HPCCproject:CNH - Dynamics of Coupled Natural and Human Systems in the Colorado Front Range Wildland/Urban Interface: Causes and Consequences

In the US, the wildland-urban interface (WUI) occupies 9% of the conterminous surface area and contains nearly 39% of all housing units. Severe modifications of the interactions between environmental and socio-economic dynamics in the WUI include potentially sharp increases in the likelihood of key disturbances (such as wildfires and insect outbreaks) and of their interactions in large portions of these areas. The central goal of this project is therefore to analyze the interactions between environmental, social, and economic domains at multiple spatial scales, and to forecast the effects of these interactions on patterns of dynamic changes and ecological resilience across the WUI of the Colorado Front Range (COFR).

An overarching hypothesis provides the focus of the research: The increase in connectivity between landscapes and people, reflecting the increased use of cultural services (exurbanization, recreation) in the COFR WUI, along with increasing punctuated climate-driven disturbances, such as fires and mountain pine beetle outbreaks, increases the connectivity of disturbances among landscapes, leading to new stable states, less landscape heterogeneity, and potential decreases in key ecosystem services. To address this hypothesis, three general objectives are formulated: identify the mechanisms by which dynamics in ecological, social, and economic domains interact at three spatial scales to affect internal controls and feedbacks; identify the mechanisms by which ecological, social, and economic attributes contribute to maintenance or loss of resilience in the study area; evaluate the implications of different environmental and growth policies on resilience when threshold interactions among the three domains and spatial scales are considered.

The research approach comprises five parts: (1) narratives used to define the boundaries of the systems under study, their key components, important ecosystem drivers, and characteristics of socio-economic structures; (2) a process-based simulation framework linking a spatially explicit landscape model with a set of land-use/land-cover models and a model of housing growth and modification; (3) an analysis of housing density and building/landscaping characteristics to investigate land use within an environmental economic framework; (4) integrated sustainability assessment of current conditions, analysis of patterns of sustainability under a diversity of policies, and characterization of environmental and economic indicators of sustainability and potential thresholds using a spatially explicit Decision Support System; and (5) synthesis and scenario planning to collectively address the objectives.

The LANDIS-II model, which simulates forest succession, disturbances (including fire, wind, and insects), and climate change across large landscapes, serves as the core of our modeling efforts. This landscape model manages and executes discrete extensions for different ecological processes that interact with the landscape – and each other – through the central LANDIS-II program. We are able to track the spatial distribution of individual tree species, obtain community statistics (such as richness and evenness), evaluate changes in C and N cycling and availability, estimate fire spread and severity, and assess insect outbreak extent and severity, which allows for sophisticated land-use change scenario testing. We are examining different growth and development scenarios, under varying climate futures and are applying the wicked-problem framework to the effects of interactions between climate and human-mediated changes.