Please cite this article in press as: Jørgensen, S.E., et al., Recent progress in systems ecology. Ecol. Model. (2015), http://dx.doi.org/10.1016/j.ecolmodel.2015.08.007 ARTICLE IN PRESS G Model ECOMOD-7650; No. of Pages 7 Ecological Modelling xxx (2015) xxx–xxx Contents lists available at ScienceDirect Ecological Modelling journa l h om epa ge: www.elsevier.com/locate/ecolmodel Recent progress in systems ecology Sven E. Jørgensen a , Søren Nors Nielsen b , Brian D. Fath c,d,∗ a Copenhagen University, Health Faculty, Institute A, Section of Environmental Chemistry, Universitetsparken 2, DK-2100 Copenhagen Ø, Denmark b Section for Sustainable Transitions, Department of Planning, Aalborg University-Copenhagen, A.C. Meyers Vænge 15, DK-2450 Copenhagen SV, Denmark c Advanced Systems Analysis Program, International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria d Department of Biological Sciences, Towson University, Towson, MD, USA a r t i c l e i n f o Article history: Received 26 March 2015 Received in revised form 5 August 2015 Accepted 7 August 2015 Available online xxx Keywords: Systems ecology Hierarchies Thermodynamics Networks Maximum power Information a b s t r a c t Systems ecology is sufficiently developed today to offer a consistent theory about ecosystem function due to the contributions from a number of system ecologists during the last forty to fifty years. During the last five years, additional important contributions to systems ecology have been published in Ecolog- ical Modelling in the areas of hierarchy theory, landscape processes, and thermodynamic indicators. For example, research showed that hierarchical organization has an important damping effect in the higher levels on disturbances occurring in the lower levels and that the damping effect increases with increasing biodiversity; this result is consistent with experimental and model results. A first attempt has been made to integrate hierarchical and network theory on the levels of ecosystems/landscapes using model exper- iments. The model experiments point toward an expansion of the Ecological Law of Thermodynamics (ELT) to ecosystems developing on the landscape, where it previous was shown valid for populations fitting in an ecosystem. Regarding thermodynamic indicators of ecological organization, flow transfers were used to quantify the usable work energy, including the work energy of information, in ecologi- cal networks. In particular, this new approach included the cycling of information, which is changed by transfers of work energy due to different values of the donors and the receptors. These changes, however, distribute to all the components of the network. The cardinal network hypotheses proposed by B. Patten have been expanded (published in this issue of Ecological Modelling) and it has been shown that both the maximization of power (the flows of useful work energy) and the maximization of the storage of usable work energy including that of information in ecosystems’ networks are valid and complementary. This result represents a first integration of the Maximum Power Hypothesis and the Ecological Law of Ther- modynamics with Network Theory, and it is presumed that a complete integration of all three theories, hierarchical, network and thermodynamic, could be expected in the coming years. © 2015 Elsevier B.V. All rights reserved. 1. Introduction During the last quarter of the 20th century, several scientists contributed to the development of systems ecology with a number of important publications. Today, systems ecology is considered an important ecological sub-discipline as the application of ecological models, use of ecological engineering, selection of ecological indi- cators, and quantifications of ecosystem services inevitably require a good knowledge of how ecosystems are working as systems – or in other words – their basic ways of functioning (e.g., Bondavalli and Bodini, 2014; Farnsworth et al., 2012; Sciubba, 2013). ∗ Corresponding author at: Department of Biological Sciences, Towson University, Towson, MD, USA. Tel.: +1 410 704 2535; fax: +1 410 704 2405. E-mail addresses: msijapan@hotmail.com (S.E. Jørgensen), bfath@towson.edu (B.D. Fath). Systems ecology builds on the four columns of (1) hierar- chy, (2) thermodynamics, (3) networks, and (4) biogeochemistry (Jørgensen, 2012). These approaches, each with its own strengths, weaknesses, and perspectives, have often been developed in par- allel and further progress arises with their continued integration. Each of the four foundational columns is described briefly below and later within and across column advances are presented. (1) Hierarchy theory—the understanding of the hierarchical struc- ture of ecosystems in all its forms, physically embedded as vertical hierarchies, but also control hierarchies thereby form- ing a boundary to the cybernetics processes of the systems (Nielsen, 2015). (2) Thermodynamics—the understanding of the use, need, and transfer of energy by ecosystems, understood as a breakdown of an imposed gradient by irreversible, dissipative process http://dx.doi.org/10.1016/j.ecolmodel.2015.08.007 0304-3800/© 2015 Elsevier B.V. All rights reserved.