CURVULA

The alpine sedge Carex curvula (Cyperaceae) is one of the dominant species of the alpine meadows of the Alps, the Carpathians, the Pyrenees and some of the highest Balkan summits. The Carex curvula-dominated plant communities are one of the first species assemblage described by geobotanists in the European mountains. Over the last 10 years, Mihai Puscas and I have been tracking the evolutionary ecology of this emblematic alpine species as well as the species assemblages in which it is dominant.

1. Using molecular markers (AFLP and cpDNA), we attempted to identify the ice-age refugia and the postglacial recolonization routes followed by the species. The genotyping of around 500 individuals from more than 100 populations sampled throughout the species distribution range has been achieved.

2. We compared the impact of Quaternary ice periods on two levels of diversity : the genetic diversity of Carex curvula poplations and the species richness of alpine grasslands dominated by Carex curvula.

3. We collated and analyzed the largest European data base of vegetation relevés in which Carex curvula was recorded with a high abundance (the data base comprises 850 relevés of the so-called "Caricetum curvulae")

4. More recently, we attempted to model the climate enveloppe of Carex curvula to reconstruct the past, present and future distribution of the species in response to climate changes (in coll. with W. Thuiller).

Climate enveloppe of European alpine grasslands

The following climate enveloppes for the European Alpine System (ESA) are derived from Wordclim 30". Monthly mean temperatures were interpolated to get daily means. Daily values above 0°C were summed to estimate yearly values of Growing Degree Days for each pixel (GDDy)

GDDy below 1800 gives a fair estimate of alpine and nival zones. GDDy below 3000 is a reasonable mask for alpine species niche modelling.

Given a 200 day-long growing season length, an increase of 2.5° means an increase of 500 GDDy. Accordingly, GDDy mapping in the range 1500-3000 possibly illustrates scenarios of downward shifts of the high elevational zones during cold ages.

  
  
From top left to bottom right: (i) GDDy < 3000; (ii) GDDy < 1800; (iii) 1800 < GDDy < 2400; (iv) 2400 < GDDy < 3000

Note the

  • the limited areas suitable for alpine species during cold ages in the Southern ranges (iii)
  • Eastern Alps, Carpathians and the low mountains of Northern Austria and Czech republic as likely thermal refugees for alpine plants
  • the corridor between the cold steppes from Ukraine and temperate mountains (iii)