Opengl java bouncing entities

Question

Hello this is actually my first question here.. I have been developing a opengl lwjgl game and I'm working on the entities class.I have accomplished to make an entity jump(ill use this for animals) but the "issue" (99.9% sure its my fault) is that each time the entity touches the terrain and jumps again the jump is higher as seen in the video I recorded this is the code for jump thz =D I just want the tree to move up always the same.

Video

    double velocity = 0;
double initVelX;
double initVelZ;
double time = 0;
float x;
float y;
float z;

public void bounce() {

    double initialVelocity = 0.1;       
    double speed = 1/2500.0;

    if(time == 0) {
        velocity += initialVelocity;
    }
    time += speed;
    velocity = velocity - 9.8 * speed;
    if(y + velocity < 0.1){
        velocity *= -1;
    }
    y += velocity;
    setPosition(new Vector3f(getPosition().x,y,getPosition().z));
}

Answer 1

Fixed it just had to do a simple line of code and it even has the speed fluctuations correct:

double velocity = 0;
    double initVelX;
    double initVelZ;
    double time = 0;
    float x;
    float y;
    float z;

    public void bounce() {

        double initialVelocity = 0.1;       
        double speed = 1/2500.0;

        if(time == 0) {
            velocity = initialVelocity;
        }

        time += speed;
        velocity = velocity - 9.8 * speed;
        if(y + velocity < 0.1){
            velocity *= -1;
            velocity = initialVelocity;
        }
        y += velocity;
        setPosition(new Vector3f(getPosition().x,y,getPosition().z));
    }