One of the representative species of this flora, the cypress Cupressus atlantica, is experiencing year by year a decrease in its biomass production and the surface areas it occupies. This species contributes to efforts to control erosion and degradation of forest soils. But it is highly sought after by local communities particularly for the quality of its wood. In addition, the young shoots are subjected to overgrazing (by sheep) which hinders the species’ natural regeneration. Replanting operations have been undertaken, but have proved largely unsuccessful, with nearly 70 % of the young saplings planted dying after the first year.
To counter the threat hanging over this species, a research programme was set up in 2003, jointly between the Cadi Ayyad University of Marrakech, the High Atlas Regional Forestry Directorate and scientists from IRD research unit UR 040 (1). The IRD researchers proposed an original ecological approach, founded on the study of interactions between the cypress, the shrubby plants–lavender and thyme–associated with them and the soil microflora, in order to define new practices for cypress replanting schemes in the Moroccan Atlas.
Cypress develops symbiotically with soil micro-fungi, arbuscular mycorrhizal fungi (2). This association yields mutual benefits, the plant providing sugars for the fungi which in return helps provide the tree’s supply of water and mineral salts, mainly of nitrogen and phosphorus. In controlled mycorrhization glasshouse experiments, the researchers inoculated strains of these fungi, sampled from the study zones in the Moroccan High Atlas, into young nursery plants. There resulted a distinct improvement in the development of these young cypress with inoculated mycorrhizal fungi, which had a higher level of minerals in their leaves (21 % more phosphorus, in particular). Other experiments, conducted in the field, confirmed this result: the fungi favour better nutrition for the young cypress which enables them to build up greater resistance to transplantation-linked hydric stress for when they are adult. Although it is effective, this plant-by-plant inoculation technique remains cumbersome and costly, which limits its large-scale use.
In the cypress stands of the Moroccan High Atlas, several species of lavender and thyme are associated with the trees. These pioneer species, which form sparse clumps of vegetation, are the first to colonize the stony eroded soils of these arid and semi-arid ecosystems. Soil analyses revealed that these species generate islands of fertility, resource islands, rich in nitrogen and phosphorus, as well as in mycorrhizal fungi with which these plants also live in symbiosis. However, what role do they play in the development of young planted cypress saplings?
Lavender and cypress grown together and inoculated with mycorrhizal fungi under glass showed significantly higher growth than when they were cultivated and developed separately. Moreover, the concentration of propagules (3) appeared greater around the lavender roots than around those of cypress and, even more so, than around bare soil (244.5, 179.7 and 7.82 for 100 g of dry soil respectively). Lavender therefore favours the proliferation of mycorrhizal fungi and of their mycelium in the soil. As it reproduces, this “nurse” plant multiplies the number of resource islands generated, which eventually increases the fertility of the whole of the terrain involved. It therefore creates conditions that encourage growth of the planted cypress, stabilizing the soil as it does so by its roots.
Increased understanding of the process of natural regeneration of cypress trees has allowed the application of a new method of replanting of this species in the Moroccan High Atlas. In the sites that must be re-wooded, bands of lavender were planted in strips of earth built up perpendicularly to the slope so as to retain water. The cypress saplings were planted the following year. The first results confirm the beneficial role lavender has on these young plantations: their mortality after one year proves to be very low and soil erosion remains limited.
Research investigations were also conducted on other associations of species, such as cork oak and cysts, or again thujas and lavender. The latter are the subject of a trial conducted by the Rabat Regional Forestry Directorate in areas undergoing reforestation in the North of Morocco.
Marie Guillaume-Signoret - IRD
(1)These investigations were conducted by the IRD, in conjunction with and at the request of Moroccan partners, jointly with the ‘Laboratoire Ecologie and Environnement’ of the Semlalia Faculty of Sciences (Université Cadi Ayyad). The IRD team (UR 040, led by R. Duponnois) belongs to the ‘Laboratoire des symbioses tropicales and méditerranéennes (LSTM)’, UMR 113, which also involves CIRAD, INRA, Agro-Montpellier and the University of Montpellier II. This work takes up the thesis of Lahcen Ouahmane, produced in the team of Prof. Mohamed Hafidi in conjunction with R. Duponnois and which is due to be judged in February 2007 at Marrakech.
(2)Arbuscules are fungal structures that symbiotic fungi form inside the root cells of most cultivated plants and many forest tree species. They are the site of nutritional exchanges between the two partners in the symbiosis. The fungi moreover develop a vast network of mycelial threads in the ground, which acts as a vital interface between the soil and the plant.
(3)In the fungi, these are the groups, of cells that initiate the development of the tubular mycelial threads (a process of asexual reproduction).
Marie Guillaume | alfa
Waste in the water – New purification techniques for healthier aquatic ecosystems
24.07.2018 | Eberhard Karls Universität Tübingen
Plenty of habitat for bears in Europe
24.07.2018 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
08.08.2018 | Event News
27.07.2018 | Event News
25.07.2018 | Event News
17.08.2018 | Materials Sciences
17.08.2018 | Information Technology
17.08.2018 | Physics and Astronomy