If you need an accessible version of this item please contact JSTOR User Support

Interactions between Vegetation Development and Island Formation in the Alpine River Tagliamento

J. Kollmann, M. Vieli, P. J. Edwards, K. Tockner and J. V. Ward
Applied Vegetation Science
Vol. 2, No. 1, From Basic to Applied Ecology: Vegetation Science for Nature Conservation (May, 1999), pp. 25-36
Published by: Wiley
Stable URL: http://www.jstor.org/stable/1478878
Page Count: 12
  • Download PDF
  • Cite this Item

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If you need an accessible version of this item please contact JSTOR User Support
Interactions between Vegetation Development and Island Formation in the Alpine River Tagliamento
Preview not available

Abstract

Early-successional stages of woody vegetation on gravel bars were studied in an island-braided section of the River Tagliamento in northeastern Italy. We mapped landscape-level changes in the study area (125 ha) by GIS-based analysis of aerial photographs for two time periods (1984-1986, 1986-1991); we surveyed island vegetation, and estimated island age by tree ring analysis. The study area experienced considerable changes between 1984 and 1991 due to at least two major floods in 1987 and 1990. The development of woody vegetation on bars follows three distinct phases: (1) gravel bars plus large woody debris (LWD), (2) pioneer islands, and (3) established islands. Established islands have sections dominated by shrubs of Salix elaeagnos, S. purpurea, S. daphnoides and S. triandra, and tree-dominated sections with Populus nigra. Salix alba and Alnus incana. Large woody debris seems to play a key role for plant colonization on gravel bars. The succession from bars to established islands took about 10 - 20 yr, and the probability of an island being washed away decreased with island age. Erosion produced new LWD which again initiated successional processes in the active zone of the river. Most species were already present in the early-successional stages, although the number of species increased with island development. Established islands were characterized by a distinctive species composition, including an assemblage of species less tolerant of inundation. The results are discussed within the framework of island dynamics and its significance for restoration of early-successional habitats in more regulated rivers.

Page Thumbnails

  • Thumbnail: Page 
25
    25
  • Thumbnail: Page 
26
    26
  • Thumbnail: Page 
27
    27
  • Thumbnail: Page 
28
    28
  • Thumbnail: Page 
29
    29
  • Thumbnail: Page 
30
    30
  • Thumbnail: Page 
31
    31
  • Thumbnail: Page 
32
    32
  • Thumbnail: Page 
33
    33
  • Thumbnail: Page 
34
    34
  • Thumbnail: Page 
35
    35
  • Thumbnail: Page 
36
    36