Age and Inventory Structure of the Forests 2014

Introduction

Because of their multiple functions, the Berlin forests and woodlands are exposed to heavy use pressure. The primary function of the forest is recreational, but it also serves the protection and equalization of the water, soil and climate, and as a habitat for animals and plants. In Berlin, the forest plays a subordinate role in terms of its economic significance. Almost 20 % of the Berlin urban area is covered with forest. Thus, Berlin has a very high share of forest in comparison with Hamburg or Munich, which have 5.7 and 5.1 %, respectively.

A forest is a complex system. Depending on the prevailing soil and climatic conditions, a certain herbaceous layer, a richly structured shrub and tree layer, and the corresponding fauna will have formed. In Berlin, there are today no longer any natural forests. The areas are characterized by centuries of forestry management and by the functions which near-urban forests fulfill today. Depending on stocking conditions and the measures taken, they have developed very differently over the course of the past century. While monocultures are still to be found in most areas; there are many places where appropriate management measures have engendered a situation approaching that of near-natural vegetation.

The natural forest associations occurring under existing local conditions are shown in Map 05.02 – Vegetation. On the other hand, the present Economic Forestry Management Map shows the actual situation of the forest.

With passage of the State Forest Law (LWaldG) in 1979, the entire wooded area of then-West Berlin was proclaimed as protected and recreational forestland, in which recreation was to receive precedence over wood production. Berlin thus adopted a policy unique in the then-Federal Republic of Germany, a policy which took into account the special situation of a city still surrounded by the wall.

In former East Berlin, the precepts for the economic use of the forest were more strict. But here, too, reduced clear-cut limits and exploitation amounts were used, in contrast to the usual procedure in the rest of the GDR.

Since the consolidation of the two forestry administrations in 1990, the State Forestry Law has applied to the entire city. The goal of near-natural and site-appropriate forestry was concretized in the new Forestry Guidelines of 1992. The express goal of these Forestry Guidelines is to gradually develop the entire area of the Berlin forest to a near-natural forest consisting of site-appropriate tree and shrub species. The policy of sustainable forestry was thus extended to include essential conservationist and species protection aspects, as well as factors supporting naturalness and structural wealth.

State of the Health of the Forests

Since the mid-80s, development processes became apparent that were recognised as a serious threat to the long-term stability of forests. Pollution accumulating in the stock and in the ground, particularly from sulfur dioxide (SO₂) and nitrogen oxides (NO_x), led to soil acidification, damage to needles and large-scale dieback of threatened forest stocks. The complex facts and links attracted global attention under the title “Waldsterben” [forest dieback].

The survey of forest conditions [German only] documents forest health in a procedure that is uniform across the country. In Berlin, the development of forest conditions is being observed since 1991 in a uniform sampling raster. The raster density varied in the different years of acquisition; since 2001 the treetop condition of the forest trees is being recorded in a 2 km x 2 km raster at currently 41 sampling points within the state boundaries of Berlin.

Although the emissions of particularly critical substances such as sulfur oxides have dramatically decreased since then, both the historical and the current pollutant input into the ecosystems still play an important role for the state of the forests. The nitrogen inputs still lie above the critical input rates and continue to exhibit an increasing trend. This further exacerbates the soil acidification, and important nutrients such as calcium and magnesium are washed out of the soils with the percolation water. This plays an important role on the predominantly base-poor sites of the Berlin forests. Moreover, the nitrogen input leads to a change in the soil flora with an increase in nitrophilous plants.

Climatic changes also have significant influence on the state of the health of the forests. While it is hard to make concrete statements about the reaction of certain tree species e.g. to changing precipitation values and distribution, it is quite safe to assume that the risk of extreme weather conditions rises with climate warming. The concomitantly increasing risks of forestry need to be taken into account by carefully selecting tree species, selecting suitable origins, checking the suitability of sites and maintaining forest stocks to grow vigorous, stress-tolerant forests. Based on this, Berlin forests are still following the concept of developing, as far as possible, near-natural forest stocks rich in structure and species with indigenous forest and shrub species that exhibit a high resilience towards environmental changes. In this context, it is very important in our region to preserve and increase the humus stocks in order to increase the storage capacity of the forest soils both for water and nutrients.

The progress achieved so far in reducing the contaminant load and in climate protection is not sufficient for sustainably stabilising the forest ecosystems in the region.

From a forestry perspective, pollution control should focus on reducing the nitrogen emissions from agricultural sources in Brandenburg and reducing the emissions of precursors of ozone formation, particularly from traffic-related emissions. Here the metropolitan area Berlin bears a particular responsibility.

Development History of the Berlin Forests up to the 2nd World War

Prior to colonization in the 12th century, the area of that is today Berlin was largely covered with forest. Oak and hornbeam forests were the prevailing forest types on the clayey soils of the plateaus (the Teltow, Barnim and Nauen plateaus), and pine and oak forests on the valley and plateau sands of the glacial spillway and the Grunewald Forest. In locations remote from groundwater, the pine-oak forest occurred in the form of durmast oak-pine forests, in locations near groundwater, in the form of English oak-beech forests or English oak-birch forests with a share of pines. This share was generally below 50 % in the original pine-oak forests, however, so that deciduous trees prevailed. In the river valleys and the flood areas, elm alluvial forests and oak-hornbeam forests grew. The woodland was interrupted only by some mires. Before colonization, the oak-hornbeam and the pine-oak forests each accounted for approx. 45 % of the wooded area, of which only 9 % consisted of pure pine stands. The forests of moist to wet locations thus accounted for only 10 % of the wooded area.

The earliest extensive use of the forest was for forest pasturing. The cattle were driven into the forest and fed on foliage, bark and fruit as well as the seedlings of the young trees. This caused a thinning of the forest, i.e. fewer young trees grew to maturity. The consequence was a changed species composition and the formation of stands of the same age. The colonization and cultivation of the countryside and, with it, the clearing of the forest, began on the most fertile soils, which were transformed into farmland. Thus, the oak-hornbeam forests were displaced on the clayey soils first. The heavy settlement development beginning in the 19th century also led to the build-up of fertile areas of arable land. Additional wooded areas were cleared, so that the forest survived only on the poorest soils, the pine and oak sites, strengthening the dominance of these species.

The constant retreat of the forest was not caused only by direct soil utilization. With the rising population, the need for wood as a raw material and energy source also increased. Mismanagement soon resulted in a wood supply shortage, so that as early as around 1700, the first legal regulations were imposed. The oak receded increasingly in favor of the pine in the Berlin forests, since the latter grew better on soil considerably damaged by forest pasturing, and since the oak was no longer favored as a source of feed. Since the beginning of the 19th century, the primary cause for the growing loss of wooded areas has been real estate speculation. Thus, the Berlin Council determined in 1823, despite furious citizens’ protests, to clear-cut the Cöllnish Heath. By 1875, the city of Berlin had no more public forest property in its possession. In 1890, the Grunewald Forest consisted almost entirely of pine monoculture. At the turn of the century, the State Forestry Administration began to sell large wooded areas of the Grunewald Forest to real-estate speculators; by 1909, some 1,800 ha had been sold (cf. SenStadtUm 1991).

As part of the property acquisition for the extensive establishment of sewage farms, the city acquired the forestry districts of Buch (1898) and Gorin (1909). In order to guarantee the drinking-water supply for the growing population, the Wuhlheide Heath was added in 1910-‘11. In 1911, Berlin and the surrounding communities combined to form the Administrative Association of Greater Berlin. One essential purpose was the acquisition and conservation of large areas which were to be kept free of development. In 1915, the “Permanent Forest Purchase Agreement” was concluded between the Royal Prussian State and the Administrative Association, under which the latter acquired large parts of the forestry districts of Grunewald, Tegel, Köpenick, Grünau and Potsdam (approx. 10,000 ha) from the State of Prussia, and obligated itself not to build upon or to resell the acquired wooded areas, but to preserve them permanently for the citizens as near-urban recreational areas. In order to provide the inhabitants of the populous industrial borough of Wedding with recreational possibilities to the north, the city bought the Lanke Forest area as well. With the establishment of Greater Berlin in 1920, the municipal forests of Spandau and Köpenick as well as the Wansdorf, Carolinenhöhe and Tasdorf woodlands, which had belonged to sewage farms, became the property of the city. Not until after the inflation of the early ’20s could Berlin acquire additional small forest areas in 1928 (e.g. the Düppel Manor and Neu-Kladow). The last large purchase occurred in 1937, with the acquisition of the Stolpe Forest, bordering Tegel. The forest land of the City of Berlin, located both within and outside the city limits, thus covered 25,480 ha at the beginning of World War II (cf. Fig. 1).

Fig. 1: Survey of the City Forests in the Area Surrounding Berlin in 1945

The Berlin forests suffered severe damage during the course of World War II. Between 1937 and 1944, more than twice as much wood was cut “to strengthen raw material supply” in Berlin than would have been sustainable from the point of view of forestry planning – 150,000 solid cubic meters per year (fm/a) instead of 71,000 fm/a. At the same time, the planting of new trees was neglected, and thus the principle of sustainability abandoned (cf. SenStadtUm 1995a). This systematic depletion increased still more during the last two years of the war: For the defense against the advancing Allies, a large number of trees were indiscriminately felled by the Wehrmacht, leaving behind extensive desolation. However, there was also large-scale theft of firewood, both by the Wehrmacht and by the population, which did great damage to the forest (570,000 fm during 1945-‘46).

With the end of the Second World War, a period of separate development of the forests began in the eastern and western parts of the city, as well as in the districts located outside the city.

West Berlin after the 2nd World War

In West Berlin, after the war’s end and the ensuing blockade (1948-‘49), approx. 45 % of the original wooded areas had been cleared and/or greatly thinned. For lack of other plant material, mainly pines were used for the extensive reforestation of the barren areas. This is the reason for the relatively excessive proportion of 50 to 70 year-old pine monocultures existing today.

Since the beginning of the ’50s, the West Berlin forestry assessments have been using the opportunity to transform the forest and taking a step towards a mixed forest by deciduous undergrowth seeding and planting in clearings in open stands of old trees. The goal has been forestry on the basis of a selection forest, and the development of a permanent forest. At the same time, however, such florally foreign tree species as the larch, the Douglas fir, the Weymouth pine and the red oak were also introduced into the inventory by hurst and cluster. The 1979 State Forest Law and the 1982 Basic Forestry Plan for the Berlin Forests were oriented toward naturally compatible management of the Berlin forests. The most important goals of these operational guidelines were:

• an increase in the deciduous share from 40 % to 60 %;
• the promotion of a richly-structured mixed forest;
• the improvement of the conservation and landscape care;
• a 1-ha limit on clear-cutting;
• the adoption of natural rejuvenation;
• and abandonment of the use of herbicides and melioration measures.

East Berlin after the 2nd World War

The forest lands in East Berlin developed differently. The destruction of the old growth had not been as extensive as in the western part of the city. Those trees which, by the end of the war, had surpassed pole-timber age, but not yet reached felling maturity, were not subjected to harvesting during the ’50s to the same extent as in West Berlin. This affects many areas in the districts south of the Müggel Lake. Thus, the old-growth proportion (stocks over 80 years old) was able to grow to 53 % by 1975. In addition, the rotation age has been raised for pines from 100 to 120 since 1975. The result was a deficit in wood production, which was tolerated out of consideration for the recreational function of the Berlin forests. Thus, the Berlin forests assumed a special place in East Germany. They received a recreational function, in addition to their primary role of raw material production. Due to the staged clear-cutting of the pines, wooded areas were characterized predominantly by the structures typical of an age-class forest.

Forestry in East Germany was greatly centralized. This was further intensified during the ’70s. The goals were maximum increase in domestic wood production and the transition to industrial production methods. In the Berlin forests, the following measures were to be carried out:

• removal of all low-production stocks;
• no toleration of afforestation delays;
• fertilization and melioration measures; and
• restoration of a normal age structure (i.e., removal of the high old-growth proportion).

Because of the goal of multiple use of the Berlin forests, these guidelines could be somewhat diluted. The forest was broken down into classes of recreational functions. Maximum allowable clear-cut areas were established. For instance clear-cutting was forbidden at key recreational areas, while in recreational park forests, clear-cutting of up to 3 ha was allowed, compared with the up to 10 ha allowed in normal economic-use forests. In the areas of the former city forests outside the city limits, however, work was carried out according to the guidelines of optimal economic use under the direction of the respective locally responsible state-owned forestry operations.

As early as the ’60s, smoke-damage investigations were carried out in the East Berlin forests, and damage to the trees was ascertained. As a result, a smoke-damage area amounting to 36 % of the total area was certified in 1974 (by 1975, it was already 43 %). For “revitalization,” damaged pine forests were fertilized with nitrates. Between 1977 and the cessation of fertilization in 1985, 100 to 800 kg of nitrogen/ha were spread in the Fahlenberg and Müggelheim Districts.

A major problem in the East Berlin forest is the wide dissemination of chee-reed grass (Calamagrostis epigeios), which complicates natural rejuvenation. Its center of dissemination is found particularly in the relatively clear, single-layer pine stands which are devoid of a shrub layer and are of medium age. The spread was encouraged by the former practice the clear-cutting and complete re-plowing, and the fertilization of the forests.

In the northeast of the city, large former sewage-farm areas were transferred to the Berlin Forestry Operation in 1985 and afforested in connection with the 750-year anniversary festival of the founding of Berlin (1987). This was carried out under heavy deadline pressure and without sufficient preliminary examinations, with the goal of the creation a recreational forest. After grading, the sewage farms were planted predominantly mechanically with over 50 different tree and shrub species, such as poplar, mountain ash, birch, alder, European beech, pine and spruce. The site problems, including heavy-metal pollution, the disturbed soil surface and ground-water conditions, and difficulty in the selection and procurement of suitable seed stock (including decorative trees and shrubs) resulted in unsatisfactory growth results and poor stock vitality (cf. SenStadtUm 1995a).

Current Situation

In 1992, the Berlin Forests published the Forestry Guidelines for Greater Berlin, which brings together the interests of forestry, conservation, recreational use and landscape esthetics to form a uniform concept for action. The orientation is toward careful, sustainable and naturally appropriate forestry. To preserve the climatic, hydrological, hydrochemical and public-health effects of forest areas, extensive measures for the protection and development of near-natural forest structures with rich animal and plant life are carried out in the entire wooded area.

The abundant dissemination of the black cherry, which was introduced about 100 years ago from North America, presents a considerable Berlin-wide problem, since it suppresses natural rejuvenation of florally appropriate tree species and the development of a herbaceous layer. In former West Berlin, it has been increasingly cleared since 1985. For financial reasons, removal measures are currently possible only on limited plots, and they need to be supplemented by the establishment of indigenous tree species through natural rejuvenation or plantation, so that areas once cleared cannot be recolonised.

Wood production, still an important function of modern forestry, in view of Germany’s commitment to measures aimed at binding CO₂ and the policy of increased use of renewable raw materials, is currently subordinated to the State of Berlin’s cultural and social priorities. Nevertheless, the use fulfills not only the function of the provision of wood, but also provides an important large-scale effective method for the attainment of Berlin’s forestry goals with regard for the creation of a mixed deciduous and coniferous woodland with a variegated structure and a large number of species.

The forests emerging in the future should contain a web of all stages of development, from the rejuvenation through the aged phase. Important structural elements, like standing deadwood or glades, should exist in sufficient quantity and quality and be distributed throughout the entire wooded area, and/or should emerge anew. The essential criteria for natural management of the Berlin forest are:

• Gradual reduction of the florally foreign tree species;
• Promotion of site-appropriate and florally appropriate tree species;
• Stock renewal through promotion of natural rejuvenation;
• Promotion of mixed stands with rich structural and species diversity;
• Abandonment of fixed rotation times while preserving and creating permanent forest structures;
• Selective, tree-by-tree wood harvesting;
• Abandonment of clear-cutting;
• Protection of hollows and nest-trees;
• An increase in the proportion of deadwood;
• No complete replowing of areas; and
• Renunciation of fertilizer and pesticides (cf. SenStadtUm 1992).

The Berlin Forests in 1990 applied to the Trust Agency (which managed former East German government property) for the restoration of approx. 13,000 ha of former Berlin city forest land in Brandenburg. The restoration of this area to the ownership of the state Berlin has now been almost completely concluded. The forest areas adjacent to Berlin to the south, in the Ludwigsfelde/ Grossbeeren/ Königs Wusterhausen area, were managed by the Berlin City Properties through January 1st 2002, and were then taken over by the Berlin Forestry Management. Of the total of approx. 29,000 hectares presently managed by the Berlin Forestry Management, approx. 16,500 hectares are within the State of Berlin, and the other approx. 12,500 hectares in the State of Brandenburg. Besides forested areas, the total area includes approx. 3,000 ha open spaces of diverse quality. They comprise water bodies, wet and dry open country areas, power line routes and many other habitats.

Since June 2002, the Berlin forests have been certified according to the criteria of FSC and Naturland. Thus the preservation of strict forestry standards is annually monitored and confirmed by independent third parties.

Present Structure of the Berlin Forestry Agencies

Since 2004 the Berlin forests have consisted of the four Forestry Agencies Grunewald, Tegel, Pankow and Köpenick with a total of 28 forestry districts. Leaving Kyritz aside, they are spread throughout an area extending over 65 km from north to south and 70 km from east to west.

The average size of the areas is approx. 980 hectares.