Table 1. Pre-defined topics covered by semi-structured interviews, and themes that emerged within these topics.

Topic (pre-defined)	Theme (emergent)
T1. Main features of habitat quality	a) Combination of features
	b) Habitat structure
	c) Vegetation composition and structure
	d) Geographical and temporal variability
	e) Ecosystem services
	f) Applicability and practicality
T2. Value of individual species	a) Structural and functional species
	b) Scarce species
	c) Invasive species
	d) Historical context
	e) Comparative values of species
T3. Plant & lichen indicator-species	a) Characteristics of positive indicator-species
	b) Characteristics of negative indicator-species
	c) Context of indicator-species
T4. Taxa other than plants and lichens	a) Importance of other taxa
	b) Management conflicts
	c) Barriers to using other taxa
	d) Proxy indicators of suitability for other taxa
T5. Species-groups	a) Pros and cons of using species-groups
	b) Identifying useful species-groups
T6. Reference communities	a) Defining a reference community
	b) Potential reference community definitions