Andrew J. Hansen


National Aeronautics and Space Administration (NASA)

Resulting Manuscripts

  • Hansen, A.J., L.B. Phillips, C.H. Flather and J. Robison-Cox. 2011. Carrying capacity for species richness as a context for conservation: A case study of North American breeding birds.  Global Ecology and Biogeography 20, 817-831. PDF and Cover
  • Phillips, L.B., Hansen, A.J., C.H. Flather and J. Robison-Cox. 2010. Applying species-energy theory to conservation: a case study for North American birds. Ecological Applications 20(7) 2207-2023.    PDF


Ecologists widely agree that context matters. In different places, we recognize that interactions among abiotic variables, ecological processes, species, and humans play out differently.  Are there general properties of ecosystems that, if recognized, might help us set conservation goals more reliably? To address this question, I retraced the historical roots from which conservation biology has grown and found one property, ecosystem energy levels, which, while once widely recognized as important, has received little emphasis since. In contrast, the allied fields of ecosystem analyses and biogeography have made ecosystem energy a basis component of their research and its application. In this paper, I first review the current state of knowledge relating ecosystem energy to attributes of populations, communities, and landscapes critical to the interests of conservation biologists. Those hypotheses that are adequately supported are used as the basis to derive generalizations on the traits of ecosystems differing in energy levels and habitat heterogeneity.  As a result of the review, I present a scheme that uses ecosystem energy levels as a strategic framework to help identify conservation priorities and those management practices most likely to be effective.  Management strategies are then presented for ecosystems of each of three energy levels to achieve conservation objectives.  The geographic distribution of each type of ecosystem is illustrated globally and applications are described in case studies of landscapes in the Pacific Northwest, northern Rocky Mountains, and Mid-Atlantic regions of the United States.  Finally, I suggest research to reduce uncertainty on the implications of ecosystem energy serving as a framework for conservation planning under changing climate and land-use pressures.  It is my hope that the framework will make conservation biology a more predictive science and help managers develop strategies that better meet their objectives.