City Trees

November/December 2016

City Trees is a premier publication focused on urban + community forestry. In each issue, you’ll learn how to best manage the trees in your community and more!

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24 City Trees 24 City Trees S M A R O U N D T A B L E Conifers in the Urban Forest The predominant mature forest type in many coastal areas of the Pacific Northwest is comprised primarily of coniferous trees such as Douglas-fir (Pseudotsuga menziesii), western redcedar (Thuja plicata), grand fir (Abies grandis), Sitka spruce (Picea sitchensis), and western hemlock (Tsuga heterophylla). Accordingly, coniferous species are important to Surrey's urban forest. More than 927 hectares (2291 acres) of forested natural areas on City park land are classified as coniferous or mixed forests (both coniferous and deciduous), representing 62% of all natural areas on City park land. In addition to conifers in forested park land, more than 12,500 individually planted coniferous trees are located in park open spaces and along streets, representing 12% of Surrey's shade tree inventory. Most of the conifers growing in Surrey's forested areas arise from natural regeneration that has occurred over the last 100- plus years post-logging. In the last 15 years, conifers have been purposefully planted in the City's forested natural areas. Conifers are commonly prescribed in the establishment of new forest areas (for example, areas that are converted from grass to forest). They are planted in deciduous forests as a means to give forest succession a head-start towards mixed forests. In addition, conifers are planted each year as replacement trees for trees that are removed through the City's tree risk assess- ment and abatement program. Many conifers that are growing in park open spaces as shade trees are naturally regenerated trees from the post-logging era that were retained during park development. In some of Surrey's parks, non-native conifers were planted by early European settlers. For example, the Brown brothers (Peter and David) planted numerous giant sequoia (Sequoiadendron giganteum), among numerous other exotic species, in the late 1800s and early 1900s in what is now Redwood Park, creating what is said to be the largest stand of giant sequoias outside of California. Conifers have been a part of Surrey's park shade tree planting efforts since the 1980s. In the early days, plantings were heav- ily focused on western redcedar as a favourite of park managers of the era. Today, a wide range of both native and introduced conifers are planted, with an emphasis on planting fewer western redcedar in order to reduce the percentage of the species in the City's inventory to below 20%. It is also worth noting that in recent years some mature western redcedar trees in some areas of the City have died and others are in decline, perhaps because the recent string of long, hot, dry summers is contributing to their ill health. Another possibility is that ground water regimes may have changed in some areas as a result of development, causing the trees to decline. Similar to park open spaces, there are many naturally regener- ated conifers that were retained along Surrey's streets during subdivision and road development. Surrey's street tree plant- ings have included conifers for more than 35 years. In the earlier plantings, native conifers were commonly planted along medians in conjunction with smaller native deciduous trees in pockets of native shrubs. In more recent years, conifer plant- ings in street landscaping have trended towards introduced species; presently, many species from 19 different genera are planted in Surrey, ranging from dawn redwood (Metasequoia glypstostroboides) to columnar black pine (Pinus nigra 'Arnold Sentinel') to incense cedar (Calocedrus decurrens). Surrey's planning documents further illustrate the importance of conifers in the urban forest. The Shade Tree Management Plan sets out targets for species diversity, within which conifers play an important role. The Arterial Median Landscape Guidelines Cupressus nootkatensis 'Pendula' planted in a narrow median in Surrey, BC. Photo by Neal Aven Surrey, BC still retains stands of old-growth conifers within its urban areas. Seen here is an old-growth Douglas-fir (Pseudotsuga menziesii) growing in a stand where 25 trees are over 55 m (184 feet) in height and the tallest of the trees is 62.1 m (204 feet). The man in front is Surrey Manager of Parks Planning & Design Ted Uhrich. Photo by Owen Croy

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