Specht _ ACEAS Phenocams

Dec. 1994 Mar 2002

The phenology of the plant community – more properly, a

story of exploration

Alison Specht

What controls vegetative growth? Hypothesis 1

• Light-mediated hormone triggers

• Temperature-mediated hormone triggers

• Whatever…

• Affects survival, distribution and community composition and structure

Investigation 1

• Is it temperature?

– In-situ adult individual monitoring of canopy dynamics

• tagging and

• litter collection

– Controlled environment studies

– Other things….

Shoot tagging (three adults 35m)Corymbia intermedia

Shoot tagging (three adults circa 32m)

Litter – Moggill State Forest

Litter – Moggill State Forest

Phytotron

• Chose two species that co-occurred but had different distributions: E. maculata (now Corymbia variegata subsp citriodora) and E. drepanophylla (now bundled in with E. crebra)

• Two experiments – one in Plant Industry phytotron in Canberra, one in Brisbane

Putting together

Putting together

Hypothesis 2

• Vegetative growth is triggered by temperature, but mediated by availability of resources.

• Observational evidence. 1992 fire in southern Australia – killed around 100 people. Out-of-season shoot growth, dried due to drought -> paper thin, flammable shoots in canopy, tops and bottom fire

Availability of resources

• Second study – temperature x nutrients (phytotron & field studies) not available for today

• Third study – field observations and collation of temperature x water balance x nutrients?

rainforest

rainforest

rainforest

rainforest

rainforest

rainforest

But this is wandering into productivity and broad questions of biodiversity

the community – temporal partitioning of

resource demand through phenology

the community – temporal partitioning of

resource demand through phenology

the community – temporal partitioning of

resource demand through phenology

the community

the community

the community

the community

the community

These three species co-occur because their demand for limited resources is staggered in time.

So what is the point?

• The period in which a plant can produce new leaves and remain active is critical to its competitiveness and survival

So what is the point?

• The period in which a plant can produce new leaves and remain active is critical to its competitiveness and survival

• Temperature is a major trigger of meristematic production, followed by availability of resources. This appears increasingly to be a bit chicken and egg–mediated by sucrose, not hormones.

So what is the point?

• The period in which a plant can produce new leaves and remain active is critical to its competitiveness and survival

• Temperature is a major trigger of meristematic production, followed by availability of resources. This appears increasingly to be a bit chicken and egg–mediated by sucrose, not hormones.

• Temperature perception of the meristem is of key importance