How can I introduce dead trees into a model of a forest fire?

I am trying to model a forest fire and have got the following code so far:

n = 50;
X = zeros(n,n);
X(n/2,n/2) = 1;
 
p = [n 1:n-1];
q = [2:n 1];
r = [1:5];
 
Pr = 1; %propability of fire spreading to neighbouring trees
Z=zeros(n,n);
 
for t = 1:30
 
    Y = rand(n,n);
 
    X = ((X(:,p) | X(:,q) | X(p,:) | X(q,:)) & (Y <= Pr)) | X;
    
    Z=Z+X;
    
    pause(0.5)
    pcolor(Z);
    colorbar;
    title(num2str(t));
    drawnow; 
end

This doesn't account for dead/burnt trees, I want to set a tree's death to be after 3 generaions of being on fire. I have tried setting Z(Z>3) = 0 but the new 0's become 1's shortly after, which then become 3's eventually then back to 0.

Any help on this matter wil be greatly appreciated!

Answer 1

[darova]

Z(Z>3)=3;

[Oliver Tremlett]

Thank you, would you have any idea how I would change the tree density so that not every cell contatins a tree?

[darova]

Read about how imdilate() works

You can also create whatever you want and place it in matrix with imdilate()