Link zu WSL Hauptseite Swiss Federal Institute for Forest, Snow and Landscape Research WSL
 
Duration: 2008 - 2011

Plants and mycorrhizal fungi in wind erosion control

In many dry areas around the world, wind erosion gradually converts fertile land into deserts. Wind tunnel and laboratory experiments are conducted to investigate how plants and mycorrhizal fungi protect the soil from wind erosion.

Sanddünen
Sand dunes immediately beside human settlings on the Tibetan Plateau.


Wind erosion is the process by which soil is detached from the ground surface and transported by wind. All over the world, wind erosion causes huge annual soil losses and promotes the formation and spreading of deserts, thereby posing a threat to the livelihood of numerous people. Furthermore, wind erosion increases the content of mineral fine dust in the atmosphere. High concentrations of fine dust cause lung diseases and change the global radiation balance, which affects the earth’s climate.


Wind erosion control

Revegetation

Revegetation of degraded soils is regarded the most effective strategy against wind erosion. Plants provide both above- and below-ground protection by sheltering the soil from the erosive force of the wind and stabilising it with their roots, respectively. However, the conditions on eroded soils are adverse to plant growth. Hence, revegetation measures are often confronted with major difficulties.

Mycorrhizal fungi

One way of improving plant growth on degraded soils is to add mycorrhizal fungi to the soil when seeding or planting. Almost all plants live in symbiosis with mycorrhizal fungi, which help them uptake nutrients and water. On degraded soil, there often exists a lack of mycorrhizal fungi. Therefore, the artificial introduction of mycorrhizal fungi promises to substantially improve revegetation success. Besides their beneficial effect on plant growth, mycorrhizal fungi improve soil structure and stability with their vast underground network of fungal strands (hyphae).

Pilzkarikatur

Mycorrhizal fungi provide a twofold benefit in wind erosion control: On the one hand, they improve plant growth, and on the other hand, they stabilize the soil (drawings of fungi: V. Graf).

Investigations

How do plants influence wind erosion processes?

In a 20 m long wind tunnel, we conduct experiments with grass canopies of different planting densities. In contrast to other wind tunnel studies, living grasses (Lolium perenne) are used instead of artificial imitations of vegetation.

At the end of the test section, a sediment sampler is positioned to trap airborne sand grains at different heights during the experiment. Furthermore, we measure the fine dust concentration in the air above the test section. Colored quartz sand is used to visualize erosion and deposition patterns.

First results show that wind erosion processes decrease with increasing vegetation cover. A vegetation cover of only 15% decreased soil loss to 7% and fine dust emission to 50%. A vegetation cover of 55% inhibited these processes almost completely.

planting densities in wind tunnel

Test section (8 m) in the wind tunnel unplanted and with vegetation covers of 3%, 15% and 55% (from left to right).


Split_sedimentsammler_farbiger Sand

Sediment sampler in the wind tunnel (left) and accumulations of red quartz sand (right).


Do mycorrhizal fungi improve plant growth on desert-like soils?

In this study, the adverse soil and climate conditions of deserts are simulated in a climate chamber. We cultivate various grass species on sandy, nutrient-poor substrates and water them only rarely. Half of the grasses are provided with mycorrhizal fungi in the substrate, the other half not. Thus, it is possible to test whether mycorrhizal fungi improve survival rate, above-ground biomass production and health of the grasses.

Do mycorrhizal fungi improve soil resistance to wind erosion?

This study combines the two previous questions. Erosion processes are investigated in three soil treatments:

a) unplanted soil

b) soil planted with grasses (without mycorrhizal fungi)

c) soil planted with grasses and inoculated with mycorrhizal fungi.

In the wind tunnel, all treatments are subjected to the same wind force. Afterward, we compare the soil losses and fine dust concentrations. It is assumed that soil erosion rate and fine dust emission is lowest in the planted and inoculated soil. If experiments confirm this hypothesis, this will be a strong argument to promote the use of mycorrhizal fungi in wind erosion control.

Contact

Participants

Link: Wind tunnel facility

 

Spacer