Network Conceptual Models

Conceptual models are critical elements in the design of scientifically credible monitoring programs for the management of ecological systems. Models provide a way to organize information pertaining to the complex natural systems. An ecological conceptual model is a visual or narrative summary that describes current understanding of ecosystem components, identifies important processes, and illustrates connections between indicators and ecological states or processes. Developing conceptual models helps explain how physical, chemical, and biological elements of a monitoring program interact, promotes integration and communication among scientists and managers from different disciplines, and informs on the choice of indicators. The conceptual models for the MOJN attempt to simplify reality by presenting information most relevant to understanding and preserving natural resources within the Mojave and Great Basin Deserts

The objectives of the MOJN conceptual models are to:

• Formalize current understanding of ecosystem functioning and structure in the MOJN.
• Identify major system drivers and stressors, the system attributes most affected by these drivers, and the dynamics of these features.
• Identify and articulate relations between attributes of interest and indicators.
• Aid in defining relevant spatial and temporal scales for monitoring.
• Aid in the development, interpretation, and presentation of monitoring data.
• Serve as a means of communicating a common understanding of the connections between management decisions and natural systems to NPS and others.

Conceptual Model Hierarchy and Framework

We have developed a series of models that underlie a highest level, general framework model. The framework model illustrates fundamental ideas about ecosystem sustainability, describing the interactive controls on an ecosystem and how broad-scale drivers such as climate and human disturbance influence the ecosystem. Nested under the framework model are system-specific models

Wet Systems Model

This model illustrates climate controls on groundwater and streams via recharge and runoff, as well as interactions among the main components (shown as large colored boxes). The model emphasizes groundwater as a foundation of all wet system components. Drivers such as altered flow regime, groundwater withdrawal, and invasive species enter into the model in several places, demonstrating the potentially complex effects of a given disturbance.

Dry Systems Model

This model illustrates climate controls on soils, vegetation, and animals. The model emphasizes the shrubland system. Climate drivers, along with topographic influences, dictate the availability of soil moisture, which is further modulated by surficial deposits and pedogenesis as landscape-scale structure for vegetation and animal communities. Vegetation structure and function influence animal communities, which in turn modify soils and nutrients, and plant communities. The model also incorporates categories of human drivers