Regeneration and woodland renewal

While Autumn often appears to be a season of decay, the berries, nuts and seeds that appear on trees (and other plants) in abundance point to regeneration and new life. This year the rowan branches were drooping under the weight of the their berries, until big flocks of redwings and various other birds descended in late October. While it was not the best year for acorns, the jays still managed to find some and could be seen flying from the big oak trees by the river across to our hillside woodland. Some of the acorns they deposit here will grow into a new generation of oak trees. This can already be seen by the number of small oak seedlings in the wood. Now that we are starting to open up small areas in the woodland, there will be enough light in these spaces for oaks and other self-sown tree seedlings to grow. Tree regeneration (regen) is crucial to the future evolution of the woodland, and understanding how this is likely to develop will influence my management decisions as I continue to remove small areas of spruce trees.

Successful regeneration of trees also requires a low level of browsing by deer and other herbivores. We finally managed to fence the local feral sheep out of the wood last year. Deer are present, but so far browsing levels appear to be low enough to allow growth of tree seedlings. As we start to have more areas of regenerating trees (as groups of spruce are cleared) I will monitor this closely and anticipate the need to do some deer management.

Tree regeneration in the areas around the house has been good. These are areas of spruce that were felled in 2019, before we built the house. I planted a mix of native species in early 2020, including hazel, holly, hawthorn, blackthorn, guelder rose, juniper, oak, rowan and wych elm. Many of these trees are now well established and have been joined by natural regeneration of birch, alder, bird cherry, larch, Scots pine and spruce. Interestingly, there seems to be a steady number of Scots pine seedlings appearing, especially in areas of bare ground. The nearest Scots pine trees are half a mile away, demonstrating how effective these pines are at dispersing their seed. This year I started re-spacing some of the larch and spruce regen in this area, using a pair of loppers, in order to favour other species and prevent the larch and spruce from becoming dominant. This was relatively quick, easy and enjoyable to do.

The edges of the tracks that were built in 2020, where the ground was disturbed, have seen prolific regen in areas where light levels allow. There has been a lot of spruce regenerating in these areas, as well as birch, alder, bramble and many ground flora species. Being immediately adjacent to the tracks, I will need to remove trees from these edges when they get slightly bigger, probably with a brushcutter.

I am keen to see how natural regeneration develops in the coupe that was felled during winter 2022-23. This was an area of poor spruce about 30m x 40m across. I plan to gradually remove the spruce from the rest of the woodland by felling small coupes like this (or slightly bigger) and this was the first, so a kind of experiment. The area is surrounded by birch trees, a few alder and bird cherry, as well as spruce and some larch, so I am anticipating plenty of birch and lots of spruce regeneration.

We planted alder in the wetter, lower half of the coupe in the spring. I was keen to plant, and to get some new trees established, but perhaps I should have waited to see what regenerated naturally first. However, no trees were planted in the other half of the coupe, so it will be interesting to compare how the two halves develop. I envisage managing the regenerating trees for future hardwood timber production and had anticipated a mix of primarily birch and alder, but I will be guided by what regen appears. I expect there will be large amounts of spruce regen and I will aim to remove this during the re-spacing process. I noticed large numbers of spruce seedlings appearing in a mossy area at the bottom of the coupe where it must be easy for them to germinate and I spent a little while pulling these out to avoid a dense thicket of spruce growing up. Given the current prevalence of spruce throughout the woodland, I expect managing spruce regen will be a major challenge as I open up more small coupes.

We began felling a second small coupe last winter and plan to finish felling this winter. My plan for this one is to restock with a mixture of silver birch and Douglas fir. While I wish to help a diverse range of native species re-establish in the woodland, I would like to include a (relatively small) proportion of certain non-native conifers, such as Douglas fir, in the mix. These trees grow well in our area and can produce quality timber. Douglas fir is not invasive in the same way as Sitka spruce. If managed appropriately (i.e. pruned and thinned and in a mixture with other species) then I don’t see them as being detrimental to biodiversity and they may actually enhance the diversity and range of habitats in the woodland.

While natural regeneration of certain species in the woodland is likely to be good, such as silver birch and perhaps alder, seed sources of other desirable species are more limited, so I plan to plant some types of tree to increase diversity. Such species include oak, hazel, hawthorn, holly, willow and perhaps rowan, bird cherry and alder depending on natural regen levels. Given that I am only going to be felling and restocking a relatively small area in any year (current plan is around half a hectare per year, split between two coupes), I thought it could be possible to grow the trees I need myself. This would allow me to collect and propagate local seed and to save some money on purchasing young trees. I like the idea of growing trees as a further dimension to our project here and if I have surplus stock I could grow it on to sell locally. However, I have never grown trees before, so I have a lot to learn about the practicalities and I have been reading up on it.

This summer/autumn I have been collecting seed from the species I thought I would try initially: silver birch and rowan in late August, hazelnuts in mid-September, hawthorn berries in early October. I planned to collect acorns but there was hardly an acorn to be seen on local trees this year and the ones I did see were very small, so I decided to leave oak for this year. I will collect alder seed in November.

The seeds then have to be processed in certain ways to promote germination in the spring, by doing something called stratification, which seems to be a little bit of a dark art. So rowan berries were mashed up and then mixed with a 50:50 mixture of sand and compost and left outside in a freely draining flower pot. Hawthorn berries were treated similarly, though I made more effort to wash the flesh off the seeds. Hazelnuts were also mixed with sand and compost but left in a mouse-proof bucket in our shed. Birch seeds were air-dried and are now in a tub in the larder until late winter, when they can be soaked and sown. Alder will be the same.

I am learning that tree seeds behave differently depending on species and the type of seed (e.g. nut/berry/cone). Some have chemicals in them which inhibit germination (to avoid the seed germinating too early). They need to go through cycles of cold and warmth to stimulate germination. The berry flesh can also inhibit germination. From what I have read, the hawthorns will probably not germinate until the spring after next – 2026! Some of the rowans may germinate next year and some the following year. Birch and alder germinate more freely and hazel should germinate in the spring.

I plan to grow the trees in trays of cells rather than beds as I am only growing small numbers and I don’t have anywhere suitable for beds. Assuming I get some germination I will need to prick out the seedlings into compost-filled cells. I’ll then need to look after my cohort of new trees that, hopefully, will be able to be planted into the woodland a winter or two later. These baby trees will supplement the efforts of the jays and other birds, squirrels, mice and wind in bringing a renewal of diverse woodland as I gradually remove the spruce from Comar Wood.