Bradley Andrews (Community Engagement and Conservation Intern) writes:
Improving the forests hydrology to combat the effects of climate change is great idea. But, how do we know if making dams along the forest watercourse will have actually made a difference?
Well, we could take a stroll along the Sarre Penn in a couple of months’ time and decide if things are looking a bit more soggy, but that wouldn’t paint the whole picture. Luckily at RSPB Blean we have some specialised tech to help us understand what is really going on beneath the surface.
Since the initiation of the rewetting project we have been gathering a series of soil moisture readings from specific sites across the Blean. These soil moisture readings will act as our control data, providing us with a baseline of measurements that we can compare after the implementation of our dams. We have been able to gather this data using a soil moisture meter, a device which uses a pair of probes placed in the soil to get a voltage reading. The higher the voltage reading, the more moisture there is in the soil.
We have currently been conducting our soil moisture readings across Kent Wildlife Trust's South Blean reserve, where we have a wonderful bog habitat, and around RSPB Blean where the main body of the Sarre Penn flows. Each location is split into two soil moisture points. The first point at each location is a control site. This is situated downstream of where a dam will be placed. The second reading point will be our modified site, located upstream from the dam which will be placed there in the coming weeks. The area downstream of the dam is considered to be the control site because, in theory, it will encounter less change. The majority of the dams effect will occur upstream of the dam site, where the water will pool and spill over the banks and, hopefully, flood the areas adjacent to the river.
Ok, so we’re creating all of this wet, saturated soil across the Blean. You’ve heard the grand plan of increasing the forest’s resilience to climate change. But what is really happening when we create our wetter Blean?
Firstly, the more water we can encourage the forest to hold throughout the year, the more resistance to drier months it will have. As well as this, increasing the volume of moisture saturated soil will increase the ability for the forest to store carbon. This is achieved through the quantity of humus present in the soil (that’s humus not hummus, I promise you it’s not a delicious chickpea product). Humus is the result of the accumulation of soil organic matter. Think leaf litter, deadwood and decaying organisms. This is the equivalent of compost for the forest. An increase in soil organic matter leads to increases in total soil surface area, water holding and buffering capabilities. As well as this, it should lead to an increase in biotic activity. That means a whole host of invertebrates will be very happy with the increase in moisture content and will get busy circulating nutrients throughout the soil, as well as themselves increasing the bounty for our lovely woodland birds.
Our improved hydrological conditions may also be of benefit to forest fungi. Fungi play an important role in the ecosystem. You may be familiar with fungi presenting themselves as mushrooms above ground. Think of the mushrooms like the fruits on a tree. They provide the fungi with a mechanism for dispersal through airborne spores. However, that really is only the tip of the iceberg, as the really interesting stuff happens below ground. The main fungal mass is in the form of mycelium. This is a vast network of interconnected organic strands which spreads all across the forest. The mycelium act similarly to a neural network, allowing chemical communication across different fungal species and even the trees they surround. In fact, the mycelium are in business with the trees. Through a chemical barter system the mycelium trades glucose molecules with the trees roots in exchange for carbon molecules and the tree may even trade up to 70% of its carbon with the mycelium. WOW!
It’s pretty amazing what can be achieved with a few strategically placed sticks in the water. What’s even more amazing is that, given half a chance and the right conditions, nature will steer itself back on course at an incredible rate.
If you feel inspired to be on the front line of climate change resilience in one of the country’s best examples of an ancient woodland, make sure you come along to one of our Tuesday or Saturday volunteer sessions. All are welcome and all are appreciated - just drop an email to milo.sumner@rspb.org.uk