Valuable Areas for Flora and Fauna 1993
There exists a multitude of criteria which can be used for the appraisal of biotopes. According to region, differences in utilization effect and biotope type, appraisal criteria differ. They are difficult to standardize. Quantification, such as species mapping, is expensive and time-consuming. The data obtained are usually not suitable for exact classification, because there are no generally valid rules to fall back on. By comparison, other elements of the natural household are relatively simple to assess: For instance, a demonstrable pollutant in the air can be classified according to a valid limit as specified in the Air Technical Guideline (TA Luft).
Due to the expense, a targeted field survey is frequently impossible. Therefore, it is necessary to rely on the evaluation of aerial photography. Here, other criteria must be used than for a field survey. The lack of any codification makes great technical knowledge and a wealth of experience necessary on the part of the expert, and accordingly leaves wide scope for subjective judgment.
Given this situation and the assignment to evaluate only the existing conditions, it was necessary, for Berlin, to proceed in the following manner:
The appraisal methodology is based on the 1984 Species Protection Program (Artenschutzprogramm) and the 1992 investigation by PLANTAGE. In the Species Protection Program, 57 biotope types were differentiated for (then still West) Berlin. For the present map, the settlement-characterized and the special biotope types were not considered. In contrast to the Umweltatlas Map of 1985-‘87, the 36 rated biotope types were no longer distinguished according to the criteria natural or cultural, because this distinction did not always appear conclusive: For example, the forest in the Berlin urban area can no longer be considered fully natural. Instead, the biotope types were grouped together in five categories, which are distinguished by color on the map. This makes possible a crude substantial assignment. Over and above this, each area is marked by a number indicating the exact biotope type. The five groups are:
- Biotopes of bodies of water, shorelines and bogs;
- Biotopes of the forests and woodlands,
- Biotopes on farmland,
- Urban vacant area biotopes, and
- Horticulturally-characterized biotopes.
The assignment of the individual biotope types and their value according to the Species Protection Program is shown in Table 1.
The value of the biotope types describes all-inclusively the value potential of a biotope type and makes possible at this level the mutually comparison of the types.
The appraisal of the individual biotopes is accomplished by comparison within a biotope type. The biotope type value is not considered here. The categories are the appraisal levels “valuable biotopes” and “especially valuable biotopes.” Biotopes which, while they have potential, do not attain the classification “valuable” because of their current condition, and/or have no possibilities for development, are not shown here.
If one or several of the following criteria are fulfilled to a high degree, the assignment is to the class “especially valuable.” Accordingly, an average fulfillment of one or several criteria is needed for an assignment to the class “valuable.” In practice, it has been shown during the appraisal that not only one criterion, but rather several were usually fulfilled.
The measure of fulfillment is defined for each criterion differently. In the description of the criteria, this is elucidated by means of examples. All criteria are not requisite for each area. Some are especially suited for the appraisal of a certain biotope type or a biotope type group. Frequently, on the other hand, the few available data do not permit an evaluation on the basis of the relevant criteria. Therefore, a fundamental distinction is made in the appraisal process:
Biotopes on which one or even several expert studies exist are rated according to the criteria a – h. For biotopes on which no sufficient faunal or floral investigations exist, the appraisal results on the basis of aerial photography, information from locally knowledgeable experts, and, in individual cases, on the basis of field observation. Here, correspondingly different criteria needed to be fulfilled (i – l).
Appraisal Criteria for Biotopes with Expert Investigations
a) Species and association diversity
A judgment is made regarding the diversity of species and associations characteristic of the respective biotope type.
The determination of whether high or average species numbers are present and of which organism groups are to be considered depends on area size and biotope type:
For urban vacant areas of approx. 5 ha in size, a figure of approx. 140-150 plant species is an average value. Thus, the 1.2 ha vacant area on Hermsdorfer Strasse in Reinickendorf, for instance, with approx. 180 species, has high diversity. The Südgelände (“southern area”), which likewise has a high species diversity, shows approx. 395 plant species on 70 ha.
For small green spaces of the Biotope Type 29, species numbers of approx. 100 are average, and of 130-140 are high, while for the large parks, which generally extend over 50 ha, a value of approx. 330 species is average. The palace gardens in Charlottenburg have a high value, with 357 plant species on 53 ha, while the Rehberge Park, with 328 species on approx. 70 ha, show medium species diversity.
For pools, small bodies of water and ditches, the number of the amphibians species reproducing there is usually used. For assignment to the class “valuable,” it suffices for at least one species to reproduce a stable population in the body of water. A figure of 6 amphibians species or more is classified as high. If less than 6 species occur in the body of water, it can still be classified as “especially valuable” if the number of individuals of individual species are outstandingly high. The Rohrpfuhl (“reed pool”) in Rudow, for instance, shows very high pointed-nose frog (Rana arvalis) and spade-footed toad (Relobates fuscus) numbers, in addition to which it must be considered that 4 of the 5 species shown are endangered.
In areas inhabited by highly specialized animal and plant species, for instance open vacant areas and gravel quarries, species diversity is not always a suitable criterion. For instance, in the open fallows of the former garbage dumps, only relatively few nesting-bird species occur. Those that do, however, are usually endangered or rare, since open and vegetation-poor areas occur only very rarely in the nature landscape.
b) Proportion of rare and endangered species in viable populations
This criterion is usually coupled with “species diversity.” With high species numbers, the share of Red Data Book species is often also high. This is particularly the case for species-poor organism groups such as amphibians, in which case 10 of the 13 species currently still occurring in Berlin are endangered.
For the ferns and flowering plants, a share of approx. 10% of endangered species in the species inventory is as a rule considered high. The Südgelände, for instance, shows 46 Red Data Book species. That is a share of 11.6%. The palace gardens in Tegel, with 54 endangered plant species, have a share as high as 16.9% of the species inventory.
c) Biogeographic particularity
When viewed in the broader geographical context, range boundaries of certain species can be ascertained in Berlin. Thus, the gray thistle, for instance, has its northernmost occurrence in Central Europe in the Malchow flood-plain. This criterion is either fulfilled or not. A gradation is not possible.
Some species originating from southern Europe can live in Central Europe only in the warmer inner cities. For instance the Adriatic oak occurs in the wild only in isolated spots north of the Alps; on the railroad property between Gleisdreieck and the City Rail Pape Strasse Station, it grows bountiously.
In the bogs, cool-weather species occur which have survived here as relics of the late Ice Age.
d) Old anthropogenic structures
These contribute partially to the conservation of species diversity and/or to the conservation of rare and endangered species, or, at least, to the increase of the association diversity. This is particularly true for elements of the traditional agrarian landscape, such as hedges, ditches, tree-lined avenues, individual trees on the former sewage farm areas in the northeast of Berlin or on the Gatow Fields. There, the old structures are still well preserved, and the criterion is fulfilled to a high degree. If only individual elements are preserved, the criterion is fulfilled to an average degree. This criterion is requisite for biotopes on cultivated land.
“Near-natural” describes the degree of anthropogenic change. In this method, this criterion applies only to the remaining natural landscapes, such as forests, bogs, pools and lakes. Only biotopes with little anthropogenic change are classified as near-natural and thus especially valuable. For instance a lake is rated as highly near-natural if it has an unreinfoced shore and distinctive site-typical vegetation, while if it has partial shoreline reinforcement and/or only partially site-typical vegetation, it is classified as average near-natural. A forest with a layered structure consisting of a grass layer, a shrub layer and a mixed population of domestic tree species with variously-aged individuals is rated high; if it has a single-layer structure and/or non-domestic tree species, or monocultural growth, or strong outside influences due to recreational use, the assignment will be “average near-natural.” All bogs still existing in Berlin are rated as “highly near-natural.”
f) Time-related replaceability
This criterion is requisite only for biotope types in which the single areas are to be classified differently with regard to replaceability. In urban fallows, for instance, there is a difference between areas with pioneer associations and stocks of trees with decades of development. The same is true for forests and wooded areas, which are also classified as more valuable with increasing age of the stock. By contrast, all bogs are irreplaceable in terms of periods relevant to a human life-span.
The following criteria are not value-determining on their own; they are used complementarily, and can effect an increase in evaluation:
Some species require certain minimal area sizes as a requirement for their settlement, for instance birds of prey. Large areas usually have undisturbed core areas; the outer areas serve as buffers. A certain size cannot be determined here however; it differs according to biotope type. The criterion was utilized, for example, at the Karolinenhöhe sewage farms and at the Gatow Fields. For this criterion, no value gradation is provided; it is either fulfilled or not.
Some biotopes are classified only as conditionally valuable because of their characteristics. Since, however, they serve an important function as stepping-stone or connecting biotopes, as buffers for valuable areas or as retreat biotopes in a biotically hostile environment, they have been classed as valuable areas on this map. Thus, areas of arable land in Hellersdorf were classified as valuable despite slight structural diversity, because of their connection to the Kaulsdorf Lakes. Also, valuable areas can be upgraded in their value level if they serve a corresponding function.
Appraisal Criteria for Biotopes without Expert Investigations
Here, too, the fulfillment of one of the criteria suffices for the determination of the value of the respective area. Only the criterion “special plant populations” is not alone value-determining, but rather has a value-increasing effect. The appraisal criteria are:
i) Near-natural shore and water biotopes
The factors rated are the degree reinforcement of banks and beds, and the occurrence of aquatic plants and reeds. These information are taken predominantly from the Map 02.06 “Waterside Ecology “ in the Umweltatlas. Bodies of water with unreinforced, mostly flat banks and well-developed site-typical vegetation are classified as “especially valuable.” Classed as “valuable” are bodies of water with predominantly non-built-up shores, and remainders of site-typical vegetation, or well-developed non-native vegetation.
j) Use and care intensity
Undisturbed or extensively used partial areas occurring within biotope types which are subject to intensive use and frequent care measures. This applies first of all to parks and cemeteries, but also to biotopes on cultivated land. Undisturbed or feral areas tend to harbor the larger biotopes. If an area receives extensive care and/or has feral and undisturbed parts, it is rated as having slight care intensity, and the criterion is fulfilled above average. If only partial areas receive extensive care, medium care intensity is assumed.
k) Structural diversity
Particularly in the eastern part of the city, the evaluation for many vacant areas, biotopes on agricultural land and, to some extent, also parks and cemeteries, occurs on the basis of the diversity of available structural elements and/or vegetation formations. Different vegetation layers could, for example, be ascertained by aerial photography. For these biotope types, high structural diversity offers a point of reference indicating that species and association diversity can potentially also be assumed; it is thus classified as “especially valuable.” An average structural diversity provides the basis for classification as “valuable.”
l) Special plant stocks
The occurrence of particular plant stocks, such as old tree populations (parks, cemeteries), reed-beds (ditches, small bodies of water) and dry meadows (parks, fallows), is the basis for an upgrading in value.
Since the information does not always suffice to rate the biotopes clearly according to individual criteria, several elements are often weighed reciprocally, case-by-case.
The forest presents a special case. In consultation with the forestry commission, each wooded area is classified as at least “valuable,” i.e. all wooded areas, even comparatively non-natural segments, are entered into the map as “valuable.” The reason is that the forests, as large coherent biotopes, offer protective habitats, and can be replaced only over the very long term.
As part of the selective biotope mapping program, areas of statewide significance are charted for the State of Brandenburg. This is based on the uniform map key of the “Biotope Mapping of Brandenburg,” which is in turn based on the map keys developed in East Germany at the end of the eighties. The assignment of valuable areas mapped is accomplished primarily on the basis of phytosociological criteria, which are oriented toward major vegetational units (classes, orders or associations).
The mapping was the responsibility of the subordinate conservation agencies in the counties. After special training course, it was carried out by staff members, Job-Creation Program workers, authorized firms or volunteer conservationists.
By contrast to the Berlin assignment, tree-lined avenues were assigned to the category “biotopes on agricultural land.”
For the classifications of an area as a statewide significant biotope, the following criteria apply:
- occurrence of at least one animal or plant species threatened by extinction;
- occurrence of several endangered animal or plants species with a lower threat degree;
- rare, endangered or especially well-developed and/or especially species-rich plant associations;
- endangered biotopes (Brandenburg state list);
- biotopes which impressively documented historical use forms (such as heaths, orchard meadows, pole-wood stocks, etc.); and
- richly endowed biotopes especially typical for Brandenburg.
The biotopes were mapped according to the three categories “conditionally valuable,” “valuable,” and “very valuable.” “Conditionally valuable” covers biotopes which are mostly small in area, species-poor and/or subject to major impairments. Their significance derives mostly only from their part in the biotope system. The “valuable” biotopes are mostly species-rich and/or especially typical. They provide an important contribution to scenic diversity. Their impairment is slight. Very species-rich biotopes with no or very slight impairments as habitats for endangered species are classified as “very valuable.”
In the map, this differentiation is not shown; rather, all areas have the same color intensity as the “especially valuable areas” within Berlin. This is based on the statement of the state Environmental Agency of Brandenburg that most biotopes mapped in Brandenburg are comparable in quality with the “especially valuable” areas within Berlin, and/or display qualities which no longer occur in Berlin.
Regardless of the present condition, the biotope mapping also covers all biotope types endangered in Brandenburg. The following are counted as endangered biotopes:
- biotopes with an especially high species number of one or more organism groups;
- biotopes characterized by endangered species;
- habitats which are especially rare and/or are becoming rare; and
- biotopes with particular significance for the biotope system (cf. Tab. 2).
For representation of individual biotope types, the following minimal sizes are required:
- for bodies of water, 0.25 ha,
- for meadows and pastureland biotopes, 0.5 ha, and
- for forests, 1 ha.
Linear biotopes, such as hedges and ditches are not shown true-to-scale, biotopes smaller than 0.25 ha are shown as symbols (this is particularly the case for small bodies of water).
Some areas east of Berlin were not covered by the selective biotope mapping of the State of Brandenburg; rather, they had already been mapped during the period 1986-1989, during the preparation of the “Planning Atlas of the Region of the City of Berlin and its Surroundings.” These data were adopted for the state-wide mapping project after appropriate evaluation and adaptation to the mapping key, which had been developed further.
With respect to bodies of water in Brandenburg, unlike the delimitation of Berlin biotopes, the entire water area may have been mapped. This has been done around bodies of water with distinctive reed belts, because it is assumed that, given an undisturbed shore area, the entire water area is also a valuable habitat for birds. For water with partially damaged bank areas, only the valuable bank segments have been shown, as in Berlin.