This document discusses a study examining how seedling allocation and survivorship in sugar maple and American beech are influenced by light, nutrients, and moisture. The study found that seedling biomass was not nutrient limited in the first two years. Sugar maple biomass growth increased with soil moisture. Phosphorus increased relative root allocation in sugar maple. Nitrogen decreased sugar maple survivorship. Survivorship of both species decreased with increasing canopy cover, indicating response to light availability. The conclusions were that beech seedlings are less plastic than sugar maple, survivorship depends on light, and mortality at early life stages may be stochastic under canopy.

1. I mean a lot
more than I
look….
Hungry and neglected seedlings:
Does light matter more than
nutrients?
Presented by: Shinjini Goswami
Contact: goswams@miamioh.edu

2. Why do we care about seedlings in a forest?
Reproductive
adult density &
distribution
Seed density &
distribution
Seedling
density &
distribution
Forest
regeneration
potential
Seed production per adult (timing)
Seed dispersal in space
Seed to seedling transition stage
(time & space)
Survival, persistence and growth
Possible limiting factors

3. Why do we care about seedlings in a forest?
Reproductive
adult density &
distribution
Seed density &
distribution
Seedling
density &
distribution
Forest
regeneration
potential
Seed production per adult (timing)
Seed dispersal in space
Seed to seedling transition stage
(time & space)
Survival, persistence and growth
Possible limiting factors
Light?
Nutrients?
Moisture?

4. • Seedlings
- Rapid response to fertilization
- Whole plant allocation patterns (variable among species)
- survivorship  future regeneration potential
Sugar MapleBeech

5. • Seedlings
- Rapid response to fertilization
- Whole plant allocation patterns (variable among species)
- survivorship  future regeneration potential
• Sugar maple and American beech masted in most of MELNHE mature forest stands in
2011; same year we started fertilization
Sugar MapleBeech

6. Questions:
• Does seedling allocation respond to nutrient, light, or water
resources?
• Which resources most influence survivorship?

7. All seedlings (<50 cm): identified to species and surveyed from 2012
Studying allocation response to nutrients, moisture and light:
• Harvested 20 beech and sugar maple seedlings/treatment plot in 3 mature
stands
• Root:Shoot was calculated on mass basis
• Soil moisture and canopy cover was measured for each seedling subplot
Study design and methods

8. 0.00
0.05
0.10
0.15
0.20
0.25
0.30
C N NP P
Seedlingbiomass(g)
Beech
Sugar maple
Biomass growth was not nutrient limited in the
first 2 years (p= 0.14)

9. R² = 0.2114
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
20 22 24 26 28 30
seedlingbiomass(g)
Soil moisture
Beech
Sugar maple
Seedling biomass differed significantly
between the two species (p< 0.00)
Sugar maple biomass growth increased with
soil moisture (p= 0.12)

10. Shallow rooting by sugar maple may cause
moisture sensitivity

11. P increased relative allocation to roots in sugar
maple (p= 0.02)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
C N NP P
Root:Shoot
Beech
Sugar maple

12. 0
5
10
15
20
25
30
35
C N NP P
Seedlingsurvivorship(%)
Beech
Sugar maple
N decreased sugar maple survivorship (p= 0.07)

13. 0
10
20
30
40
50
60
70
80% 82% 84% 86% 88% 90% 92% 94%
Seedlingsurvivorship(%)
Canopy cover
Sugar maple
Beech
Survivorship of beech (p= 0.09)
and sugar maple (p= 0.03)
decreased with increasing canopy
cover
Response to light
availability

14. Conclusions
• Beech seedlings are relatively non-plastic with respect to the variables
measured
• Seedling survivorship depends on light availability but not strongly
• It is unclear why fertilizing with N reduces survivorship.
• Seedling mortality at earlier life stages might be mostly stochastic; possibly
under the canopy environmental variables are not important at this life
stage