ABSTRACT. Ecological restoration, particularly in urban contexts, is a complex collective decision-making process that involves a diversity of stakeholders and experts, each with their own perceptions and preferences about what landscapes should and can look like, how to get them to the desired state, and on what timeline. We investigate how structural and behavioral factors may influence collective decision making in the context of ecological restoration, with the purpose of establishing general relationships between management styles (defined by structural and behavioral factors of the organization) and decision outcomes. Informed by existing literature on collective decision making and by empirical data from the Chicago Wilderness region, we present a stylized agent-based model that maps out and simulates the processes by which individuals within restoration organizations communicate, discuss, and ultimately make a decision. Our study examines how structural and behavioral characteristicsincluding: (a) the number of actors and groups involved in decision making, (b) the frequency and type of interactions among actors, (c) the initial setup of positions and respect, (d) outside information, and (e) entrenchment and cost of dissent-lead to or prohibit group convergence in terms of collective position, variation in position across actors, and final decision strategies. We found that formal meetings and group leaders are important facilitators of convergence, especially when multiple groups are present, new information is introduced in the process, and participants are polarized around an issue. Also, intergroup interactions are particularly important for overall convergence. Position entrenchment slows the convergence process and increases the need for decision strategies involving outside intervention. Cost of dissent can reinforce these effects. Our study formalizes collective decision-making processes within the context of ecological restoration, establishes generalizable relationships between these processes and decision outcomes, and provides a foundation for further empirical and modeling research.

Many studies have linked the spread of exotic, invasive species to high nitrogen supply, but most of this work does not distinguish between various inorganic forms and different concentrations of available nitrogen. Previous research has suggested that exotic, invasive species common in eastern deciduous forests may preferentially utilize nitrate in contrast to native species that preferentially make use of ammonium. We tested this hypothesis by comparing the growth response of two common forest invaders, Berberis thunbergii and Microstegium vimineum, and two co-occurring native species (Vaccinium pallidum and Hamamelis virginiana) to different forms of nitrogen under varying concentrations in a greenhouse experiment. Two forms of nitrogen (nitrate or ammonium) were added at different concentrations (22, 106, and 212 mg N l -1 ) to all species. Growth response variables included survival, stem length, stem diameter, above and belowground biomass, and estimated seed production (Microstegium only). Unexpectedly the exotic species did not respond preferentially to nitrate addition. Microstegium responded most strongly to both nitrogen forms depending on the response variable. Berberis and Hamamelis surprisingly reacted similarly to nitrogen additions. As expected, Vaccinium fared poorly under most treatment conditions, but did show some growth in NH 4 ? treatments. Our findings suggest species response to nitrogen addition is complex, and that exotic species do not all respond similarly to nitrogen inputs. In this study, the response of exotic and native species to available nutrients does not provide a general mechanism of invasion success.

We summarize the factors that shaped the biodiversity of Chicago and its hinterland and point out the conservation significance of these ecological systems, addressing why conservation of Chicago’s biodiversity has importance locally and beyond. We highlight Chicago Wilderness (CW), a regional biodiversity conservation alliance committed to protecting nature and enriching the lives of the region’s residents. Chicago Wilderness, with over 250 institutional members, has for over a decade coordinated the efforts of diverse institutions, including federal, state, and local agencies, public land-management agencies, conservation organizations, and scientific and cultural institutions. Chicago Wilderness is committed to using science and emerging knowledge as a foundation for its conservation work. CW has several specialist teams that promote an interdisciplinary approach to conservation; we focus on the work of the CW Science Team, the one team with a research mission. The scientific investigations that are undertaken to provide a knowledge base for the work of Chicago Wilderness have drawn upon a wide variety of conservation paradigms, including that of resilience thinking, which we illustrate in a series of case studies

Ecological restoration actions generally result from collective decision-making processes and can involve diverse, at times contentious, views. As such, it is critical to understand these processes and the factors that might influence the resolution of diverse perspectives into a set of coordinated actions. This paper describes the adaptation and calibration of a stylized collective decision-making agent-based model using ethnographic data, to advance theory on how decisions emerge in the context of ecological restoration in the Chicago Wilderness. The prototypical model provided structure and organization of the empirical data of two Chicago Wilderness member groups and revealed organizational structures, patterns of interactions via formal and informal meetings, and parameter values for the various mechanisms. The organization of the data allowed us to identify where our original model mechanisms required adaptation. After model modifications were completed, baseline scenarios were contrasted with observations for final parameter calibration and to elaborate explanations of the study cases. This exercise allowed us to identify the components and mechanisms in the system to which the outputs are most sensitive. We constructed relevant hypothetical scenarios around these critical components, and found that key liaisons, agents with high interaction frequencies and high mutual respect values are useful in promoting efficient decision processes, but are limited in their ability to change the collective position with respect to a restoration practice. Simulations suggest that final collective position can be changed when there is a more equitable distribution of agents across groups, or the key liaison is very persuasive (i.e. interacts frequently and is highly respected) but is non-reciprocal (i.e. does not respect others highly). Our work advances our understanding of key mechanisms influencing collective decision processes and illustrates the value of agent-based modeling and its integration with ethnographic data analysis to advance the theory of collective decision making.