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Seeing the wood for the trees

Forest pictureIf you have ever been to a dense forest, or have been lucky enough to go to a rainforest (I have! Not that I’m bragging…) you may have looked down by your feet and wondered how the plants that grow very low to the ground survive. We all know that plants need sunlight to grow, but even in the height of summer, in a very dense forest, very little light can get through to the plants at the bottom.  Nonetheless, there may also be advantages to growing close to the ground – smaller plants need smaller roots, and when there is lots of competition for nutrients in the ground, having smaller roots may be a distinct advantage.

Recent research has shown a second benefit of being a small plant hidden under a blanket of larger ones. This canopy effect over the top of the smaller plants can create what’s known as a micro-climate. In short, this means that underneath the trees the climate is very different to the climate above the trees. Next to the forest there may be warm, dry sun, but inside the forest it is likely to be cool and humid, and this is less likely to vary throughout the year. This means that certain plants have adapted to like this kind of environment and thrive within it and in fact 80% of the plants in a temperate forest are on the forest floor – so it’s a huge percentage of the biomass.

The really good news to come out of this research is that this canopy effect can help regulate the effects of climate change on the forest floor, and the effect is already being seen in temperate forests in the northern hemisphere. So there is hope for our forests after all. If enough of the taller, canopy trees can adapt and change to cope with climate change (and namely a drier climate) – and this is a big IF – then the plants underneath will be able to carry on with the vital work that they do in nutrient cycling (where plants harness certain nutrients from the sun, air and water and when they die these nutrients are released back into the ground – the mushy leaves all over the floor in autumn are actually really important ecologically for this reason) and all will not be lost. BUT, to do this we have to stop cutting down the big trees, and we have to try to stop the big trees becoming victims of climate change or disease.

So, this is just one more great reason to get involved with preserving forests. The more tall trees that can be saved, the more smaller plants will also be saved and the more habitats for animals will also be preserved. The Woodland Trust works to preserve woods and forests in the UK and there are similar bodies working in other countries the world over – why not see what you can do to help today?


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Blog post by Linda Seward of Seward Technical Writing, providers of original science content.

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