Foliar nutrient resorption reflects interactions of N and

P availabilityKara Phelps SUNY-ESF

Resorption Trees retranslocate elements from senescing

leaves Helps establish nutrient balance in trees Nutrient conservation and recycling

Questions What can green leaf concentrations tell us about

limitation?

Can we see N and P interactions in resorption?

ARE WE THERE YET?!

What did Craig See

(see)?

See et al. 2015. Ecology. 96(9).

What do we see? 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

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)

Green Leaves Green leaf

N higher with N

Lower with P!

Green leaf P higher with P

No effect of N!

Green Leaf N:P

Leaf Litter

Resorption efficiency The percent difference between green leaf and

litter concentrations of an element

Efficiency

Summary 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!

Thank you to: The B9 bunch and Shoestring crews, past and present Ruth Yanai, Mariann Johnston, Dylan Parry