Vol. 51â1997 - NorthEastern Weed Science Society
Vol. 51â1997 - NorthEastern Weed Science Society
Vol. 51â1997 - NorthEastern Weed Science Society
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
69<br />
LlNGSNOW ECOSYSTEM PROJECT: MICROCLIMATE<br />
P<br />
Eight Licor wear er stationswere used to monitor 2 blocksand 4 treatments (unharvested control,<br />
untreatedcontrol Vision'"[a.i. glyphosate], and brushsaw in 1994 and 1995 (i.e., I and 2 years<br />
fforts in 1995 were intensified on blocks 2 (drier, cooler) and 3 (wetter,<br />
warmer) to c pitalize on microclimatic extremes identified in 1994. Fiberglass<br />
thermister/resis ce soil cells were also installed at 15 and 30 cm depth at 5 locations! treatment,<br />
inclusiveof all 4 locks and remainingtreatments(SilvanaSelective and Release" [a.i, triclopyrl).<br />
The cells were r ad bimonthly to determine soil moisture and temperature.<br />
~st-treatments.<br />
All release trea ents increased the amount of photosynthetic radiation (PAR) above (2.0 m) or<br />
on the forest flo r in 1994. By August, regrowth of non-spruce vegetation resulted in a decline<br />
in forest floor P for both brushsaw and Vision" treatments, but this decline occurred sooner<br />
for the Vision" t tment. The type of regrowth controlled the degree of forest floor irradiation.<br />
This was prima ily herbaceous (Vision") and resprouting brush (brushsaw). Increased solar<br />
radiation on the orest floor resulted in significant soil warming (duff [- 5 ern], 15 em, 30 cm)<br />
for release trea ents. They were highest for the Vision" and Release treatments. Mean<br />
temperatures ne (0.25 m) and 2.0 m above the forest floor did not differ among clearcut<br />
treatments by id-August. Temperatures near the forest floor were generally cooler in late<br />
summer than th se at 2.0 m; highest for Vision", intermediate for brushsaw, and lowest for<br />
untreated contro. Concurrently, relative humidity (RH) near the forest floor was lowest for<br />
Vision", interme iate for brushsaw, and highest for untreated control. Soil moisture levels were<br />
highestfor conife release treatments in 1994, but significant differences among these treatments<br />
were rarely obse ed. However, they tended to be highest for the 2 herbicides.<br />
Cumulativepreci itation (205.0 mm, June 1 through September 5) was approximately 20% less<br />
in 1995than in 1 94. However, by November 6, cumulative precipitation for 1995 (422.0 mm)<br />
exceeded that att ined in 1994 (336.0 mm). More light was measured on the forest floor for all<br />
treatments in 19 5 than in 1994, probably because of lower leaf area index resulting from mild<br />
drought condition . Treatment differencespersisted into the second post-treatment growing season<br />
(1995), especial y for soil temperatures, forest floor PAR, and soil moisture. Often these<br />
parameters wer statistically higher for the two chemical treatments. Significant treatment<br />
differences obse ed for RH near the forest floor in 1994, narrowed or became nonsignificant,<br />
likely because 0 increased revegetation of treated areas. Overall, the 2 control treatments were<br />
similar, and the conifer release treatments were similar.
Change language