ZEND_Auth, deactivate navigation area

I´ve built a Login Page using Zend_Auth. Now my question ist how can I deactivate areas which are loaded with my layout.phtml?

Here the part of my code of my layout.phtml which I don´t want to see in my login and logout forms:

<div id="navigation">
    <ul>
            <li><a href="<?php echo $this->url(array('controller'=>'arbeitskalender', 'action'=>'index'), null, false);?>">Arbeitskalender</a></li>
            <li><a href="<?php echo $this->url(array('controller'=>'pdf', 'action'=>'index'));?>">Arbeitskalender download</a></li>
            <!--<li><a href="<?php echo $this->url(array('controller'=>'bibliothek', 'action'=>'index'));?>">Bibliothek</a></li> -->
            <!-- <li><a href="<?php echo $this->url(array('controller'=>'schwestern', 'action'=>'index'));?>">Schwestern</a></li> -->
    </ul>
</div>

How can I work with different layouts? In which place and how can I load them?

You can have multiple layouts in an application. If you create another without the navigation HTML and configure it in your module.config.php, you can simply select which layout to use from within the controller.

'template_map' => array(
    'layout/layout'       => __DIR__ . '/../view/layout/layout.phtml',
    'layout/layout_login' => __DIR__ . '/../view/layout/layout_login.phtml'
)

Then in your controller:

$this->layout('layout/layout_login');

EDIT:

Alternatively if you'd like to dynamically change your layout you can use the Identity View Helper to check whether a user is logged in or not. e.g.

<!-- if logged in, show logout link -->
<?php if (null !== $this->identity()) : ?>
    <a href="/logout">Logout</a>
<?php endif; ?>