The Role of Models in Sustainable Forest Resource Management
If we think of forests in the narrowest possible way, we think of trees. Trees are among the types of resources that can be characterized as renewable. This simply means that given the right conditions and a certain amount of time, trees will keep growing back in suitable pieces of land. Mankind took large advantage of the fact that trees are renewable, but failed to do it wisely. This effectively changed the world's landscapes, as shown by the State of the World's forests by the World Resources Institute.
After realizing that forest resources were becoming scarcer and less accessible, people started to manage and plan their use. In order to try to assure the steady supply of timber for everyday use, societies started to plan for the forest's regeneration and make the most of its cycle of planting, growing, cutting, replanting and so on. As we gained more knowledge about related topics such as silviculture and ecology, these plans became more flexible and more complex.
After some time, societies figured out that simply planning for a steady supply of timber was not enough to help guarantee the preservation of such complex environments. For this reason, the idea of Sustainable Forest Management (SFM) started to be an important requirement for all those managing forest resources. According to the PEFC, sustainable forest management has to account for environmental, social and economical aspects, assuring that economic gains in the present do not compromise the survival of the ecosystems and livelihoods of surrounding populations. In much simpler terms, SFM requires that a forest manager combines different objectives and excels at it.
But how does one watch over a complex environment that evolves over time and has management cycles that can last up to 100 years in some places? When trial and error is absolutely not an option, one needs to find better, more reliable methods.
Many scientific disciplines make constant use of modeling to help them better understand and even predict the world that surround us. In a given context, models are representations of reality that aim to capture the most relevant aspects of the real world and remove from the analysis aspects that are considered less important. Good examples of models found in everyday life are: road maps, miniatures, plane models, a globe and so on.
Researchers dealing with natural resources management make use of several different types of models that range from conceptual to more concrete ones, and they all play an important role. Nevertheless, yet another type o modeling is seen as invaluable when managing forests: mathematical modeling. With the help of mathematical models, researchers and practitioners represent very well a great number of interdependent variables and also quantify them, creating a very good fit for modeling the complexity found in forests.
Mathematical modeling in Forestry
When managing forest resources, it is quite common to model land expectation value as a function of expected land productivity, forest biometric relations and allometry. Although it is possible to model much more complex relationships, including biological, economical and business related aspects.
Since these variables are closely connected, systematic prediction errors can lead to grave problems later in the process. For instance, incorrectly modeling a forest's growth and yield will certainly lead to inaccurate yearly projections and incorrect estimates of the cumulative yield. Such inaccuracies will likely be reflected as poor results in the business side of the operation as much as the ecological. Unless the manager is able to deal with these variables together, it would be very hard to end up with satisfactory sustainable results.
Mathematical modeling allows managers to group individual models as a system and, consequently, understand and predict how each variable affects others within that system. Only after one understands these relationships it is possible to actually understand the consequences of a management decision and assess alternatives. The use of such analytical methods to improve the decision making process is further studied in a discipline called Operations Research.
As one can imagine, solving these systems of models is not a very straightforward activity and it can take a lot of time. That is why managers need to resort to computers to solve them in a more efficient manner. Using specialized computer algorithms to solve SFM problems is the most sensible way to optimize model results that will serve as parameters to guide managers' decisions.
Nowadays, computers are ordinarily used to help us tackle most problems of forest management. For instance, computers can model tree growth, define the optimal harvesting schedule and integrate it with possible scenarios for price and cost trends, market pull, resource availability and transport costs, generating insightful knowledge that any forest manager would be able to use to achieve sustainability.
If you are interested and would like to know more about the use of mathematical models in forestry, check out:
Decision Methods for Forest Resource Management by Buongiorno, J. and Gilless, K.- http://www.amazon.com/dp/0121413608