ModMED
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ModMED
Modelling Mediterranean
Ecosystem Dynamics
Abstracts of Selected Publications
Modelling vegetation dynamics in Mediterranean ecosystems: Issues of Scale
Colin J. Legg, Robert I. Muetzelfeldt and Duncan N. Heathfield
Institute of Ecology and Resource Management, The University of Edinburgh
There are rapid changes taking place in the shrub-dominated vegetation of the Mediterranean Basin due to recent abandonment of marginal land. The sudden release from grazing and changes in fire frequency in several countries have resulted in the widespread development of woody vegetation.
The ModMed project is devoted to the prediction of changes to the vegetation of these areas. Successional models are being used to investigate the development of vegetation within the landscape mosaic. The successional patterns are in turn predicted by the modelling of individuals within plant communities under different environments and grazing regimes. The growth of individuals is simulated in terms of physiological processes. A hierarchical modular modelling approach will allow information collected at the level of the individual plants to contribute to the prediction of patterns in the landscape. Some of the practical and theoretical considerations that are raised by this approach will be discussed.
Scale in the Modelling of Vegetation Dynamics
Colin Legg, Robert Muetzelfeldt, Duncan Heathfield and Stefano Mazzoleni
Institute of Ecology and Resource Management, The University of Edinburgh;
Dipartimento di Science Animalia Vegetali e dell'Ambiente, Universita' degli Studi del Molise
Some of the principal problems facing vegetation ecologists include the prediction of patterns of successional change and the way that vegetation responds to environmental disturbances. If we try to address this problem using purely empirical data we are unlikely to succeed in producing more than a local solution. A general model of vegetation dynamics requires an understanding of the underlying mechanisms of vegetation change. General solutions normally require an analysis of processes at a level lower than that at which predictions are required, but may also in some circumstances require an understanding of processes at a higher level. For example, patterns of post-fire succession (the community level) can best be understood by analysis of the growth rates and ecological attributes of the component plants (the individual level). However, some knowledge of the pattern of vegetation at the landscape level may be necessary to understand the occurrence of fire, or the behaviour of grazing animals and their influence on the successional development of vegetation.
Vegetation can be viewed at a range of levels on three main scales: the spatial scale (centimetres to kilometres), the temporal scale (days to centuries) and the organisational scale (individuals to communities). Models of vegetation dynamics differ with respect to the level of their predictive output and the degree to which they use lower-level processes to make predictions at the higher level. The importance of scale in modelling will be discussed in the context of the ModMed project which concerns the dynamics of mediterranean vegetation and responses to changes in grazing patterns and fire frequency. The project aims to produce a model that will have predictive value at the community and landscape levels by representing ecological processes at the individual, community and landscape levels.
Resource allocation patterns of Mediterranean plants: the case of Arbutus andrachne L.
Arianoutsou M. and Kazanis D.
Section of Ecology and Systematics, Faculty of Biology, University of Athens
Abstract Fire is an important ecological factor in the Mediterranean ecosystems inducing fluctuations in the ecological conditions. These fluctuations induce, consequentially, shifts in vegetation dynamics. This can be seen in the modification of phenological behaviour of the woody plants during the first post-fire years. The evaluation of the phenological phases as well as the resource allocation were studied in two populations of Arbutus andrachne L., in a mature and a 13-year-old post Aleppo fire pine forest. According to the obtained results, no significant modifications were observed, something that has been also reported in the literature, when the comparison is performed between intermediate and old post-fire successional stages. However, a slight enhancement of the reproductive organs in the burned stand was observed.
Litter Accumulation In Mediterranean Pinus Halepensis Forests Of Attica
Canella Radea and Margarita Arianoutsou
Section of Ecology and Systematics, Faculty of Biology, University of Athens
The litter accumulated on the soil surface was comparatevily studied in two forests, a regenarating Pinus halepensis forest thirteen years after fire and a mature one, situated on the mountain Parnitha. The quantity, the composition and the structure of the litter layer were quite different in the above forests. This fact can be attributed to both the different age of forests and the local biotic and abiotic environmental factors.
All comments on these pages to:
Colin Legg
Institute of Ecology and Resource Management
The University of Edinburgh
Darwin Building, King's Buildings
Mayfield Road
Edinburgh EH9 3JU
Scotland, UK
Last update: 4/4/2000