Collaborative decision-analytic framework to maximize resilience of tidal marshes to climate change

Abstract

ABSTRACT. Decision makers that are responsible for stewardship of natural resources face many challenges, which are complicated by uncertainty about impacts from climate change, expanding human development, and intensifying land uses. A systematic process for evaluating the social and ecological risks, trade-offs, and cobenefits associated with future changes is critical to maximize resilience and conserve ecosystem services. This is particularly true in coastal areas where human populations and landscape conversion are increasing, and where intensifying storms and sea-level rise pose unprecedented threats to coastal ecosystems. We applied collaborative decision analysis with a diverse team of stakeholders who preserve, manage, or restore tidal marshes across the San Francisco Bay estuary, California, USA, as a case study. Specifically, we followed a structured decision-making approach, and we using expert judgment developed alternative management strategies to increase the capacity and adaptability to manage tidal marsh resilience while considering uncertainties through 2050. Because sea-level rise projections are relatively confident to 2050, we focused on uncertainties regarding intensity and frequency of storms and funding. Elicitation methods allowed us to make predictions in the absence of fully compatible models and to assess short-and long-term trade-offs. Specifically we addressed two questions. (1) Can collaborative decision analysis lead to consensus among a diverse set of decision makers responsible for environmental stewardship and faced with uncertainties about climate change, funding, and stakeholder values? (2) What is an optimal strategy for the conservation of tidal marshes, and what strategy is robust to the aforementioned uncertainties? We found that when taking this approach, consensus was reached among the stakeholders about the best management strategies to maintain tidal marsh integrity. A Bayesian decision network revealed that a strategy considering sea-level rise and storms explicitly in wetland restoration planning and designs was optimal, and it was robust to uncertainties about management effectiveness and budgets. We found that strategies that avoided explicitly accounting for future climate change had the lowest expected performance based on input from the team. Our decision-analytic framework is sufficiently general to offer an adaptable template, which can be modified for use in other areas that include a diverse and engaged stakeholder group.

Impacts of Coastal Land Use and Shoreline Armoring on Estuarine Ecosystems: an Introduction to a Special Issue

“…Permanent armored structures alter connectivity through habitat fragmentation and block the landward migration of natural shoreline habitats in response to sea-level rise ("coastal squeeze"), leading to further loss of coastal habitat (Doody 2004;Bozek and Burdick 2005;Pontee 2013). Thus, there continues to be a need to conserve and restore coastal wetlands (Zedler 2004;Wigand and Roman 2012;Thorne et al 2015), while identifying and disentangling the major drivers of wetland loss.…”

Using the Value of Information to improve conservation decision making

“…Two papers used monetary values for costs only, and relative benefits that can be achieved at those costs (Convertino et al ., ; Maxwell et al ., ). Another eight (27%) papers used a unitless value that reflected a weighted response across multiple objectives (Runge et al ., ; Williams et al ., ; Smith et al ., ; Johnson et al ., , b , ; Thorne et al ., ; Williams & Johnson, ). Other papers used a range of performance metrics, namely cost ratio (Sahlin et al ., ), probability of survival of different age classes (Canessa et al ., ), population growth rate in per cent (Cohen et al ., ), species retention rate at the end of a 20‐year simulation period (Grantham et al ., ), increase in gas extraction while maintaining brook trout ( Salvelinus fontinalis ) populations (Smith et al ., ), probability of population persisting for 256 years (Tyre et al ., ), utility function reflecting both yield (kilotons) and risk of falling below critical spawning mass (Kuikka et al ., ), and proportion of maximum phylogenetic diversity retained (Hartmann & Andre, ).…”

“…Other papers focused on management of multiple species. Of those, fisheries were the subject of five papers (Sainsbury, 1991;Costello et al, 1998;Kuikka et al, 1999;Mäntyniemi et al, 2009;Costello et al, 2010) and the management of ecosystems was also the subject of five papers Convertino et al, 2013;Runting et al, 2013;Perhans et al, 2014;Thorne et al, 2015). The use of phylogenetic diversity for deciding which species to protect was used by one study (Hartmann & Andre, 2013) and the sustainable harvest of a species by another .…”

Multi‐criteria decision analysis for nature conservation: A review of 20 years of applications

“…In this respect, it is worth noticing that existing frameworks, such as the Common International Classification of Ecosystem Services (Haines-Young & Potschin, 2013), could help to structure the objectives during or after an initial round of stakeholder involvement to define the problem. More in general, prior to the selection of objectives and criteria, there ought to be a problem definition step aimed at identifying a decision question along with relevant decision-makers, stakeholders and topic experts, ideally facilitated by an expert on participatory decision analysis (see, for example, Thorne et al, 2015).…”