A hedge offers the best entertainment almost all year round. At least for nature lovers. In autumn, pink-orange pfaffenhütchen and red rose hips shine around the bet, in spring shells and hawthorn the hedge in a white flower coat. In summer, nightingales and hedge browns sing their songs between the thorny branches. Even in winter, many of their residents protect and eat, from hibernating hedgehogs to the throttle, which is amicable on the blue fruits of the sloe.
"Hedges are real jacks of all trades," says Axel Don, deputy head of the Thünen Institute of Climate Agriculture in Braunschweig. They slow down the wind, store and filter rainwater, form humus and beautify the landscape. They protect against soil erosion, bind excess nitrogen and store carbon. In addition, hedges combine very different microclimatic conditions in a confined space, from shady-moist in the core of the hedge to sunny-dry at its edge. This makes it one of the most species-rich habitats of all. (see box »Biodiversity hotspot«)
However, hedge is not the same. Garden hedges are narrow and often consist of only a few types of tree or shrub- such as hornbeams or evergreen plants such as cherry laurel or thuja. Special field hedges, on the other hand, are several meters wide, rich in domestic bushes, often with a core of some large trees and a hem of herbaceous vegetation. Sometimes they are therefore also referred to as a double edge of the forest. Typical hedge plants are thorny shrubs such as shell, hawthorn and wild roses, which quickly form an impenetrable thicket - without barbed wire or electric fence. In addition, in field hedges there are often hazelnut, elderberry, hardwear, oak, pastures and fruit trees.
Hedging as a climate defender
Axel Don, Sophie Drexler and her colleagues at the Thünen Institute, examined in a complex Germany-wide study of how hedges store carbon. To do this, they collected rehearsals at 23 hedge locations - and not only above ground, but also - with excavators, spades and probes - in the root room of the hedges. "We analyzed 3900 soil samples up to one meter depth and washed out roots for months, dried, flooded and weighed in order to be able to determine the carbon content in it," Don describes the meticulous work.
Biodiversity hotspots
Scientists have counted over 70 different plant species on a square meter of hedge surfaces. Where there are many different plants, many animals also live: nightingale, ninthinthols, gold -king, thorn grass mosquito, vineyards, badger, dormouse, culy lizard and thirr. Hecken also serve numerous animals as connecting routes, such as the shy wild cat, which changes from one forest to another in the protection of the hedges.
Even though the evaluations in the "CarboHedge" project have not yet been completed, interesting results are already available: Plant biomass, i.e. roots, trunks, twigs and leaves, is responsible for more than 80 percent of the carbon storage potential of hedges, while the humus content of the soil accounts for almost 20 percent. The differences between different hedges are naturally considerable, but on average the woody plants store a similar amount of carbon per square meter as forests. Hedges manage this despite their comparatively low growth height and mostly thin trunks due to their optimal sun exposure. Relatively high hedges, individual tall trees and certain woody species such as the hazelnut improve the storage effect. "We were amazed when we saw how big the hazelnut rootstocks were," says Don.
Only for climate protection would it not be worth planting new hedges, says Don, but the special thing about them is that they fulfilled an incredible number of functions on a very small part of the agricultural area. They practically provided the climate protection for free. The approximately 50,000 hectares remaining hedge area in Germany only occupies a fraction of the 17 million hectares of agricultural land: Even if you double the hedge area, you would remain well below one percent of the area managed. With hardly any other measure, so many positive effects could be achieved in the agricultural land in the so small area, emphasizes Don.
Hedges perform function
Despite all the advantages of hedges, Germany has lost around half of its hedges since the 1950s. Lates to increase agricultural effectiveness were the main reason for this (see box "the end of the hedge magic"). Today, quite a few would like to have the flowering landscapes back: beekeeping associations, water management, hunting associations, landscape, nature and climate protectionists- everyone likes hedges. There is only one catch, says Axel Don: "The actual actors - the land administrators - are very reserved." From their point of view, it is quite understandable that there are hardly any hedges at the moment, because new plantings are expensive and hedges should be maintained. "In any case, it means work for the companies."
The special structure of a hedge ensures high diversity and productivity, but it also requires regular care. Similar to a coppice, a hedge must be "put on the hive" in sections about every eight to twelve years, i.e. completely cut off. The hedge trees tolerate this well and grow back quickly and multi-shoot with the power of the rootstocks. Without regular pruning, the hedge slowly loses its shrub and herbaceous layer, because more and more trees grow – or shrubs become trees – and take the light away from the lower layers. Such a »mature hedge« becomes »holey« and loses not only many species, but also a good part of its functions such as wind protection.
In order to motivate the land administrators, various hedge funding from the large pot of the EU agricultural subsidies are available. But "the creation of hedges is one of the most unpopular measures among the farmers and farmers," confirms forest scientist Christian Böhm, who researches agricultural landscape at the BTU Cottbus-Senftenberg on AgroforstSystemen and the effect of hedges. He sees the main reason for the hesitation of farmers in the fact that the trees are considered landscape elements that once created, in the future no longer may be transformed back into arable land, meadow or pasture. “This is a red line for many. They do not want to miss their operational flexibility, even if they are currently not planning to remove the hedges at some point, «says Böhm.
Hedges, Hage, Knicks
Hecken (also called "Hag") has existed since the Neolithic period when people began to create gardens and fields, from which they wanted to keep away from the "insertion". At that time, the hedges mostly limited themselves to the immediate vicinity of the villages. They were relevant to the landscape in Germany around 500 years ago at the end of the Allmende when the jointly used country around the villages was gradually privatized and hedges were laid on a larger style than border fences. In "stone -rich" areas such as in Franconia and in the Swabian Alb also spontaneously formed on a foundation of reading stones, which the farmers struggled to collect from their fields and opened them on the edge. In the protection of the stones, trees and shrubs could germinate and grow up.
A special hedge shape is also formed by the North German wall hedges, which are called »Knicks« in Schleswig-Holstein. They were laid on a rampart and bent every few years, that is, the trunks were sawn and folded in one direction. Typical German hedge landscapes are the Knicks in Schleswig-Holstein, the wall hedges in Lower Saxony or the Upper Bavarian Haglandschaften. Other hedge-rich landscapes can be found in the Rhön, the Eifel, the Hunsrück, the Erzgebirge or in the Heckengäu near Stuttgart. In France, Belgium, England, Wales and Ireland, hedges also dominate the landscape in many regions.
More scope and support for the companies could help that more hedges decorate the landscape again. "We are at a point where we have to start thinking hedges completely new," Axel Don also demands. In the past, hedges and their care were an integral part of the companies, today they have to be anchored again in the companies. Especially in times of climate change, in which soil protection, humus formation and carbon storage are becoming increasingly important, hedges could do important services than a multifunctional cropping tool.
Protection through use
100 years ago, climate protection was not an issue. At that time, hedge trees were particularly in demand as raw material and food suppliers: the leaves of the ash were fed to cattle, gained litter for the stables and used the shoots of pastures and hazels to braid. From birch rice you bang brooms, the wood of oak and hornbeam were used to heat and cook and the fruits of roses ("rose hips"), sanddorn, sloes and fruit trees enriched the peasant cuisine.
Today, the climate protection effect of hedges could be further improved if they were used again in the traditional way to obtain firewood and timber. Thanks to their high productivity, considerable quantities of wood can be obtained from hedges, which could then replace fossil energy, for example, as a renewable energy source. Christian Böhm was involved in a practical test on hedge use near Oranienburg, north of Berlin: There, experts in the GoÖko project ("Woody Use Optimizes Ecosystem Services") produced wood chips from outdated poplar hedges and developed usage concepts.
The end of the hedge magic
In order to manage the country more effectively, farmers and authorities designed many German landscapes from scratch during the land consolidation since the end of the 19th century. That was an abomination to the northern German poet Hermann Löns in 1909 when he wrote his poem "coupling", in which it says: "A man goes through the colorful country; He holds the measuring chain in his hand. Looks and looks around; ›Everything is wrong here and crooked!‹ […] He looks at the stream in the valley; ›The bushes there has no sense!‹ […] The hedge is a horror; ›Of course we remove the blinds!‹ The wild bulb tree is too crooked for him; ›We are the first to knock it over!‹ […] And so with many art, the Feldmark is literally controlled. ”Most of the» adjustments «were not yet implemented at Löns' times, they only followed after the Second World War the land consolidation laws from 1953 and 1976 or with the establishment of the large "agricultural production cooperatives" in the GDR.
Scientific data on the full extent of the losses have never been collected, but estimates assume the loss of well over half of all hedges in Germany. For individual regions, there are more precise data: In various districts of Schleswig-Holstein, for example, more than 70 percent of the typical wall hedges were lost (see box »Hecken, Hage, Knicks«). In the Lower Saxon municipality of Ganderkesee, between Bremen and Oldenburg, there were still hedges with a total length of over 1300 kilometers in the 19th century. In 1987, about 280 kilometers were left, of which only 50 kilometers of hedges were in good condition. Between 1897 and 1969, the hedges there lost a third of their length, and by 1985 88 percent of the hedges had disappeared.
However, hedges could not be managed financially in any of the tried and tested approaches. One reason: hedge management or new planting requires a high level of personnel effort and often larger machines and logistics that very few farmers can hold up. Nevertheless, Böhm is to promote the rear use much more. Even if no monetary profits could be generated, the income from the woodcut could significantly reduce the care costs. The municipalities could play an important role in implementation, for example by creating usage concepts, creating sales for the wood that arises or taking on hedge care.
A label of excellence for hedges
Paradoxically, the nature conservation of the hedges sometimes stands in the way, reports Böhm: On the one hand, certain funding opportunities could be omitted as soon as hedges were used for wood production, on the other hand, there are restrictive regulations through tree protection regulations and similar regulations. Some companies are facing the further hurdle to coordinate with the nature conservation authorities. And certain requirements for agricultural support can also harm hedges. For example, you miss the eligible agricultural area by satellite. When the expansive branches and branches of a hedge protrude across the field or the meadow, they reduce the funding area when viewing. For example, some companies miss an Iroquy cut to the hedges, which are not officially integrated into the agricultural area as a landscape element - which in turn sensensively reduces their ecological value.
Some developments in modern agriculture could also benefit the hedges in the medium and long term: the increasingly digital and automated procedures make work easier. In this way, arable cultures, hedges and rows of trees along the off -road profile can be created and managed much more easily with the help of GPS and drone recordings, which counteracts the erosion and the rainwater optimally distributes over the surface. Christian Böhm, who is also the chairman of the German Association for Agroforstwirtschaft, still sees the trend towards ever larger tractors and machines, but considers the future vision of a technology -based, small -scale agriculture to be realistic. Many managers are already working with GPS-controlled devices. "Once set, you just have to sit in and check whether everything is going properly". The new technology would offer a lot of potential. For example, in the shadow area of a hedge, a narrow strip of a shadow -tolerant culture could be growed.
Last but not least, climate change has triggered a rethink in agriculture: "The dry summers have shown many people the advantages of hedges in terms of water storage and cooling," observes Böhm. Politicians are also sending positive signals for more woody plants in the landscape, but so far there has been a lack of attractive concepts for hedge planting and maintenance. One model could be the hedge seal »Label Haie« established in France, which certifies that the managers are given exemplary care. For example, wood from such hedges is labelled as local and particularly sustainable, and the services of hedges for the common good can be quantified and rewarded nationwide according to uniform criteria. In this way, hedges could become more attractive again in the future – and everyone would benefit from it.
