Arboriculture & Urban Forestry 39(5): September 2013 given different amounts of fertilizers, depending on stan- dard procedures for the production method. BR, B&B, and RP trees were equally treated with one fertilization of NPK (11-5-18), distributed as 60 kg/10000 m2 , in the spring of 2007. The AP trees were fertilized one month after instal- lation in the production system with approximately 1 l NPK (21-3-10) for each tree. At installation of the FC trees, 220 g Osmocote® Pro (16-11-10), released over 8–9 months was included in each bag. Before the growing season started in the spring of 2008, 10 trees from each group were trans- planted at the sites. The remaining two trees in each group were delivered to the experimental fields in Alnarp, Swe- den, but not transplanted, and later used for root analysis. Four trees from each group were planted in an urban environment in the city of Malmö, Sweden (55°36’21”N, 13°0’9”E), and the other six in the experimental fields at the Swedish University of Agricultural Sciences, Alnarp (55°39’30”N, 13°05’0”E). The trees were organized in a com- pletely randomized block design for each site. The two sites are approximately 10 km away from each other. Both sites have a mean annual rainfall of approximately 600 mm and the dif- ference in monthly mean temperature is 0.1°C, with Malmö being the slightly warmer site. The trees planted in the city of Malmö were replacing old Ulmus trees, and were planted along two similar, parallel streets in a high-rise area, one species per street. The trees were planted in the positions that the Ulmus trees had previously grown until two years prior to replace- ment. Each pit was placed in a 3 m wide grass-covered area, irregularly interrupted by transverse pedestrian paths or minor roads to parking areas. The sidewalks of each street adjoined the planting areas on one side, and the driving lanes on the other. The streets ran from north to south, and were partially shaded by buildings. An area around each tree, one meter in diameter, was kept grass-free by a layer of gravel. The trees were managed by the municipality and irrigated approximately every second week during the first two growing seasons. The planting site in Alnarp was an open field and all trees were sun-exposed during the whole day. The trees were placed at a distance of 4.5 m in rows and 4.5 m apart. The soil was covered with a single layer of polypropylene ground cloth (Mypex® ) to inhibit weed growth. A drip-irrigation system was installed, and the plant water availability was regularly controlled using a HH2 moisture meter (Delta T Devices, Cambridge, UK) to avoid drought stress during the first two seasons. The irrigation frequency and amount was continuously modified so that the trees would have a suf- ficient water supply at all times. The trees were not fertil- ized at either of the two sites and no pruning was carried out. Measurements Shoot growth measurements were performed once every year between 2007 and 2011. The measurements were made after shoot growth cessation in each season. Two terminal shoots, and the lateral shoot next to the terminal, were measured in the middle part of the crown in the north, the south, the east, and the west (i.e., a total of 8 terminal and 8 lateral shoots in each tree). Any second flushes in the red oaks were noted, and the two parts were measured separately. The total shoot length of the growing season was used in the analysis. RESULTS Tree survival was close to complete for all production meth- ods and species during the study. One sweet cherry FC tree died in the nursery and one of the BR red oaks transplanted in Malmö died during the first winter after transplanting. One RP sweet cherry tree was excluded from the analysis be- cause it was suspected that the roots had not been pruned. All B&B trees and AP trees survived throughout the experiment. Comparison of the Two Sites As can be seen in Figure 1, site had a clear effect on shoot growth for both species during the two last years of the study (2010, 2011), with significantly lower shoot growth in Malmö than at Alnarp (sweet cherry P = 0.0004 and 0.0005; and red oak P = 0.0026, and 0.0013 respectively). Sweet cherry shoot growth, however, was higher at the Malmö site 2009 (P = 0.0049), but for red oak, the shoot growth was higher at Alnarp also that year (P = 0.01). No differences between the sites were seen during the first post- ©2013 International Society of Arboriculture Data Analysis The trees were randomly distributed within each block. The blocks were species-specific and contained all production methods, resulting in a total of five trees per block. Annual shoot growth data were analyzed separately for the two spe- cies in a block design in SAS, using a model with block(site), site, production method, and the interaction site*production in the model. Accumulated shoot growth was calculated by sum- ming the mean annual shoot growth for each tree and were then analyzed statistically with a General Linear Model, with production method and blocks as factors. To make a test to see if the trees had reached back to the shoot growth level of the undisturbed trees in the nurseries, a block design in PROC MIXED in SAS was used with repeated measurement for the trees where the unstructured covariance matrix was used be- cause it turned out that this one had the smallest AIC. The con- trast comparing the production method and year versus the mean of the undisturbed trees showed if the trees had recovered. The analyses were conducted using Minitab 15 Statistical Software (2007) for Windows (Minitab, Inc., State College, Pennsylva- nia, U.S.) and SAS (2008) (SAS version 9.2., SAS Institute Inc., Cary, North Carolina, U.S.) with a 5% significance level. 203 BR and B&B trees were not subjected to any kind of treat- ment during the nursery year (2007), and their shoot growth, during that year, can therefore be considered normal for the species (Struve et al. 2000; Li et al. 2010). Their nursery shoot growth was thus used as a reference for comparisons of the post-transplant shoot growth for all treatments during the consecutive years. The root systems of the two randomly chosen trees in each group that were not transplanted were washed clean from soil and peat. Visual evaluations of root system density, amount of fine roots, and root depth and dispersal were recorded and the roots photographed. All roots less than 2 cm in diameter were then collected from the root ball and their root length was ana- lyzed using a winRHIZO scanner (Régent Instruments, Canada). The roots were separated into fractions of 0–0.1 mm, 0.1–0.2 mm, 0.2–0.4 mm, 0.4–0.6 mm, 0.6–0.8 mm, 0.8–1.0 mm, 1–2 mm, 2–3 mm, 3–4 mm, 4–5 mm, 5–10 mm, and 10–20 mm.
September 2013
| Title Name |
Pages |
Delete |
Url |
| Empty |
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. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
