CHANGES IN FOREST COVER OF SZCZECIN LOWLAND FROM THE 16^TH TO THE END OF THE 20^TH CENTURY, IN RELATION TO SOIL COVER

Paweł Pieńkowski, Marek Podlasiński

ABSTRACT

The area of Szczecin Lowland used to be covered by forests. Only the wetlands, flooded areas and coastal sand dunes were not covered by forest. Changes of the use of land depended mostly on soil texture and hypsometry, which can be seen clearly in case of forests - their largest complexes remained on sandy terraces, outwash plains and terminal moraines.

Key words: historical analysis, landscape, forest cover, Pomerania.

INTRODUCTION

In the past, forest used to cover most of the area of Szczecin Lowland. Only the wetlands, flooded areas and sand dunes along the seashore were not covered by forest. Due to the development of agriculture and spreading settlement, the area of cultivated land grew that of forest fragmentation, which in turn caused several changes of the flora and fauna [8]. The primeval, rather monotonous landscape has become refined and diversified, and consisted of fields, meadows and natural forests as well [6].

Changes of the intensity of land use depended mostly on the soil texture, configuration of the surface, which can be clearly seen in the case of forests the largest patches of which remained on sandy terraces, on outwash plains and terminal moraine. The first large scale thinning of forests in this area occurred during colonisation in the 8^th to 9^th centuries [7]. At the beginning of the 12^th century Slavic settlements were established along better soils, and the terminal moraine and outwash plains were poorly settled [11]. At the time of the second colonisation (14^th to 16^th century) the percentage of forests in the former Szczecin District was about 66%. In 1980 the forest area has shrunk considerably, though some larger forests, like the Puszcza Wkrzańska and Goleniowska have endured, and their area decreased only slightly [7]. The shrinking of forests in Pomerania in the 19^th century was also due to an increased de mand for wool, thus for pastures for sheep. This lasted to about 1870, and the area of forests decreased by a dozen or so percent. After the French-Prussian war (1871) the sheep keeping was abandoned, and the grazing areas were afforested again [9]. After Second World War (WW2), due to economical changes in Poland the area of forests in Szczecin Lowland increased again. It can be assumed that due to subsidies the area of forests will increase, according to the act of Parliament of June 8.2001 about afforestation of agricultural land.

This study aimed at presenting changes of forest areas in Szczecin Lowland from the 16^th to 20^th centuries, considering various soil conditions in that area.

MATERIAL AND METHODS

The area of forests in history was assessed on the basis of utilisation charts by Hartnack [4], scale of 1:1,500,000. This author developed the forest charts basing upon charts: Lubinus 1618, Zierhold 1789, Engelhard 1811. Data from 1930 were taken from the Chart of the German Reich, scale of 1:100,000, and Survey Map of Central Europe, scale of 1:300,000. The condition of forests at the end of the 20^th century was described according to Polish topographic charts, scale of 1:200,000, published by WZK in the nineties, showing the conditions of forests in 1986-1987.

Division of the area into meso-regions based upon physico-geographic regionalization of Poland [5].

The digital map of soil cover based upon soil chart of the scale of 1:500,000, published by Wydawnictwo Geologiczne in 1972. The authors into 10 classes grouped all the existing soil contours. The main criterion of the division was a combination of the soil type and texture. The following soil types were distinguished:

All cartographic materials were warped and registered in the ArcInfo (WGS 84 projection), and later the outlines of forests and soils were digitalized. Using the Idrisi programme the polygons were rastered, and the changes of the forested areas calculated according to soil conditions.

STUDIED AREA

The tested area was of 8040 km². It consisted mainly of Szczecin Lowland, with minor inclusions of Western Pomerania Lakeland (Fig.1, Table 1). The western and northern part of this area is now the Polish border, whereas the southern part is the former border of Pomerania Province (prior to WW2). The eastern border was designed along the 16^th meridian of the east geographic longitude.

The landscape of the studied area had been formed during the last glaciation (Vistulian). Flat and undulating plains of the ground moraine, split by a net of subglacial channels and river valleys are the dominant landscape features. Characteristic of this region are also wide, sandy areas of the Odra flood plain and Pyrzyce ice-dammed basin, filled with silt and clay formations. Lessive and brown earth cover the largest area upon clay and loamy sands (Table 2). These are present mostly in the south, east and north-east part of this region (Fig. 2). In the central and west central part sandy soils are dominant, common particularly on the Odra flood plain. Western Pomerania is characterised by a large area of black earths in the region of Pyrzyce ice-dammed basin, which because of their fertility were deforested rather early [2,3].

RESULTS AND DISCUSSION

Between of the 14^th and 16^th centuries, mainly due to agricultural settlement, forests covered about 55% of the studied area (Table 3). Compact forested areas were present only on the Wkrzańska Plain and the meso-region of Bukowe Hills (Fig.3a). In the lake region, forests covered from 60 to 75%, and the lowest percentage of forests could be found on the Pyrzyce-Stargard Plain (26%). The greatest changes were found on the Pyrzyce- Stargard Plain and the Trzebiatów Coast, the Ińsko and Choszczno Lakeland, where about 80% of the forests present in the 16^th century were destroyed. On the other hand, in the meso-regions that in the 16^th century had the biggest forest areas, their loss was very small, that is from 16.4% in the Bukowe Hills, to 26.5% on the Goleniów Plain. The least decrease of forested area was on the Wolin Island and Uznam Island - 7% (Fig. 3b).

Between 1790 and 1930, on the whole considered area the deforestation percentage was 25.6%, and if compared to the stand of the 16th century, it decreased by 64.6%. The time span from 1930 to 1986 was characterised by increased afforestation - from 19.5% in 1930 to 28% in 1986. The forestation thus exceeded the stand of 1970, though the forested areas were rather scattered. Similar tendencies were found in the Puszcza Kampinowska [1].

The changes described above were caused mostly by the various soil conditions in the regions. Soil conditions in the ground moraine of Szczecin Lowland were the main factor which determined the usage of land. An exception were small areas of diversified hipsometry, such as Bukowe Hills, where quite a large share of forests was found, despite the presence of fertile soils.

Analysis of forestation in connection with soil conditions has shown that as early as in medieval times the forest cover was differentiated according to the soil quality. At that time the least forests were found on soils which developed from lake silt formations, covering black earths (D), brown and lessive soils (BP1, BP2), where the forestation decreased below 25% (Fig.4). On brown and lessive soils which had developed from heavy and medium loams and loamy sands (BP3 and BP4) forests covered 50-55%, and on the poorest podzolic soils (A) forests grew on more than 90% of the area. The area of forests on water dependent soils: peat (T), muck and alluvial soils (M) were about 50%, which was the result of habitat factors, not of human activity.

Soil conditions determined also the irregular decline of the forest areas during the following years. Up to the end of the 18^th century the whole area of black earths (D) was taken for cultivation. On poorer brown and lessive soils remained patches of forest (7-10%). At that time forestation of areas of loamy sands (BP4) and heavy loams (BP3) decreased significantly - one half of forests that had been there in the 16th century disappeared. A similar situation was found on hydrogenic soils, which was related to extensive ameliorations in mid 19^th century, the reason being their rendition to agricultural use [10]. On podzolic soils the area of forests decreased insignificantly.

From 1790 to 1930 the brown and lessive soils developed from silt (BP1) or sandy loams (BP2) had been completely deforested. On the other areas the changes were small, only several percent. An exception was the meso-region of Bukowe Hills which despite its rich soil had in 1930 about 35% of forests (Table 4). This was the result of a rich differentiation of its relief, which in turn allowed taking into agricultural use only the best soils. On brown and lessive soils of that meso-region forests grew on 25% of the area, whereas on the very same soils in the rest of the areas it did not exceed 5%.

The deforestation process was stopped in the 20^th century, after the Second World War, which was caused by afforestation of poor and devastated land. This tendency could be seen particularly on rusty soils (RD1, RD2), where the forestation increased by about 20%, as compared to the stand of 1930. The forest area will probably further increase due to economical subsidies from the Polish State for afforestation of poorest agricultural land.

CONCLUSIONS

Analysis of forestation changes in the Szczecin Lowland, as connected with soil conditions made the following conclusions possible:

1. As early as at the turn of the 14^th and l6^th centuries a distinct differentiation of the Szczecin Lowland forested area, connected with the soil quality could be seen. At that time the lowest percentage of forests (below 25%) grew on soils created from lake silts and clays and sandy loams, these being black earth, brown and lessive soils. On the poorest podzolic soils the forests covered over 90% of the area.

2. During the 15^th to 18^th centuries the area of forests decreased significantly (from 55 to 25%). By the end of the 18^th century all the area of black earths was taken for agricultural use. On brown and lessive soils of lower quality remained some small patches of forests. Sandy soils and heavy loam soils also suffered a decrease of forests, reaching 50% of the stand in the 16^th century.

3. From 1790 to 1930 the brown and lessive soils developed from silt and sandy loams were completely deforested, whereas areas belonging to the other soil groups have not suffered major changes.

4. After the Second World War the forested area increased: from 19.5% up to 28% in 1986. It pertained mainly to areas of rusty soils where the forested area increased by about 20%.

REFERENCES

1. Bojarowski K., Szacherska M. K., 1996, Ocena zmian kompleksów leśnych z wykorzystaniem komputerowego systemu przetwarzania informacji pozyskanych z map XVIII-XX wieku [Evaluation of forest-range alterations using a computer system of management of information collected from maps, 18^th-20^th century]. Konf. Nauk. pt: Kartograficzne Metody Badania Zmian Środowiska, Poznań 25 X 1996, 115-136 [in Polish].

2. Borowiec S., 1961, Zróżnicowanie warunków glebowo-rolniczych obszaru plejstoceńskiego zastoiska wodnego na tle powiatu pyrzyckiego [Differentiation of soil-agricultural conditions on the water sediment origin of Pleistocene period in Pyrzyce county]. Roczniki Nauk Roln. 84-A-4: 613–630 [in Polish].

3. Borowiec S. 1984, Zróżnicowanie przestrzenne ekologicznie ważnych właściwości gleb uprawnych Pomorza Zachodniego a występowanie zbiorowisk chwastów segetalnych [Spatial differentiation of important ecological properties of west Pomerania arable soils and occurrence of segetal weeds communities]. Zeszyty Nauk. AR w Szczecinie 107, Seria Przyr. 34:21-35 [in Polish].

4. Hartnack W. 1934, Wirtschafts- und verkehrsgeographischer Atlas von Pommern. red. W. Witt Ostsee-Druck und – Verlag A. –G. Stettin.1934 [in German]

5. Kondracki J., 2000,. Geografia regionalna Polski [Regional Geography of Poland]. Wydawnictwo Naukowe PWN. Warszawa 2000 [in Polish].

6. Kornaś J., 1972, Wpływ człowieka i jego gospodarki na szatę roślinną Polski [Human impact on Polish flora]. [In:] W. Szafer, K. Zarzycki (red.), Szata roślinna Polskic [Flora of Poland], 1, PWN W-a, 95-128.

7. Mikołajski J. 1966. Geografia województwa szczecińskiego. [Geography of Szczecin Province]. STN, Department of Social Science, Szczecin [in Polish].

8. Loster S., 1991, Różnorodność florystyczne w krajobrazie rolniczym i znaczenie dla niej naturalnych i pół naturalnych zbiorowisk wyspowych [Floristic richness in agricultural landscape and the maintenance of natural and semi-natural island communities]. Fragm. Flor. Geobot. 36(2): 427–457 [in Polish].

9. Łapiński W. 2000, Przyroda i Leśnictwo Pomorza Środkowego [Environment and Forestry in Middle Pomerania]. Wyd. W. Łapiński . Szczecinek 2000 [in Polish].

10. Quast J., Mellentin U., Dannowski R., 1997, Auswertung von Materialien zu den Anlagen der Wasserregulierung im UG 3 und Thesen zum Zukünftigen Umgang mit den noch vorhandenen Anlagen aus hydrologischer Sicht. Institut für Hydrologie des ZALF. Müncheberg 1997 [in German].

11. Ślaski K., Zientara B., 1969, Historia Pomorza: tom 1 do roku 1466 [History of Pomerania: volume 1 to 1466] Wydawnictwo Poznańskie, Poznań [in Polish].

Podlasiński Marek
Department of Soil Erosion and Soil Reclamation
Agricultural University in Szczecin, Poland
71-434 Szczecin ul. Słowackiego 17

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