LANDSCAPE / Great Dune Ridge / Dune Reinforcement Works

Reinforcement and landscaping of high dunes is one of the key works. Such works were launched at Smiltynė and Kopgalis in 1810. The southern part of the Spit towards Šarkuva was planted by year 1829. The afforestation in Nida was initiated in 1825, and in the littoral plain (palvė) next to Rasytė - in 1843.  Nevertheless, the consistent dune planting works were started only since 1870, when the government of Prussia had been warned by G. Berendt, a geologist, regarding potential adverse effects of uncontrolled dune movement. Urbas and Angių dunes were reinforced and planted in 1875 - 1885, sands near Juodkrantė - in 1881-1900. Stabilization of the area between Preila and Pervalka was started in 1887.



Landscaping of high dunes near Pilkopė (1938).

As F. Mager wrote in 1902, that "yellowish-white Ost-Prussian Sahara" from Smiltynė to Juodkrantė has disappeared, except for the open sand plots at the southern part of this section, <...> little by little the Curonian Spit "is turning dark green characteristic to Juodkrantė forest".

Dune landscaping required lots of expenses. For instance, 1620 Deutsche Marks/1 hectare were spent for planting of drifting dunes at Preila. Work simplification allowed reducing expenses by almost 2,5 times: 690 DM for one hectare reinforcement based on pricing as of 1897-1898. Particularly for the Curonian Spit section owned by Lithuania (approx. 3000 ha planted) 326,050 DM were spent in 1862-1888, and 1,453,000 DM - from 1889 to 1904.



Great dune reinforcement with poles near Pilkopė (1938).

Reinforcement works of drifting dunes appeared to be the most difficult and were carried out on the basis of mixed techniques. The first step was to reinforce the dunes by various mechanical barriers.  Uneven hummocky sand surface was slightly leveled and only afterwards 30-40 cm high reed or tree branch fencing was applied, prior to mechanical barrier arrangement. Such fences were installed alongside and perpendicular to the prevailing winds (in squares). Distance between the fences was 2 - 4 m.: fences were placed at rare intervals in case of smooth slope with low gradient, and at dense intervals - in case of steeper slope.  Afforestation in such stabilized dunes was held in spring. Since such works appeared to be very expensive, some of them were simplified over time and thereby made less costly. Fencing at more rare intervals each 4 m. Application of shortened tree branches 45-50 cm. Space increased between tree branches by 4 times (1:4). Therefore, approx. 120 m3 tree branches were required for 1 ha reinforcement. Moreover, later on such branches were replaced with reeds (only approx. 40 m3 /1ha needed). Dune surface was covered with small twigs to decrease potential deflation and protect sand against overdrying and overheating.

Tree planting areas were strewed with clay and lagoon marl, and mixed with sand, one year in advance. Lagoon sludge excavated by earthmoving machines from Klaipėda Port was applied as a fertilizer for such plants. In order to obtain a crumbled sludge it was stored in piles for one or several years. Such sludge required no mixing with sand, therefore, in autumn, it was just placed into planting holes where sprouts had been planted in spring. 

Several groups of sprouts were planted in each fenced square, 4 sprouts in each group. Groups of sprouts were planted at a distance of one meter from each other, thereby 4 groups of sprouts are planted in 4 m2 (2x2 m), and 9 groups - in 9 m2 square (3x3 m), and etc. Planting material access roads were left every 25-45 m. 

High dry sand dunes were exclusively planted with mountain pine (Pinus Montana Mill.) because the system of pine roots, appropriately developed and situated in surface layers, perfectly stabilizes the moving sand. This mountain pine is known in the Curonian Spit since 1876. The very first sprouts of such pine were delivered from Denmark.



Reinforcement works of Parnidis dune (1954). Photo © KNNP

During World War II, war actions, fire, deforestation, military facilities (trenches, observation points, fortification, and dugout shelter) caused severe damage to the stabilized dunes and reinforced forests in the Curonian Spit. In 1949, the forest and land reclamation expedition arranged by the Ministry of Forestry stated that the Curonian Spit contained over 5000 ha of burnt plants and over 2000 ha of unplanted sands, including more than half of bare and wind-drifted ones. 

The first dune stabilization works in postwar as of 1951-1955 were not very successful.  There was a substantial shortage of local material suitable for planting at that time. Plants delivered from neighboring areas used to adapt very badly, however locally grown sprouts took root for 70-80%. Adaptation was also minified due to delivery of clay loam and peat soil to the planting places in spring just prior to planting, but not since autumn. It used to stick in big lumps and to dry rapidly. This was also contributed by late planting - the only earliest planted sprouts took root, and the others got dried. By that time the planting plans were large in scope and extent, however lacking of experienced and skilled labor force. There was a rush in works and disregard of work quality. Loam clay rather often was not put to the bottom of planting hole but placed at the surface that is subject to drying in summertime. The following mistakes were not avoided: no replanting in the places of solute plants in the planting areas, too small amount of sprouts planted in one hectare, plants too sparse.  The proposals indicated in the expedition project as of 1949 were not taken into account while planting the burnt areas in great haste. The only one kind of trees was planted without any consideration of particular terrain, resulting in favorable conditions for pests.


Reinforcement and planting works of shifting dunes in the Lithuanian part of the Curonian Spit were completed 50 years ago. The major part of dunes is afforested and sand is no longer endangering.

 


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