Background and Aims <p>In reclaimed coal mining ecosystems, the microbial taxa forms a complex ecological matrix characterized by a dynamic interplay between abundant and rare biospheres that collectively maintain ecosystem functioning. To explore the ecological processes of abundant and rare microbial taxa in various reclamation patterns, we conducted a comprehensive soil sampling across various reclamation patterns in a semi-arid open-cast coal mining area, focusing on the abundant (AT), rare (RT), and conditionally rare taxa (CRT) of the microbial community.</p> Methods <p>We employed a phylogenetic null model to quantify the relative contributions of deterministic and stochastic processes in shaping the AT, RT, and CRT of the bacterial and fungal communities. Random forest models were implemented to assess the relative importance of different environmental factors in mediating community assembly processes. Linear regression analyses were performed to establish quantitative relationships between the most influential environmental variables and community assembly processes.</p> Results <p>Our study showed that bacterial assembly processes in AT and RT were stochastic, while bacteria-CRT followed deterministic processes. Fungal taxa were primarily assembled by stochasticity. The key environmental variable governing bacterial taxa assembly processes were NO3--N content. As NO3--N levels increased, strengthened the variable selection. The soil organic carbon (SOC) dominated the fungi-AT assembly, with elevated SOC changes enhancing stochastic processes. Total carbon (TC) primarily influenced the fungi-RT assembly, with increased TC changes intensifying stochastic dominance. Total nitrogen (TN) governed CRT assembly dynamics, with rising TN changes weakening stochastic processes.</p> Conclusion <p>These findings clarified microbial assembly mechanisms in reclaimed ecosystems and underscore how environmental factors govern community dynamics.</p>