164 Tirado-Corbalá and Slater: Soil Compaction Effects on Three Tropical Tree Species Arboriculture & Urban Forestry 2010. 36(4): 164–170 Soil Compaction Effects on the Establishment of Three Tropical Tree Species Rebecca Tirado-Corbalá and Brian K. Slater Abstract. Tree seedlings planted in containers along sidewalks in urban environments show restricted growth and development over time. This is the result of limited soil volume and soil compaction that hampers nutrient availability and water movement. Using tree species commonly used in urban forestry in Puerto Rico, this study was conducted to determine their growth response when planted in compacted soils. Seedlings of three ornamental tropical tree species, trumpet bush [Tecoma stans (L.) Juss. ex Kunth], bottle brush [Callistemon citrinus (Curtis) Skeels], and pink trumpet (Tabebuia rosea dc.) were transplanted into pots of sandy clay loam or clay soils at three levels of compaction: control (no compaction), 1.2 g/cm3 cm3 and 1.4 g/ bulk density, respectively. Plant height, shoot diameter, leaf number and color, foliar area, and root, shoot, and leaf dry weights were measured on two plants every two months for six months. All species exhibited better growth in sandy clay loam at 1.2 g/cm3 a reduced root-shoot ratio. When planted in clay at 1.4 g/cm3 ; after six months, all species showed , all trumpet bush seedlings died within two months. No leaf color differences were observed between species at different compaction levels. Bottle brush showed less growth suppression by increasing compaction level in both soils. Key Words. Callistemon citrinus; Root Growth; Root-Shoot Ratio; Tabebuia rosea; Tecoma stans; Tree Establishment; Urban Forestry; Urban Soils. Trees planted in urban environments often encounter myriad problems, both biophysical and those attributable to human ac- tivities such as lack of management and vandalism. Biophysical problems are numerous and include transplant stress (Waring and Schlesinger 1985), soil compaction (Patterson 1977; Craul 1992), water stress, high soil temperature (Craul 1992), high pH, soil salinity, poor soil drainage (Kozlowski, 1985; Kelsey and Hootman 1990; Craul 1992), root volume reduction (Lind- sey and Bassuk 1991), root loss during tree transplant (Waring and Schlesinger 1985), increase of vapor pressure deficit caused by urban microclimate and reflected heat (Bassuk and Whitlow 1988; Kjelgren and Clark 1993), and eventually, increase in mortality. Thus, arborists and horticulturists have the challenge of establishing trees under less than optimal conditions for root growth (Neal and Whitlow 1997). Tree establishment in urban areas requires an understanding not only of the physiological and biological factors but also institutional factors such as legisla- tion and planning, which are necessary for the development of urban forest landscapes (Bradley 1995). Urban soils are often the result of severe disturbance and alterations by processes associ- ated with the development of urban infrastructure (Craul 1992). Soil compaction occurs from pressure applied to the land surface during the construction of new buildings and roads. Compaction occurs either deliberately or as an unintended con- sequence of construction. Deliberate compaction is imposed to ensure physical soil stability for structures; unintended compac- tion results from such inadvertent activity as vehicular or pedes- trian traffic (Randrup 1997). Compaction changes the physical properties of the soil, increasing the bulk density and strength, and decreasing total porosity (Patterson 1977). Compaction causes a reduction in water and oxygen infiltration as well as ©2010 International Society of Arboriculture drainage. These altered properties inhibit woody plant growth and significantly reduce shoot growth (Chiapperini and Donnelly 1978). Altered soil properties have been shown to be the primary factors in sugar maple (Acer saccharum) decline in urban areas (Ruark et al. 1983). Furthermore, dense soil offers greater resis- tance to root development (Foil and Ralston 1967; Patterson et al. 1980; Lindsey and Bassuk 1991; Handreck and Black 1994). Inadequate soil root space in compacted soils is the major factor causing premature mortality of trees in urban areas (Pat- terson et al. 1980; Krizek and Dubik 1987; Jim 1998). There is a conflict between the biological needs of trees whose roots generally spread laterally near the surface and the requirements for construction. In the urban environment, a tree is often con- fined to a street tree pit, narrow parkways or above-ground plant- ers, which restrict the rooting area, slow or halt root penetra- tion, and increase branching and radial thickening of the roots (Materechera et al. 1991). These confined situations may allow the roots to spread laterally but only for very short distances. Different soil textures and poor soil structure, togeth- er, play a major role in the growth of tree roots (Craul 1985; Day and Bassuk 1994). A clay soil may have a bulk density of approximately 1.4g/cm3 , whereas san- dy soils may have a bulk density of 1.7 g/cm3 or higher. Species vary in their ability to penetrate compacted soil, partially due to different soil textures (Zisa et al. 1980; Pan and Bassuk 1985; Day and Bassuk 1994). Root growth of Forsythia ovata was significantly restricted at bulk densities as low as 1.2 g/cm3 (Alberty et al. 1984). In a container experiment, sugar maple seedling roots were evenly distributed throughout the pot for uncompacted soils, while the roots were confined to the upper portion of the pot in higher bulk density soils. At a
July 2010
| 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
