Draft:Hohenbodman lime tree

The Hohenbodmaner Linde, also known as the thousand-year-old lime tree, stands in the center of Hohenbodman, a district of Owingen in the Lake Constance district in Baden-Württemberg.

Description
The summer lime (Tilia platyphyllos) is 400 to 1000 years old according to various estimates and has been listed as a natural monument by the district of Überlingen since July 25, 1939. The tree is approximately eleven meters high and has a trunk circumference of ten meters, making it one of the largest trees in Germany. The "German Tree Archive" lists the lime tree as a "Nationally Important Tree (NBB)", the most important selection criterion for which is the trunk circumference at a height of one meter. The German Dendrological Society (DDG) lists the lime tree as a "champion tree"; the DDG selects the thickest tree of the species in the federal state. The condition of the lime tree, which is owned by the municipality, was assessed in 1982, 2001, 2004 and 2010. Maintenance measures were carried out in 1983, 1994 and 2010.

Location
The village of Hohenbodman with about 230 inhabitants is located northeast of the shore of Lake Constance near Überlingen and about 280 meters above sea level. The lime tree stands at about 680 m on a small road branch of Lindenstraße next to the fire station in the middle of a slightly raised, roughly triangular and grassy road island. This is surrounded by an approximately 40 centimeter high base made of natural stones, the adjacent road surfaces are asphalted on two sides, on the other two perforated concrete stones replace a former tarred surface.

Early history
According to oral tradition, the lime tree was planted by the Herren von Bodman, Reichsministeriale of the Hohenstaufen and the Bischof von Konstanz. The Lords of Bodman were resident in the village until 1282 and are associated with the lime tree because their coat of arms contained three lime tree leaves. In 1859, the Jahreshefte des Vereins für Vaterländische Naturkunde in Württemberg reported: "The small village of Hohenbodmann, located a little higher than the Warte, rests on the Diluvium and on this near the village stands an old hollow lime tree of 10′ diameter." In his book Bemerkenswerte Bäume im Grossherzogtum Baden, the German botanist and biologist Ludwig Klein wrote in 1908:. Ludwig Klein in 1908: "The strongest lime tree in Baden and Baden's strongest tree of all is the large summer lime tree at the entrance to the village of Hohenbodman, 2½ hours inland from Überlingen (Eichrodt) (Fig. p. 181).The ancient tree, which looks extremely stately and completely healthy from a distance, has a height of approx. 26 m and a trunk circumference of 9.40 m! At a height of about 3 m above the ground, the trunk forks into three very strong branches. The trunk is hollow, and thoroughly so, with a large gap on the north side; the solid shell of the trunk (wood and bark) is on average no thicker than 25 cm. The necessary stability with which the free-standing tree, which has been hollow for centuries, has successfully withstood so many storms, including some extraordinary ones, is probably due to the fact that powerful aerial roots grow into the spacious trunk cavity, a phenomenon not uncommon in old, hollow lime trees. At the overhanging edges of former trunk cracks and other 'penetrating' injuries to the hollow trunk, as can be seen here several times, adventitious roots form, which gradually grow into the ground through the mulm-filled cavity, becoming stronger and stronger over time and finally growing together in part and with the trunk itself. The strongest of these aerial roots is over 1 m in diameter, a second about 40 cm!"

The botanist Friedrich Oltmanns wrote in 1922 in Das Pflanzenleben des Schwarzwaldes: "The 26 m high tree has a trunk circumference of 9.4 m, which is unheard of by our standards." H. von Bronsart wrote in 1924 in Die heimische Pflanzenwelt: "So near Hohenbodman on Lake Constance there is a lime tree with a trunk circumference of 9.5 meters, the strongest tree in all of Baden." In 1938, the lower branches were tied with strong iron bands, so-called Schlaudern, so that the large crown would not break apart. The lime tree was declared a Reichsnaturschutzgesetz on July 25, 1939 in accordance with the Reich Nature Conservation Act (RNG) with the Ordinance on the Protection of Natural Monuments in the District of Überlingen. Literature also mentions 1936 as the year of protection.

Construction work on the lime tree and renovations
When digging a one and a half meter deep trench for a drinking water pipe about two meters next to the foot of the lime tree in 1964, its roots were damaged. With the incorporation of Hohenbodman in the course of the territorial reform in Baden-Württemberg on January 1, 1972 to Owingen, the Lower Nature Conservation Authority of the Bodenseekreis became responsible for the lime tree. In 1975, another two-metre deep trench was dug for sewage disposal about ten meters from the trunk. Again, the root system was damaged and the vitality of the lime tree declined sharply within a few years. In the fall of 1982, the tree care company Michael Maurer drew up a tree report, which mainly blamed these construction measures of 1964 and 1975 in the immediate vicinity of the tree for the severe decline in the vitality of the lime tree. According to the tree expert, the root loss was "quite considerable and extensive". In view of the projection of the branches, the expert estimated that 35 to 40 percent of the total root mass had been destroyed or damaged during the two construction works. Although the stability of the lime tree had not suffered as a result, a considerable part of its roots had been destroyed. The expert opinion rated the lime tree as "absolutely worth preserving" due to its uniqueness and as "worth preserving" despite its poor condition. In 1983, restoration work was carried out on the lime tree at a cost of 20,000 German marks. The once 30 meter high crown was shortened by 30 percent to give the tree a chance of survival. After the restoration, it was certified to have a life expectancy of 30 to 50 years. In 1994, the lime tree was again treated with tree surgery. In 2001 and 2004, further expert opinions were carried out to check its stability and initiate the necessary measures. These examinations also revealed that the infestation with blight crust fungus had spread considerably. In 2005, the lime tree was transferred from the district administration to the responsibility of the town of Überlingen as part of the administrative reform. At a meeting in June 2010 to discuss the future of the lime tree, local head Jörg Nesensohn and the Überlingen district forester and tree expert Rolf Geiger agreed that the lime tree should be felled in the fall due to the municipality's duty of care. Mayor Henrik Wengert also thought it was too risky to leave the tree standing with its weighty crown on a dilapidated trunk. The trunk was completely rotten and the crown was only held up by the remaining bark. However, if the lime tree was cordoned off over a wide area, it could possibly remain standing. The administrative community would have had to create the legal conditions for felling it. As hikers and walkers were resting and children were playing right next to the tree, it had already been provisionally cordoned off with a construction fence some time beforehand so that no one would be hit by falling branches. In a survey, the vast majority of the more than 50 citizens present were in favor of removing the tree, with only three voting to preserve the lime tree.

Expert opinion in 2010 and refurbishment
On July 27, 2010, forester Geiger from the Überlingen forestry district reported on the condition of the lime tree at a public council meeting. He suggested having a new report drawn up on how long the tree could still stand. It should take into account the necessary traffic safety and aesthetics of the local lime tree, which is surrounded by three roads, and also state the costs for its preservation. The municipality then commissioned another expert opinion from tree expert Marco Wäldchen with financial support from the district's Lower Nature Conservation Authority. After the previous inspection, he produced a 13-page expert report by 14 November 2010. During the inspection, the location with tree surroundings, the standing area, the roots, the trunk, the strong branches and all parts of the crown down to the fine branches were visually inspected. The focus was on vitality and the biomechanical aspects relevant to traffic safety. The vitality of the tree was classified as Vs 1-2 according to the forestry scientist Andreas Roloff's key, which ranges from Vs 0 (tree without signs of damage) to Vs 3 (tree dying), meaning that the lime tree was in the transitional area from the degeneration phase (Vs 1=tree weakened) to the stagnation phase (Vs2=tree with significant loss of vitality).

The report shows that the lime tree could still be saved, but was no longer safe for traffic. This should be remedied as quickly as possible. The crown should be pruned back considerably to provide mechanical relief in the event of wind load. Pruning of new shoots should then be repeated every seven to ten years. The dead trunk segment should also be shortened by 50 percent; the old threaded rods that connected the individual trunk segments and no longer provided support should be removed. After pruning, all loops installed in the crown to stabilize the branches would have to be checked to see if they needed to be readjusted.The city of Überlingen informed the municipality on the basis of the expert opinion that no exemption permit for felling the registered natural monument could be granted. The lime tree was to be inspected every nine months. The maintenance measures were carried out, with the municipal building yard taking care of the pruning. After the renovation, the construction fence around the lime tree was removed.

Description
The lime tree stands in the village, but quite freely, so that it could develop a very large trunk thickness, extremely strong branches and a huge crown. The trunk is completely hollow and has a large opening to the southwest, on this side the wood is almost completely missing. At a height of around five meters, the trunk abruptly transitions into today's small crown. The lime tree has lost more and more of its crown volume and height over the last 30 years due to various pruning measures. The remaining branches are suspended from a construction of steel tubes and cross struts. Currently (2014), the lime tree is still 11 meters high and only a few branches form the spherical crown.

At the beginning of the 20th century, the lime tree was at the peak of its growth. The trunk with a circumference of over ten meters was hollow inside, but only had a gap on the north side, which is now closed again. It was 3.8 meters high and branched out into two upwardly striving partial trunks, which formed a crown up to about 30 meters high and almost completely preserved.

Before the first maintenance measures after the World War II, the crown was so large that three hay wagons could be placed under the lime tree without the hay getting wet. There are still reports from the 1960s that the Hohenbodman farmers used to shelter their hay vehicles with their draught animals or tractors there to protect them from the rain.

Trunk circumference
The following table lists the values for the trunk circumference of the lime tree given in the sources consulted. Exact and comparable measurements are difficult due to the oval shape of the trunk, the indentations and defects. In the last 150 years, the size has been measured several times at varying heights, and it often remains unclear at which height.

Age
The age of the lime tree can only be determined approximately. An annual ring count - for example with the help of a drill core extraction or by means of a resistograph - is not possible because the oldest wood in the center of the trunk is missing. For the same reason, an age determination via the content of radioactive carbon (radiocarbon dating, also called 14C dating) is also not feasible. In the current literature, there are different data ranging from 400 to 1000 years.

In 1981, the forester Hartwig Goerss estimated the age of the lime tree at 1000 years. In his report in 1982, the tree expert Michael Maurer gave an age of 800 years and Anette Lenzing gave an age of 1000 years in 2005. The German Tree Archive, whose age information is based on the trunk circumference and an annual average circumferential growth of the corresponding species, estimated the age of the lime tree in 2012 at 450 to 600 years. Hans Joachim Fröhlich assumed an age of around 800 to 1000 years in 1995. The forester Mathias Schuhmacher estimated the age at 400 to 500 in 1991 and Michel Brunner at 500 years in 2007.

Inschriftentafel
A metal plaque by the lime tree bears the following inscription:

 Sommerlinde (Tillia platyphyllos)

Popularly known as the tree of lovers - the tree of fertility, the lime tree was considered a sacred tree in ancient times in both Slavic and Germanic regions.

This lime tree is one of the oldest lime trees in Germany and is estimated to be 800-1000 years old. In its best years, the lime tree was around 30 meters tall and had a trunk circumference of over 10 meters. In 1964 and 1975, around 40% of the roots were destroyed when the drinking water and sewage pipes were laid. The loss of vitality was dramatic. In 1983, the lime tree was extensively renovated and was given a life expectancy of 30-50 years after the renovation.

Weblinks

 * Deutsches Baumarchiv
 * Ansicht von 1966
 * Linde in Hohenbodmann bei Monumentale Eichen
 * Linde in Hohenbodmann bei Monumentale Eichen