PhD Candidate: @PWaryszak

Offset or off-the-mark?Seedling emergence and survival following topsoil transfer in Banksia woodland (“Biodiversity Offset”).

Old LandscapeNutrient poor soilsHeatFire

SWA Mediterranean Type Ecosystems

50% new to science since 19906759 plant species in SWA & still growing (Hopper 2004)80% of Banksia Woodlands have been cleared (Hotspot)

High Dormancy High Species Pool

(Go Topsoil!)

History of Topsoil Soil Seed Bank Transfer

• Cost-effective biodiversity return versus planting

Time of the year is very important

Direct Transfer

• Pioneering work by Alcoa in Jarrah Forest (1963) but only in mine (clay) settings

• Important lessons:

Topsoil a restoration tool

to mitigate environmental

filters?

• Clear Land, Strip, Dig, Re-apply

Regional species pool

Local community

Dispersal filter

Testing the model for Banksia woodland

Dispersal Limitation

(depths treatment)

Abiotic Barrier (ripping

treatment)

Biotic Barrier (herbivory exclosures treatment)

2015June September December 2013-2014March 2012

Murdoch University (Perth, WA)

Jandakot Airport

Anketell Road

Forestdale Lake

Site & Plot (4m²) - scale Treatments Design

ripped

unripped

ripped

unripped

N

150 m

The Filter in Spring I Emergence:

[ 4 plants per m ̴ 2 ]

Dispersal Limitation [ 11 plants per m ̴ 2]

The Filter in Spring II Emergence:

Data: The Most Abundant Native Families

Winner Families in Annual Category:• Asteraceae• Araliaceae• Crassulaceae

Winner Families in Perennial Category:• Fabaceae• Ericaceae• Asparagaceae

Nr Species Year I Year II

Annual 28 26

Perennial 101 89

Total 129 115

Big Site-scale Treatment Survival

Annual Rainfall

733.4 (mm)872.8 (mm)

No summer storms

Abiotic Filter misidentified?

TERM t P

Big Treatments X X

Small Treatments X X

Season 200.11 P<0.001Block X X

Trait Suit Winner Trait Suit Runner-up

NATIVE NO

N-FIXER NO

RESPROUTER YES

WOODY NO

GROWTH CATEGORY WOODY

SEED SIZE SMALL

MAXIMUM HEIGHT 0.7 m

NATIVE YES

N-FIXER YES

RESPROUTER NO

WOODY YES

GROWTH CATEGORY WOODY

SEED SIZE SMALL

MAXIMUM HEIGHT 1.0 m

Native emergence abundant.

Climate = important abiotic

filter to consider ($$$)

CONCLUSIONS

Very low survival.

THANK YOU

@TERG_MurdochUni

Supervisors: • Dr Joe Fontaine,• Dr Rachel Standish • Prof. Neal Enright,• Dr Phil Ladd,

Industry Partners: • JAH• DPaW

@PWaryszak

Diversity Index ~ Plant Density