Category Archives: Lower Saxony

The nature reserve “The big and the white bog”- “Großes und Weißes Moor”

The nature reserve “The big and the white moor” (Fig. 1) is located in the Lower Saxony, in the district of Rotenburg (Wümme). Even though it used to be almost dry, it has been recovered and naturalised due to the drainages made for agricultural purposes. Today, it is among the best preserved raised bogs in the North-West Germany.

Raised bogs are acidic, wet habitats, poor in mineral nutrients, populated by plants adapted to live in such extreme conditions (Fig. 2). In north Germany they can develop only under ideal climate conditions – wet with a balanced distribution of precipitations over the year.

The development of the bog started around 4000 years ago. At first a flat bog developed thanks to sand deposition and accumulation of water. Slow acidification of the trapped water allowed the accumulation of partially decomposed plant material under low oxygen levels, which developed into peatland. At this stage, the inhabiting plants were sedges, rushes, deergrasses, Phragmites and alders. In the transition stage, other plant species folowed – bushes, trees, peat mosses and cotton-grasses. The rised bog developed very slowly, in a period of many centuries, along with strong rainfalls.

The peat, accumulating over time, traps CO2 gasses by reducing their amount in the atmosphere. Therefore bogs are important for the climate and by protecting them, we protect the climate.

About 60% of plants of the german bogs are threatened. Among them, the heather (Calluna vulgaris, Fig. 3), and the cross-leaved heath (Erica tetralix, Fig. 4) are very common. Both are low growing perennial shrubs, easily found in the heathland and moorland, growing in acidic soils in sunny or partially shady places, adapted to live in low nutrient conditions. Cross-leaved heath is particularly vulnerable because the increased drainage creates drier conditions, where it is quickly replaced by the moor grass Molinia. However, gradual naturalisation is essential for the survival of this plant in this protected area.

Increased drainage permits the growth of Molinia, birch and pine trees (Fig. 5). As the forest develops, it absorbs more water so that the typical conditions for bog plants survival are quickly lost.

Fig. 5 As the conditions get drier, Molinia, birches and pine trees are slowly replacing the typical bog plants. Constant management via irrigation is necessary for the recovery of the raised bog.

Among animals, we can find the slow worm (Anguis fragilis), the moor frog (Rana arvalis), the common water frog (Fig.6), the Araneus spider (Fig. 7) etc.

However, last summer (2016) was extremely hot and dry, the precipitations were not well distributed and the temperatures were well above the average. While in July everything looked fine, in September the picture was a bit different. The pond where the frog from the Fig. 5 has been found become almost dry in September (Fig. 8 and 9), even the blueberries were flaccid or dry. The conditions worsened in the next weeks, with temperatures above 30°C and no rain.

I like to think that it was just an exceptional year and that it will only rarely happen to have such extreme conditions in Northern Europe, but I´m not that optimistic for the future of this peculiar biotope.

Photos by Ingrid Ugussi Vukman

The twin lakes of the Lower Saxony in Germany (Die Bullenseen)

The twin lakes (Großer and Kleiner Bullenseen) are situated in the Wümme depression that was covered by ice during the Ice Age. As the ice retired, the two depressions filled with water remaind and today they are replenished by the Wümme´s branches. The small lake is since 1938 part of the nature reserve “The big and the white moor” (“Großes und Weißes Moor”).

Since the water of the big lake (Fig. 1) is surrounded by a bog, it is rich in humic substances, therefore very acid  (pH 4.5-5) and not suitable for fish. However many other animals can thrive in such conditions – so here we can find various water bird species, snakes, like the grass snake Natrix natrix, frogs (Fig. 2), dragonflies and even bats in the evenings.

Fig. 1 The big lake (Großer Bullensee)
Fig. 2 A frog captured at the border of the big lake

Typical plant species found near the shore are the bulrush or Typha latifolia, the water-dropwort (genus Oenanthe), Fig. 3a,  the bog arum or Calla palustris, Fig. 3b and the carnivorous plant Drosera anglica.

Fig. 3a The bulrush and the water-dropworth; Fig. 3b The bog arum.

The small lake (Fig. 4a and b) is accessible by a trail with informative panels made by the Nabu association. It is positioned north of the big lake, surrounded by a pine forest and blueberry bushes which densely grow at the forest floor (FIg. 5a and b).

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The lake can be observed only by a certain distance since this environment is very vulnerable and the soil is muddy and soft, so it can easily trap you.

Various water bird species can be found, the most common are the tufted duck Aythyla fuligula, the mallard Anas platyrhynchos and the Eurasian teal Anas crecca.

Photos by Ingrid Ugussi Vukman