[MCN] Dead wood --> living streams and rivers

[Lance Olsen]

Journal of Applied Ecology 2007 44, 1145-1155
© 2007 British Ecological Society

The use of large wood in stream restoration: 
experiences from 50 projects in Germany and 
Austria

JOCHEM KAIL, DANIEL HERING, SUSANNE MUHAR, MARC GERHARD and SABINE PREIS

Summary

1.Wood is increasingly used in restoration 
projects to improve the hydromorphological and 
ecological status of streams and rivers. However, 
despite their growing importance, only a few of 
these projects are described in the open 
literature. To aid practitioners, we conducted a 
postal mail survey to summarize the experiences 
gained in central Europe and compile data on 50 
projects.

2.Our results indicated the potential for 
improvement from an ecological point of view, as 
the number and total wood volume, and the median 
volume of single wood structures placed in the 
streams per project, were low compared with the 
potential natural state. Moreover, many wood 
structures were placed nearly parallel to the 
water flow, reducing their beneficial effect on 
stream hydraulics and morphology.

3. Restoration success has been monitored in only 
58% of the projects. General conclusions drawn 
include the following. (i) The potential effects 
of wood placement must be evaluated within a 
watershed and reach-scale context. (ii) Wood 
measures are most successful if they mimic 
natural wood. (iii) Effects of wood structures on 
stream morphology are strongly dependent on 
conditions such as stream size and hydrology. 
(iv) Wood placement has positive effects on 
several fish species. (v) Most projects revealed 
a rapid improvement of the hydromorphological 
status.

4.Most of the wood structures have been fixed, 
called 'hard engineering'. However, soft 
engineering methods (use of non-fixed wood 
structures) are known to result in more natural 
channel features for individual stream types, 
sizes and sites, and are significantly more 
cost-effective.

5.Synthesis and applications. Large wood has been 
used successfully in several projects in central 
Europe, predominantly to increase the general 
structural complexity using fixed wood 
structures. Our results recommend the use of less 
costly soft engineering techniques (non-fixed 
wood structures), higher amounts of wood, larger 
wood structures and improved monitoring 
programmes for future restoration projects 
comparable with those in this study. We recommend 
the use of 'passive restoration' methods 
(restoring the process of wood recruitment on 
large scales) rather than 'active restoration' 
(placement of wood structures on a reach scale), 
as passive restoration avoids the risk of 
non-natural amounts or diversity of wood loading 
developing within streams. Local, active 
placement of wood structures must be considered 
as an interim measure until passive restoration 
methods have increased recruitment sufficiently.

Key-words: alpine streams, lowland streams, 
monitoring, mountain streams, passive 
restoration, restoration success, 
soft-engineering, woody debris

Journal of Applied Ecology (2007) 44, 1145-1155 
doi: 10.1111/j.1365-2664.2007.01401.x
Correspondence: Jochem Kail, University of 
Duisburg-Essen, Department of Hydrobiology, 
D-45117 Essen, Germany
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===============================================================================
"Limiting atmospheric carbon dioxide (CO2) 
concentrations to low levels requires strategies 
to manage anthropogenic carbon emissions from 
terrestrial systems as well as fossil fuel and 
industrial sources."

Marshall Wise, et al. Implications of Limiting 
CO2 Concentrations for Land Use and Energy. 
Science 324, 1183 (2009); DOI: 
10.1126/science.1168475
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