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Study Group “Ecological Effects of Climate Change”

Ilex aquifolium L.
  • "ALARM" -
    A
    ssessing Large environmental Risks with tested Methods
  • Distribution, Dispersal, and Boundaries of the Cherry Laurel (Prunus laurocerasus L.) in Germany and Adjoining Areas

  • The European Holly (Ilex aquifolium L.) as a Bioindicator of Climate Change

  • Impact of Global Warming on the Succession Processes and Population Dynamics of the Vegetation in Alpine Altitudes

  • Continuance of the project: Distribution and Boundaries of Laurophyllous Plant Species in Switzerland

The European Holly (Ilex aquifolium L.) as a Bioindicator of Climate Change

The distribution range of many plant and animal species is decisively limited by climate parameters. If the climate changes, territorial shifts in the distribution of the species are to be expected. Conditional for an early recognition of such territorial shifts is historical evidence not only of the distribution boundaries of a certain species, but also the ecologically relevant climate parameters. The European holly (Ilex aquifolium L.) is an exceptional example in this regard, as both conditions mentioned are fulfilled with a high level of details when it comes to this species. Iversen (1944) related the local distribution of the European holly in central and northern Europe to local climate conditions. Since the climate has verifiably changed since that time, a variation in the distribution pattern of the European holly must be assumed. Testing this hypothesis would implicate that not only a possible change in the zonal distribution could be evidenced, but also that this territorial shift could be directly correlated with the climate data measured in the same area. A fact which could hitherto not be proven this way, but which would present significant evidence of a climate-induced territorial shift.


Impact of Global Warming on the Succession Processes and Population Dynamics of the Vegetation in Alpine Altitudes

The temperature rise in the Alpine region recorded during the last three decades amounts to 0.5°C/decade and thus lies over the global average (0.1-0.2°C/decade). Records of Alpine flora are available since the penultimate change of the century and have been reproduced and updated at later events. The resulting time series nearly encompass one whole century. This research projects intends to draw on the database and discuss the following questions:

  • How did the warmest decade (the 1990s) according to climate records affect the Alpine summit flora?

  • How did climate change influence the long-term succession (time intervals: 1919-1930-1973-2003) in an area of isolated rock surrounded by glaciers (nunatak)?

  • What are the consequences of these vegetation-changing effects on the structure, function, and dynamics of the affected ecosystems? To this end, the study will not only include the quantitative changes in the spectrum of plant species (“species richness”), but also qualitative parameters such as autecological and population dynamical characteristics of the species (“functional traits”).

Finalized Projects:

Distribution and Boundaries of Laurophyllous Plants in Switzerland

A great number of exotic indeciduous plant species have begun to grow wild in Swiss lowland forests during the recent decades. Nowadays, there are forest areas in southern Ticino where the undergrowth is dominated by these exotic laurophyllous species.

The study submitted gives an overview of the important xenocoenic species and their migration history. Field experiments permit drawing conclusions on the most important ecological factors controlling the growth of seedlings. In general, the determined trends reveal stronger mesic conditions, the habitat conditions have generally become more humid, richer in nutrients, and darker. Indicative of a change toward warmer climate conditions are both the decline of the montane species and the increase of thermophilic species, the latter being supported by the mentioned appearance of exotic indeciduous plants.

The structure and composition of the forests of southern Switzerland below 600 meters above sea level has markedly changed as a result of the transition from deciduous to indeciduous species. The exotic laurophyllous species have become fully naturalized and have grown to an ecologically relevant factor of the ecosystems affected. The special character of these species and/or groups of species as well as their synchronous introduction into the wild and obviously cumulative emergence within the last decades, suggest the concomitant existence of a changed external ecological factor. The changing climate is becoming a co-decisive factor of this development on two counts: the absolute minimum temperatures and the frequency of frost days have decreased during the study period to such an extent that they have sustainably favored the colonization of the exotic indeciduous species.

Much is still unknown about the situation of numerous neophytes in our flora, this article makes an important contribution to our knowledge about the distribution of laurophyllous species in Switzerland. Certainly, the ZDSF gladly accepts finding reports referring to these and other neophytes in the Swiss flora.” (D.M. Moser et al., 1999).

"Les forestiers ont déjà observé ici et là différents signes du réchauffement climatique, les plus évidents et les plus visibles étant peut-être l'essor des espèces exotiques comme les palmiers et les laurophylles dans certaines forêts tessinoises." (M. Rebetez, 2002).