A baseline study is an analysis of the current situation to identify the starting points for a programme or project. It looks at what information must be considered and analyzed to establish a baseline or starting point, the benchmark against which future progress can be assessed or comparisons made. 

Source: EUROSTAT

Article 2(14) of the Environmental Liability Directive provides that ‘baseline condition’ means ‘the condition at the time of the damage of the natural resources and services that would have existed had the environmental damage not occurred, estimated on the basis of the best information available.’

Source: EURO-Lex

(baseline data) fundamental units of basic inventory information that are crucial for biodiversity conservation planning and management. These are both biotic and abiotic and usually include: (1) the presence and/or abundance of species and other units; (2) other dependent biotic data (e.g. plant cover for macroarthropods); (3) the appropriate influential abiotic variables, and (4) human variables. 

Source: EEA Glossary