Mycorrhizae
  
   
Case studies  

Elwha Dam Removal
A recent study preformed in the pacific northwest relating to the removal of the Elwha Dam explores the use of mycorrhizal inoculation and mulch on the reestablishment of native plants in the sediment created by the damming of the Elwha River. The study established that while mycorrhizal inoculation is not necessary at the smaller scale of the study it would be helpful in the rapid reestablishment of both native plant species and mycorrhizal fungi on the scale of the reservoir.

Initially anaerobic sediments were believed to be low in fertility and lacking in mycorrhizal fungi.
While not all test plots were inoculated, most plants became mycorrhizal due to close proximity to healthy forest ecosystem.
The study shows that a combination of mycorrhizal inoculation and mulch application were the most successful and produced:
Twice the aggregate stability than anaerobic sediment, leading to reduced runoff,
Lowered pH, total Kjedahl nitrogen, and organic matter, and
Lowest ratio of roots to shoots and the highest biomass.

Overall recommendation is that while mycorrhizal inoculation is not necessary on smaller scales, it could be greatly beneficial to the rapid reestablishment and growth of native ecosystems.

  
   
 
Aerial view of Lake Aldwell and Elwha Dam.
Source: http://www.video-monitoring.com/construction/olympic/img/lake_adwell.jpg		  
   
 
Reservoir sediments at the delta of Lake Aldwell, upstream of Elwha Dam, Puget Sound is visible in the distance.
Source: http://www.venturariver.org/2011/09/elwha-river-dam-removal.html		  
   
 
View of the sediments in Lake Aldwell delta.
Source: http://www.video-monitoring.com/construction/olympic/s3latest.jpg		  
   

Figure 4. Plan view and soil profiles of representative plots for each treatment. Clockwise, from upper left: U, unplanted and uninoculated; P + I, plantswith inoculum; P + I + M, plants with inoculum and mulch; and P, planted but uninoculated. Boulder Creek Delta, Elwha River, Washington, May 2007.
  
     
 


Figure 2: Species richness of native and exotic volunteer plant species in experimental plots. Values are means (n = 3); bars represent standard error of the mean. For each plant type (native or exotic) treatments with different letters are significantly different. (U, unplanted and uninoculated; P, planted but uninoculated; P + I, plants with inoculum; P + I + M, plants with inoculum and mulch).
　

  
 


View of sediment erosion.
Source: http://www.venturariver.org/2011/09/elwha-river-dam-removal.html

Kew Gardens
The use of mycorrhizal inoculation delivered via an injection of nitrogen gas in conjunction with other biostimulants and ground mulching has been used at Kew Gardens. The technique, called “terravention”, has been used successfully on mature trees, some of which were planted in the 1760’s. The claims of the treatment are that it reduces soil compaction, aerates soil, and improves drainage. This has become part of a decompaction program for mature trees at Kew.


The Terravent being used to relieve soil compaction around the chestnut-leaved oak.
Source: http://www.kew.org/plants/trees/decompaction.html


Pagoda tree, Sophora japonica that has been treated with Terravention.
Source: http://www.kew.org/plants/trees/styphnolobium-japonicum.html


Oriental Plane (Platanus orientalis), one of Kew’s five ‘old lions’, that has been treated with Terravention.
Source: http://www.kew.org/plants/trees/platanus_orientalis.html