Falling on land when over trees - how to prevent?

[Rinoldo]

Code:

int Graviplant = 715;
    
object obj = radar(Graviplant);
    
if (distance2d(this.position, obj.position) <= 32)
{
    message("very close to graviplant");
}

I'm not sure that I uderstand this code quite clear. I tried to change meaning of int Graviplant. It works only within 710-715. Why is that?