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© Andreas Bolte
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Institute of

WO Forest Ecosystems


National Forest Condition Survey

Visual assessment of the crown condition as part of the forest condition survey
© Nadine Eickenscheidt
Visual assessment of the crown condition as part of the forest condition survey

How is the forest doing in Germany? The Forest Condition Survey (WZE; Level I monitoring) investigates this question. The nationwide survey takes annually place on an area-representative sample grid in order to assess the vitality condition of forest trees.

Background and Objective

The forest vitality is annually assessed within the Forest Condition Survey (WZE). The crown condition represents the most widely used indicator for the vitality of forest trees. The WZE has taken place in the old West German states since 1984 and in the newly-formed German states since 1990. Since 1 January 2014, the WZE is conducted on the basis of a federal regulation called ForUmV, which is based on National Forest Act (§41a Absatz 6 BWaldG). The nationwide survey is carried out every July and August on a systematic 16 km x 16 km grid (Level I grid) at approx. 10,000 trees and provides representative results for the main tree species at federal level.  Within the German states grid densifications are common. The field work and the first examination of the data are conducted by the states. The survey data of the 16 km grid of the different states are delivered to the Thünen institute of forest ecosystems, joined in the national data base, checked and evaluated. As part of the reporting obligation, the annual results are provided to the Federal Ministry for Food and Agriculture, which publishes the national Forest Condition Report. Moreover, the data are used within the European Forest Monitoring and are annually supplied to the Programme Coordinating Centre (PCC) of ICP Forests.


The crown condition survey is based on the visual assessment of the externally visible condition of single trees. The key parameter of the crown condition survey is defoliation, which is assessed as needle/leaf loss in 5% scores in relation to a reference tree. Additionally, several further parameters that give hints regarding the tree vitality and causes for defoliation are examined. These include fructification, discolouration of leaves and needles, insect and fungi attacks as well as trunk and crown damages.

The survey is conducted according to the internationally harmonised manual of ICP Forests. Measures of quality assurance and quality control have additionally been implemented in order to achieve a methodically consistent data collection within the WZE. The annually conducted national calibration course represents one of the main components of quality assurance. The Thünen institute of forest ecosystems analyses the data of the course and writes a report, which is made available to the participants.

Eichhorn J, Roskams P, Ferretti M, Mues V, Szepesi A & Durrant D (2010): Visual assessment of crown condition and damaging agents. In UNECE (ed.), Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests (pp. 49). Hamburg, Germany: UNECE, ICP Forests Programme Co-ordinating Centre.

Meining S, Bauer A, Dammann I, Gawehn P, Schröck HW & Wendland J (2007). Waldbäume - Bilderserien zur Einschätzung von Kronenverlichtungen bei Waldbäumen (pp. 128). Kassel, Germany: Verlag M FASTE.

Wellbrock et al. (2014): Deutsche Anleitung zur prep.

Links and Downloads


  1. 0

    Knapp N, Wellbrock N, Bielefeldt J, Dühnelt P, Hentschel R (2024) From single trees to country-wide maps: Modeling mortality rates in Germany based on the Crown Condition Survey. Forest Ecol Manag 568:122081, DOI:10.1016/j.foreco.2024.122081

  2. 1

    Knapp N, Danescu A, Dühnelt P, Eickenscheidt N, Keding H, Meining S, Wellbrock N (2023) Leitfaden für den Abstimmungskurs im Rahmen der Inventurleitungstagung zur Waldzustandserhebung. Braunschweig: Johann Heinrich von Thünen-Institut, 16 p, Thünen Working Paper 223, DOI:10.3220/WP1696571355000

  3. 2

    Knapp N (2023) Zustand und Herausforderungen der Wälder. Loccumer Prot 69/2022:13-21

  4. 3

    Bolte A, Block J, Eichhorn J, Sanders TGM, Wellbrock N (2019) Chapter 12: Sustainable use and development of forests and forest soils: A resume. Ecol Stud 237:355-374, DOI:10.1007/978-3-030-15734-0_12

  5. 4

    Mellert KH, Weis W, Grüneberg E, Göttlein A (2018) Schwellenwerte für bodenchemische Präferenz- und Mangelbereiche der forstlichen Hauptbaumarten abgeleitet aus Waldernährungsdaten der BZE II. Waldökol Landschaftsforsch Natursch(17):55-67

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