Ecosystems regulate water cycles through various processes such as transpiration, evaporation, precipitation, infiltration, and groundwater recharge. Plants play a crucial role in regulating water cycles by absorbing water from the soil through their roots and releasing water vapor through transpiration. This process helps maintain the balance of water in the atmosphere and on the ground. Additionally, wetlands and forests act as natural sponges, absorbing excess water during periods of heavy rainfall and releasing it slowly during drier periods, thus regulating water flow and preventing flooding. Overall, ecosystems play a vital role in maintaining the water cycle and ensuring a sustainable water supply for all living organisms.