tj final version of poster
TRANSCRIPT
Methods • Study Species
o Scientific name: Acer Saccharum o Common name: Sugar maple
• Study Site o W1 and W6 in HBEF, NH
• Definition o dbh: diameter at breast height (1.37m) o Vigor: an indicator of tree health measured on a 1-6 categorical scale
o Canopy transparency: relative amount of light that passes through
the tree crown All light passes through No light passes through o Crown dieback: the percentage of branches with newly dead twigs in the live crown No crown No dead branches
• Procedural Overview o Data collection (2005-2012)
o Data analysis (2013) Growth rate j=(ln (dbh j,k+1))-ln(dbh j,k))/t Average growth rate w=(∑ 𝑔𝑔𝑔𝑔𝑔𝑔 𝑔𝑟𝑔𝑟 𝑗𝑁
𝑗=1 )/n Annual mortality rate=(ln N k+1-ln N k)/t j: individual tree; k: survey t: the time interval between survey k and survey k+1 N: the number of live individuals in one survey
US range map of sugar maple
Background • In the 20th century, acid rain caused soil Ca depletion from the forest ecosystems in HBEF. • Ca plays an important role in regulating the physiological processes of sugar maples. • The decreasing availability of soil Ca is one of the causes for sugar maple forest decline in HBEF. • In October 1999, researchers restored the soil Ca of W1 to pre-industrial level. W6 is the reference site. • We compare tree growth and mortality and canopy condition between W1 and W6 to better understand the effect of acid rain on forest health.
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Results and Discussion
The Effects of Soil Calcium Restoration on the Growth Rate and Mortality of Sugar Maples in Hubbard Brook Experimental Forest (HBEF)
Tianjun Hou1, Timothy J. Fahey1, John J. Battles2 1Department of Natural Resources, Cornell University
2Department of Environmental Science, Policy, and Management, University of California, Berkeley
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W1 W6Aver
age
grow
th ra
te (%
/yr)
Watershed
Average Growth Rate of SM in W1 and W6
W1 W6
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W1 W6
Mor
talit
y (%
/yr)
Watershed
Mortality of SM in W1 and W6
W1 W6
y = -1.137x + 1.118 R² = 0.78
y = -0.423x + 0.384 R² = 0.53
-0.20.00.20.40.60.81.01.21.4
0 10 20 30 40 50 60 70 80 90 100Aver
age
grow
th ra
te (%
/yea
r)
Crown dieback class (%)
W1 RGR (%)
W6 RGR (%)
y = -0.0094x + 1.2271 R² = 0.7057
y = -0.0041x + 0.381 R² = 0.3467
0.00.20.40.60.81.01.21.4
0 10 20 30 40 50 60 70 80 90 100Aver
age
grow
th ra
te (
%/y
ear)
Canopy transparency class (%)
W1 RGR
W6 RGR
Average Growth Rate-Canopy Transparency in W1 and W6
Year Data 2005 canopy transparency and crown dieback of SM in W1 and W6 2006 dbh and vigor of SM in W1 2007 dbh and vigor of SM in W6 2011 dbh and vigor of SM in W1 2012 dbh and vigor of SM in W6
Hypotheses • Soil Calcium (Ca) restoration will decrease the mortality and
increase the growth rate of sugar maple. • The growth rate of sugar maple decreases with increasing
canopy transparency and dieback
Figure 1: Average growth rate of SM in W1 is significantly higher than that in W6 (P<0.05).
Figure 2: Annual mortality of SM in W1 is significantly lower than that in W6 .
Figure 3: Growth rate decrease significantly with increasing crown dieback. However, the slope of W1 regression line is significantly larger than that of W6 (P<0.1). The y intercept of W1 is significantly larger than that of W6 (P<0.05).
Figure 4: Growth rate decreases significantly with increasing canopy transparency. However, the slope of W1 regression line is not significantly larger than that of W6 (P>0.1). The y intercept of W1 is significantly larger than that of W6 (P<0.05).
Summary of Discussion • Hypothesis 1 is true.
o Soil Ca depletion by acid rain has resulted in reduced growth and increased mortality of sugar maple. o Canopy dieback accompanies reduced growth and mortality in the typical tree decline spiral. o Reduced tree leaf area associated with canopy decline probably contributes to reduced tree growth rate.
• Hypothesis 2 is true. o But the relationships between growth rate and canopy condition differ a lot between reference and treated watersheds:
trees with similar crown condition are growing much more slowly in the reference watershed. o This result indicates that reduction of tree growth by soil Ca depletion involves more than just loss of leaf area. o Reduced soil Ca may impair tree wound repair and increase the cost of Ca acquisition, thereby contributing to reduced
growth rate.
References Huggett BA, Schaberg PG, Hawley GJ, & Eagar C (2007) Long-term calcium addition increases growth release, wound closure, and health
of sugar maple (Acer saccharum) trees at the Hubbard Brook Experimental Forest. Canadian Journal of Forest Research 37(9):1692-1700.
Juice, S. M., Fahey, T. J., Siccama, T. G., Driscoll, C. T., Denny, E. G., Eagar, C., Cleavitt, N. L., Richardson, A. D. (January 01, 2006). Response of sugar maple to calcium addition to northern hardwood forest. Ecology, 87, 5, 1267-80.
Likens, G. E., Driscoll, C. T., Buso, D. C., Siccama, T. G., Johnson, C. E., Lovett, G. M., Fahey, T. J., Bailey, S. W. (May 01, 1998). The biogeochemistry of calcium at Hubbard Brook. Biogeochemistry, 41, 2, 89-173.
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6 5 4 3 2 1 Standing dead lower dbh
Standing dead w/- dead branches
Standing dead w/+ many dead branches
Living w/+ many dead branches
Living w/+ few dead branches
healthy
Measure tree diameter
Average Growth Rate-Crown Dieback in W1 and W6
Hubbard Brook Experimental Forest Apply CaSiO3 to W1