One of the examples I used in class this week when talking about 'Complex Systems' and associated modelling approaches was the Forest Fire Cellular Automata model. I've produced an implementation of the model in NetLogo, complete with plots to illustrate the frequency-area scaling relationship of the resulting wildfire regime. I've updated the wildfire behaviour page on my website to include an applet of the NetLogo model (if that page gets changed in the future, you can view and experiment with the model here).
No sooner am I back from a fun weekend in Toronto (photos on the photos page soon) than the fall semester starts at MSU (is summer over already?!).
Today was the first day of the graduate-level class I am teaching, FW852 Systems Modeling and Simulation. During the course we will:
Review systems theory and the systems modeling and simulation process
Introduce modeling and simulation methods and tools, specifically the STELLA and NetLogo modeling environments
Apply modeling theory, methods and tools to natural resource management and other areas of research
Term projects are a critical component of the course and students will have opportunities to develop their own models, usually related to their dissertation and thesis research. Students will peer-review others' work, and present their results in class. Through regular and guest lectures, discussion, and hands-on experience, the course will provide students with a holistic view and integrative tools for their future research, decision-making, and management activities.
As the course progresses I may post some of the examples and topics we look at, and anything interesting that arises out of our discussions in class.
Theory Into Practice: Landscape Ecology Being Used to Conserve Habitats and Species
As with all IALE conferences there will be a field trip that attendees can join. This year the IALE-UK trip will visit the Great Fen Project and Wicken Fen, part of the largest wetland restoration in Europe.
The conference programme is now full, but there are still opportunities to submit posters. Registration to attend also remains open. For submissions and registrations, contact Pete Carey, and for more information visit the conference webpage.
Earlier this week I submitted a manuscript to Earth Surface Processes and Landforms with one of my former PhD advisors, John Wainwright. Provisionally entitled Mind, the Gap in Landscape-Evolution Modelling (we'll see what the reviewers think of that one!), the manuscript argues that agent-based models (ABMs) are a useful tool for overcoming the limitations of existing, highly empirical approaches in geomorphology. This, we suggest, would be useful because despite an increasing recognition that human activity is currently the dominant force modifying landscapes geomorphically, and that this activity has been increasing through time, there has been little integrative work to evaluate human interactions with geomorphic processes.
In the manuscript we present two case studies of models that consider landscape change with the aid of an ABM - SPASIMv1 (developed during my PhD) and CybErosion (a model to simulate the dynamic interaction of prehistoric communities in Mediterranean environments John has developed). We evaluate the advantages and disadvantages of the ABM approach, and consider some of the major challenges to implementation. These challenges include potential process scale mis-matches, differences in perspective between investigators from different disciplines, and issues regarding model evaluation, analysis and interpretation.
I'll post more here as the review process progresses. Hopefully progress with ESPL will be a little quicker than it has been for the manuscript I submitted to Environmental Modelling and Software detailing the biophysical component of SPASIMv1 (still yet to receive the review after 5 months!)...
The BBC have taken these ideas, of looking down from on high and exploring the dynamic interplay of human activity across space, and produced some incredible movies for a new show. Checkout some of the footage below - looks awesome.
If you're in the UK, the new series Britain From Above starts at 9pm on Sunday 10th August, BBC One.
Regional partitioning for wildfire regime characterization
Fighting wildfires is a strategic operation. In fire-prone areas of the world, such as California and the Mediterranean Basin, it is important that managers allocate and position fire trucks, water bombers and human fire-fighters in locations that minimize the response time to reach new fires. Not only is this important to reduce risk to human lives and livelihoods, the financial demands of fighting a prolonged campaign against multiple fires demands that resources be used as economically as possible.
Characterizing the wildfire regime of an area (the frequency, timing and magnitude of all fires) can be very useful for this sort of planning. If an area burns more frequently, or with greater intensity, on average, fire-fighting resources might be better placed in or near these areas. The relationship between the frequency of fires and the area they burn is one the characteristics that is particularly interesting from this perspective.
As I've written about previously with colleagues, although it is well accepted that the frequency-area distribution of wildfires is 'heavy-tailed' (i.e. there are many, many more small fires than large fires), the exact nature of this distribution is still debated. One of the distributions that is frequently used is the power-law distribution. Along with my former advisors Bruce Malamud and George Perry, I examined how this characteristic of the wildfire regime, the power-law frequency-area distribution, varied for different regions across the continental USA (see Malamud et al. 2005). Starting with previously defined 'ecoregions' (area with characterized by similar vegetation, climate and topography) we mapped how the frequency-area relationship varied in space, finding a systematic change from east to west across the country.
More recently, Paolo Fiorucci and colleagues (Fiorucci et al. 2008) have taken a slightly different approach. Rather than starting with pre-defined spatial regions and calculating the frequency-area distribution of all the fires in each region, they have devised a method that splits a large area into smaller regions based on the wildfire data for the entire area. Thus, they use the data to define the spatial differentiation of regions with similar wildfire regime characteristics a posteriori rather than imposing the spatial differentiation a priori.
Fiorucci and his colleagues apply their method to a dataset of 6,201 fires (each with an area greater than 0.01 sq km) that burned between 1987 and 2004 in the Liguria region of Italy (5400 sq km). They show that estimates of a measure of the wildfire frequency-area relationship (in this case the power-law distribution) of a given area varies significantly depending on how regions within that area are partitioned spatially. Furthermore, they found differences in spatial patterns of the frequency-area relationship between climatic seasons.
Using both a priori (the approach of Malamud et al. 2005) and a posteriori (the approach of Fiorucci et al. 2008) spatial delineation of wildfire regime areas, whilst simultaneously considering patterns in the processes believed to be driving wildfire regimes (such as climate, vegetation and topography), will lead to better understanding of wildfire regimes. That is, future research in this area will be well advised to look at the problem of wildfire regime characterization from both perspectives - data-driven and process-driven. The approach developed by Fiorucci et al. also provide much promise for a more rigorous, data-driven, approach to make decisions about the allocation and positioning of wildfire fire-fighting resources.
Citation and Abstract Fiorucci, P., F. Gaetani, and R. Minciardi (2008) Regional partitioning for wildfire regime characterization, Journal of Geophysical Research, 113, F02013 doi:10.1029/2007JF000771
Wildfire regime characterization is an important issue for wildfire managers especially in densely populated areas where fires threaten communities and property. The ability to partition a region by articulating differences in timing, frequency, and intensity of the phenomena among different zones allows wildfire managers to allocate and position resources in order to minimize wildfire risk. Here we investigate “wildfire regimes” in areas where the ecoregions are difficult to identify because of their variability and human impact. Several studies have asserted that wildfire frequency-area relationships follow a power law distribution. However, this power law distribution, or any heavy-tailed distribution, may represent a set of wildfires over a certain region only because of the data aggregation process. We present an aggregation procedure for the selection of homogeneous zones for wildfire characterization and test the procedure using a case study in Liguria on the northwest coast of Italy. The results show that the estimation of the power law parameters provides significantly different results depending on the way the area is partitioned into its various components. These finds also show that it is possible to discriminate between different wildfire regimes characterizing different zones. The proposed procedure has significant implications for the identification of ecoregion variability, putting it in a more mathematical basis.
US-IALE 2009: Coupling Humans and Complex Ecological Landscapes
Coupling Humans and Complex Ecological Landscapes is the theme of the 2009 annual conference of US-IALE (U.S. Regional Association, International Association for Landscape Ecology). The conference will be held in Snowbird, Utah, from April 12-16, 2009. Proposals for symposia and workshops are due September 15, 2008; and abstracts are due November 17, 2008.
Several types of financial support for attending and presenting at the conference are available:
(1) the "Sponsored Student Travel Awards Program" of local sponsors (USGS, Utah State University, and Utah Department of Natural Resources),
(4) the 'CHANS Fellows Program' of the new International Network of Research on Coupled Human and Natural Systems (CHANS-Net, supported by NSF, see background papers in Science and Ambio).
US-IALE conferences are particularly students-friendly, with two popular programs -- Lunch with Mentors and NASA-MSU dinner, and a new program -- We'll "Pick Up The Tab!".
More information about the conference is available from the web site.
I'm back from fieldwork in Michigan's Upper Peninsula. It was quite a short, but eventful, trip to get some forest stand cruises going - lightning, flat tyres, and an incident with some angry bees (we escaped with only a couple of stings). Unfortunately I didn't have my camera on hand to record any of these (mis)adventures. Now, on with preparing my Systems Modeling and Simulation course for the fall and coding our model to integrate with FVS...
Effective Modelling for Sustainable Forest Management
In many forest landscapes a desirable management objective is the sustainability of both economic productivity and healthy wildlife populations. Such dual-objective management requires a good understanding of the interactions between the many components and actors at several scales and across large extents. Computer simulation models have been enthusiastically developed by scientists to improve knowledge about the dynamics of forest growth and disturbance (for example by timber harvest or wildfire).
However, Papaik, Sturtevant and Messier write in their recent guest editorial for Ecology and Society that "models are constrained by persistent boundaries between scientific disciplines, and by the scale-specific processes for which they were created". Consequently, they suggest that:
"A more integrated and flexible modeling framework is required, one that guides the selection of which processes to model, defines the scales at which they are relevant, and carefully integrates them into a cohesive whole".
This new framework is illustrated by the papers in the Ecology and Society special feature'Crossing Scales and Disciplines to Achieve Forest Sustainability: A Framework for Effective Integrated Modeling'.
The papers in the special feature provide case studies that reflect two interacting themes:
interdisciplinary approaches for sustainable forest landscape management, and
the importance of scaling issues when integrating socioeconomic and ecological processes in the modeling of managed forest ecosystems.
These issues are well related to the project I'm currently working on that is developing an integrated ecological-economic model of a managed forest landscape in Michigan's Upper Peninsula. One paper that caught my eye was by Sturtevant et al., entitled 'A Toolkit Modeling Approach for Sustainable Forest Management Planning: Achieving Balance between Science and Local Needs'.
Sturtevant et al. suggest that forest managers are generally faced with a "devil's choice" between using generic 'off-the-shelf models' where information flows primarily from researchers and planners down to local communities versus developing case-specific models designed for a specific purpose or locale and based on information from the local actors. To avoid this choice, which Sturtevant et al. believe will seldom result in a satisfactory management result, they outline their proposal for a hybrid 'toolkit' approach. Their alternative approach "builds on existing and readily adaptable modeling 'tools' that have been developed and applied to previous research and planning initiatives".
Their toolkit approach is
collaborative - including stakeholders and decision-makers
a 'meta-modelling' approach - the model is derived from other models and tools.
They then illustrate their toolkit approach using a case study from Labrador, Canada, highlighting the stages of establishing the issues, developing a conceptual model, implementing the meta-model, and then refining the model iteratively. They conclude:
"A toolkit approach to SFM [Sustainable Forest Management] analytical support is more about perspectives on information flow than on technical details. Certainly expertise and enabling technology are required to allow a team to apply such a framework. However, the essence of this approach is to seek balance between top-down (off the shelf, science-driven) and bottom-up (case-specific, stakeholder-driven) approaches to SFM decision support. We aim to find a pivot point, with adequate information flow from local experts and stakeholders to scientists, while at the same time avoiding “reinventing the wheel” (e.g. Fig. 1) by making full use of the cumulative experience of scientists and tools they have constructed."
Although this 'meta-model' approach may save time on the technical model building side of things, many resources (time, effort and money) will be required to build and maintain relationships and confidence between scientists, managers and local stakeholders. This approach is really a modelling toolkit for management, with very little emphasis on improving scientific understanding. In this case the modelling is the means to the end of integrative/participatory management of the forest landscape.
The authors continue:
"The mixture of local experts and stakeholders who understand how the tools work, scientists who are willing and able to communicate their science to stakeholders, and integrated analytical tools that can simulate complex spatial and temporal problems will provide powerful and efficient decision support for SFM."
Unfortunately, unless the scientists in question have the explicit remit to offer their services for management purposes, this sort of modelling approach will not be very appealing to them. In a scientific climate of 'publish or perish', management outcomes alone are unlikely to be enough to lure the services of scientists. In some cases I'm sure I will be wrong and scientists will happily oblige. But more generally, unless funding bodies become less concerned with tangible outputs at specific points in time, and academic scientists are judged less strictly by their publishing output, this situation may be difficult to overcome.
This situation is one reason the two sides of the "devils' choice" are more well developed to the expense of the 'middle-ground' toolkit approach. 'Off-the-shelf' models, such as LANDIS, are appealing to scientists as they allow the investigation of more abstract and basic science questions than asked by forest managers. The development of 'customized' models is appealing to scientists because they allow more detailed investigation of underlying processes and provide a framework for the collection of empirical data collection. No doubt the understanding gained from these approaches will eventually help forest managers - but not in the manner of direct decision-support as the toolkit modelling approach proposes.
As a case in point, the 'customized' Managed Forest Landscape Model for Michigan I am working on is raising questions about underlying relationships between deer and forest stand structure. I'm off into the field this week to get data collection started for just that purpose.
This week one of the papers I have been working on as a result of my PhD research has been accepted for publication in the Journal of Artificial Societies and Social Simulation (JASSS). The paper, written with Raúl Romero-Calcerrada, John Wainwright and George Perry, describes the agent-based model of agricultural land-use decision-making we constructed to represent SPA 56 in Madrid, Spain. We then present results from our use of the model to examine the importance of land tenure and land use on future land cover and the potential consequences for wildfire risk. The abstract is below, and I'll post again here when the paper is published and online.
An Agent-Based Model of Mediterranean Agricultural Land-Use/Cover Change for examining Wildfire Risk
Abstract Humans have a long history of activity in Mediterranean Basin landscapes. Spatial heterogeneity in these landscapes hinders our understanding about the impacts of changes in human activity on ecological processes, such as wildfire. Use of spatially-explicit models that simulate processes at fine scales should aid the investigation of spatial patterns at the broader, landscape scale. Here, we present an agent-based model of agricultural land-use decision-making to examine the importance of land tenure and land use on future land cover. The model considers two ‘types’ of land-use decision-making agent with differing perspectives; ‘commercial’ agents that are perfectly economically rational, and ‘traditional’ agents that represent part-time or ‘traditional’ farmers that manage their land because of its cultural, rather than economic, value. The structure of the model is described and results are presented for various scenarios of initial landscape configuration. Land use/cover maps produced by the model are used to examine how wildfire risk changes for each scenario. Results indicate land tenure configuration influences trajectories of land use change. However, simulations for various initial land-use configurations and compositions converge to similar states when land-tenure structure is held constant. For the scenarios considered, mean wildfire risk increases relative to the observed landscape. Increases in wildfire risk are not spatially uniform however, varying according to the composition and configuration of land use types. These unexpected spatial variations in wildfire risk highlight the advantages of using a spatially-explicit ABM/LUCC.
