Arboriculture & Urban Forestry 37(1): January 2011 Arboriculture & Urban Forestry 2011. 37(1): 1–5 1 Aboveground Growth Response of Platanus orientalis to Porous Pavements Justin Morgenroth and Rien Visser Abstract. Integrating healthy, mature trees into paved urban environments is a challenging task for urban foresters, as impervious pavements are associ- ated with reduced tree growth and survival. It is thought that porous pavements may alleviate this problem due to their permeability to air and water. The authors of the following study tested whether porous pavements affect tree growth relative to impervious pavements by measuring aboveground growth in trees treated with an augmented factorial arrangement of pavement profile designs and pavement types. Fifty oriental plane (Platanus orientalis) seedlings were evenly distributed to control plots or one of four treatments. Treated plots were characterized either by porous or impervious pavement pads measur- ing 2.3 m × 2.3 m, that were underlain either by fine sandy loam or a gravel base and compacted subgrade, reflecting two pavement profile designs. Results show stem height, diameter, and biomass increased as a result of porous pavements. Greater growth proffered by porous pavements was negated by profile designs including a compacted subgrade and gravel base. Finally, impervious pavements did not negatively influence tree growth, relative to control trees. Key Words. Biomass; Oriental Plane; Permeable; Pervious; Road; Sidewalk; Soil Compaction; Street Tree. The urban forest is a major infrastructure element, providing environmental, economic, and social benefits. Healthy, ma- ture trees improve air and water quality (Xiao et al. 1998; Heckel 2004), moderate extreme temperatures (Long-Sheng et al. 1993), reduce energy consumption (McPherson 1994), increase real estate values (Anton 2005), provide wildlife habitat (Dunster 1998), and provide intangible benefits in- cluding aesthetic and recreational amenities. Street trees planted alongside roads and sidewalks are a major compo- nent of the urban forest. Street trees are subject to environ- mental stresses, both biotic and abiotic, which fluctuate and interact to affect plant function and growth. Furthermore, anthropogenic stresses compound the natural environmental stresses already imposed on trees. Buildings and pavements render ground surfaces impervious; stormwater management systems divert water away from soil and into designated res- ervoirs; soils are compacted to meet engineering standards; and trees are often planted in confined growing spaces. The additive effect of these and other factors is that urban trees have comparably shorter life spans and reduced annual growth than their forest-based conspecifics (Quigley 2004). One defining characteristic of the urban environment is impervious pavement. This infrastructure element is used for roads, parking lots, and sidewalks. It is pervasive, and in some cases covers more than 50% of land surfaces (Fergu- son 2005). Trees surrounded by pavements have their grow- ing environment altered; soil chemistry and physics are both modified by overlying pavements (Craul 1985; Macdonald et al. 1993; Jim 1997; Celestian and Martin 2004), as are a number of localized atmospheric factors, such as surface temperature and vapor pressure deficit (Kjelgren and Mon- tague 1998). This has led to speculation that pavements cause decreased growth, premature decline, and death (Kjelgren and Clark 1994; Iakovoglou et al. 2001; Schröder 2008). The pavement profile for a load-bearing pavement will in- clude, from bottom to top, compacted parent material (hereaf- ter referred to as a subgrade), a gravel base, and typically, an impervious surface course. In contrast, the pavement profile design for non-load-bearing pavements may include only a surface course installed over a compacted subgrade. Surface courses such as concrete or asphalt, combine a well-graded mix of aggregates and a binder to maximize density and limit permeability. An alternative pavement type precludes the in- clusion of fine aggregate and thus, results in a porous pave- ment. In contrast to impervious pavements, porous paving is characterized by a matrix of interconnected pores, which render it permeable to air and water. Porous pavements are generally perceived to promote tree growth and survival by enhancing moisture infiltration and increasing soil aeration (Tennis et al. 2004; Ferguson 2005). Theoretically, this is plausible, but these hypotheses have never been experimen- tally tested in a system including live trees. In the follow- ing experiment, this gap in knowledge is addressed by test- ing the effects of porous and impervious pavement profile designs on tree height, diameter, and aboveground biomass. METHODS Study Site The experiment was located at the city council nursery in Christchurch (Lat: -43.493, Long: 172.437), the larg- est city in New Zealand’s South Island. The top meter of soil is a fine sandy loam (Raeside 1974), and it overlies a ©2011 International Society of Arboriculture
January 2011
| 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
