View scope reset fields to default after performing an action

[admin]

First of all, my beans are managed by spring not by JSF and I am using custom view scope as described in <a href="http://cagataycivici.wordpress.com/2010/02/17/port-jsf-2-0s-viewscope-to-spring-3-0/" rel="nofollow">this article</a>. So if the behavior is weird for regular JSF2 and might be related to Spring, please tell me.

Bean:

public class DepartmentBean {

    private DefaultTreeModel model;

    public void preRender(ComponentSystemEvent event) throws Exception {
        if (model == null) {
            model = myService.buildModel();
        }
    }

    public String clear() {
        // resetting stuff
        return "pretty:";
    }

}

View:

<h:form>
    <ice:panelGroup styleClass="crud-links">
        <h:commandLink value="Delete" action="#{department.deleteDepartment}" />          
    </ice:panelGroup>
</h:form>
<h:form>
    <ice:panelGroup>
        <ice:tree id="tree" value="#{department.model}" var="item" hideRootNode="false" hideNavigation="false" imageDir="./xmlhttp/css/xp/css-images/">
            <ice:treeNode>
                <f:facet name="content">
                    <ice:panelGroup style="display: inline">
                        <ice:commandLink  value="#{item.userObject.text}"></ice:commandLink>
                    </ice:panelGroup>
                </f:facet>
            </ice:treeNode>
        </ice:tree>
    </ice:panelGroup>
</h:form>

When page is loaded for first time the

model

object is populated with data, but when clicking delete button I notice that after clearing

preRender()

method is executed and the model (which was populated before clearing becomes null, and gets populated again, although I am in same page, and it should maintain the value)

Does the code have a problem that leads to such behavior, or this is the normal behavior?
If the problem maybe related to Spring or the custom view scope or the IceFaces, please advise.

<strong>UPDATE</strong>- <strong>REQUIREMENT</strong>:

I want to initialize the tree model on construction of the page, and while i am still on the page the tree model doesn't gets initialized again until i do that programatically .