Springtime recovery of photosynthetic activity of white pine in Michigan

1988 ◽  
Vol 66 (1) ◽  
pp. 138-141 ◽  
Author(s):  
Thomas W. Jurik ◽  
George M. Briggs ◽  
David M. Gates

The CO2 exchange of a field-grown eastern white pine (Pinus strobus L.) in Michigan was monitored during the winter–spring periods of 1983 and 1985. Its light-saturated photosynthetic rate in ambient CO2 and temperature was depressed during the winter, but recovered very rapidly during the last week of April in both years. The depressed rates in the winter were not due solely to low air temperatures, since the rates remained low even on warmer days or when the air temperature was artificially increased. Photosynthetic activity was more highly correlated with soil temperature at 30 cm than with air temperature or soil temperature at shallower depths. However, photoperiod or endogenous factors could not be eliminated as potential controls on photosynthetic activity.

2013 ◽  
Vol 10 (7) ◽  
pp. 4465-4479 ◽  
Author(s):  
K. L. Hanis ◽  
M. Tenuta ◽  
B. D. Amiro ◽  
T. N. Papakyriakou

Abstract. Ecosystem-scale methane (CH4) flux (FCH4) over a subarctic fen at Churchill, Manitoba, Canada was measured to understand the magnitude of emissions during spring and fall shoulder seasons, and the growing season in relation to physical and biological conditions. FCH4 was measured using eddy covariance with a closed-path analyser in four years (2008–2011). Cumulative measured annual FCH4 (shoulder plus growing seasons) ranged from 3.0 to 9.6 g CH4 m−2 yr−1 among the four study years, with a mean of 6.5 to 7.1 g CH4 m−2 yr−1 depending upon gap-filling method. Soil temperatures to depths of 50 cm and air temperature were highly correlated with FCH4, with near-surface soil temperature at 5 cm most correlated across spring, fall, and the shoulder and growing seasons. The response of FCH4 to soil temperature at the 5 cm depth and air temperature was more than double in spring to that of fall. Emission episodes were generally not observed during spring thaw. Growing season emissions also depended upon soil and air temperatures but the water table also exerted influence, with FCH4 highest when water was 2–13 cm below and lowest when it was at or above the mean peat surface.


2013 ◽  
Vol 10 (3) ◽  
pp. 4539-4574
Author(s):  
K. L. Hanis ◽  
M. Tenuta ◽  
B. D. Amiro ◽  
T. N. Papakyriakou

Abstract. Ecosystem-scale methane (CH4) flux (FCH4) over a subarctic fen at Churchill, Manitoba, Canada was measured to understand the magnitude of emissions during spring and fall shoulder seasons, and the growing season in relation to physical and biological conditions. FCH4 was measured using eddy covariance with a closed-path analyzer in four years (2008–2011). Cumulative measured annual FCH4 (shoulder plus growing seasons) ranged from 3.0 to 9.6 g CH4 m−2 yr−1 among the four study years, with a mean of 6.5 to 7.1 g CH4 m−2 yr−1 depending upon gap-filling method. Soil temperatures to depths of 50 cm and air temperature were highly correlated with FCH4, with near surface soil temperature at 5 cm most correlated across spring, fall, and the whole season. The response of FCH4 to soil temperature at the 5 cm depth and air temperature was more than double in spring to that of fall. Emission episodes were generally not observed during spring thaw. Growing season emissions also depended upon soil and air temperatures but water table also exerted influence with FCH4 highest when water was 2–13 cm below and least when it was at or above the mean peat surface.


1959 ◽  
Vol 35 (1) ◽  
pp. 19-21 ◽  
Author(s):  
J. L. Farrar ◽  
W. D. McJannet

1952 ◽  
Vol 5 (2) ◽  
pp. 303 ◽  
Author(s):  
ES West

Soil temperatures recorded at Griffith over an 8 year period at a depth ranging from 1 in. to 8 ft. have been examined and compared with air temperatures. The observed fluctuations m the soil temperatures fit closely the theoretical equation for the propagation of a simple harmonic temperature wave into the so11. The diffusivity of the sol1 has been deduced and compared with values found by other workers in other localities. The annual wave of the daily mean temperature at the surface of the soil has been deduced and compared with the annual wave of the dally mean air temperature and the differences in the means, amplitudes, and phase displacements have been discussed.


Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 347
Author(s):  
Kara K.L. Costanza ◽  
William H. Livingston ◽  
Shawn Fraver ◽  
Isabel A. Munck

Eastern white pine (Pinus strobus) is considered a signature species in eastern North America, particularly in New England. In recent years, however, white pine has experienced increased damage due to native pathogens that reduce the species’ growth, productivity, and economic value. One disease of concern is Caliciopsis canker, caused by the fungal pathogen Caliciopsis pinea, which is associated with excessive resin production, cankers, rough bark, bark fissures/cracks, and reduced growth in white pine. Recent studies have documented the extent of Caliciopsis canker in New England and its association with soil and stocking conditions, yet few studies have focused on the biological impacts of the disease. This study used dendrochronology and whole-tree dissections to reconstruct Caliciopsis canker history in three New England white pine sites, quantify its impact on tree growth and vigor, identify pre-disposing factors, and assess potential silvicultural management options. Dendrochronology and whole-tree dissections provided a unique insight into canker damage throughout trees’ development. Canker damage was first reported in New Hampshire in the mid-1990s, yet cankers were present as far back as 1967 and have steadily increased since the mid-1980s. Increased canker damage was significantly associated with decreased live crown ratios and declining tree growth. Trees maintaining a 30% live crown ratio or greater generally experienced the least canker damage. Furthermore, peaks in canker occurrence were consistent across sites, indicating a regional synchronization of infection and damage. Canker damage was closely associated with climatic events such as droughts and a New England hurricane. The results suggest that Caliciopsis canker has been affecting white pine health over the last 40 years, and that the disease has become more prevalent in the past 20–30 years. Yet, our results suggest that if silvicultural prescriptions target low density thinnings that favor trees with higher live crown ratios (>30%) and low Caliciopsis symptom severity ratings, the risk of canker damage can be reduced in white pine stands.


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