This spring is especially important to the Birmingham Institute of Forest Research (BIFoR), because it marks 12 months until a major new experiment is switched on. Director, Professor Rob Mackenzie, explains more.
Carbon dioxide plus water plus light gives sugar and oxygen. That’s photosynthesis, and from the sugar all carbon-based life proceeds, as long as nitrogen, phosphorus, and the other nutrients are available in the right amounts. Like a green carpet of photovoltaic cells, the plant world captures energy, uses that energy to build itself, and sacrifices large parts of itself to us and every other respiration-only organism that hitches a ride on the plant world’s air solidification trick.
Respiration, as every adolescent biologist knows, is essentially the reverse reaction to photosynthesis, completing a circle that uses the energy of sunlight to sustain an immense and balanced complexity. We used to call all this ‘life’ and ‘nature’, and enjoy the delicate tracery left by human activity. Now we must speak of Natural Capital and Ecosystem Services and translate the various stocks and flows of global metabolism into a single unit of exchange, like carbon or money. Why? Because we have pushed the living planet beyond the boundaries of its resilience by intervening in the natural circular flow of carbon and nutrients, resulting in a pressing need to remember, to quantify, and to value the work done by the non-human inhabitants of Earth.
We still do not know where the carbon goes in a mature forest. When human activity, especially emissions of carbon, nitrogen and phosphorus, move the ecological goalposts, the sun will no longer support a steady, circular flow of elements through a forest ecosystem. Instead, the system will respond by moving material from one reservoir to another. So far, the response of the world’s land surface (especially its forests) to the carbon dioxide we have put into the air by burning fossil fuels is to absorb about a third of the emissions and store the carbon somewhere. It is not entirely clear where all the carbon is stored, for how long the carbon will be stored, and whether this storing process will keep pace with our carbon emissions.
These are the uncertainties to be clarified in a major new experiment: the BIFoR Free-Air Carbon Dioxide Enrichment (FACE) experiment at Mill Haft woodland in Staffordshire. The FACE technique isolates the effect of carbon dioxide changes while retaining the complexity of the oak woodland ecosystem in which it is established. The experiment, including preparatory measurements, is designed to run for more than a decade — much, much longer than conventional lab and chamber experiments — and so much better suited to establishing by just how much we are moving the carbon, nitrogen and phosphorus goalposts.
Each dawn and each spring, as photosynthesis begins, extra carbon dioxide will be made available to patches of oak-and-hazel woodland. Each dusk and each autumn, respiration will dominate and the carbon dioxide be returned in part to the atmosphere. As the days and seasons pass, each part of the ecosystem – above and below ground; plant, invertebrate and microbe — will be monitored for change and to see by how much, and in what ways the circular cycling of carbon and other nutrients has changed.