Experimental tree nursery (Grimminge)
The Research Institute for Nature and Forest (INBO) has a 30-hectare experimental tree nursery that produces forest plants, shrubs and seeds for research and practical forestry applications. The experimental tree nursery is located in Grimminge (Geraardsbergen), close to the Helix, the Flemish Knowledge and Training Centre for Nature and Environment.
The experimental tree nursery serves not only as a hub for scientific study, but also as a living repository of rare native tree and shrub species, contributing to the preservation of genetic diversity. Here, we cultivate trees and shrubs for field trials, using the site as a living laboratory to investigate disease and pest resistance, as well as the adaptability of tree species to a changing climate. Additionally, the research centre houses seed orchards and stoolbeds, officially recognized as basic material for the production of forest reproductive material.
INBO tree nursery (Photo: Wim De Clercq, August 2015)
Google Maps (Lat 50.7826936; Long 3.9354683)
1/ COLLECTIONS OF TREE AND SHRUB SPECIES
Poplar (Populus spp.)
The tree nursery is home to several 'populeta'. A populetum is a collection of living poplars. The poplars in this populetum belong to the North American species Populus deltoides and Populus trichocarpa, on the one hand, and to the European black poplar (Populus nigra), on the other, forming a unique collection in Europe. These poplars are used in the INBO breeding programme in order to create healthy trees with fast growth, straight trunks and excellent wood quality for the wood processing industry.
Populetum black poplar (photo: Kurt Schamp, june 2014)
Willow (Salix sp.)
A 'Salicetum', a collection of living willows, was established at the tree nursery. These willows belong to the native crack willow (Salix fragilis), the shooting willow (Salix alba), and hybrids between the two species (Salix x rubens). The willows used for the crosses are from native willows found in Belgium. The willows in the Salicetum were obtained from artificial crosses between native willows and were selected for good vigour and tolerance to watermark disease (Brenneria salicis). This disease is widespread in Flanders and can cause the willow to die if severely affected.
Biennial willows in nursery (Photo: Wim De Clercq)
Common ash (Fraxinus excelsior)
The tree nursery houses a first collection of ash trees that, after long-term observation, prove to be tolerant to ash disease, caused by the fungus Hymenoscyphus fraxineus. The survival of the common ash tree is threatened in Europe and also in Flanders by this invasive fungus. INBO systematically monitors the vitality of the ash tree, and the spread and evolution of ash disease in Flanders, and investigates whether the infection rate of trees is influenced by specific site characteristics. In collaboration with INRAe Orléans (France) and Alterra (Netherlands), genetic markers are being sought in order to detect disease-tolerant ash trees at an early stage via lab tests. The aim of this research is to eventually develop a collection of disease-tolerant ash trees that produce healthy plants and can be included in the list of recommended provenances.
- INBO Newsletter article: Ash disease threatens ash trees in many European countries
- Article in De Landeigenaar in Flanders: The decline of the ash tree. In search of healthy ash trees
- INBO Report: The health status of ash trees in Flemish forests
Selected ash, tolerant of ash disease (Photo: Kurt Schamp)
Elm (Ulmus spp.)
In the early 1980s, a collection of hybrid elms was planted as starting material for the selection of trees resistant to elm disease. Elm disease is a highly contagious fungal disease that leads to wilting. Elm spider beetles transfer this fungus from diseased to healthy trees. The native field elm and rough elm are highly susceptible to elm disease. Therefore, crosses were carried out at the time between native elm and disease-tolerant elm from Asia and Russia, among others. This created hybrids that are also tolerant to elm disease. These hybrid elms are still planted in the Netherlands and Belgium, mostly as avenue trees.
2/ SEED ORCHARDS OF NATIVE TREES AND SHRUBS
Autochthonous populations of trees and shrubs are adapted to local conditions due to their long presence of sometimes thousands of years and therefore of great importance as genetic heritage. The establishment of orchards makes native seed available to forest private nurseries. INBO is also investigating how native provenances behave under predicted climate change compared to non-native provenances.
>> List of approved forestry materials
Contact: Kristine Vander Mijnsbrugge & An Vanden Broeck
Seeds of Wild Cherry (Prunus avium)
The seed orchard of wild cherry was established in 2012 and covers an area of 1.2 ha. It is composed of 45 different genotypes (clones) selected after 12 years of observation of 23 trial plots. The selected trees were grafted on the dwarfing rootstock Gisela 5. The seed garden contains 1,178 grafted trees that were planted in hedge form. Every year from late June to early July, cherries are picked in the seed garden. The cherries are then cleaned, stripping the pips from the flesh. The harvest of pips goes to interested Flemish nurseries and seed dealers.
INBO Report: Genetic diversity of the INBO seed orchard of wild cherry
Wild cherry (photo Bart De Cuyper, INBO)
Contact: Bart De Cuyper
3/ PRODUCTS
Cultivars of poplar
Poplar - roundwood
The poplar breeding programme, started in 1948 by Swedish Match, is INBO's longest-running programme and resulted in the production of several cultivars over the years. Eight cultivars are marketed since 1999:
The cultivars are listed as approved forest reproductive material under the category 'tested'. Cuttings material of these cultivars are offered to several recognised nurserymen at home and abroad for production and sale of trees. These cultivars are European protected by Community Plant Variety Rights granted by CPVO (Community Plant Variety Office).
>> Dossier Populier in Silva Belgica juillet-août 2018
Contact: Wim De Clercq
"Vesten"(photo Marijke Steenackers, 2020, left) and "Remus" (photo Wim De Clercq, Aug 2015, right)
Poplar – Short Rotation Coppice
Short Rotation Coppice is one of the most efficient forms of energy crops you can produce in our region and provides green energy. It is a crop consisting of a dense planting of fast-growing tree species, mostly poplar and willow, harvested every 2 to 4 years. Cultivation uses no pesticides and fertilisers. Annual yields can be up to 15-20 tonnes of dry wood chips per year and per hectare. There are plantations at the research centre that aim to select the best poplar and willow cultivars for short rotation wood.
Short rotation coppice plantation with the cultivar Vesten: annual shoots on six-year-old root