Olympic Rebirth
Aleppo pine (Pinus halepensis) is well-adapted to fire as an obligate reseeder (regenerated only by seeds). Because mature trees usually die during the fire, the Aleppo pine's survival depends on the annual production of mature cones and seeds, as well as on the maintenance of a large fraction of the annually produced seeds in closed cones in the canopy. An important parameter for evaluating the potential for natural postfire regeneration of an Aleppo pine forest is the burned stand age, which is directly associated with forest productivity in cones and seeds, respectively. In the burned area of Olympia, the burned Aleppo-pine-stand age varied between 20 and 130 years. The forest was made up of mature trees with a rich canopy seed bank. Post-fire measurements found that the mean density of pine seeds on the ground was 6,780,000 seeds per hectare, enough for natural pine forest regeneration.
Lighting of the Olympic Torch on March 24th, 2009.
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In the burned area, many resprouting plant species (Quercus sp., Pistacia sp., Asparagus sp.) were already present and regenerating as shown in field measurements at the end of September 2007. Aleppo pine seedlings appeared only after the start of the autumn rainy season. By November 2007, pine regeneration was already very satisfactory, with the mean pine seedling density reaching 11.55 seedlings per square meter.
An additional measure had to be taken on some of the steepest slopes — especially on Kronios Hill, where slope gradient exceeded 100% at many locations — to quickly establish a vegetation cover of grasses that would stabilize the soil and contribute to the quick greening of the area. This was achieved by hydroseeding, which is often selected as a priority measure for the protection of inclined slopes from soil erosion. A mix of seeds of selected herbaceous plants, fertilizer, glue, fiber-wood, organic soil improver and water was applied to 21 hectares, generally on the steepest slopes. The mix was applied to a distance of 120 meters and an elevation difference of 90 meters.
In particularly steep slopes (an area of about 3 hectares), a biodegradable geotextile made of jute was used to cover the soil before hydroseeding. In some cases jute matting was applied, even between log erosion barriers. It would retain and protect the soil surface and provide a favorable micro-environment for the plants.
To enhance the resistance of the future forest against fires, increase plant biodiversity, and make the new forest similar in composition and structure to the ancient forest, it was obviously necessary to enrich the natural regeneration of Aleppo pine with artificial planting. This would also serve the need for greening-up the site as much as possible by March for the Olympic Flame lighting ceremony. References to the site of Olympia and its forest by ancient Greek writers were used as guides to the composition and structure of the ancient, mainly oak, forest. Additional broadleaved species were introduced to enrich and partially replace the Aleppo pine forest with mixed stands, which are less flammable.
Planting was planned very carefully. A specific plan for plant establishment was prepared and applied for each hill, taking into consideration the form, color and height of each plant species and, of course, its environmental needs. Scientific personnel of IMFE&FPT oversaw and guided planting works on a daily basis, using 26 different plant species that occur naturally in the broader area. About 37,800 plants were planted, and more than 2,000 individuals of the local aromatic shrubby vegetation were used in the Archaeological Museum's garden.
Two months after the fire, the burned area was filled with wildflowers. The natural regeneration of Aleppo pine, coming up strong, also sent a message of hope that Olympia had already started to recover. In addition, the natural regeneration of evergreen broadleaved shrubs has been highly satisfactory.
The whole restoration effort has been a success. The site was vastly improved visually by March 24, 2008, when the Olympic Flame was lit, and the whole effort received positive comments. In addition, erosion problems — apart from a small land movement on Kronios — were avoided. The effectiveness of the applied treatments was rated qualitatively during a site survey. The rating for contour-felled logs was "excellent" or "good" in 70% of the measurements, while the rating for hydroseeding was 60% "excellent." For the jute matting technique, which had been applied on particularly steep slopes, the rating was 60% "good" or "fair." According to the measurements, none of the treatments was considered "poor."
In regard to the planted species, establishment success was estimated at 95% after the first year with the exception of certain difficult microsites. A few more plants died in the second summer, especially due to competition of grasses that were plentiful after the wet spring of 2009. Such competition was especially strong where hydroseeding had been applied. There, manual grass mowing had to be applied just before the start of the tourist season to reduce competition with planted shrubs and also to reduce the risk of fire.
From the beginning it was recognized that the high risk of erosion in the broader area would affect the success of planting works. Furthermore, the need to irrigate for the next few years and replace plants that did not make it was foreseen and budgeted for. Nevertheless, the aesthetic and functional re-establishment of vegetation will require time. The broader area should be managed as a high-biodiversity spot with the necessary care and cultivation efforts, something clearly justifiable for such an important archaeological site.
IMFE&FPT will monitor the evolution of the restoration until 2012, proposing additional or corrective measures if needed. Additional planting is foreseen for the future, depending on the success of natural regeneration and the survival of planted species. Also, special cultivating care and irrigation of the established and natural regenerated plant species will be needed. The long-term plan also includes fuel treatments for fire hazard reduction. During the first years these treatments will be focused mainly on grasses that dry out in the summer. Later, it is expected that lower branches of young trees will have to be limbed. Depending on the density of regenerating pines and the final survival of planted species, the new stands may also have to be thinned.
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