Die Karte „Ökologische Standorttypen“ 1:750 000 im „Atlas DDR“

Summary

This paper introduces the Ecological Site Type Map (Ökologische Standorttypen, scale 1:750,000) from the second series of publications of the Atlas of the German Democratic Republic (Atlas DDR). This map is dedicated to Professor Martin Schretzenmayr on the occasion of his 60th birthday. Unlike general maps with specific thematic content, this map belongs to a cartographic type characterized by a higher degree of abstraction and stronger model features, aiming to achieve a complex typification in geographical and cartographic terms based on the description of specific individual phenomena. The task of such maps is "to present, in an intuitive manner, complex facts that have been abstractly simplified." The theoretical foundation of this map is the conception of natural space as the "environment" of biological systems (organisms) in a systemic sense. Ecological quality depends on properties that are ecophysiologically relevant, i.e., significant for the life processes of organisms. The "potential supply" of water, energy (light and heat), and nutrients and building materials (including CO₂ and O₂, in addition to mineral nutrients) to plants is understood as a function of the two "determining elements": climate (atmospheric conditions) and soil (pedospheric conditions). The interaction of these ecological growth factors determines the (natural) productivity of a site. Limiting factors present at minimum or supra-optimal levels exert a decisive influence on plant development, stress resistance, and production quality. At the given scale, the three ecological growth factors—water, heat, and mineral nutrients—are most suitable for regional differentiation studies. The light factor, being strongly influenced by terrain (aspect, slope, elevation) and stand structure, cannot be represented within this framework; CO₂ in the air is uniformly sufficient everywhere; and the oxygen supply to plant roots is closely coupled with water supply, as excessive water leads to reduced soil aeration. Methodologically, the study makes full use of existing data: the climate atlas of the GDR region, climate maps from the Atlas, climatic standard values, and supplementary meteorological data; the 1:500,000 soil map of the GDR; and natural vegetation maps at scales of 1:500,000 and 1:150,000. The interpretation of soil mapping units is conducted from two independent perspectives: potential water supply and potential nutrient supply. Climate analysis employs a modified Walter climate diagram method (derived from Gaussen's proposal), utilizing monthly mean temperature and precipitation values to characterize seasonal dynamics and their ecological significance. Based on the degree of limitation in water, heat, and nutrient supply, a classification system for ecological site types is established. Site types with dual limitations (e.g., types 232 and 322) exhibit more unfavorable conditions for agricultural use, manifested in lower yields, reduced reliability of harvests, a narrowed cropping spectrum, and higher additional inputs. Sites at the outer edge of the classification triangle, with the most severe limitations, have at least one ecological growth factor at a minimum level, permitting only limited agricultural cultivation at the cost of high additional inputs, with significant impacts on yield levels, quality, and stability. In extreme cases, both agricultural and forestry use are impossible. The paper concludes that ecologically based site planning in agriculture—combined with knowledge of crop ecological requirements and deliberate regulation through breeding—enables the effective utilization of natural resources. This map provides a basis for determining the regional differentiation of relatively immutable natural production conditions.