Benefits of integrating complementarity into priority threat management

Abstract

Conservation decision tools based on cost-effectiveness analysis are used to assess threat management strategies for improving species persistence. These approaches rank alternative strategies by their benefit to cost ratio but may fail to identify the optimal sets of strategies to implement under limited budgets because they do not account for redundancies. We devised a multiobjective optimization approach in which the complementarity principle is applied to identify the sets of threat management strategies that protect the most species for any budget. We used our approach to prioritize threat management strategies for 53 species of conservation concern in the Pilbara, Australia. We followed a structured elicitation approach to collect information on the benefits and costs of implementing 17 different conservation strategies during a 3-day workshop with 49 stakeholders and experts in the biodiversity, conservation, and management of the Pilbara. We compared the performance of our complementarity priority threat management approach with a current cost-effectiveness ranking approach. A complementary set of 3 strategies: domestic herbivore management, fire management and research, and sanctuaries provided all species with >50% chance of persistence for $4.7 million/year over 20 years. Achieving the same result cost almost twice as much ($9.71 million/year) when strategies were selected by their cost-effectiveness ranks alone. Our results show that complementarity of management benefits has the potential to double the impact of priority threat management approaches.

Cost-Effective Resource Allocator: A decision support tool for threatened species management

“…Joseph et al, 2009), as prioritizing at the strategy-level allows for more flexible resource allocation across multiple species (described in Game et al, 2013). It also provides a further example of a non-target based conservation prioritization framework, where the objective is to maximize the sum of expected extant years across a group of species, as opposed to maximizing the number of species that meet a specific persistence target (see Di Fonzo et al, 2016 for further examples of this approach, Chadés et al, 2015).…”

“…Auerbach et al, 2014;Carwardine et al, 2012), algorithms which iteratively remove low-ranking strategies and update cost-efficiency rankings (e.g. Joseph et al, 2009;Chadés et al, 2015), and spatially explicit systematic conservation planning software that solve integer programming problems (e.g. Marxan and Zonation; Ball et al, 2009;Moilanen, 2007).…”

“…Resource allocation algorithms that account for these specific issues could be applied in situations where this is the case (e.g. Chadés et al, 2015;Firn et al, 2013).…”

Effective monitoring for biodiversity conservation

“…We considered two management strategies: (1) fire management; and (2) combined feral ungulate and domestic herbivore management. Species persistence under different management strategies available in Chadès et al (2015) and insights from published studies (see Woinarski et al 2010) indicate that threats influence all species negatively, though the degree of impact may be variable. Details on actions constituting each strategy and their associated costs were also obtained from Chadès et al (2015).…”

“…Despite a growing a number of examples of decision-making in optimal management in the face of multiple threats (e.g. Wilson et al 2007;Evans, Possingham & Wilson 2011;Chadès et al 2015;Tulloch et al 2016a), similar studies for optimal monitoring choices to learn about and manage multiple threats have received relatively little attention.…”