DOI: 10.5061/dryad.sn02v6x3k
title: Diverging conditions of current and potential future urban forest patches

description: Forested natural areas in cities provide a range of social, ecological,
 economic, and health benefits. Ensuring the delivery of these benefits
 requires an understanding of current and potential future forest
 conditions yet urban forest dynamics are not well understood. Here, we
 address this knowledge gap by examining forest structure and composition
 in 126 plots distributed across three forest patch sizes (large (95-126
 ha), medium (1-19 ha), and small (0.05-0.65 ha) patches) in the city of
 New Haven, CT, USA. We detected significant shifts in forest structure and
 composition suggesting a suite of distinct successional trajectories
 within each patch size. Large patches comprised 95% native tree species in
 the canopy ( &gt; 5 cm DBH), sapling (1-5 cm DBH), and seedling
 (&lt; 1 cm DBH) layers, suggesting that these large patches will
 continue to be native-dominated in the future— a primary objective for
 urban forest management. Moreover, in these large patches, shifts in the
 dominant species in each strata suggest that as large patches move through
 succession they will transition from moderately-shade tolerant forest
 types (i.e., oaks) to shade-tolerant types (i.e., American beech)— a
 similar successional trajectory to surrounding second growth forests in
 the region. Medium patches were the most heterogenous patch size sampled.
 Despite this heterogeneity, they generally resembled large patches in the
 canopy and sapling layers but diverged in the seedling layer. In medium
 patches, the invasive Norway maple replaced American beech as primary
 seedling species suggesting a future shift towards non-native dominated
 forest in the future. Small patches were the most compositionally and
 structurally distinct patch size sampled. Only 36% of the canopy trees and
 saplings in small patches were native species, however, this increased to
 71% native in the seedling layer. Additionally, the most important
 seedling species included those that are bird-dispersed highlighting the
 potentially valuable role that these small, non-native, forest fragments
 play as wildlife corridors. Collectively, our study demonstrates that
 multiple forest types, dynamics, and conditions can be found within a
 single city and that forest patch size offers a helpful framework to begin
 to parse out these differences.
description: We sampled from 126 plots spread across 24 forest patches within
 the city of New Haven. Plots were designed to collect data on forest
 structure and composition and included a 10-m radius overstory plot, with
 a 5-m midstory subplot, and eight 1-m<sup>2</sup> understory
 subplots nested within. All data analysis was done with R Core statistical
 software. 
description: This project consists of 6 data frames. "Disturbance"
 measures disturbances within the 10-m radius plot, "Overstory"
 measures all woody plants &gt;5 cm DBH within the 10-m radius plot.
 "Midstory" measures all woody plants 1-5 cm DBH within a 5-m
 radius plot and "Understory" measures all woody plants &lt;
 1cm DBH within eight 1-m<sup>2</sup> quadrats. "Species
 Cover" estimates percent cover for all plant species within the eight
 1-m<sup>2</sup> quadrats and "EnvDatII" measures a
 suite of environmental factors for each plot.  All variables measured and
 described are explained in the associated manuscript and in the
 "ReadMe" file.