Timestep 0 in State Classes Report

[Mike Gough]

Hi guys,

If I specify a Start Timestep of 0 in the Run Control tab, run the scenario, and then export the State Classes report, are the values under the Proportion of Landscape field for timestep 0 (shown below) supposed to represent the initial conditions, or the modeled results for the first future timestep? And if it’s the former, why wouldn’t these numbers match the initial conditions values?

Thanks in advance,

Mike

Iteration Timestep Vegetation Type State Class Area (Acres) Proportion of Landscape

1 0 Basin Big Sagebrush Upland Ann Gr Mono:Open 5810.23 0.0512
1 0 Basin Big Sagebrush Upland Ann Gr:Open 5469.78 0.0482
1 0 Basin Big Sagebrush Upland Crst Wht Gr:Open 6491.11 0.0572
1 0 Basin Big Sagebrush Upland Early:Open 6127.97 0.0540
1 0 Basin Big Sagebrush Upland Late:Closed 6241.46 0.0550
1 0 Basin Big Sagebrush Upland Mid:Open 6218.76 0.0548
1 0 Basin Big Sagebrush Upland Seeded:Open 6082.58 0.0536
1 0 Basin Big Sagebrush Upland Sh Ann Gr:Closed 5583.27 0.0492
1 0 Basin Big Sagebrush Upland Sh Dpl:Closed 6014.49 0.0530
1 0 Montane Sagebrush Upland Ann Gr Mono:Open 6264.15 0.0552
1 0 Montane Sagebrush Upland Ann Gr:Open 5969.10 0.0526
1 0 Montane Sagebrush Upland Crst Wht Gr:Open 5991.80 0.0528
1 0 Montane Sagebrush Upland Early:Open 5991.80 0.0528
1 0 Montane Sagebrush Upland Late:Closed 6014.49 0.0530
1 0 Montane Sagebrush Upland Late:Open 5605.96 0.0494
1 0 Montane Sagebrush Upland Mid:Open 6309.54 0.0556
1 0 Montane Sagebrush Upland Seeded:Open 5651.35 0.0498
1 0 Montane Sagebrush Upland Sh Ann Gr:Closed 5946.40 0.0524
1 0 Montane Sagebrush Upland Sh Dpl:Closed 5696.75 0.0502

[colin-daniel]

Because STSMs are stochastic, the state class of each cell is a random variable. As a result in ST-Sim the initial state of each cell is sampled from a distribution for each Monte Carlo realization. The distribution used to set this initial state will depend on your model settings – it can be configured to be anything you like. Often, however, the initial state class of each cell is specified as a multinomial distribution.

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