142 percentage of sugar maple in the smallest size classes (2.5 to 15 cm) increased from an esti- mated 22% to 33% to all trees in these classes. The decline of American beech is likely explained in part by the loss of beech-maple for- est through direct habitat destruction or con- version. Seventy-six percent of the county was covered by beech-maple forest in presettlement times (Barr et al. 2002). Upland forest was pref- erentially cleared for agriculture in the early part of the 19th century (Brothers 1994), which is reflected in the current estimated remaining for- est cover in the county of 13% (Barr et al. 2002). Additional factors that may have contrib- uted to the decline of American beech in Marion County include poor tolerance of disturbance (especially disturbance to its shallow roots), com- pacted urban soil, low preference in the landscape industry due to its not doing well as ball-and- burlap stock, and the fact that its smooth bark is subject to vandalism in street and park settings (Carrie Tauscher, urban forester, Indiana Depart- ment of Natural Resources pers. comm.). It should also be noted that American beech frequency may have been overstated in the historical sur- veys. This species may have been preferentially selected for witness trees due to its smooth bark which would have been easy to blaze and mark. The species shiſts observed in Indianapolis may also be due in part to larger regional changes. Increasing presence of sugar maple and decline of American beech was noted in Indiana as early as 1977 (Abrell and Jackson 1977). The increase in sugar maple has been attributed to release from competition with American beech and alteration of natural fire regimes (USDA 2006). Decreased fire favors fire-sensitive species like sugar maple. The large proportion of small sugar maples in Indianapolis suggests the species will continue to increase in importance. As it becomes more dominant, sugar maple can have a cascad- ing effect, further influencing forest composi- tion through secondary effects, including altered nitrogen cycling (Lovett and Mitchell 2004). Recent surveys also support a large increase in elm species, an increase in frequency from 5% to 23%, compared with historical records. Native elms may be any of three species, American elm (Ulmus americana), rock elm (U. thomasii), or ©2015 International Society of Arboriculture Dolan: Two Hundred Years of Forest Change slippery elm (U. rubra). Dutch elm disease, intro- duced in the 1950s in Indiana, killed almost all large elms. Natural populations have rebounded in some areas, but the disease still kills larger, older trees. Size of elm has decreased from a mean DBH of 43 cm to 14 cm in current remnants. Street tree elms include non-native Siberian elm (Ulmus pumila). Blackcherry (Prunus serotina) was not reported in the historical data. This may be because of its extremely flaky bark, which is hard to mark, and it might have been avoided by sur- veyors. It may also be that as a fast-growing tree of forest openings, it has become much more common with the forest disturbance that accom- panied settlement and urbanization. Interest- ingly, Sassafras, the most common tree in urban forests in a recent statewide study (Nowak et al. 2007), and another fast-growing tree of spe- cies of forest openings, was not recorded in his- torical surveys and was very rarely encountered in recent surveys in natural remnant woods. Boxelder, a fast-growing disturbance-tolerant species, remained of similar low importance. Cottonwoods, the trees with the largest increase in mean size between historical sur- veys and current remnants, are primarily found along streams and creeks and in floodplain forests bordering streams and creeks. Many of the rem- nant patches of this habitat type in Indianapolis are now protected as parks. The increase in tree size may be due to protection from disturbance. The most striking difference between urban street tree composition and that of historical or current natural woods is the large percentage of sil- ver maple. Its predominance has increased almost thirty times over presettlement values. In Chicago, dominance of silver maple has increased an amaz- ing 80,000 percent over the same recorded period (Fahey et al. 2012). This species was oſten a street tree of choice in the 20th century because of its fast growth. It is not recommended for planting in urban forests in Indiana (IDNR 2015) because its quick growth makes it weak and susceptible to damage in wind and ice storms. The species is not among those currently being planted on city streets (Table 3). Although all trees recorded in the historical sur- vey records are found among Indianapolis’ street trees, many other species are now planted in the city. The proportion of importance represented by
May 2015
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
