Activate gameobject that is deactivated with c#

Hi, I have a gameobject called Trees that have some trees inside, it begins inactive or I also can disable through this code in C#:

if(Input.GetKeyUp(KeyCode.Space)){         
   GameObject.Find("Trees").active = false;
}

But when i want to reactivate it with:

GameObject.Find("Trees").active = true;

unity can find the gameobject, is there a way to find it and activate it again?

14754-question.png

public GameObject Trees;

void Update(){
   if(Input.GetKey(KeyCode.Space)){
       Trees.SetActive(false);
   }
   else{
     Trees.SetActive(true);
   }
}

set trees in the inspector.

i need without public or serializable field

could you please help me for that