Robinia pseudocacia, also known as False Acacia or Black Locust, is native to the Appelatian Mountains of North America. It was introduced to Europe over 300 years ago where is widely planted and is an important commercial species. Robinia is virtually unknown in Ireland, except for ornamental varieties as garden trees. Robinia is the third most commonly planted Broadleaf species in the World, only Eucalyptus and Hybrid Poplars are more widely used. Robinia is a Nitrogen fixer and produces highly durable timber, it is a favoured tree for Silvopasture.
In Ireland we presently have a very limited list of suitable species for afforestation, even prior to the recent loss of Ash (and Elm before that). The possibility of another species for afforestation and Agroforestry is of enormous interest to Farmers and Foresters.
Robinia
It can be a ready substitute for Tropical Timber
produces a naturally durable timber, suitable for use outdoors
can be used for fencing, durable for 30 years without any chemical treatment.
Garden Furniture, Playgrounds, decking, and exterior cladding.
It is highly valued as fuel for wood burning stoves.
"Shipmast" Robinia is a naturally occuring straight growing variety. There has been extensive reserarch particularly in Hungary selecting vigorous trees with good stem form and we have sourced a number of these for planting April/May 2021. In marked contract with the more common form of Robinia with is of poor quailty in terms of straightness which is mainly grown for firewood.
We are establishing trial plantings of Robinia around Ireland to assess their early performance on a wide range of site types . One particularly site type for inclusion next year will be where diseased crops of Ash are being replaced.
Fodder
The leaves are used for livestock feed for Cattle and Sheep . Branches above the reach of livestock are cut when other green forages are scarce, and the wood is used later for fuel. Ground black locust tops including woody stems, from first and second harvests, were found to be comparable to alfalfa with 23-24% crude protein, 7% lignin, and 4.2 kcal/g. When planted at close spacing, the new growth can be harvested with conventional farm machinery for silage or hay.
Toxicity
The bark and foliage are toxic to horses. The toxicity of the Locust tree is also responsible for its historic use as a treatment for disease. The Cherokee Indians chewed the root bark to induce vomiting and to ameliorate the pain of a toothache. The flower contain the glycoside robinin, which has been shown experimentally to act as a diuretic. A tea made from the flowers was used to treat everything from headache to nausea. Juice from the leaves purportedly inhibited viruses. The seed pods are edible when cooked, and the flowers are used to make fritters and are added as a flavouring for pancake batter.
Bees and Honey
In Hungary Robinia provides nectar for making high-quality Honey. In Hungary Robinia provides it provides around 25,000 tons of honey a year – this represents 40-50% of all Robinia (Acacia) Honey production in Europe. ((EU Science for Environment Policy - 01 June 2017 Issue 489). While In Poland in terms of the nectar content in its flowers Robinia is only second to Lime in terms of its capacity to generate honey. The climate in Poland is cooler than Hungary, Romania and Bulgaria where as much as 50% of honey sold commercially derives from black locust (Robinia) flowers.
Invasive Species
The fact that Robinia is classified as being Invasive in some countries may be of concern - hopefully this will only be an initial reaction. There was considerable debate about Robinia in Europe when EU Regulations in relation to Invasive species were being drawn up, however in the end Robinia was not included in the first list. Individual Member States can include it on their own list of invasive species of concern. In Hungary, where Robinia accounts for 24% of the forest area, Robinia is now the National Tree. Where it is more likely to be a potential problem this is confined to Countries with dryer conditions and higher temperatures than we ever used to in Ireland. From observation in Ireland where Robinia trees 100 years old are to be seen there is no sign of these trees spreading. In the USA Steve Gabriel Author of "Silvopasture - a guide to Managing Grazing Animals, Forage Crops, and Trees in a Temperate Farm Ecosystem" describes Robinia as his favourite tree and where it is inclined to spread (New York State) it is kept in check on his farm by grazing animals
Robinia Forest Succession
Robinia (Black locust)seedlings are sensitive to shading, which means that seedling mortality is high
in forests with closed canopies or in habitats where there is a dense ground
vegetation. In general, Robinia (black locust) stands have plenty of light
reaching the forest floor over the whole vegetation period as the foliage holds
for a relatively short period of time; i.e. the leaves
appear late in spring (May) and begin to fall rather early, usually during
summer droughts (August). High light levels reaching the forest floor enable
the survival of local light demanding species in the herb layer or dense shrub
layer.
Although it can take a long time, old Robinia (black locust) stands and scattered black locust trees in forests are naturally replaced during succession by more competitive trees. Robinia (Black locust) will disappear from the community by shade tolerant trees over 70 years.
Climate Change
With increasing summer temperatures and decreasing rainfall in significant parts of Europe, Robinia is seen in extreme cases, as one of the few trees that has any potential to even survive. In Europe it is widely expected that conditions will be favourable for the expansion of the range and importance of Robinia in forestry. In Ireland with our generally moderate temperatures and relatively high rainfall, growing conditions for Robinia can only be expected to improve.
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