68 Fair et al.: Maple (Acer spp.) Response to Soil Compaction and Pre-plant Nitrogen zero, which also indicates a higher flow rate in the lower den- sity soils (Table 1). Water content at the permanent wilting point was lower in the NC soils than in the compacted soils, and NC soils had more AVWC than the compacted soils (Table 1). Tree Growth For each year of the study, height varied based on cultivar type, but did not differ due to any other experimental treat- ment (data not shown). The rate of annual height growth also differed between cultivars in 2003 and 2004 (Table 2), but was unaffected by other experimental treatments. Caliper growth rate (cm·yr-1 ) across all cultivars varied sig- nificantly due to soil treatment in 2002 (Table 3; Table 4; Fig- ure 2) and 2003 (Table 3; Table 4). In 2002, trees growing in NC plots increased caliper on average 83% more than did trees growing in the compacted plots (Figure 2). ‘Celzam’ Freeman maple put on significantly more caliper growth than all other cultivars despite compaction treatment (Table 3; Table 4; Figure 2). When compared to ‘Morgan’ Freeman maples (poorest per- former in 2002), ‘Celzam’ averaged 118% more annual caliper growth in NC plots, and in compacted plots ‘Fairview Flame’ put on 142% more caliper growth than ‘Morgan.’ In 2003, trees growing in NC plots put on 22% more caliper growth than trees in compacted plots, and cultivars differed significantly (Table 3; Table 4). In 2004, cultivars differed in annual caliper growth, but not in response to compaction or pre-plant N rates (Table 2). When comparing annual caliper growth in 2002 and 2004, Table 1. Mean dry bulk density (ρb), log-transformed air-filled pore space [Log(AP)], log-transformed saturated hydraulic con- ductivity [Log(Ks)], water content at permanent wilting point (PWP), and available volumetric water content (AVWC) for each soil treatment for each study year. Values were obtained by measuring 9 intact soil cores taken each year from each whole plot (soil treatment). Year 2002 2003 2004 Soil treatmentz NC C1 C2 NC C1 C2 NC C1 C2 ρb (g·cm-3 ) 1.43 ± 0.04 a 1.67 ± 0.05 b 1.58 ± 0.09 b 1.43 ± 0.05 a 1.58 ± 0.04 b 1.58 ± 0.02 b 1.42 ± 0.06 a 1.63 ± 0.03 b 1.49 ± 0.06 ab Log(AP) (cm3 ·cm-3 ) -1.11 ± 0.15 a -1.66 ± 0.16 b -1.80 ± 0.07 b -0.99 ± 0.12 a -1.31 ± 0.13 b -1.39 ± 0.18 b -1.37 ± 0.14 a -1.73 ± 0.14 b -1.55 ± 0.12 ab Log(Ks) (cm·hr-1 ) 1.1 ± 0.2 a 0.01 ± 0.1 b -0.3 ± 0.3 b 1.2 ± 0.3 a 0.6 ± 0.2 b 0.2 ± 0.2 b 2.2 ± 0.3 a 0.9 ± 0.1 b 0.5 ± 0.2 b PWP (cm3 ·cm-3 ) 0.20 ± 0.02 a 0.26 ± 0.02 b 0.23 ± 0.003 b 0.20 ± 0.01 a 0.24 ± 0.01 b 0.22 ± 0.003 c nm nm nm AVWC (cm3 ·cm-3 ) 0.18 ± 0.02 a 0.10 ± 0.01 b 0.13 ± 0.01 b 0.21 ± 0.02 a 0.13 ± 0.01 b 0.16 ± 0.01 b nm nm nm z NC = non-compacted treatment, C1 = compacted once, C2 = compacted twice; n = nine samples for each soil treatment per year. Means ± standard errors followed by different letters indicate a significant difference between treatment measurements within each year, at P ≤ 0.05 (Tukey’s honestly significant difference test, HSD); “nm” means not measured in that year. Table 2. Analysis of variance effects significance for mean height growth, mean caliper growth, mean leaf area, mean leaf dry weight, and mean stem dry weight for each soil treatment, with eight maple cultivars, three soil treatments, two pre-planting nitrogen (N) rates, the interactions between soil treatment, cultivar, and pre-planting N rate for all study years. Analysis of variance effects 2002 Cultivar (C) Soil treatment N rate (N) Soil treatment*cultivar Cultivar*N rate Soil treatment*N rate Soil treatment*C*N 2003 Cultivar Soil treatment N rate Soil treatment*cultivar Cultivar*N rate Soil treatment*N rate Soil treatment*C*N 2004 Cultivar Soil treatment N rate Soil treatment*cultivar Cultivar*N rate Soil treatment*N rate Soil treatment*C*N z *** ns ns ns ns ns ns *** ns ns ns ns ns ns *** ** ** ns ns ns ns *** ** ** ns ns ns ns *** * *** * ** ns ns Asterisks (*, **, ***) and “ns” indicate statistical significance of the treatment at P ≤ 0.05, P ≤ 0.01, P ≤ 0.001, or not significant, respectively; “nm” means not measured in that year. All possible interactions for the main experimental treatments (soil treatment whole plots, pre-plant nitrogen rate sub-plots, and cultivar sub sub-plots) were tested. ©2012 International Society of Arboriculture *** ns ns ns ns ns ns *** ** ns ns ns ns ns *** ** ** ** ns ns ns *** ** ** ** ns ns ns nm nm nm nm nm nm nm Height growth (cm) nsz ns ns ns ns ns ns Caliper growth (cm) *** * ns * ns ns ns Leaf area (m2 ) *** ns * ns ** ns ns Leaf dry weight (g) *** ns * ns ns ns ns Stem dry weight (g) nm nm nm nm nm nm nm
March 2012
| Title Name |
Pages |
Delete |
Url |
| Empty |
Ai generated response may be inaccurate.
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.
Downloading PDF
Generating your PDF, please wait...
This process might take longer please wait
