DOI: 10.5061/dryad.qnk98sffm
title: Positive long-term impacts of restoration on soils in an experimental urban forest

description: As urbanization increases worldwide, so too are investments in
 nature-based solutions that aim to mitigate urban stressors and counter
 the impacts of global climate change. Tree planting on degraded urban
 lands—or afforestation—is one form of nature-based solution that has been
 increasingly implemented in cities around the world. The benefits of
 afforestation are, however, contingent on the capacity of soils to support
 the growth of planted trees, which poses a challenge in some urban
 settings where unfavorable soil conditions limit tree performance.
 Soil-focused site treatments could help urban areas overcome impediments
 to afforestation, yet few studies have examined the long-term (&gt; 5
 years) effects of site treatments on soils and other management
 objectives. We analyzed the impacts of compost amendments, interplanting
 with shrubs, and tree species composition (six species vs. two species) on
 soil conditions and associated tree growth in 54 experimental
 afforestation plots in New York City, USA. We compared baseline soil
 conditions to conditions after six years and examined changes in the
 treatment effects from one to six years. Site treatments and tree planting
 increased soil microbial biomass, water holding capacity, and total carbon
 and nitrogen and reduced soil pH and bulk density relative to baseline
 conditions. These changes were most pronounced in compost-amended plots,
 and the effects of the shrub and species composition treatments were
 minimal. In fact, compost was key to sustaining long-term changes in soil
 carbon stocks, which increased by 17% in compost-amended plots but
 declined in unamended plots. Plots amended with compost also had 59% more
 nitrogen than unamended plots, which was associated with a 20% increase in
 the basal area of planted trees. Improvements in soil conditions after six
 years departed from the initial trends observed after one year,
 highlighting the importance of longer-term studies to quantify restoration
 success. Altogether, our results show that site treatments and tree
 planting can have long-lasting impacts on soil conditions and that these
 changes can support multiple urban land management objectives.
description: This study was conducted within long-term research plots (NY-CAP)
 located in Kissena Corridor Park, a 40-ha urban park in Queens, New York,
 USA. The NY-CAP experimental plots test the impacts of three treatments on
 planted tree growth and soil conditions over time. Treatments
 include: tree species composition (two species or six species), compost
 addition (compost-amended or unamended), and interplanting with shrubs
 (presence or absence). We sampled soils four times over the course of the
 experiment in 2009, 2010, 2011 and 2016. In 2011 and 2016 we measured DRC
 and DBH, respectively, for all planted trees in experimental plots. Soils
 were processed and analyzed at Yale University. 
description: This dataset is comprised of three tabs in a single excel file.
 See the "MetaData" tab for information pertaining to the
 variables measured and analyzed. The "SoilData" tab includes
 values for all the soil variables analyzed and reported on and
 "TreeData" includes values for all the tree growth variables
 analyzed and reported on in the manuscript.