Woodland Ground Flora Project

Woodland Ground Flora Project

Although the initial work of Trees for Life was focused on helping a new generation of young trees to become established in the Caledonian Forest, our project has always encompassed all elements of the forest ecosystem. As part of this, we’ve had a long standing interest in the woodland ground flora – the flowering plants that flourish on the forest floor, underneath the trees.

Because of past deforestation many woodland ground flora species have lost most of their former habitat. Even where old remnants of the Caledonian Forest still survive, they are mostly highly overgrazed, and the diversity of ground vegetation has been greatly reduced and many species have been removed completely. Woodland ground flora species provide food and shelter for a range of invertebrate species, which are food for small predators like spiders, wood ants and centipedes. In turn, those invertebrates are eaten by birds and small mammals higher up the food web, who will themselves be fed upon by predators such as hawks, owls and the pine marten (Martes martes). Thus the loss of flowering plants ripples through the entire forest ecosystem.

Some species of flowering plant are able to disperse quite readily. The seeds of cowberry (Vaccinium vitis-idaea), for example, are distributed by the birds that eat the berries and deposit the seeds in their droppings, often a long distance away. They are therefore able to colonise areas of new or regenerating native woodland by themselves. For other species such as twinflower (Linnea borealis), however, where their main method of reproduction is vegetative, it is very difficult for them to re-colonise areas where they have been lost, even if the habitat for them has been restored. In those cases, active restoration work can assist their recovery, and it’s to address this that we established our Woodland Ground Flora Project.

There are several elements to the project, including surveying for evidence of woodland ground flora species and mapping their occurrence and distribution; carrying out research projects associated with the ecology of various species and aspects of our restoration work for them; propagation of a range of species, including specialised techniques for rare or hard to grow species; planting of woodland flora species to boost existing populations and establishing new ones; and linking our work with that of other organisations. 

Practical work on the Woodland Ground Flora Project began in 2003, when we carried out a survey of an area of birchwood at the east end of Glen Affric. The results showed that the flowering plants there were typical of an upland oakwood vegetation community, not a birchwood. Although there were virtually no oak trees in the area, the survey indicated that it would formerly have been an oakwood, with the ground flora having persisted after the removal of the oaks, most likely for their timber. This enables us to make the measure for implementing measures to achieve regeneration of oak and other trees such as hazel there.

Subsequently, we’ve carried out a number of surveys at various other sites, and have mapped the locations where a number of scarce ground flora species, such as creeping ladies tresses (Goodyera repens), intermediate wintergreen (Pyrola media) and twinflower (Linnea borealis) are occurring. This mapping exercise enables us to evaluate the sites where these species survive, and plan out measures to expand their populations there. It also provides the information we need to locate the seeds and cuttings for the propagation element of our project.

The woodland ground flora component of the Caledonian Forest has been relatively little-known until recently, so research projects are an important element of our work. For example, we have had MSC students from Imperial College London and Leeds University carry out projects on the ground flora regeneration in replanted native Caledonian woodland 
in Glen Affric, and the local environmental factors that determine the health and success of twinflower populations respectively. Currently, we have an ongoing, multi-year research project being carried out by undergraduates from Edinburgh Napier University on the impact that the wild boar (Sus scrofa) we are using for bracken control at our Dundreggan Conservation Estate are having on the woodland ground flora there.

We have also been participating in educational or skill-sharing events about woodland ground flora with other organisations, including the Woodland Trust, Forestry Commission Scotland and Scottish Natural Heritage.

Our practical work began with planting some common woodland ground flora species that were absent from areas where we were either planting new trees, or putting up fenced exclosures to achieve natural regeneration of existing overgrazed woodlands. This got underway in 2005 with species such as primrose (Primula vulgaris), wood sorrel (Oxalis acetosella) and cowberry (Vaccinium vitis-idaea), which were planted out in native woodland restoration areas near the Athnamulloch bothy at the west end of Loch Affric in the Glen Affric National Nature Reserve.

After a fundraising appeal to our supporters in 2007, we expanded this work, focusing on the propagation of the scarcer species of flowering plants, including twinflower (Linnea borealis) and the orchids, creeping ladies tresses (Goodyear repens) and lesser twayblade (Listera cordata), which are grown from cuttings taken from mature plants. Others, such as intermediate wintergreen (Pyrola media) and serrated wintergreen (Orthilia secunda), have been propagated from both seeds and cuttings. This work is particularly important for twinflower, as the species is very rare in Scotland now, and in Glen Affric there are only two small populations known to exist. These are separated from one another by over 10 kilometres, so they cannot cross pollinate each other. In that case our work has focused on raising new plants from cuttings from each of the source populations and then planting those out beside the other population to provide the opportunity for genetic exchange through cross pollination.

We have also carried out propagation of small cow-wheat (Melampyrum sylvaticum), a hemiparasitic plant that is a priority for conservation under the UK Biodiversity Action Plan, and have done a trial planting of this scarce species at Dundreggan.

In addition to continuing the propagation of rare species such as twinflower in our nursery at Dundreggan, we are also growing some of the commoner species of flowering plants, including bluebell (Hyacinthoides non-scripta) and devilsbit scabious (Succisa pratensis), which is a pollen source for a rare mining bee (Andrena marginata).

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