Thanks Peter_L. I figured it out for anyone that cares.
if (get_query_var('wood_type')) {
$taxonomy_term_id = $wp_query->queried_object_id;
$taxonomy = 'wood_type';
$unwanted_children = get_term_children($taxonomy_term_id, $taxonomy);
$unwanted_post_ids = get_objects_in_term($unwanted_children, $taxonomy);
// merge with original query to preserve pagination, etc.
query_posts( array_merge( array(
'post__not_in' => $unwanted_post_ids
), $wp_query->query) );
}
