This review paper examines the mechanisms underlying the impacts of exotic plant invasions on community structure, ecosystem processes, nutrient cycling, hydrology, and fire regimes. While many studies have documented the effects of invasive plants on plant diversity and composition, fewer have tested the specific processes driving these impacts, such as competition, allelopathy, or changes in ecosystem variables. Competition was frequently observed as a key mechanism, with invasive species often outcompeting native plants for resources. However, other mechanisms, such as changes in nitrogen cycling, hydrology, and fire regimes, were also significant, often linked to specific traits of the invaders. The review highlights the need for more research linking community structure changes to ecosystem processes and understanding the factors controlling invasibility and impact. It also emphasizes the importance of studying the mechanisms behind impacts to predict which invaders are likely to have large effects and which communities are at risk. The paper concludes that while competition is a common mechanism, other factors like fire regime changes can have more severe impacts. Understanding these mechanisms is crucial for predicting the effects of global climate change on invasive species and for developing strategies to manage and restore ecosystems affected by invasions.This review paper examines the mechanisms underlying the impacts of exotic plant invasions on community structure, ecosystem processes, nutrient cycling, hydrology, and fire regimes. While many studies have documented the effects of invasive plants on plant diversity and composition, fewer have tested the specific processes driving these impacts, such as competition, allelopathy, or changes in ecosystem variables. Competition was frequently observed as a key mechanism, with invasive species often outcompeting native plants for resources. However, other mechanisms, such as changes in nitrogen cycling, hydrology, and fire regimes, were also significant, often linked to specific traits of the invaders. The review highlights the need for more research linking community structure changes to ecosystem processes and understanding the factors controlling invasibility and impact. It also emphasizes the importance of studying the mechanisms behind impacts to predict which invaders are likely to have large effects and which communities are at risk. The paper concludes that while competition is a common mechanism, other factors like fire regime changes can have more severe impacts. Understanding these mechanisms is crucial for predicting the effects of global climate change on invasive species and for developing strategies to manage and restore ecosystems affected by invasions.