NetLogo User Community Models

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## WHAT IS IT?

NOTE: This version of the model is only a prototype and proof-of-concept of the final model. Thus, the functionality and features are much less than implied in this description.

The purpose of this model is to simulate the impact that increasing temperature from anthropogenic climate change will have on the composition, structure, and functioning of the McMurdo Dry Valley (McMurdo Dry Valley) soil food web, which is a model microbial ecosystem. The model will describe the most significant changes in the food web, and it will provide a mechanistic explanation of why those most significant changes occurred (i.e., proximal causes).

## HOW IT WORKS

The model is designed to replicate the activity of soil microorganisms in a polar cryodesert. Organisms, represented by agents, move about in a simulated soil environment, represented by patches/grid units. They move, feed, search for mates (if sexual), mate (if sexual), reproduce, enter and exit cryptobiosis, avoid negative environmental stimuli whenever possible, and die of old age, environmental insult (e.g., freezing), or biotic interactions (e.g., predation).

The default starting month is November in order to simulate the middle of the austral spring (in the future, the start date can be changed), which is generally before soils have warmed enough to enable biological activity. Patch state variables are initialized according to default settings and/or manual input from the user at this time. Certain patch state variables (e.g., distribution of moisture, legacy-carbon, and total carbon across patches) can be set to display on the UI at initialization.

## HOW TO USE IT

In its current iteration, the user can specify: which taxa are present (using green toggle switches); their starting abundances (using green input boxes); the starting year (default 2020); the starting photosynthesis and decomposition rate (default 5 and 0 respectively; exogenous carbon input into the system is low relative to overall biomass); starting totalcarbon (green input box), and whether to show moisture, total and legacy carbon in the background (blue, green, & red; randomly distributed across patches in present iteration; cannot show more than one at a time).

In the future, the following values will be adjustable during initialization: dispersal rates, the number of soil samples to be simulated, the generation rate of novel species during the model run (representing invasive species), the frequency of disturbance events (i.e., exceptionally warm years), the addition and population sizes of many more species, etc.

## CREDITS AND REFERENCES

This model is currently in development. For questions, contact author Andrew Thompson at opabinia33@gmail.com.