Humboldt-Universität zu Berlin - Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences


Seit Januar 1998 werden als interne Reihe die "Agrarmeteorologischen Schriften" publiziert. In den Heften werden vorwiegend aktuelle Forschungsergebnisse veröffentlicht, die als preprint zu verstehen sind.


Bisher sind folgende Hefte erschienen.

Heft 01:

F.-M. Chmielewski (1998):
Gebiete der Angewandten Meteorologie
-unter besonderer Berücksichtigung der Agrar- und Medizinmeteorologie

Heft 02:

G. Hörmann, F.-M. Chmielewski (1998):
Mögliche Auswirkungen einer globalen Klimaänderung auf die Land- und Forstwirtschaft

The chapter summarizes the effects of climate change on agriculture and forestry with a main focus on temperate regions and Germany. It starts with an overview of agriculture as a producer of trace gases, especially of methane from animal production and rice paddies and N2O from soils. The next chapter gives a short introduction to the fundamental relations between phenology and yield of  crops and temperature and CO2-concentration of the atmosphere. Based on these concepts, we discuss the results of simulations for main field crops in Europe. While temperate regions may even profit from global change, the food security in developing countries may get lower. Combined with conflicts about limited water, this effects on agriculture may seriously aggravate already critical situations in many parts of the world. Finally, the state of  the art of the potential development of forests as a sink and source of trace gases is presented.

Heft 03:

F.-M. Chmielewski, W. Köhn (1998):
The agrometeorological field experiment at Berlin-Dahlem - a description

In order to investigate the relationships between atmospheric influences and crop yields, long-term observations of meteorological and agronomic parameters are necessary. The agrometeorological field experiment at Berlin-Dahlem (Germany), which was established in autumn 1953 by E. Tamm, is a unique basis for such studies. The original aim of this experiment was to show how the variability of weather affects the growth, development and yield formation of different crops.

On eight plots potatoes, winter rye, field beans, oats, sugar beet, maize, spring barley, and yellow lupines are grown as a permanent crop rotation. The crop management from year to year is nearly unchanged so that the annual variability of crop yield is alone the result of climatic fluctuations. Now, after more than 45 years of intensive and comprehensive observations the results of the experiment will be presented. In this paper the long-term experiment is described and the observed crop yields are shortly discussed. In following investigations it is planed to analyse the relationships between atmospheric influences and crop yields for the spring and winter cereal, the root crops and the legumes in detail. This knowledge can help to understand better the yield formation with respect to climatic fluctuations and hereby the causes for the annual yield variability. It also allows to evaluate possible impacts of climatic changes on different crops which are grown in the north-eastern territory of Germany.

Heft 04:

F.-M. Chmielewski, W. Köhn (1998):
The impact of weather on the yield formation of spring cereals

This investigation examines the relationships between atmospheric influences and the grain yield of spring cereals (spring barley, oats). Over and above that the three yield components crop density (ears/panicles m-2), number of kernels per ear/panicle and thousand kernel weight are also considered. The study uses the data of a long-term field experiment at Berlin-Dahlem in the period 1962-1996.

The results show that the grain yields as well as the formation and differentiation of yield parameters are clearly influenced by weather fluctuations. Altogether it was possible to explain nearly 60 % of the grain yield variability by meteorological variables for both species. First of all the weather conditions in May and June are important for the annual grain yield. The yield components are clearly influenced by weather in different months: the crop density first of all in June during the period of tiller reduction, the number of kernels per ear/panicle in May in the period of spikelet formation and development and finally the thousand kernel weight in June and July in the period of grain filling. Grain yields of spring barley are mainly influenced by the crop density and the number of kernels per ear, for the grain yield of oats the most important component is the kernel number per panicle which depends highly on the weather conditions in May.
Negative atmospheric influences on yield formation in one month (mostly high temperatures, insufficient precipitation combined with a high potential evapotranspiration and a low relative humidity) can be partially compensated by favourable humid weather conditions in other months. Warm and dry weather from May to July leads with a high probability to a disastrous harvest. A concrete example is the dry and hot summer in 1976 and 1992. On the other hand weather conditions with moderate temperatures and a low potential evapotranspiration, with a high air humidity and a good water supply during the whole growth period (April through July) is favourable for all yield components and leads to maximum yield (for example in 1996).

Heft 05:

F.-M. Chmielewski, W. Köhn (1999):
Impact of weather on yield components of winter rye over 30 years

This study examines the relationships between atmospheric influences and grain yields as well as yield components: crop density (ears m-2), number of kernels per ear and kernel weight of winter rye. The study uses data of a long-term field experiment at Berlin-Dahlem for the period between 1962 and 1996.

The crop density and kernel number of winter rye were positively influenced by warm and sunny weather in autumn. An early start of the growing season after winter was also important for satisfactory development of these components. Moderate temperatures prior to the beginning of shooting prolonged the period of spikelet formation and led to an increased number of spikelets and finally to a high number of kernels per ear. The kernel weight was negatively influenced by high temperatures and drought during the ripening stage. This weather situation reduced the duration of the grain filling period and thus the kernel weight.

The yield of winter rye increased continuously from the mid of the eighties as a result of a higher crop density and kernel number. Probably this is a positive climate change effect. Particularly the higher temperatures in winter time and an earlier beginning of the growing season seem to be favourable in this context.

Heft 06: pdf-file

Th. Rötzer, F.-M. Chmielewski (2000):
Phenological Maps of Europe

The geographical distribution of the timings of phenological phases are a precondition for detecting regional trends of the annual timings of phenological phases and finding their relationships to climate changes. Therefore phenological maps of Europe were computed showing long-term means, trends and annual timings of extreme years. In this study maps of the beginning, the end and the length of the growing season as means over the years 1961 to 1998 as well as for the warm year 1990 are presented. Strong dependences on altitude, longitude and latitude were computed both for single phenological phases and the end resp. the beginning of growing season. The goodness of fit for the regression equation was between 32% for the end and 83% for the beginning of growing season. A high conformity was found with the results of similar investigations.

Heft 07: pdf-file

F.-M. Chmielewski, Th. Rötzer (2000):
Phenological trends in Europe in relation to climatic changes

A nearly Europe-wide warming in the early spring (February to April) over the last 30 years (1969-1998) led to an earlier beginning of growing season by eight days. The observed trends in the onset of spring corresponded well with changes in air temperature and circulation (NAO-index) across Europe. In late winter and early spring the positive phase of NAO increased clearly, leading to prevailing westerly winds and thus to higher temperatures in the period February to April. Since the end of the 80s the changes in circulation, air temperature and the beginning of spring time were striking.

The investigation showed that a warming in the early spring (February to April) by 1°C causes an advanced beginning of growing season of 7 days. The observed extension of growing season was mainly the result of an earlier onset of spring. An increase of mean annual air temperature by 1°C led to an extension of 5 days.

Heft 08: pdf-file

F.-M. Chmielewski, Th. Rötzer (2000):
Annual and spatial variability of the beginning of growing season in Europe in relation to air temperature changes

To investigate the annual and spatial variability in the beginning of growing season across Europe, phenological data of the International Phenological Gardens for the period 1969-1998 were used. The beginning of growing season was defined as an average leaf unfolding index of four tree species (Betula pubescens, Prunus avium, Sorbus aucuparia and Ribes alpinum).

The study shows significant changes in the mean air temperatures from February to April and in the average beginning of growing season in Europe since 1989. In the last decade the mean temperature in early spring increased by 0.8 °C. As a result the average beginning of growing season advanced by 8 days. Between 1989 and 1998 eight out of ten years tend towards an earlier onset of spring. The absolutely earliest date was observed in 1990.
The relationships between air temperature and the beginning of growing season across Europe were investigated by canonical correlation analysis (CCA). The spatial variability of both fields can be described by three pairs of CCA-pattern. The first pattern, which explains most of the variance, shows a uniform structure with above resp. below normal temperatures in whole Europe and consequently an advanced resp. delayed beginning of growing season. The next two patterns show regional differences in the anomaly fields. Whereas the second CCA-pattern has a meridional structure, the third pattern shows a zonal distribution. In all cases the anomalies of  the regional air temperature and of the beginning of growing season correspond very well. The correlation coefficients between the anomaly fields range between 0.90 and 0.66. For all patterns appropriate examples in the observed data were found.

Heft 09: pdf-file

F.-M. Chmielewski (2001):
Rezente Veränderungen der Lufttemperatur und der Niederschlagshöhe in Berlin-Dahlem (Albrecht-Thaer-Weg)

Die Auswertungen der Dahlemer Klimabeobachtungen am Albrech-Thaer-Weg zeigen, daß sich klimatische Veränderungen am Standort vor allem bei den thermischen Größen und jahreszeitlich am deutlichsten im Winter nachweisen lassen. Hierfür spricht sowohl die signifikante Zunahme der Lufttemperatur im Winter als auch die Abnahme der winterlichen Kältesumme und jährlichen Anzahl von Frosttagen sowie die markante Verfrühung des Vegetationsbeginns. Diese Veränderungen im zeitlichen Verlauf der Klimaelemente korrespondieren mit Schwankungen der Zirkulation über Europa, die ebenfalls für die Wintermonate nachgewiesen werden konnten (Schubert und Hupfer, 1992; Gerstengarbe et al., 2000; Schönwiese und Hupfer, 2001; Chmielewski und Rötzer, 2001).
Sehr markant ist die Zunahme der Minimumtemperatur, die am Standort in allen Jahreszeiten auftritt. Der stärkere Anstieg der Minimum- gegenüber den Maximumtemperaturen der Luft ist für viele Klimastationen der mittleren und höheren Breiten belegt (Houghton et al., 2001). Die gute Korrelation der Berliner Temperaturreihe mit der Reihe für Deutschland (Rapp, 2000) legt nahe, daß die am Standort beobachteten Klimavariationen nur in relativ geringem Umfang auf lokale bzw. stadtklimatische Effekte zurückzuführen sind.

Heft 10: pdf-file

F.-M. Chmielewski, A. Müller, E. Bruns (2002):
Climate changes and trends in phenology of fruit trees and field crops in germany, 1961-2000

In mid- and high latitudes the plant development is mainly driven by air temperature. The higher the temperature after the release of dormancy the earlier the pheno-phases, usually appear in spring. Distinct changes in air temperature since the end of the 1980s led to clear responses in plant phenology in many parts of the world.

In Germany phenological phases of the natural vegetation as well as of fruit trees and field crops have advanced clearly in the last decade of the 20th century. The strongest shift in plant development occurred in the very early spring phases. The late spring phases and summer phases reacted also to the increased temperatures, but they usually show lower trends.

While an extended growing season could have some positive effects for agriculture and horticulture, the shift of individual phenophases of crops and fruit trees is to be evaluated differently. For example, the advanced blossom of fruit trees can increase the risk of late-frost damages. For field crops a shortening of developmental periods can also affect yield forming processes. Until now the changes in plant development are still moderate, so that no strong im-pacts on crop yields were observed. But further climate changes will probably in-crease the effect on plants, so that in the future stronger impacts on crop yields are likely.

Heft 11: pdf-file

U. Wittchen, F.-M. Chmielewski (2003):
Das Mikroklima in Winterroggen-Beständen

Die Studie beschreibt das Mikroklima eines Winterroggen-Bestandes (Bestandeskli-ma) im Vergleich zu einer vegetationslosen Basisstation. Betrachtet werden Lufttem-peratur und Luftfeuchte. Grundlage der Beschreibung sind langjährige Messungen (1981 bis 1999) in 0,2 m Höhe auf dem Versuchsfeld der Landwirtschaftlich-Gärtnerischen Fakultät der Humboldt-Universität zu Berlin.

Die Studie zeigt, dass das Bestandesklima vom Entwicklungsstadium der Pflanzen (BBCH-Stadium ) sowie von meteorologischen und pflanzenmorphologischen Bedin-gungen bestimmt wird. In Abhängigkeit vom Entwicklungsstadium der Pflanzen vari-ieren sowohl die Stärke des Einflusses meteorologischer und pflanzenmorphologi-scher Parameter auf das Bestandesklima als auch die Parameter selbst. Daraus folgt eine unterschiedliche Erwärmung und Abkühlung des Bestandes sowohl im Tages-verlauf als auch innerhalb der Vegetationszeit.

Grundsätzlich ist der Winterroggen-Bestand zwischen 7 und 15 Uhr wärmer als die Basisstation. Bei Sonnenhöchststand erwärmt sich der Bestand am stärksten. Die wesentlichste Einflussgröße ist die Intensität der Globalstrahlung. Die höchsten Temperaturdifferenzen im Vergleich zur vegetationslosen Basisstation werden unmit-telbar vor der Ernte gemessen; die maximalen Stundenwerte betragen +9 K. Die stärkste Abkühlung des Pflanzenbestandes gegenüber der vegetationslosen Basis-station erfolgt in den späten Abend- und den frühen Morgenstunden. Ein hoher Blatt-flächenindex  verstärkt diesen Effekt. Die extremen Stundenwerte betragen –6 K.

Beginnend mit der Entwicklung des Fahnenblattes erhöht sich die Luftfeuchte inner-halb des Winterroggen-Bestandes deutlich. Die stärkste Feuchtezunahme ist kurz nach Sonnenaufgang zwischen 5 und 7 Uhr zu verzeichnen. Die Maxima der Feuch-tedifferenzen zwischen Pflanzenbestand und Basisstation werden bei hohem Blatt-flächenindex erreicht. Die extremen  Stundenwerte überschreiten +6 hPa Dampf-druck bzw. +30 % relativer Luftfeuchte. Mit lichter werdendem Bestand verringert sich dessen Luftfeuchte. Mit Erreichen der Gelbreife werden in den Mittagsstunden im Bestand teilweise geringere Werte der relativen Luftfeuchte gemessen.

Heft 12: pdf-file

F.-M. Chmielewski (2003):
Phenology and Agriculture

This chapter deals with both traditional aspects of phenology in agriculture (length of growing season and different applications of phenological data in agriculture) as well as modern aspects which focus on impacts of climate change on phenophases of filed crops and fruit trees.

Generally, phenology has a long tradition in agriculture and horticulture. The knowl-edge of the annual timing of phenophases and their variability can help to improve the crop management which leads finally to higher and more stable crop yields and to an improved food quality. Phenological observations are essential for many aspects in practical agriculture. The data can be used to define the length of growing season in a region. On the basis of the available time in the year, cropping schedules can be developed which include suitable crops and varieties, the organization of crop rota-tion and catch cropping. Phenological observations also play an important role in the following processes that are relevant in practical agriculture as the timing of irrigation, fertilization and crop protection. The data are also necessary to evaluate the risk of frost damages and to make forecast of plant development and harvest dates.  In agrometeorological studies phenological data are used to analyse crop-weather rela-tionships and to describe or model the phytoclimate. The individual sections of this chapter give some examples for the use of phenological data in agriculture and horti-culture.

The chapter ends with more recent aspects in plant phenology, showing that the rela-tively small changes in air temperature have had already distinct impacts on plant development of fruit trees and field crops.