Vegetation Dynamics
This topic is presently at the frontiers of science in several ways.
It touches also several disciplines (Biology, Chemistry, Physics, Geoscience, etc.).
I came to three talks:
1. Towards modeling of vegetation dynamics
Role of vegetation dynamics in climate change
2. Investigation of forest standings
Field work, physiology
3. Theoretical ecology
population ecology, modeling of fire, stability of semi-aride zones
Recent research initiatives aim at analyzing the mechanisms
which control the growth dynamics and stability of ecosystems, at
modelling and predicting how the ecosystem is disturbed by human activity and climate change,
and at developing remedial management options.
The changes have significant impacts on
important wetland functions (biodiversity, stability of river and lake margins, water quality)
and local economies.
The scientific approach is multidisciplinary and comprises observational
field studies, field experiments, controlled greenhouse and laboratory experiments,
data collation and treatment, and mathematical modeling.
Dynamic Vegetation Models are capable of
simulating both ecosystem structure (vegetation distribution
and phenology) and function (biogeochemistry).
The new feature of this kind of model ansatz is
that theses do not assume an equilibrium state between
climate and vegetation. This is essential for the
responses and impacts of the terrestrial biosphere under a rapidly changing climate.
Short-term transient effects such as forest die-back in
mid-latitudes, forest expansion in the boreal region or
replacement of tropical forest can be captured by the models.
They include the explicit
representation of dynamic vegetation processes, e.g. resource
competition and production, growth, mortality, establishment, soil
and litter decomposition.
This is based on a mechanistic description of
photosynthesis,
respiration, surface or canopy energy balance and allocation of carbon
within the plant.
References:
Foley JA, Prentice IC, Ramankutty N, Lewis S, Pollard D, Sitch S,
Haxeltine A, 1996, An integrated biosphere model of land surface
processes, terrestrial carbon balance, and vegetation dynamics. Global
Biogeochemical Cycles, 10, 603-628
Friend AD, Stevens AK, Knox RG, Cannel MGR, 1997, A process-based,
terrestrial model of ecosystem dynamics (Hybrid 3.0). Ecological
Modelling,
95, 249-287
Woodward FI, Lomas MR, Betts RA, 1998, Vegetation-climate feedbacks in a
greenhouse world. Philosophical Transactions of the Royal Society of
London
Series B - Biological Sciences, 353, 29-38