Tree Improvement Program Project Report 2006 / 2007

slide monitor 4. Figure 31 shows the daily pollen catch in
the WFP orchard 189. The monitor was adjacent to WFP
slide monitor 8.
The monitoring period was February 13 to March 13
(note the monitor clock stopped for five days in orchard
189) at WFP and February 11 to March 13 at TW. The
receptivity period for WFP orchard 189 was February 20 to
March 8, and at TW it was February 16 to March 5. Table
9 shows the pollen load values for each of the three orchard
sites, including the pollen load values calculated for WFP
monitoring data for the two slide monitors (4 and 8). The
7-day monitor was adjacent to each of the slide monitors,
and pollen load values for the 7-day was 38 compared to
160 at the reservoir site and 55 compared to 137 in the
orchard. There are two important differences between these
monitors. First the slides were located at 2 meters height
whereas the 7-day monitors were placed at 3 meters height.
Also the 7-day monitors are protected from the weather
(capped), whereas the slides are exposed to the weather.
Because this was the first time we compared side-by-side
monitoring efficiencies, it is too early to suggest that one is
better than the other.
Figure 32 shows the daily pollen catch at the TW
orchard 140. The pollen catch values were similar to those
observed at WFP, but we do not have comparable data for
TW western redcedar pollen monitoring.
Conclus ons
The magnitude and extent of western redcedar pollen
on the Saanich peninsula was as great as for any coastal
species monitored. However, since western redcedar pollen
is among the smallest (30µ) of all local conifers, the error
in counts will also be considerably higher than those for
Douglas-fir, which is among the largest pollen grain of our
local conifers (95µ).
A second difficulty in counting western redcedar
pollen is its size and form. It is very similar to red alder
pollen. Western redcedar pollen is about 20 to 30 µ in
diameter with some warty structures (orbicules) on the
excine. At x100 magnification, it is possible to identify
redcedar pollen, but it is very difficult to separate it from
red alder pollen. Red alder is slightly smaller (20 to 25 µ
in diameter) with pores. It looks very similar to redcedar at
x100 magnification but with smaller orbicules. Positively
distinguishing the two species at x400 is possible (glass
slide and cover slip). However, distinguishing the two
species at x400 on the Vaseline-coated charts (no cover slip)
is very difficult. In general, the two are separated on the
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
basis of shape and phenology. When dry, redcedar pollen
is irregularly shaped, and at X100, the orbicules appear
as bright spots on the excine. Red alder is, in general,
pentagonal and the orbicules do not appear as bright spots.
However, when the two mix, it is not possible to determine
the extent of either.
Separation of redcedar pollen from red alder was
particularly difficult in 2005 and 2006 because there
was considerable overlap of shedding periods. However,
in 2007 there was a clear separation between the end of
redcedar pollen shed (March 6 to 10) and the start of red
alder pollen shed. All data shown in Figures 29-32 are for
redcedar pollen only.
With the magnitude of pollen counts for western
redcedar at both the monitoring sites, it is likely that
significant contamination exists. This is certainly true
for 2007 and 2005 when pollen capture levels were 3 to
4 times that observed in 2006. Whether this is a serious
problem is not known. Certainly, any orchard clone sired
with contaminated pollen should have a small positive
effect over selfing. However, because the breeding value
of contaminated pollen would be at best neutral, any
contamination will have a negative effect on higherbreeding-value
clones.
This is the third year for monitoring western redcedar
pollen shed from indigenous stands on the Saanich
peninsula. However, the pollen monitoring technique used
for Douglas-fir may not be applicable for western redcedar.
The actual monitors do an excellent job of capturing the
pollen, but the charts coated with Vaseline make positive
identification difficult even with compound microscopes
using x100 magnification. Data collected for 2007 also
shows that there are considerable differences between
the total pollen catch for slides and the catch for 7-day
monitors. This will contribute to substantial error when
calculating contamination values for redcedar orchards on
the Saanich peninsula.
L terature C ted
Webber, J.E. and Painter, R.A. 1996. Douglas-fir pollen
management manual. 2nd Edn. Ministry of Forests and
Range, Research Branch. Work. Pap. 02/1996. 91pp.
Woods, J.H., Stoehr, M.U., and Webber, J.E. 1996.
Protocols for rating seed orchard seed lots in British
Columbia. Ministry of Forests and Range, Research
Program, Res. Report 06. 26pp.
37