Skip to main content

Table 2 Paired comparison tests for burn and control treatments comparing 1989 baseline data to 2017 sample data for eight vegetation parameters at Gibbons Creek Barrens Natural Area, Pope County, Illinois, USA. se = standard error. If “mean ±” is shown, data were analyzed with paired t-tests; if “mdn” (median) is shown, data were analyzed with related samples Wilcoxon signed-rank tests because either 1989 or 2017 data were not normally distributed. GCB = Gibbons Creek Barrens, FSB = Forest Service Barrens, Change (%) = difference between 1989 and 2017, df = degrees of freedom, Test stat = test statistic, P = probability, NA = not applicable. P values shown in bold are significant (<0.05)

From: Do early trends in oak barrens fire treatment predict later outcomes? Insights from three decades of vegetation monitoring

Parameter Treatment: Burn (GCB)
1989 (mean ± se) 2017 (mean ± se) Change (%) Test stat df P
Overstory
 Tree density (stems per 0.05 ha) 47.27 ± 12.50 21.87 ± 7.18 −53.74 8.40 14 <0.001
 Tree basal area (m2 per 0.05 ha) 0.89 ± 0.06 0.76 ± 0.06 −15.04 4.60 14 <0.001
 Shrub and sapling density (stems per 0.005 ha) 27.73 ± 3.70 46.27 ± 5.35 66.83 −5.68 14 <0.001
Ground layer
 Species density (species per 0.25 m) 4.37 ± 0.60 6.75 ± 0.42 54.45 −6.66 14 <0.001
 Species richness (total species per plot [12 quadrats]) 21.00 mdn NA 26.00 mdn NA 23.81 113.00   0.003
 Species diversity (H' per 0.25 m2) 2.76 mdn NA 2.90 mdn NA 5.07 108.00   0.006
 Dominance (C per 0.25 m2) 0.08 mdn NA 0.07 mdn NA −13.75 8.50   0.003
 Cover (%) 90.42 ± 13.06 55.31 ± 4.93 −38.83 2.85 14 0.013
Parameter Treatment: Control (FSB)
1989 (mean ± se) 2017 (mean ± se) Change (%) Test stat df P
Overstory
 Tree density (stems per 0.05 ha) 50.25 ± 3.02 46.75 ± 2.17 −6.97 3.44 7 0.011
 Tree basal area (m2 per 0.05 ha) 0.92 ± 0.05 0.94 ± 0.08 2.03 −0.48 7 0.644
 Shrub and sapling density (stems per 0.005 ha) 25.50 ± 5.31 29.13 ± 3.92 14.22 −1.09 7 0.311
Ground layer
 Species density (species per 0.25 m) 4.38 mdn NA 4.42 mdn NA 1.03 8.50   0.352
 Species richness (total species per plot [12 quadrats]) 22.50 ± 2.76 18.63 ± 2.03 −17.22 1.53 7 0.169
 Species diversity (H' per 0.25 m2) 2.69 ± 0.13 2.55 ± 0.13 −5.20 1.38 7 0.210
 Dominance (C per 0.25 m2) 0.10 ± 0.01 0.11 ± 0.01 9.74 −0.91 7 0.392
 Cover (%) 98.42 ± 7.26 41.12 ± 7.27 −58.22 9.30 7 <0.001