Julian Days 

 Figure 7 — Smoothed curves for a 23-day period 

 contrasting windspeed on the instrument tower 

 between a thinned and unthinned lodgepole pine 

 stand. 



205 



2T5 



225 



Julian Days 

 Figure 8 — Smoothed curves for a 23-day period 

 contrasting windspeed on the instrument tower 

 and in the crown between a thinned and 

 unthinned lodgepole pine stand. 



a. 



Julian Days 



Figure 9 — Smoothed curves for a 5-day period 

 contrasting windspeed on the instrument tower be- 

 tween a thinned and unthinned lodgepole pine stand. 



Wind Direction (23 Days) — Wind direction was meas- 

 ured on the instrument tower and was obtained mainly 

 for reference purposes. Wind direction varied between 

 200° and 250°, indicating the average wind direction is 

 from the south to southwest. Also, there was no major 

 difference in direction between the two stands. 



Wind Direction (5 Days) — The average wind direction 

 for the 5 days varied between 130° and 250° compared to 



between 200° and 250° for the 23-day period. The larger 

 range in wind direction for the 5 days shows that some 

 detail is being lost when smoothing techniques are used 

 over longer periods. As in the 23-day period, no major 

 difference in wind direction occurred between the thinned 

 and unthinned stands. 



Stand Temperatures — Temperatures of the ground 

 and south sides of trees were significantly higher 

 (P <0.05) in thinned than unthinned stands (ground tem- 

 perature: thinned i = 30.8 °C; unthinned X = 26.0 °C) 

 and south side at breast height (thinned x = 26.6 °C; 

 unthinned x = 24.3 °C). North sides of trees were not 

 significantly different (thinned x = 24.2 °C; unthinned 

 i = 23.5 °C) (table 2). 



Beetle Response 



The number of MPB caught in pheromone-baited traps 

 in a thinned stand was only about 5 percent of the total 

 caught in both thinned and unthinned stands. These 

 stands were 1 km from stands where microclimate meas- 

 ures were made. The average numbers of beetles caught 

 per trap were: thinned x = 8.7; unthinned x = 159.3. 

 Most trapped beetles were females, with a higher percent- 

 age being caught in thinned than unthinned stands 

 (thinned = 88.5 percent female; unthinned = 81.2 percent 

 female) (table 3). Stands in which microclimate measures 

 were made had 14.2 trees/ha (2.0 percent) killed by MPB 

 in the thinned stands compared to 174.1 trees/ha (16.0 

 percent) killed in the unthinned stand. 



7 



