Measuring ecosystem exchanges of carbon from photosynthesis can be tough on upland peatlands: light conditions are often challenging and highly variable, and every piece of equipment must be carried long distances across uneven and/or boggy ground. To address both the light conditions and practical concerns, the authors investigated whether supplementary light from a hand-held LED torch might offer a viable solution.
Two of the authors in action, using an LED torch to improve light responsiveness modelling.
Photo: Tom Holmes / SEI
Plant and soil fluxes are a vital part of carbon cycling; these must be measured effectively to understand net carbon balances. The use of chambers – as seen in the image above – to monitor photosynthesis and respiration from plants and soil is a key way of measuring these ecosystem exchanges of carbon. However, these measurements have, historically, relied on natural light. This is a problem in upland peatlands, which frequently have thick cloud cover, mist, or fog.
Previous light solutions had included fixing an LED light to the top of the flux measurement chamber. However, this had the unintended consequence of blocking out natural light present and generating artificial heat, influencing photosynthetic rate. Moreover, the fixed LED lights had a high-power demand and were heavy – unhelpful for remote fieldwork.
The authors decided to trial using an LED torch to address this problem. They found that the LED torch worked well as a supplementary light source, without compromising results: a flexible, low-power and low-weight solution. The light provided from the torch enabled the team to improve confidence their overall model fit for light responsiveness of photosynthesis, and helped them to better understand the amount of light needed for the net ecosystem exchange to switch from a net carbon source to a net carbon sink. The authors also highlighted that – when modelling annual ecosystem carbon balances – seasonal changes in light response should be considered.
Additional funding was provided by the Moorland Association and the Law Family Charitable Trust.
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