Tree Improvement Program Project Report 2006 / 2007

complete report on pollen capture at all five stations for Hw
and Ss for 2006 is available for project SPU 0313 (2006)
from the OTIP coordinator.
Methods
The ministry standard for monitoring pollen cloud
density uses seven-day recorders (see Webber and Painter
1996) mounted on rotating platforms at 3 m height.
Daily pollen catch was expressed as the number of pollen
grains per mm 2 . Five pollen monitoring stations were
used in the Saanich peninsula, which correspond to the
same stations used by the Ministry of Forests and Range,
Tree Improvement Branch, for their annual regional
pollen monitoring of coastal Douglas-fir pollen. Bruce
MacPherson (MoF Coastal Seed Orchards) was responsible
for maintaining the five Saanich peninsula monitoring
stations (erecting monitors, changing charts).
We counted two replicates on each chart for a 24-hour
period and averaged the total number of pollen grains for
the two replicates. To determine the pollen cloud density,
we then divided the average daily counts by 44 mm 2
to represent the number of pollen grains per mm 2 for a
24-hour period. We also compared results for regional
monitoring of western hemlock and Sitka spruce pollen
flight with the receptivity periods and pollen cloud density
values monitored at the Western Forest Products (WFP)
Saanich seed orchard site (Hw orchard 170 and Ss
orchard 172).
Results
Figure 49 shows the daily western hemlock pollen cloud
density values averaged over the five Saanich peninsula
stations. Figure 50 shows the daily Sitka spruce pollen
cloud density values averaged over the same five stations.
In 2006, the mean western hemlock pollen shed on the
Saanich peninsula ranged from March 24 to April 30. The
period of Sitka spruce pollen shed was April 14 to April 30
(the end of regional monitoring, although WFP orchard
172 continued to shed for one more week). Table 17 shows
the total pollen load for western hemlock and Sitka spruce
in years 2005 and 2006. Pollen load represents the daily
pollen cloud density summed over the monitoring period.
Compared to 2005, pollen capture for the western hemlock
and Sitka spruce was about 20 percent and 50 percent
lower, respectively, than in 2005.
The total regional pollen load (mean for all five stations)
for western hemlock and Sitka spruce for the six-week
monitoring period was 9.2 and 1.9 and 1.6 and 0.8 pollen
0
T R E E I M P R O V E M E N T P R O G R A M
P R O J E C T R E P O R T 2 0 0 6 / 2 0 0 7
grains/mm 2 for each of 2005 and 2006, respectively.
Although the corresponding values for pollen load
for the receptivity period of WFP orchards 170 and 172
are not strictly comparable (slide counts versus seven-day
recorder counts), we can still estimate potential western
hemlock pollen contamination from slide counts taken
within the orchard and regional counts from the Saanich
peninsula. Table 18 shows the pollen load (mean for all five
stations) from regional counts during the receptivity period
2005 and 2006.
The corresponding pollen load values (regional) for
western hemlock and Sitka spruce were 1.3 and 1.0 and
0.3 and 0.7 grains/mm 2 , respectively. Table 19 shows the
corresponding values for pollen load (orchard) summed
over the receptivity period of western hemlock orchard 170
and Sitka spruce orchard 172 (slides).
According to Woods et al (1996), regional pollen
capture for the receptivity period of the orchard is adjusted
for the differences in capture efficiency between the regional
monitors (seven-day) and the orchard monitors (slides).
The orchard adjustment factor (OAF) is determined by
averaging the ratio of daily pollen capture of the orchard
slides to the regional seven-day monitors. Thus, by
averaging the early orchard pollen capture (EOA) to the
early regional average (ERA) for a period of seven to ten
days (prior to orchard pollen flight), a factor is calculated
that can be applied to the regional counts for the orchard
receptivity period. However, in practice the calculation of
the OAF has been inconsistent. Often there are not enough
days prior to orchard shed to give a reliable result (regional
shed and orchard receptivity period overlap). Because
of this, the OAF was not considered in the following
calculations of percent contamination. Table 20 shows
the estimate of percent contamination for both western
hemlock and Sitka spruce using only the regional pollen
counts and orchard counts.
Conclus on
For both 2005 and 2006, the pollen counts for western
hemlock were lower than those observed for Douglasfir
and significantly lower for Sitka spruce. For example,
regional pollen loads for the six-week monitoring period
for Douglas-fir in 2005 and 2006 was 18.3 and 15.0
grains/mm 2 , respectively. This corresponded to an estimate
of percent contamination (no OAF) of 4.8 and 12.3,
respectively. The estimates of contamination based on
pollen monitoring have also been confirmed in Douglasfir
with DNA paternity analyses. For the two years of