**5. Conclusion**

IAS management must take into account all impacts of new species in a certain ecosystem. Natural resource management bodies should base their management plans on the real effects of a particular species in an ecosystem and not on traditionally repeated claims of non-selective negative effects of alien species. All species have some useful potential in an ecosystem, and many have easily defined services. Although some non-native species can cause serious problems that should be taken into account, a wider perspective on the role of each species in an ecosystem is needed. Their role is also mixed with new challenges arising from other environmental changes such as climate changes and human interventions. Land managers must focus more on the function of a species in an ecosystem than on their origin. As our understanding of biological invasions is growing, our capability to describe the ecological and economic consequences is more precise enabling the environmental managers to make objective decisions about IAS management.
