G. Simioni et al., Treegrass: a 3D, process-based model for simulating plant interactions in tree-grass ecosystems, ECOL MODEL, 131(1), 2000, pp. 47-63
The function and dynamics of savanna ecosystems result from complex interac
tions and feedbacks between grasses and trees, involving numerous processes
(i.e. competition for light, water and nutrients, fire, and herbivory). Th
ese interactions are characterised by strong relationships between vegetati
on structure and function. Given the heterogeneous structure of savannas, m
odelling appears as a convenient approach to study tree-grass interactions.
Most current models that describe carbon and water fluxes are not spatiall
y explicit, which restricts their ability to simulate plant interactions at
small scales in heterogeneous ecosystems. We present here a new 3D process
-based model called TREEGRASS. The model aims at predicting, in heterogeneo
us tree-grass systems, plant individual radiation, carbon and water fluxes
at a local spatial scale. It is run at a daily time-step over periods rangi
ng from one to a few years. The model includes (i) a 3D mechanistic submode
l simulating radiation and energy (i.e. transpiration) budgets; (ii) a soil
water balance submodel, and (iii) a physiologically based submodel of prim
ary production and leaf area development. The ability of TREEGRASS to predi
ct the seasonal courses of grass dead and leaf mass, soil water content and
light regime as observed in the field has been tested for grassy and shrub
by areas of Lamto savannas (Ivory Coast). Simulations showed that the spati
al distribution of primary production can be strongly affected by the spati
al vegetation structure. Potential applications involve predicting net prim
ary production and water balance from the individual to the ecosystem and f
rom the day to the annual vegetation cycle (e.g. effects of tree spatial pa
tterns on carbon and water fluxes at the ecosystem level). (C) 2000 Elsevie
r Science B.V. All rights reserved.