State-and-transition simulation model - fire and drought effects Mediterranean ecosystems

Code of the simulation model and simulation runs that forms the basis of the manuscript:
Batllori, E., M. De Cáceres, L. Brotons, D. D. Ackerly, M. A. Moritz, and F. Lloret. 2017.
Cumulative effects of fire and drought in Mediterranean ecosystems. Ecosphere 8(8):e01906. 10.1002/ecs2.1906

The simulation model, programmed in R statistical language (R version 3.2.2; R Core Team
2015), corresponds to a STSM integrated in a landscape of 400 (20 9 20) cells where vegetation dynamics is influenced by stochastic regimes of fire (implemented as a spatially explicit process) and sporadic, extreme drought. Each cell is described by the following state variables: the proportion of six major vegetation types, their corresponding live and dead biomass values, and a cell-level counter of time since disturbance that modulates processes of vegetation state change. Vegetation types are defined by broad formations, constituted by sparse vegetation, shrublands, and two developmental stages (young vs. mature) of a tree seeder and a tree resprouter.