The Doctoral Program Environment and Society does not entail funding.
The Federal Ministry of Education and Research (BMBF) provides an interactive platform that serves as a good tool for a detailed overview of all current scholarship schemes and finding out which ones you are suitable for you.
The German Academic Exchange Service (DAAD) offers individual scholarships for doctoral students, both for longterm projects, as well as for shorter time periods (e.g. research trips or support for conference presentations).
Please note that these scholarship schemes are usually very competitive. The application and decision process will take at least several months.
Limited funding to support conference and researchs trips for doctoral students is available through the doctoral program.
A list of external short-term funding opportunities can be found here.