STRESSED ECOSYSTEM RESEARCH 



Barrow Terrestrial Manipulations'*' 



Larry Tieszent 

 Paul Gerspert 

 Rod Arkley 

 Steve Mac Leant 

 Bob Benoitt 



Augustana College 

 University of California 

 University of California 

 University of Illinois 

 Virginia Polytechnic Institute 



Gunter Weller 

 Jerry Brown t 

 Dave Schaefer 

 Bill Powell 



University of Alaska 

 USA CRREL 

 University of Alaska 

 University of Alaska 



The objective of the manipulation experiments and the description of the treatments at sites 1 

 and 2 are presented in the section on research design. Some of the effects of the manipulations 

 can be observed in the data presented in Table XXVI. The results of the oil treatments are dis- 

 cussed in a later section. Figure 20 shows one of the plots (clip and clear) with the insect 

 emergence traps on opposite corners of the plot. 



Abiotic 



Depths of thaw measurements in late summer reflect cumulative seasonal influences of the sur- 

 face manipulations. At site 2, the five control plots all produced similar average thaw depths, 

 indicating satisfactory replication for at least the physical soil properties among the control plots. 

 The most apparent effect of the natural manipulations was the reduction in thaw by varying amounts 

 of mulch, and the increased thaw on the clip and cleared plots. A trend towards increased thaw is 

 suggested on the clip and uncleared plots. For the artificial manipulations, the intensive physical 

 disturbance produced a substantial increase in thaw; however, the light intensity treatment had 

 minimal effect. The heated air of the greenhouse produced an increase in thaw of 6 cm over the 

 adjacent control by early August. Figures 10 and 11 show the seasonal progression of thaw for 

 different manipulations on the two sites. The July mean air temperatures for the greenhouse and 



control were; 



Surface 15-cm height 



Control 

 Warm air 



6.2°C 

 9.6°C 



6.1°C 

 7.4°C 



Figure 21 is a view into the partly opened greenhouse. 



The heated soil experiment was initiated in early summer at site 1 to provide an in situ year- 

 round facility to test the effects of warm soil on the biological and thermal regimes of the tundra. 

 The experiment was designed and installed as a cooperative effort between USA CRREL and the 

 Institute of Arctic Environmental Engineering, University of Alaska, '.t was originally designed to 

 simulate the heat Qow at the ground/air interface from a buried, hot oil pipeline under arctic coastal 

 conditions. The immediate objectives were 1) to determine the physical and thermal response of the 

 wet tundra soils and ice-rich permafrost to a continuous above- freezing heat input and 2) to evaluate 

 seasonal biological responses under the imposed vertical and horizontal thermal gradients. Figure 

 22 is a photograph of the experimental setup. The strings indicate the location of the buried 1.25- 

 cm-diam copper tubing. 



♦Essentially all project participants named in preceding sections of the report were involved in this inte- 

 grated program. Only the project leaders or new personnel are listed. 

 tPrincipal authors. 



59 



