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HomeMy WebLinkAboutArborist Report 950100308 & 950100309Arboricultural Assessment Helen Smith 1353 Thorndyke Road Port Ludlow WA Richard R Hefley— Consulting Arborist PO Box 177, 101 Reinier Road Nordland WA A P R 2 6 2021 Page 2 of 15 Arboricultural Assessment Client: Helen Smith 1353 Thorndyke Road Port Ludlow WA Author: Richard R Hefley Consulting Arborist Site Visit Date: 08/26/2020 Report Date : 09/13/2020 Amended: 04/06/2021 OBJECTIVES: Create a vegetation management plan for Lots #950100308 and 309, given these lots are designated as moderate landscape and erosion hazards. BACKGROUND I was contacted by Helen Smith of 1353 Thorndyke Road regarding concerns she had for acquiring and managing two lots adjacent to her residence. Richard R. Hefley — Consulting Arborist — 360-385-2921— rkheflev@olypen.com Page 3 of 15 CONTENTS: Page 04 ..... Executive Summary Page 05 ..... Observations — Aerial Photo, View Corridor Delineation Page 06 ..... Aerial Photo: Vegetation Zones of Slope Page 07 ..... Mid -Slope Zone: Douglas Firs Pages 08-09 ..... Upper Slope Zone: Blackberries, Sword Ferns, Salal Pages 10-11.... Lower Slope Zone: Bigleaf Maples Discussion Page 12 .... Waiver of Liability, Contact Information Pages 13-14 ..... Pruning Notes Richard R. Hefley Consulting Arborist — 360-385-2921— rkhefley@olypen.com Page 4 of 15 EXECUTIVE SUMMARY: I was contacted by Helen Smith of 1353 Thorndyke Road regarding concerns she had for acquiring and managing two lots adjacent to her residence. There are essentially three "Zones" associated with the slope of these two lots. The crown of the slope, the upper zone, consists of a groundcover of native salal and sword fern, a non-native low juniper, and Himalayan Blackberry (a noxious weed). The middle zone consists primarily of Douglas Fir and Western Hemlocks. The toe of the slope, the lowest zone, consists primarily of Bigleaf Maples and red Alder. Given that these lots are designated as moderate erosion and landslide zones, it is important to maintain healthy evergreen vegetation to mitigate the associated hazards. This vegetation maintenance should consist of pruning and the replacement of noxious weeds with appropriate vegetation, bearing in mind the importance of encouraging an evergreen covering of the ground using native low plants and trees. The current pruning and thinning necessity lies with the Douglas Fir and Western Hemlock trees that have grown to obscure the View Corridor associated with this property. Several suppressed and diseased trees may be removed without exposing any ground to erosion hazard. Remaining trees may be pruned using approved methods including "thinning, windowing, and crown raising." Details on pruning techniques are noted in the appendices. I attached aluminum tags and colored tape to trees. Orange tape designates trees that may be removed. Blue tape designates trees that may be pruned. The trees to be removed are numbered; 02, 04, 08, 10. Other scattered young Bigleaf Maples with trunks less than 6" in diameter located on the lower slope are not numbered but may be removed without any measurable environmental degradation to the area. The remaining conifers appear to be in good health and can sustain pruning of 25% of the canopy area with no measurable impact to their immediate environment. Removed foliage should be mulched and left in place for decomposition or removed from the slope entirely to mitigate the buildup of "fuel" for wildfire. Trunks of larger removed trees may be anchored across the slope by affixing them to remaining trees or tree stumps. In time the Bigleaf Maples and Red Alder located in the mid and lower slope may begin to obstruct the view corridor. These may be successfully controlled using "crown reduction" pruning techniques to retain the health and integrity of the tree. Smaller Maples and Alders measuring approximately 6" or less in diameter trunks may be removed. There is an abundance of the noxious weed, Himalayan Blackberry, primarily in the upper portion of the slopes. I recommend that these blackberry canes be removed and, at a minimum, be replaced with native evergreen groundcover and small shrubs that thrive in this area such as sword fern and salal. Other suitable additions to this slope may include groundcovers like mahonia and evergreen Richard R. Hefley — Consulting Arborist — 360-385-2921— rkheflev@olypen.com Page 5 of 15 huckleberry, or even Shore Pine, a native evergreen tree whose roots will bind the soils at a deeper level. Likewise, the lower portions of the lots below the canopies of the Bigleaf Maples would benefit from the addition of native evergreens to mitigate soil erosion and aid in the transpiration of stormwater in the cool and rainy seasons. Sword Fern and Evergreen Huckleberry are also excellent choices for this shady area. Suitable evergreen trees for this area are Western Red Cedar, though bearing in mind that these will eventually require pruning to keep the View Corridor open in a few decades. All work should be performed when soils are not waterlogged. Working on slopes when soils are saturated leads to soil damage and erosion if care is not exercised. All pruning will be done in accordance with ANSI A300 standards and adhering to AND Z133 Safety Standards, as well as Best Management Practices Revised 2008, Edward F Gilman and Sharon J Lilly. OBSERVATIONS: Richard R. Hefley — Consulting Arborist — 360-385-2921— rkheflev@alypen.com Page 6 of 15 The aerial photo above shows the Smith residence at 1353 Thorndyke Road. The red lines extending east roughly approximate the boundaries of two lots to acquire and manage the vegetation in a manner consistent with limiting potential erosion or landslide conditions. 1353 Thorndyke Road - Vegetation Areas �.I Write a description for your map The lots are divided into three basic vegetation types that correspond with the slope. The crown (top) of the slope is located immediately left of the Blue area and the toe (bottom) of the slope is located to the right of the yellow area (east). BLUE — This is the upper portion of the slope and most arid. It primarily consists of the native evergreen groundcovers salal and western sword fern, but also contains abundant amounts of Himalayan blackberry (a noxious weed) and scattered small trees and shrubs of a deciduous nature. RED — The middle portion of the lot is dominated by Douglas Fir trees, a conifer crucial to maintain to retain the integrity of the slope and mitigate potential erosion and landslides. Conifers, and indeed ALL evergreen trees and shrubs are critical to reduce the effects of stormwater erosion. Evergreen foliage deflects and scatters rain in the winter months when rain is (by far) most abundant and potentially damaging in this region. YELLOW — This portion is primarily associated with the lower, flatter portions of the lots where erosion and landslides are less likely to be a factor. The lowest portion is dominated by the native Bigleaf Maple (Acer macrophyllum) though a few trees are also scattered throughout the slope. There is a small number of red Alders (Alnus rubra) here as well. While their canopies aid somewhat in the mitigation of erosion, their greater benefit comes from their root systems that bind the soils. Richard R. Hefley — Consulting Arborist — 360-385-2921— rkheflev@olvQen.com