Warming experiment (温暖化実験)
To demonstrate the effects of climate chages on plants in fields, the following field experiments are important.
Types of experiments
Table 1a. Comparison of currently used methods for experimental warming of terrestrial ecosystems (Shaver et al. 2000)
| Method | Mechanisms of warming | Advantage | Disadvantage |
|---|---|---|---|
| Field greenhouse | "Greenhouse warming" (i.e., reflection of reradiated infrared energy and reduced advective energy loss) | Simple and inexpensive; requires no electrical power | Little or no temperature control and large temperature variability; other artifacts include altered light, wind, humidity, and precipitation regimes |
| Passive open-top chamber (OTC) | Same as above | Same as above | Little or no temperature control; altered wind and humidity; only small areas can be manipulated uniformly |
| Active open-top chamber (OTC) | Same as above plus warming by advection of electrically heated, forced warm air | Precise control of air temperature difference; may be combined with CO2 control | Altered wind regime, humidity, and evapotranspiration |
| Active soil warming | Warming by conduction from buried electrical resistance cables | Precise control of soil temperature difference; may be combined with greenhouses or OTCs | Altered soil moisture regime; no effect on aboveground temperatures |
| Electric infrared heat | Warming by increased infrared radiation | Precise control of energy input; direct simulation of global change in energy balance | Warming depends entirely on radiation; no change in advective energy inputs |
| Reciprocal or one-way transplantation | Transplantation of plants, soils, or whole plant?soil systems to warmer or cooler locations | Comparison of relatively natural temperature gradients | Disturbance effects; multiple environmental changes make it difficult to assign specific causes to responses observed |
[Left] Greenhouse and shaded house for monitoring the effects of climate chagne for long-term at Toolik Lake on August 8 2009. [Right] an open-top chamber established at Abisko Scientific Research Station, Abisko, Sweden on September 24 2000 (Photo by Wada N.)