CONICET | Buscador de Institutos y Recursos Humanos

This years Editors Award, for the paper in the Journal of Vegetation Science that impressed them the most, goes to Barboni et al. (2004): Relationships between plant traits and climate in the Mediterranean region: a pollen data analysis, which correlates the functional traits of plants with the climate in which they are growing. Many vegetation scientists are now interested in describing vegetation by the characteristics of the plants, as a complementary approach to description by taxonomic species (Díaz et al. 2004). This approach allows general patterns to emerge across areas that have largely distinct florae. To date, most correlations have been between functional traits and disturbance regime. The most obvious correlations to seek would be with climate, but climate varies over a broad geographic range, and comparable data on the distribution of species over such a range are difficult to obtain. Barboni et al. (2004) solved this problem by using the modern pollen rain to measure plant distributions. Pollen data are available for many, well-distributed sites, and relative abundance is routinely measured. They obtained data for 455 pollen taxa at 602 sites. Some of the correlations they found document what vegetation scientists would have supposed: trees are more abundant when water is more available, and the needle-leaved and evergreen ones are more abundant in colder climates. However, the absence of climatic correlations within their Mediterranean area for such life forms as mosses and cactoids are interesting. Several other traits did show correlations with temperature and/or moisture, including leaf size, leaf texture, wax on the cuticles and photosynthetic stems. This approach will allow an improvement over previous plant functional type (PFT) approaches, by highlighting the characters that seem to be adaptive in that their distribution is correlated with the climate. that almost all organisms modify their environment. Clements (1916) referred to this as reaction, and Braun-Blanquet (1932) as constructiveness. Animal ecologists have now realised this, and have invented new terms such as niche construction and ecological engineering. [If plant ecologists often ignore excellent work from the early decades of plant ecology (Keddy in press), animal ecologists ignore early plant ecology much more consistently.] If the direction of this environmental change is one that favours the organism that makes it, there is positive feedback a switch between two alternative states (Wilson & Agnew 1992). At least, there should be. Documenting the whole process has proved to be very difficult. George Malanson and his research group have for some time been investigating spatial patterns, ecotones, treelines and the processes that cause them. Now Alftine & Malanson (2004) have brought these ideas together in a spatial model of the alpine treeline. A model is only a hypothesis, and like a hypothesis can never be proved correct. However, Alftine & Malanson demonstrated that their model could produce patterns similar to those observed in the field, and only if a directional feedback mechanism was included, such as shelter by upwind trees strong evidence that feedback is critical to formation of the pattern. Ancient woodland species have been a long-standing puzzle in vegetation science. These are species that are frequent in forests that have never been cleared for other land-uses such as agriculture, but do not appear when a new wood is planted, sometimes staying absent for centuries (Rackham 1990). Do they require some special environmental conditions that are found only in ancient woods? Or would they be perfectly capable of growing in recent woods, but cannot disperse there?

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