ISHS Acta Horticulturae 440: International Symposium on Plant Production in Closed Ecosystems
ENVIRONMENTAL MODIFICATION AND SHOOT GROWTH IN A CLOSED ECOSYSTEM TO EVALUATE LONG-TERM RESPONSES OF TREE SEEDLINGS TO STRESS |
| Authors: | D.M. Olszyk, D.T. Tingey |
| Keywords: | controlled environment, Douglas-fir, Pseudotsuga menziesii vegetation |
| Abstract:
Determination of ecosystem responses to stress requires careful control of the environment and measurement of biological effects. Closed chambers provide appropriate environmental control and measurement, but chamber impacts on the ecosystems must be documented so that treatment effects can be interpreted properly. A set of sun-lit chambers with control of atmospheric CO2, air temperature, and dew point has been in operation for over 2 ½ years. The chambers are being used to evaluate responses of Douglas-fir (Pseudotsuga menziesii) seedlings to elevated CO2 and temperature. Comparison of trees grown in chambers at ambient CO2 and temperature (ACAT) with corresponding outside “chamberless trees” (CL) indicates that ACAT trees have less growth (e.g. smaller stem diameters, fewer branches, and shorter terminal buds) compared to CL trees. However, needle characteristics are essentially the same for ACAT and CL trees. The differences in growth for ACAT vs. CL trees likely can be attributed to less soil moisture and lower light intensities, and possibly slightly greater vapor pressure deficits in chambers vs. outside. Air temperature and CO2 levels were very similar for ACAT and CL trees and likely do not affect tree growth. Thus, growth of the trees to CO2 and temperature in the chambers are representative of the imposed climatic conditions, and can be used to estimate effects of climate stress. | |
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