Thünen Institute Forest Ecosystems
Ecological Research Station Britz
Forests play an important role in the landscape water balance. They strongly impact on the quality and quantity of ground- and drinking-water supplies. With current climate projections pointing to higher temperatures as well as prolonged and more extensive droughts, forestry needs to adjust promoting the necessary adaptation of forests.
At the ecological research station Britz, near Eberswalde, we have studied the water consumption (evapotranspiration) of important commercial tree species since 1974. Main features are the nine large-scale lysimeters, installed at a depth of 5 m with a surface area of 100 m² (10x10 m). They are planted with 0.3 ha experimental stands of Scots pine (Pinus sylvestris) (3 lysimeters), European beech (Fagus sylvatica) (2), European larch (Larix decidua) (2), and Douglas fir (Pseudotsuga menziesii) (2) spaced corresponding to the forestry practice at that time. About 15 years ago one Larch lysimeter was clear-cut and replanted with sessile oak (Quercus petraea). On two Scots Pine lysimeters, European beech was planted building now the understory. The areas surrounding the lysimeters were planted in a similar fashion. Seepage water collecting on the lysimeter surface flows down a measuring shaft and is measured mechanically by a tipping counter and registered electronically. Soil moisture is measured with probes to a total depth of 5 m in 50 cm steps. Precipitation in the open field and the stand is recorded with Hellmann rain gauges. In addition, the station is equipped with devices assessing individual tree water transport and growth (sap-flow sensors, dendrometers) as well as transpiration of the ground vegetation (small-scale lysimeter with 1.8 m depth and 1m² surface area). The studies are aimed at revealing the effects of different tree species and mixtures on the ground and landscape water balance. Moreover, the effects of drought on tree performance and tree-internal water budgets are of interest.
Scots pine (Pinus sylvestris L.)
After the last ice age, Scots pine was one of the first woody plants to migrate back into these regions, together with birch (Betula pendula L.) and hazel (Corylus avellana L.). It typically grows on poor sandy soils which are dry and have a low pH. The lifespan is normally 200 to 300 years and it can reach heights of up to 40 m. The bark is dark and flaky at the bottom and almost orange at the top. Needles are arranged in bundles of two with a length of five to seven centimetres, contrasting to other Pinus species. Scots pine prefers light conditions and is a pioneer species, and provides good wood for pulp or sawn timber products.
The satellite image below shows the exact location of the monitored tree in the experimental station of the Thünen Institute for Forest Ecosystems in Britz (Germany).