Citygreen / Case StudiesComparitive Trial at Ashfield Civic Centre in Sydney

Comparitive Trial at Ashfield...

Tree in soil vault yields 35x larger shade canopy than in conventional structural soil

About the trial

In February 2011, two different tree pits were planted at the same time with the same tree species (Chinese Elm) at the Ashfield Civic Centre in Sydney, Australia. The tree in the centre forecourt was planted using the Stratacell™ suspended pavement system while the two trees near the sidewalk were planted in structural soil (rock/soil matrix).

Over a year later, the canopy density of the tree planted using the Stratacell system (suspended pavement –  right) is significantly thicker than the one on structural soil (rock/soil – shown on left).

 

Key Facts

LOCATION:
Ashfield Civic Centre in Sydney, Australia

PLANTED IN:
Structural Soil (Feb 2011)

TREE SPECIES:
Chinese Elm (Ulmus parvifolia)

PLANTING SIZE:
200l

AVG. CANOPY HEIGHT:
4m

AVG. CANOPY RADIUS:
2m

AVG TREE VALUE*:
$419

LOCATION:
Ashfield Civic Centre in Sydney, Australia

PLANTED  IN:
Soilvault System  (Feb 2011)

TREE SPECIES:
Chinese Elm (Ulmus parvifolia)

PLANTING SIZE:
200l

AVG. CANOPY HEIGHT:
6m

AVG CANOPY RADIUS:
3m

AVG. TREE VALUE*:
$9,425

Study

These early results from the Ashfield project are well supported by a fascinating study conducted by E. Thomas Smiley, Lisa Calfee, Bruce Fraedrich and Emma Smiley, comparing structural and non-compacted soils for trees surrounded by pavement.

In the 2006 study, Snowgoose cherry and Bosque lacebark elm were planted into five different soil treatment options under pavement, including compacted soil, gravel/soil mixture, Stalite, Stalite/soil mixture, and non-compacted soil.

After 14 months, the study found that there was more trunk diameter growth with the non-compacted treatment than the other treatments. There was also more twig growth, higher relative chlorophyll rating and more root growth compared to all the other systems.

Download the study report as PDF here.

Conclusion

The comparison showed that the foliar rating with the suspended pavement system was significantly better. Aside from this, “the mean SPAD reading of foliar colour was also significantly higher” as well as “the root length at the rhizotrons”.

The study’s conclusions state that “suspended pavement over non-compacted soils provided the greatest amount of tree growth and health and should be considered when designing urban planting sites for trees”.

Citygreen Stratacell system is an engineered load-bearing matrix that supports pavement and traffic load while providing in excess of 90% uncompacted soil by volume.

Suspended pavement systems, especially those incorporating soil cell technology, are fast becoming the preferred choice for successful urban tree pit design.

Questions?

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