(Walker and Salt 2006) 1. DIVERSITY 2. ECOLOGICAL VARIABILITY 3. MODULARITY 4. ACKNOWLEDGING SLOW VARIABLES 5. TIGHT FEEDBACKS 6. SOCIAL CAPITAL 7. INNOVATION 8. OVERLAP IN GOVERNANCE 9. ECOSYSTEM SERVICES
2.2
Framework Development
The five categories for the development of a resilience theory framework come from two sources. Ahern serves as the starting point which was cross referenced with the goals outlined by Walker and Salt.
identify and respond to thresholds, promote diversity, develop redundancies, create multi-scale networks and connectivity, and implement adaptive planning and management strategies.
Identify and Respond to Thresholds
This strategy was identified as being of great importance and encompasses several ideas of Walker and Salt. They identified the acknowledgement of slow variables, tighter feedback loops, and innovation as being key ideas. In analyzing these ideas, it became apparent that they all relate to how we think about and identify critical thresholds. By acknowledging slow variables “that configure a social-ecological system, and the thresholds that lie along them, we have a greater capacity to manage the resilience of a system” (Walker and Salt 2006, 146). Similarly, by tightening feedback loops it “allow(s) us to detect thresholds before we cross them” (Walker and Salt 2006, 146). Innovation is more of a response to the critical thresholds that are identified; it is a strategy for how we engage and address them. These topics fit broadly under identifying and responding to thresholds, and this is not something addressed by Ahern in his strategies. It was included here because it is a key subject within resilience theory and focuses on how to increase adaptive capacity in response to these thresholds.
Promote Diversity
Diversity is covered by both Walker and Salt and Ahern. It is critical to promoting resilience both in terms of ecological and social systems (Ahern 2011, 5). Diversity “is a major source of future options and a system’s capacity to respond to change and disturbance in different ways” (Walker and Salt 2006, 145). The concept of diversity can also be thought of in terms of economic systems, land use, architecture, and animal species. The idea is to not put all of one’s eggs in a single basket. For instance if an economic condition in a certain area within a city is based completely upon the cash flow generated by surface parking, that is not a very diverse situation. Such an instance would be highly susceptible to shocks such as the discontinuation of the automobile or increased gas prices curtailing automobile use.
Develop Redundancies
This strategy combines three concepts proposed by Walker and Salt and Ahern. Walker and Salt discuss modularity, while Ahern looks to multi-functionality and redundancy and modularization as separate methods. Each of these three (modularity, multi-functionality and redundancy, and modularization) address the same idea. In its most basic form this idea is “to avoid putting ‘all your eggs in one basket’ and for preparing and pre-planning for when (not if) a system fails” (Ahern 2011, 5). Redundancies also work to reduce over- connectivity within systems, and with one example being decentralized water treatment cycles. Generally, systems that are dependent upon a centralized input, it is more vulnerable to failure after a disturbance.
Create Multi-Scale Networks and Connectivity
This method comes directly from Ahern and relates to the spatial connectivity of the urban landscape. “In urban environments, connectivity of built systems is generally robust but in natural systems is typically greatly reduced, often resulting in fragmentation— the separation and isolation of urban landscape elements with significant impacts on specific ecological processes that require connectivity” (Ahern 2011, 7). Other forms of connectivity refer to transportation systems, street networks, hydrological processes, and green networks. “Multi-scale connectivity is important when planning for functions that operate at multiple scales” which is critical when addressing the way different systems connect across scales e.g. walking trails linking with bus routes and urban drainage systems linking with low-order streams (Ahern 2011, 6).
Implement Adaptive Planning/Management Strategies
This final category relates to institutional management and the intangible aspects of promoting resilience. It comes from both Walker and Salt and Ahern, and deals with the difficulties in “making decisions with imperfect knowledge about change and uncertain disturbances as an ‘opportunity’ to ‘learn-by-doing’ (Holling, 1978)” (Ahern 2011, 7). This idea also directly relates to Walker and Salt’s concept of social capital in that resilience is “strongly connected to the capacity of the people in that system to respond, together and effectively, to change and disturbance. Trust, strong networks, and leadership are all important factors in making sure this can happen” (Walker and Salt 2006, 147). These networks of governance, both formal and informal, dictate the manifestation of resilience in the urban environment. This also applies to ownership of land where “overlapping rights and a mix of common and private property rights can enhance the resilience of linked social- ecological systems (Dietz et al. 2009)” (Walker and Salt 2006, 148).
Scales and Systems
Resilience theory provides an understanding for the cross-scale dynamic interactions between systems. In this case study analysis it was of great importance to provide a category in the analysis matrix that addressed scales and systems. Scale is in both spatial and
temporal terms while the systems are social, ecological, and economic. Each of the above five categories for methods are cross-referenced with three scales (regional, metro, and site) and systems (social, ecological, and economic).