42 The importance of perennial trees for the balance of northern European agricultural landscapes F. Herzog The environmental, socio- n temperate agricultural land- ate Europe. It consists of fruit-trees that cultural and economic functions scapes, forests as well as trees and are scattered (gestreut in German) on ag- of Streuobst, hedgerows and Ishrubs outside forests are indispen- ricultural land, as also expressed in Spain riparian buffers. sable for maintaining the equilibrium by the term árboles en diseminado. The between the landscape’s productive French and the English terms près ver- and ecosystem regulation functions. gers and “fruit-tree meadows” basically The amount, type and arrangement of designate the same system, but are re- woody perennials on farmland depend stricted to fruit-trees on grassland. The mainly on the farmers’ decisions. But trees, however, can also be underplanted other social groups and the authorities with arable crops. This was common intervene as well, because trees have practice until the early twentieth cen- always attracted public attention. tury. Today, Streuobst most frequently In the twentieth century, trees have occurs on grassland. been increasingly removed from Euro- Typically Streuobst consists of com- pean agricultural landscapes, mainly mon fruit-trees with densities of 20 to because of agricultural mechanization, 100 trees per hectare. Rows of fruit-trees land reallocations and the increasing along streets are also considered a form specialization of farming enterprises. of Streuobst. Fruit-trees in home gar- In recent years, however, enhanced dens, on the other hand, are not, nor are awareness of the functions of trees in intensively managed orchards consist- agricultural landscapes has provoked ing of trees managed exclusively for efforts to conserve them. fruit production. In temperate Europe trees and shrubs The history of Sreuobst started in the in agricultural landscapes occur in a sixteenth century, when fruit-trees were variety of systems including wind- increasingly planted outside home gar- breaks, rows of timber-producing trees dens on open agricultural land. At that (e.g. poplar), trees that produce non- time, market production started to gain wood forest products such as nut-trees importance and fruit was increasingly on agricultural lands (both croplands processed into products that could be and grazing lands) and small blocks of stored, such as cider, must, dried fruits, natural forest retained on farmlands. fruit purée, preserved fruit in syrup and This article focuses on three of the most walnut oil, to name only a few. The mar- prominent systems: Streuobst (fruit- ket demand increased further in the nine- trees scattered on agricultural land), teenth century when the development hedgerows and riparian buffers. The ar- of railways made it possible to sell fresh ticle briefly describes the systems, sum- fruit on a larger scale in urban markets. marizes their history and discusses their Subsistence fruit production has always major environmental, socio-cultural been important as well, particularly in and economic functions. Together, times of war. In Germany, the last large- they help preserve the ecological bal- scale planting activities of Streuobst ance of the landscape, mitigating the fruit-trees took place during and after Felix Herzog prepared this article while working loss of biodiversity and the pollution the Second World War, when the market at the Centre for of ground and surface water caused by provision of fresh fruit was insufficient Environmental Research industrialized farming methods. (Weller et al., 1986). Ltd in Leipzig, Germany. He is currently at the Swiss Market forces and subsistence produc- Federal Research Station STREUOBST tion only partly explain the success of for Agroecology and Streuobst is the most prominent tradi- Streuobst. The political authorities sup- Agriculture in Zurich, Switzerland. tional agroforestry system in temper- ported its development from the begin- Unasylva 200, Vol. 51, 2000 43 ning. For example, decrees and regula- tions linked permission for citizenship or marriage to the obligation to plant a certain number of fruit-trees or mandated the installation of tree nurseries in the villages to provide planting material for farmers. In 1752, Frederick II (the Great) ordered that: “In each village, a cooperative, well-furnished tree nursery must be in- stalled and run by a man trained in the handling and nursing of trees and capa- ble of educating the villagers. In these tree nurseries, an adequate stock of fruit- trees must always be available so that, once all gardens have been planted, the planting can be extended to streets in and near the village. ... If a surplus of fruit is produced, it is to be sold to the cities” FIGURE 1 Landscape in northwestern (translated from Lucke, Silbereisen and Switzerland in the eighteenth Herzberger, 1992). Intellectuals sup- century, with fruit-trees scattered ported Streuobst as well, forming what around the village and on the hillsides (drawing by Emmanuel would be considered today non-govern- ... and at the end of the Büchel) ... mental organizations (NGOs). In the twentieth century (photo), with hillsides still devoted to early nineteenth century, priests, medi- Streuobst cal doctors, chemists and teachers gath- ered in pomological societies (pomology being the science of the growing, storing, processing and mar- keting of fruits) and collected, described and evaluated the numerous existing fruit varieties in order to promote those of particular value (Lott, 1993). Streuobst reached its height in the middle of the twentieth century, when intensive fruit production systems based on dwarf trees began to replace it. Today, most European table fruit stems from intensively managed orchards. Again, this development can be ex- plained by the interaction of market forces and government intervention. National governments and the Euro- pean Union (EU) subsidized the removal F. HERZOG of Streuobst apple, pear and peach trees because the system was no longer considered profitable. In Baden- Württemberg, Germany, for example, Unasylva 200, Vol. 51, 2000 44 the number of Streuobst fruit-trees was often on earth banks (in northern Ger- sedimentation of water bodies from soil reduced from 24 million to 11 million many, for example) or on stone walls (in erosion on adjacent agricultural lands. between 1951 and 1990 (Statistisches calcareous hilly and mountainous re- Bundesamt Wiesbaden, 1954; Maag, gions). They serve as natural fences, ENVIRONMENTAL FUNCTIONS OF 1992). often between pastures and arable TREES IN AGRICULTURAL Today, 11 European countries have fields, and at the same time yield timber LANDSCAPES about 1 million hectares of Streuobst and non-timber tree products such as Modern, industrialized agricultural (Herzog, 1998). A belt of Streuobst fuelwood, small fruits, fodder and herbs production in Europe has boosted food stretches through northern France, for traditional medicine. security, but to a great extent it has done southern Germany and Switzerland to The earliest written documents on so at the expense of the environment. Poland (Figure 1). The share of the agri- hedgerows date from Roman times. For The main environmental problems at- cultural area planted with Streuobst is example, Caesar reported (in De Bello tributable to modern agriculture are the particularly high in hilly areas, where Gallico) that the farmers on the lower loss of biological diversity and the pol- the topography limits the potential of Rhine had established living fences lution of ground and surface waters. more intensive forms of land use. In consisting of trees and thorny shrubs Trees help mitigate these problems. northern Spain, in the French depart- which were cut and shaped in order to ments of Normandy, Lorraine and Alsace, interweave the branches and create Biodiversity in the German federal state of Baden- “walls which often provided such The potential of trees to enhance bio- Württemberg and in parts of Switzerland strong protection that it was impossi- logical diversity in agricultural areas Streuobst covers up to 5.4 percent of the ble either to walk or see through them” can be explained by the numerous agricultural surface (Herzog, 1998). Un- (translated from Speier, 1997). Hedge- physical gradients (for example, dry/ fortunately, statistics on extent of row planting was intensified in the late moist, shaded/sunny) that occur when Streuobst or other systems of trees in ag- Middle Ages, when in many places there trees and annual plants are interspersed. ricultural landscapes are not available was a shortage of wood because of A variety of ecological niches is cre- for many European countries. Similarly, overexploitation of the forests. Hedge- ated which offers a range of habitats for national statistics on trends in coverage rows provided wood and replaced plants and animals with different envi- are generally lacking. wooden fences. Their planting peaked ronmental requirements. in the eighteenth century and then The biodiversity harboured by the HEDGEROWS AND RIPARIAN started to decline. The reduction be- Streuobst system has been widely BUFFERS came particularly marked in the second noted, with emphasis on the frequency Hedgerows and riparian buffers are lin- half of the twentieth century as a result of endangered species (cf. Bünger and ear structures. Hedgerows are rows of of reallocations of agricultural hold- Kölbach, 1995). shrubs or bushes forming a hedge, some- ings to create larger