Aphalo, P.

Finér, L.

Kettunen, U.

Mannerkoski, H.

Repo, T.

Öhman, J.

Jukuri

AbstractA new facility was built in Joensuu, Finland, during 1996-1998 in order to be able to control soil temperature separatelyfrom air temperature, and to have enough soil and air space in which long term experiments, e.g. lasting for severalgrowing seasons, can be carried out with trees.Fig 2. Side view of the dasotron.Fig 1. Top view of the dasotrons.Fig. 3. Side view of a pot. Photo 1. A pot in which a Norwayspruce seedling has been grownfor two growing seasons.THE JOENSUU DASOTRONS: A NEW FACILITY FORSTUDYING SHOOT, ROOT AND SOIL PROCESSESGeneral descriptionThe facility consists of four rooms (RTR48, Conviron) calleddasotrons where air and soil temperature, air humidity and photonflux density can be controlled independently. The floor area of therooms is 9.7 m2 and volume 60.9 m3. The doors, walls and ceilingsof the rooms are insulated and the inner wall is faced with aluminiumsheeting painted white. The surface material of the floors is grey-painted concrete. Each room has inlets for tap water, deionised water,electricity and pressurized air and an outlet for waste water.Each dasotron contains four cylindrical pots (Arctest) with aremovable upper half. The maximum height of plant shoots is 3.1 m.The walls of the pots are insulated and made of black polythene.There are access holes in the walls of the pots for the installation ofsensors and minirhizotron tubes. There is a drain, with valves at thebottom of the pots for the removal of excess water from the pots orthe collection of percolation water if required. A water table can bemaintained in the pots. The pots can be filled with either organic ormineral soil, or combinations of the two. Irrigation and fertilizationof plants takes place manually.OperationAir temperature can be controlled from +1 oC to +40 oC when thelights are off, and from +10 oC to +40 oC when the lights are on. Airhumidity can be controlled within the range 37%-80% when thelights are on, and within the range 37-90% when the lights are off.Lighting is provided by means of a combination of 250 W highpressure sodium and metal halide lamps with a maximum of 4000W in each lamp canopy. The photon flux density can be controlledat five levels from 0 up to 850 mmol m-2 s-1. Filtered fresh air issupplied through the ceiling of each room at a maximum rate of 50l s-1.Soil temperature in the upper and lower parts of the pots can beregulated separately from -5 oC to +40 oC and from +1 oC to +40 oC,independently of the air temperature. Soil temperature is controlledby circulating glycol brine inside two stainless steel coils.Programming of the parameters in the rooms can be done locally(CMP4030) or through a central control system (CMP4000) runningon a personal computer.We have been using the facility since the beginning of June 1998 tostudy the effects of soil temperature on the shoots and roots of birch(Betula pendula Roth) and Norway spruce (Picea abies Karsten).The dasotrons have operated for most of the time as planned, airtemperature and humidity especially have remained well within thespecifications. In general the facility has been reliable and we havefound that it provides an excellent environment for ecophysiologicalstudies on the effects of environmental changes on the mechanismsinvolved in soil-root-shoot systems.○ ○ ○ ○ ○ ○ ○ ○ ○ ○○ ○ ○ ○ ○ ○ ○ ○ ○ ○○ ○ ○ ○ ○ ○ ○ ○ ○ ○○ ○ ○ ○ ○ ○ ○ ○ ○ ○○ ○ ○ ○ ○ ○ ○ ○ ○ ○○ ○ ○ ○ ○ ○ ○ ○ ○ ○○ ○ ○ ○ ○ ○ ○ ○ ○ ○○ ○ ○ ○ ○ ○ ○ ○ ○ ○  ^  ^  ^  ^12357  ^  ^8Room 4Room 2Room 1Room 3  ^  ^2300 mm  ^  ^4200 mm  ^  ^  ^641. Movablelamp canopy2. Evaporator3. Fresh air inlet4. Air temperature andhumidity sensors5. Light sensor6. Exhaust air outlet7. Roller blinds8. Pots  ^  ^   ^   ^   ^  ^   ^   ^1  ^  ^34  ^  ^  ^   ^Airflow  ^  ^Air out  ^1. Lamp canopy, movable2. Pot3. Evaporator4. Roller blinds5. Dehumidifier6. Filter  ^  ^4900 mm  ^  ^  ^Air in  ^5  ^  ^  ^  ^4200 mm  ^  ^62  ^  ^  ^1  ^2  ^3  ^ 3  ^45  ^Soilsurface46  ^7UpperhalfLowerhalf  ^  ^  ^  ^300 mm1300 mm  ^  ^  ^  ^700 mm850 mm1. Transparent tube for monitoring ground water depth2. Drainage water outlet with two valves3. Glycol inlet and outlet4. Soil tempering coil5. Insulating lid6. Minirhizotron tube through the pot7. Hole for installing sensors in soil  ^  ^  ^  ^  ^L. Finér1, P. Aphalo2 , U. Kettunen1, H. Mannerkoski2, T. Repo2 & J. Öhman3.1 Finnish Forest Research Institute, Joensuu Research Station, P. O. Box 68, 80101 Joensuu, Finland;2 University of Joensuu, Faculty of Forestry, P. O. Box 111, 80101 Joensuu, Finland;3 Arctest Ltd., P. O. Box 15, 02761 Espoo, Finland

The Joensuu dasotrons: a new facility for studying shoot, root and soil processes

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The Joensuu dasotrons: a new facility for studying shoot, root and soil processes

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