干旱区生态环境知识资源中心

The temporal and spatial distribution, and the life strategies, of fifteen grass species in a Mediterranean evergreen sclerophyllous formation at Petralona (Chalkidiki, Greece) were studied in order to identify the relationships between species, and among species and the environment, which allows for the coexistence of species.

The grass species were grouped into (i) early annual species that were characterized by early germination and a relatively long growth period; they did not need excessive resources and were distributed over the entire site, (ii) late annuals that were characterized by late germination and a short growth period; they required resources within this limited period and were competitive in capturing them and so were confined to the most productive sites of the site and (iii) perennial grasses that were characterized by early germination and vegetative reproduction; they were tolerant to nutrient shortages and hence maintained their distribution on the site.

The spatial arrangement of species can be considered as a response to the selective pressures of the seasonal water and resource availability in a Mediterranean environment. This environment posed temporal limitations on the activity of early annual and late annual species, which restricts them in time and space. The perennial species overcame this by being flexible in their resource capture and use, because of their ability to store nutrients.