TECHNICAL ARTICLEPedogenic Processes and Urban Tree Health in Engineered Urban Soils in Boston, Massachusetts, USAScharenbroch, Bryant C.1; Fite, Kelby2; Kramer, Eric3; Uhlig, Robert4Author Information Guest Editor: Richard K. Shaw. 1University of Wisconsin–Stevens Point, Stevens Point, Wisconsin, USA. 2Bartlett Tree Research Laboratories, Charlotte, North Carolina, USA. 3Reed Hilderbrand, Cambridge, Massachusetts, USA. 4Halvorson Design Partnership, Boston, Massachusetts, USA. Address for correspondence: Dr. Bryant C. Scharenbroch, College of Natural Resources, University of Wisconsin–Stevens Point, 800 Reserve St, Stevens Point, WI 54481. E-mail: firstname.lastname@example.org Financial Disclosures/Conflicts of Interest: The Morton Arboretum, Bartlett Tree Research Laboratories, Reed Hilderbrand, and Halvorson Design Partnership. Received March 30, 2018. Accepted for publication September 13, 2018. Soil Science: July/August 2018 - Volume 183 - Issue 4 - p 159-167 doi: 10.1097/SS.0000000000000231 Buy Metrics Abstract ABSTRACT Trees provide many ecosystem services in the urban environment. For these benefits to be realized, trees must establish and grow to large sizes. Engineered urban soils (EUS) are intended to promote tree health and sometimes also perform other functions such as supporting infrastructure. Substantial amounts of time and money are invested into these soils and trees, yet data on longitudinal soil developmental processes (i.e., pedogenic processes) and tree performance are limited for these systems. In this research, soil development in seven EUS installations in Boston, Massachusetts, was assessed. The EUS studied included sand-based structural soils, rock-based structural soils, and horticultural mixes. The sites spanned a chronosequence of 6 to 45 years since installation and included five different tree species. The data confirm the hypotheses that pedogenic processes are occurring in these soils at different rates and magnitudes. Illuviation of clay, acidification, and a decrease in the mineralization quotient (qM, or respiration divided by soil organic matter) were observed with increasing site age. The data suggest that overall soil quality may be influential on tree health, and no individual soil physical, chemical, or biological property is driving site differences important for trees. Urban vegetation managers should recognize that these are not static systems and the actions to care for these systems should evolve as the soils develop over time. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.