The forest provides a habitat for plants, animals, fungi, and other organisms. In the Level II network, the focus of the biodiversity survey is on plants: the composition of tree species and ground vegetation is recorded at regular intervals.

Recording biodiversity helps to understand how different environmental drivers affect the forest. Climate change can affect biodiversity in the forest, for example by changing the growth conditions for certain species or promoting the spread of pests. In addition, the input of air pollutants can change site characteristics.

Nitrogen deposition, in particular, can cause stress in forest ecosystems. It affects vitality and growth and can change the species composition of ground vegetation. As a significant influencing factor, nitrogen pollution is part of the reporting within the framework of the Convention on Biological Diversity. Data from the Level II network is used for this purpose.