tj final version of poster

1
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=( =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 20 th 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. 100% 0% 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 Hou 1 , Timothy J. Fahey 1 , John J. Battles 2 1 Department of Natural Resources, Cornell University 2 Department of Environmental Science, Policy, and Management, University of California, Berkeley 0.00 0.20 0.40 0.60 0.80 1.00 1.20 W1 W6 Average growth rate (%/yr) Watershed Average Growth Rate of SM in W1 and W6 W1 W6 0 0.5 1 1.5 2 2.5 W1 W6 Mortality (%/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 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 10 20 30 40 50 60 70 80 90 100 Average growth rate (%/year) Crown dieback class (%) W1 RGR (%) W6 RGR (%) y = -0.0094x + 1.2271 R² = 0.7057 y = -0.0041x + 0.381 R² = 0.3467 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 10 20 30 40 50 60 70 80 90 100 Average growth rate (%/year) 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. 100% 0% 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 CaSiO 3 to W1

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Page 1: TJ final version of poster

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.

100% 0%

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

0.00

0.20

0.40

0.60

0.80

1.00

1.20

W1 W6Aver

age

grow

th ra

te (%

/yr)

Watershed

Average Growth Rate of SM in W1 and W6

W1 W6

0

0.5

1

1.5

2

2.5

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.

100% 0%

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