Chris Field Carnegie Institution 260 Panama Street Stanford, CA 94305 cfield@globalecology.stanford.edu (650) 462 1047 x 201
This is a suggestion that NEON invest in a multi-site facility for long-term studies of ecosystem responses to the interacting effects of warming and elevated atmospheric carbon dioxide. Such a facility would provide unique opportunities to address some of the key scientific challenges facing our generation. Because the ecological community has historically lacked the resources for major facilities, we have NO experimental evidence on the long-term responses of managed or natural ecosystems to the factorial combination of warming and atmospheric CO2 that might occur in 2100. As a consequence, all of the ecosystem models used to explore the future are based on concepts that are incompletely tested.
The NEON climate-change research facility should provide the following: 1) Warming of ambient plus 4C. 2) Atmospheric CO2 at 750 ppm 3) A factorial combination of warming and elevated CO2 4) Sufficient replication (probably 4 replicates per treatment per site) 5) Sufficient capacity to explore full-scale ecosystems, including ecosystems dominated by trees 6) Replication at a number of sites sufficient to explore responses across the parameter space defined by climate, soils, and vegetation type. 7) The capacity to operate for sufficient time to capture a broad range of relevant mechanisms, including changes in nutrient availability and changes in the relative abundance of plant and microbial species.
All of the available technologies for providing the necessary combination of warming and elevated CO2, at the relevant scale, have important limitations. These limitations are minimized in a system based on greenhouses. Construction costs for the greenhouses and the control infrastructure should be no more than $200,000 per experimental plot. With 16 replicates per site, the basic facility expense will be on the order of $4 million per site ($3.2 million for chambers and $0.8 million for other infrastructure). Deployment at 8 sites will bring the total infrastructure cost to approximately $32 million.
Eight sites chosen to cover key elements of the parameter space defined by climate, soil, and vegetation should include: 1) Arctic tundra 2) Boreal forest 3) Tropical evergreen forest 4) Temperate deciduous forest 5) Mediterranean woodland 6) Agricultural crop 7) Prairie 8) Desert
Operating costs for the experimental facility will include expenses for CO2, heating, and cooling. With greenhouses, the costs for CO2 and heating will be dramatically less than with alternative technologies. Cooling costs will be low in the sites where the cooling can be evaporative (perhaps all sites). In the other sites, cooling costs will be substantial.