The Right Tree in the Right Place… for this point in the Climate Crisis
The mantra is: ‘Plant the right tree in the right place.’ OK – we’ll plant Sessile Oak trees on Welsh hillsides, Beech trees in Cotswold valleys, and Scot’s Pines in the Highlands. What’s more, we’ll plant a belt of Alders and Black Poplars in the waterlogged area near the river, and a cluster of Silver Birch on that sandy ridge.
And we can do better still. All of our native trees support different wildlife; each one offers a distinct niche for a particular suite of species. Oak leads the way. There are three hundred different species entirely dependent on it, and another two thousand species associated with it – from lichens and fungi to butterflies and badgers. We certainly want Oaks. But if we increase the number of other tree species, we can maximise our new woodland’s biodiversity potential. So we’ll include a belt of Wych Elms – perhaps they’ll attract White-Letter Hairstreaks; plant some Hazel under the Oaks – maybe some Dormice with move in; create a glade of Willows – and one day Purple Emperors might appear.
Next we need to build structure into the woodland or ‘habitat heterogeneity’ if you prefer. Rather than having uniform rows of trees, we’ll plant shrubs to create scrubby edges, leave open areas, glades and rides. The end result will be a woodland of micro-habitats, different areas with subtle variations of temperature, moisture and sunlight levels – once again, maximising its biodiversity potential. There’s nothing to this woodland creation lark!
Well, that may have been true enough until our rampant carbon emissions put a massive climate change spanner-in-the-works. Planting the right tree in the right place has become much more complicated. Now we must plant the right tree in the right place…for this particular period in the climate crisis. I hope the trees Protect Earth plants this winter will be around for hundreds of years. But the reality is, in as little as fifty years tree species that once thrived in the UK might be struggling because of higher temperatures and drier summers. In recent years just establishing new trees has become increasingly problematic. The last three or four springs have been extremely dry, a trend that looks set to continue. There is no point planting the woodland described above if half the saplings are dead by their first summer. The tree species we select for our new woodlands need to survive their first few years, and then thrive in the next three hundred.
What’s the answer? Should we only plant tree species that we know will ‘take,’ and then go on to survive frequent drought conditions? Well that’s the Alders gone, along with the Birch and Willow, as well as all the other wildlife that depends on them. So we’re left with a woodland of, maybe, Sweet Chestnut, Crab Apple and Wild Service Tree – because all three are pretty tough and good at surviving drought conditions. There will probably be less wildlife in our woodland now, but at least these trees won’t die! Is it correct to prioritise long-term carbon sequestration over shorter term biodiversity gains?
Some say ‘hedge your bets’ – plant the greatest diversity possible, both in terms of species and genetic variation. Source the seeds of familiar species such as Oak from further south, much further, France, for example. Others are more radical still, and think planting species that are currently found on the Iberian Peninsula is the answer. Bee-eaters and other exotic looking birds, more associated with the Mediterranean region nested in Britain this year, pushed north by intense heat in Southern Europe. Some conservationists advocate planting Cork Oaks in Southern England in preparation for increasing temperatures as well as all the Bee-eaters, Rollers and Hoopoes they anticipate appearing here in the next decades.
I don’t think anyone knows for sure how we best provide woodland habitat for the wildlife we currently have, plant species resilient to a changing climate, and prepare for new species of insects and birds that will undoubtedly begin to appear. What’s certain, though, going forward, is there are many more factors to consider when deciding which tree to plant and where.