摘要：Finland is officially marketed as a land of a thousand clean lakes, but people’s concerns on negative trends is common. We used questionnaires and interviews to gather information on people’s experiences on how lakes have been changed, and compared the experiences with limnological research results and administrative lake classifications. Both human observations and limnological evidence detected negative changes in lake ecosystem quality during the past 30-50 years, whereas the administrative lake classification considered lakes to be mainly in good/excellent quality. In addition, small lakes with severe ecosystem changes reported by people, were seldom covered by classification. People’s observations and limnological measurements revealed independent and identical information on the trends in water quality, whereas much of the official lake classification is based on inadequate data and lack of observations on lake littoral areas. Thus, we suggest that people’s everyday experiences should be collected and analyzed more systematically in lake quality assessment processes.
关键词：water protection;lake classification;ecosystem change;local knowledge;oral history
