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Dieren en planten

Plants   Oleaster family   Russian olive   Sea buckthorn   Elder   Micro-organisms   Bacteria   Dune flora   Trees and shrubs   

Water en land

Dune areas   Dunes (biotope)   

Mens en Milieu

Nutrients   Nitrogen compounds   

Sea buckthorn

size:

1 to 4.5 meters

color:

leaf: gray-green
flower: greenish

blossoms:

April and May

reproduction:

seed, root suckers

lifespan:

perennial

  • Dut: Duindoorn
  • Lat: Hippophae rhamnoides
  • Eng: Sea Buckthorn
  • Fren: Argousier
  • Ger: Sanddorn
  • Dan: Havtorn
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Sea Buckthorn, Ecomare

Sea buckthorn

Sea buckthorn is best known when its bright orange berries ripen in late summer. Sometimes, you can even smell a sour odor given off by the berries. Migrating birds are attracted to these berries, which are rich in vitamin C. The berries are ripe just in time for these birds and provide them with extra energy to fly further. Brown-tail moths use sea buckthorn as a food plant for their caterpillars. It's not unusual to find cocoons from these hairy insects built around one or more branches. Sea buckthorn grows in soils rich in calcium. In the Netherlands, that means relatively younger dunes. The plant needs lots of nitrogen to grow and has its own way of supplying its needs. In the process, it produces excess nitrogen, which helps various other dune plants and indirectly animals.

On Texel


, Sytske Dijksen, www.fotofitis.nl

There are lots of sea buckthorns growing in the dunes, precisely along the route that the migrating birds take. As the name indicates, sea buckthorn is thorny. Before barbed wire was invented, dead branches from sea buckthorn were placed on top of the grassy 'tuinwallen' to keep the sheep from climbing over the wall.

  • Survival
    , Sytske Dijksen, www.fotofitis.nl

    Sea buckthorn can grow a half meter per year. Therefore, the bush has little problem keeping pace with wind-blown sand, just like marram grass. To prevent dehydration, the branches are covered with star-shaped scales, which protect the plant from direct sun rays. The scales are filled with air and give the bush a silvery-gray color.

  • Nitrogen machine

    Sea buckthorn uses a lot of nitrogen to grow. Its roots cannot supply sufficient amounts and therefore the plant has its own nitrogen machine. A bacteria, which grows in its root tubers, is able to fix nitrogen from the air. Tubers don't form on older roots and older roots don't rejuvenate. After awhile, the tubers die off. After a maximum of 30 years, sea buckthorn plants also die.

    The tubers produce more usable nitrogen than sea buckthorn needs itself. The excess nutrients are used by other plants that also require lots of nitrogen, such as stinging nettles, blackberries and eventually elderberries.

    Thanks to this 'nitrogen machine', sea buckthorn forms an important link in the dune community. Its berries and leaves are a source of food for many organisms and the plant is a hiding place for game (roe deer) and a nesting place for many species of birds.

  • New sprout

    Sea buckthorn plants are either male or female. A group of sea buckthorn bushes often originates from one parent plant. Underground root stocks provide new plants. The group is then a new sprout and the bushes are all the same sex as the parent plant. Once the berries appear, you can readily identify the females.

  • Drunken birds and hungry caterpillars
    Sea buckthorn in the winter, Ecomare

    The orange berries taste very sour, which is proof of its high vitamin C content. Besides humans that use the berries for making jam, yoghurt and liqueurs, the juicy berries are gratefully consumed by birds. Sometimes, the berries start to ferment on the branches. In that case, it is not unusual to see drunken migrating birds, such as fieldfares and redwings.

    The inedible seeds that are defecated far from the parent plant rarely develop into adult plants. Lots of young sprouts die from dehydration or are eaten by birds and rabbits. There's also another problem. In order to grow, sea buckthorn needs its bacteria for providing sufficient nitrogen. This bacteria is often lacking in the ground where the seeds are released.

    During some years, all the sea buckthorn leaves are eaten by the caterpillars from the brown-tail moth. These caterpillars overwinter in conspicuous cocoons, which some people mistake for a spider web or even toilet paper.