Lake Päijänne LTER is a part of FinLTSER, the integrated network of multi-functional long-term ecosystem research platforms in Finland. Finland is one of the countries that are working together to create a European network of ecosystem research platforms, to provide an integrated system for detecting and understanding environmental change at a range of scales. Long-term Ecosystem Research (LTER) is an essential component in efforts to better understand how ecosystems function and respond to environmental change. The key feature of LTER is its long-term approach. In terms of monitoring this means building up long time-series datasets by collecting data at regular intervals, using consistent methods.