This document summarizes a study that investigated nutrient resorption efficiency in tree species across different forest stands. The study found that: 1) Nitrogen resorption efficiency in senescing leaves was correlated with higher phosphorus concentrations in green leaves, not nitrogen concentrations. 2) Phosphorus resorption efficiency was correlated with higher nitrogen concentrations in green leaves, not phosphorus concentrations. 3) Experimental fertilization showed that green leaf nitrogen was lower with phosphorus addition, while green leaf phosphorus was unaffected by nitrogen addition. This suggests trees were phosphorus-limited or co-limited in control plots.

1.  
Kara Phelps
SUNY-ESF

2.  Trees retranslocate elements from senescing leaves
 Helps establish nutrient balance in trees
 Nutrient conservation and recycling

3.  What can green leaf concentrations tell us about
limitation?
 Can we see N and P interactions in resorption?
 ARE WE THERE YET?!

4. What did
Craig See
(see)?
See et al. 2015.
Ecology. 96(9).

5.  N resorption
efficiency
correlated with
green leaf P
o NOT with green
leaf N!
 P resorption
efficiency
correlated with
green leaf N
o NOT with green
leaf P!
2014 data in C2

6. Field Methods
 Green leaves in August
 Leaf litter in October
 Eight stands
o Bartlett
• C4, C6, C8, C9
o Hubbard Brook
• HBM, HBO
o Jeffers Brook
• JBM, JBO
 Three species
o Beech (all stands)
o Red maple (mid-aged)
o Sugar maple (old)

7.  Green leaf N
higher with N
 Lower with P!
 Green leaf P
higher with P
 No effect of
N!

10.  The percent difference between green leaf and litter
concentrations of an element
𝑛𝑢𝑡𝑟𝑖𝑒𝑛𝑡 𝑔𝑟 − 𝑛𝑢𝑡𝑟𝑖𝑒𝑛𝑡 𝑠𝑒𝑛
𝑛𝑢𝑡𝑟𝑖𝑒𝑛𝑡 𝑔𝑟

12.  Green leaves
o Green leaf N lower when P added
o Green leaf P not affected by N treatment
o N:P ratios indicate that trees in control plots are P-limited or co-
limited; adding a nutrient shifts limitation
 Leaf litter
o Litter N higher with nitrogen fertilization, with or without P
o Litter P higher with phosphorus added, with or without N
 Resorption efficiency
o Nitrogen – no effect of treatment!
o Phosphorus accumulation = negative resorption efficiency!

13. The B9 bunch and Shoestring
crews, past and present
Ruth Yanai, Mariann Johnston,
Dylan Parry