Zero Power Warming – A New Technology for Investigating Plant Responses to Rising Temperature

Abstract:

Investigation of terrestrial ecosystem responses to rising temperature often requires temperature manipulation of research plots, and there are many methods to achieve this. However, in remote locations where line power is unavailable and unattended operation is a requirement, passive warming using solar energy is often the only viable approach. Current open topped passive warming approaches are unable to elevate enclosure air temperatures by more than 2°C. Existing full enclosure designs are capable of reaching higher air temperatures but can experience undesirable high temperature excursions. The ability to simulate future climate conditions using modulated temperature manipulations is critical to understand the acclimation of plant functional and structural traits to rising temperature and to enable improved model projections of a warming planet. This is particularly true for the Arctic—our target environment—where projected temperature increases far surpass those possible to achieve using current passive warming technology. To meet the research need for improved passive warming technology we have designed and tested a Zero Power Warming (ZPW) chamber capable of unattended temperature elevation and modulation. The ZPW chamber uses a novel system of internal and external heat exchangers that allow differential actuation of pistons in coupled cylinders that control chamber venting. This allows the ZPW chamber to heat the enclosed plot to a higher temperature than an open topped chamber but avoid the overheating typical of fully enclosed chambers. Here we describe the technology behind the ZPW and present data from a temperate prototype that was able to elevate and modulate the internal air temperature by 8°C, a marked increase over existing passive warming approaches. We also present new data from a recently deployed Arctic prototype. Whilst the ZPW chambers were designed for the Arctic, the concept described here can be adapted for many research environments.