Hello and thank you for your question.  I understand that you planted your Douglas Fir trees 25 years ago.  You are now concerned that the trees are too close together and may be a safety hazard.  You also want know if removing some of the trees will increase the sturdiness of the others against the wind. I recommend that you contact a certified arborist to advise you on your specific situation.  Arborists are tree care professionals.  A certified arborist can advise you regarding the safety, care and recommended pruning for your trees.   Certified arborists have specialized experience and meet professional standards.  Some tips for hiring an arborist include: 1.       Hire someone who is bonded, licensed, and insured.  Tree service companies are required to register with the State of Oregon, so ask for a contractor registration number. 2.       Ask for references.   Contact references to ensure that the customer was pleased with the service and that the arborist successfully cared for their trees. 3.       Ask for a certified arborist.  This will ensure that the information you receive is from a trained, experienced tree care professional. Additional information on selecting an arborist can be found in the OSU Extension Publication entitled, “Selecting, Planting and Caring for a New Tree”, http://extension.oregonstate.edu/catalog/pdf/ec/ec1438.pdf. To find a certified arborist in your area, you can access the Tree Care Industry Association website and conduct a zip-code search.  Another group you can contact is the Pacific NW Chapter of the International Society of Arboriculture http://pnwisa.org/.  Both of these organizations provide information about arborist certification and contact lists for certified arborists in Oregon. Thanks for contacting the Ask and Expert help line.  I wish you all the best with your trees! Susan Preston, Master Gardener Volunteer