For a researcher a model is a tool for understanding the system. By plugging together a number of black boxes, which specifics and behavior are obscure and hardly understood, we do not significantly increase our knowledge about the system. From a complex natural system we go to another system that may be also too complex to deal with. The results generated are difficult to interpret, when there is not enough understanding of the processes that are actually modeled. This is especially true for ecological and socio-economic systems, which are hard to structure and decompose. The decomposition of such systems requires careful analysis of spatial and temporal scales of processes considered and is closely related to specific goals of the model built.
In this context the modular approach is useful, if the focus is shifted from reusability and "plug-and-play" to transparency, analysis and hierarchical description of various processes and system components. With the modules being transparent and open for experiment and analysis, the researcher can better understand the specifics of the model formalism that is inherited. It is easier to decide whether the modules provided are suitable or if they should be modified to match the specifics and goals of the concrete study. It is mostly for this reason that when possible, LHEM offers modules in STELLA. We recommend the Spatial Modeling Environment (SME) to put modules together and to run them locally or spatially in conjuncture with the "user code" modules.
LHEM is an on-going project. New modules are added as they are formalized and tested. At present the general structure of the LHEM is as follows. Click on a module for more information about it.