Many species live in spatially structured populations. For example, migratory species such as these Northern Pintail ducks use discrete habitat patches during their migration. How can we tell which habitats are most important for management, and how do we measure importance? The answer depends what we want to achieve and the kind of data that we have available. Image: Wikipedia (Image credit: JM Garg)
Our new paper came out in Ecological Indicators yesterday. In the paper we review the literature on metrics for managing spatially structured populations (i.e. metapopulations, migratory species populations). We ask the question: “what is the best way to measure the contribution of a habitat to the total population?” It’s a complicated question, partly because different theoretical approaches all have their preferred metrics. In the paper, we take a quick tour of graph theory, metapopulation theory and matrix models/perturbation analysis, and try to link the metrics developed in these literatures into a usable framework. We argue that the best metric depends on the management objective and the data available, and provide a simple framework for metric selection using these ideas.
The work was completed in collaboration with scientists from the US, Austria and Canada as a product of the NIMBioS Working Group on Habitat for Migratory Species. You can see their press release here.
Mobile species with complex spatial dynamics can be difficult to manage because their population distributions vary across space and time, and because the consequences of managing particular habitats are uncertain when evaluated at the level of the entire population. Metrics to assess the importance of habitats and pathways connecting habitats in a network are necessary to guide a variety of management decisions. Given the many metrics developed for spatially structured models, it can be challenging to select the most appropriate one for a particular decision. To guide the management of spatially structured populations, we define three classes of metrics describing habitat and pathway quality based on their data requirements (graph-based, occupancy-based, and demographic-based metrics) and synopsize the ecological literature relating to these classes. Applying the first steps of a formal decision-making approach (problem framing, objectives, and management actions), we assess the utility of metrics for particular types of management decisions. Our framework can help managers with problem framing, choosing metrics of habitat and pathway quality, and to elucidate the data needs for a particular metric. Our goal is to help managers to narrow the range of suitable metrics for a management project, and aid in decision-making to make the best use of limited resources.
Nicol S, Weiderholt, Diffendorfer J, Mattsson B, Thogmartin W, Semmens D, Lopez-Hoffman L, Norris DR (2016) . A management-oriented framework for selecting metrics used to assess habitat- and path-specific quality in spatially structured populations. Ecological Indicators 69: 792-802. DOI:10.1016/j.ecolind.2016.05.027