Some aspects of the ecology of fungi in woodlands and forests are covered in Chapters 1 and 7. This chapter discusses the ecological role of fungi in more detail. After the introduction, the second part of this chapter discusses fungi in particular habitat types. As the following deals with harvesting of fungi by people, the third part of this chapter goes beyond people’s uses and discusses links between fungi, animals and conservation. Fourthly, the roles of fungi in carbon and nutrient cycling are described, followed by a fifth section dealing with human impacts on habitat, the many hidden effects on fungal communities and attempts at ecological restoration. In the last section, the concept of using functional traits of fungi as ecological tools is raised as an interesting challenge. The final part of this chapter concludes with a section on future research and the rapid development in molecular research that provides an important tool in understanding the crucial environmental role of fungi.