Abstract
Natural history collections cannot be assessed by the size of their holdings, because their scientific value is a multidimensional and dynamic property that can be deliberately shaped. The authors argue that this value can be systematically increased through purposeful curatorial and research actions, both without acquiring new material and through its continuous replenishment. We propose an analytical framework for describing the scientific value of a collection, based on five dimensions: epistemic distinctiveness, data integrity and accessibility, documented and potential research applications, unique taxonomic status, and compliance with ethical and legal standards. The framework is complemented by a dynamic perspective describing the conditions under which the value of a collection rises and falls over time. We then present a typology of actions that increase collection value incrementally, distinguishing four categories according to the object of the action: (i) enriching the data record, (ii) enriching the physical specimen, (iii) establishing formal status, and (iv) increasing visibility and interoperability. Each category of actions is linked to the corresponding dimensions of scientific value, so that the typology and the framework together form a single analytical tool. Both perspectives are illustrated with two collections deposited in the Natural History Collections of Adam Mickiewicz University in Poznań. The first is an acarological collection of soil samples together with its derivatives, comprising collections of nomenclatural types, microscope slides, SEM images and molecular sequences deposited in global gene banks. The second is a conchological and virtual collection of the Roman snail (Helix pomatia), which illustrates the transition from a set of physical specimens to a resource of spatial digital data. The proposed approach provides practical tools for planning collection development, for communicating the importance of collections to funding bodies, and for identifying the untapped research potential of existing holdings.