Oil spills. The effects and fate of hydrocarbons in the tundra environment is unknown. Two 

 experiments to qualitatively determine the influence of oil spills on the plants and microflora were 

 established. On site 1 four plots received 5 liters/m\ and on site 2 rates between 0.7 1/m^ and 

 12 1/m^ were used. Details of this experiment are given in a later section. 



Figure 5 is an aerial oblique of the site 1 test plots. Several plots are enclosed by fencing. 



The community gradient site, located approximately 200 m south of site 2, was used to investi- 

 gate the response of several ecosystem components to a wider variety of tundra conditions. This 

 site included six study plots: 



Plot 1, in a low, very wet meadow. On June 22, when the plots were marked, this plot had 

 just been exposed by melt-off. Frozen ground was just below the surface, and the plot was covered 

 with standing water. 



Plot 2, in a trough between two polygons. This plot differed from the others in being 3 x 12 m 

 rather than 6 x 6 m because of the linear nature of the habitat. Like plot 1, it was quite wet. It 

 was exposed several days prior to June 22, and was covered with standing water on that date. 



Plots 3 and 4, on mesic, meadow tundra of very gradual slope. The slope provided some 

 drainage, so that standing water never accumulated. Plot 3 was in an area of weakly developed 

 polygonization, and. occupied the center of a low-centered polygon. Plot 4 was on an unpolygon- 

 ized slope. 



Plots 5 and 6, on the tops of well-developed polygons. These plots were quite exposed; snow 

 accumulation in winter was inhibited by wind, and these were the first plots to be exposed by 

 spring melt-off. Plot 5 was bare of vascular vegetation in places and showed evidence of erosion. 

 Plot 6 was more completely vegetated. 



The aquatic program consisted of a series of small ponds (Fig. 3, site 7). Control ponds were 

 monitored for the entire summer to determine nautral variations. Several ponds were stressed with 

 nutrients and oil for reasons similar to the terrestrial perturbations. Table II contains a list of 

 plot numbers and treatments for each site. 



The main study area was established in late May and early June on both sides of Footprint 

 Creek, 4 km SW of the Naval Arctic Research Labaatory (Fig. 2, 3). This location contained the 

 large areas of relatively homogeneous tundra required for the study and could be supplied with 

 high quality, continuous electrical power from the Barrow camp. 



On both sites 1 and 2 a number of study plots, each 6 x 6 m, were selected and marked. The 

 plot size was chosen to provide an area large enough for repeated and replicated sampling at 

 intervals throughout the season, yet smaU enough to minimize within-plot heterogeneity. After 

 the plots were selected they were gridded, treatments were allocated to the plots at random and 

 a random number process was used to identify sample quadrats in each plot. 



The plot selection process was completed immediately after melt-off, and the first set of 

 samples was taken from the site 2 control plots on 15 June. Thereafter samples were taken at 

 10-day intervals. Certain measurements were taken from the manipulated plots at 10-day intervals, 

 while other measurements were taken twice, once early in the season and once at peak standing 

 crop of the current season's plant production. Wherever possible samples for the various abiotic 

 and biological measurements were taken at the same time and place to allow correlation of the 

 various ecosystem parameters. The sampling schedules are summarized in Appendix A, 

 which shows dates and kinds of samples taken from the various study plots and ponds. 



In addition to the seasonally varying observations, several projects measured relationships 

 existing between ecosystem parameters independent of time of season. Examples of such studies 

 include the relationship of photosynthetic rate to air temperatire and gas concentration, and the 

 relationship of animal metabolic rate to ambient temperature. These data complement the seasonal 

 observations, especially in our attempt to understand the mechanisms of interaction of ecosystem 

 components, and thus are an important part of the modeling effort. 



11 



