As with all nature, trees are often revered by Pagans and Wiccans. Stories about trees can be found throughout myth and folklore in just about any cultures history. Certain materials from trees are considered highly useful in magic and\or ritual for their unseen properties and affiliations.
These correspondences are listed below.
ALDER - Protection and oracular powers
Almond - Clairvoyance, divination, moon magick, wisdom
Apple - Healing, love, perpetual youth, prosperity
Ash - Protection
APPLE - Love and healing magic
Apricot - Love
Aspen - Protection
Birch - Fertility, new beginnings, protection, purification
Beech - guidance, protection?
Blackthorn -fate
Cedar - Longevity, prosperity
Coconut - Chastity, healing, purity
Cypress - Past-life workings, protection
Elder - Healing, prosperity, protection, life and death
Elm - Protection
Eucalyptus - Healing
Fig - Fertility, healing, sensuality
Hawthorn - cleansing, love, protection
Hazel - Divination, protection, reconciliation
Juniper - Protection
Lemon - Chastity, divination, friendship, healing, wishing
Maple - Divination, love
Mulberry - Divination knowledge, will power, wisdom
Oak - Healing, finances, longevity, strength
Olive - fidelity, fruitfulness, peace, security
Orange - Love, marriage
Palm - Strength
Peach - Divination, love
Pine - Fortune, fertility, health, prosperity, purification
Rowan - Protection, strength
Walnut - divination healing, oracle, protection
Willow - Enchantment, healing, moon magick, protection, fertility, feminine magic
Yew - Altered states of consciousness
Sources: http://www.magicspells.in/wiccan_tree_correspondences.htm
http://sacredwicca.viviti.com/book-of-shadows