could　create　a　unique　habitat　for　soil　microbial　survival　in　the　degraded　karst　landscapes.　Microbial　C　and　P　limitations　were　mainly　affected　by　soil　water　content　and　dissolved　organic　carbon,　indicating　that　soil　physicochemical　properties　were　important　factors　in　maintaining　microbial　metabolism　in　tiankengs.　Our　study　provides　meaningful　insights　into　ecosystem　functions　and　soil　biogeochemical　cycles　in　karst　fragment　habitats.　©　2025　Elsevier　B.V.