Full Title
The effect of Willows (Salix spp.) on freshwater ecosystem dynamics
Student
Paul McInerney
Supervisors
Dr Phil Suter and Dr Ben Gawne
Funding Body
La Trobe University
Duration
July 2009 to July 2015
Outcomes
PhD
Summary
The effects of willows and willow removal on river function and the rehabilitation process required to return willow removal sites to an ecologically and socially acceptable state need to be investigated if future willow removal works are to be conducted to their highest potential.
This PhD project will investigate how willows and willow removal have altered stream function, requirements for stream rehabilitation, rehabilitation classification, ecological niche function and changes in food web dynamics between areas with willows and areas without willows. It will also isolate and investigate social aspects associated with willow removal and best practice management.
Some key knowledge gaps to be investigated are:
· Extent of impact on fish community composition and abundance (habitat, shade, temperature, feeding and predator avoidance).
· Extent of impact on macro invertebrate community composition and abundance (feeding and habitat).
· Extent of impact on food web (timing, quantity and quality of allochthonous input, shade, temperature and algal production).
· Extent of impact on water quality (nutrient input and runoff, pH, salinity and dissolved oxygen levels).
· Extent of impact on riparian habitats (bank soils and erosion, use of riparian corridors by animals, impact of riparian zone fragmentation following de-willowing and riparian vegetation).
· Extent and timing of impacts and recovery periods.
The ongoing extent of willow invasion and the large scale movement of asexual propagules downstream from existing stands means catchment and regional planning strategies need to consider willow management in Australia. Priority setting requires quantitative knowledge of impacts, costs and benefits from willow invasion and willow removal at both reach and catchment scales (Wilson 2001). In addition, catchment managers require access to knowledge that will enable willow removal to be undertaken in a manner that minimizes detrimental short term impacts and accelerates recovery of the system. This project aims to provide answers for many of the questions surrounding the benefits and impacts of willow removal from streams in the Murray darling basin.
