This document summarizes a study that examined how the physical, chemical, and metabolic characteristics of sugar maple leaves vary with their depth in the tree crown and with the addition of nutrients. The study found that foliar nitrogen and chlorophyll increased deeper in the crown and with nitrogen addition, while foliar phosphorus increased with phosphorus addition. The study concludes that most leaves are shaded rather than just "sun" or "shade" leaves, and that examining the vertical gradient in a tree crown can help reveal relationships between leaf characteristics and nutrients.
5. Physical characteristics
● Leaf area, leaf mass, twig length, twig mass
Chemical characteristics
● N, P, Ca, Mg, Al, Mn, B
Metabolic characteristics
● Chlorophyll: A, B, carotenoids
● Amino acids: GABA, Glu, Arg, Ala, Val
● Polyamines: Putrescine, Spermidine, Spermine
Crown depth
N response
P response
6. Foliar N increased with depth, and with N addition
Per unit mass Per unit area
9. Take-away messages
The majority of the leaves in the world are shaded,
Not just “sun” and “shade” leaves, but gradient
N is important for leaves
Examining the vertical gradient can help reveal novel relationships
Acknowledgements
•P.I.’s Ruth Yanai, Melany Fisk, Tim
Fahey
•Drs. Rakesh Minocha, Stephanie Long
•Drs. John Drake, Danilo Fernando
•Yanai B9 Forest ecology lab
•Summer 2017 and 2018 crew
•NSF-REU “Canopy Herbivory and
Tardigrades”
Notes de l'éditeur
Light dependent acclimation of photosynthetic capacity per area is surprisingly similar across PFTs, the underlying traits enabling acllimation differ. For example, species with high leaf turnover and canopy development with highly dynamic light environments can adjust photosynthetic capacity by reallocating N among leaves. In contrast, plants that have low leaf turnover are predominately constrainted by leaf structure which stabilizes after 30-60 days after leaf out. Niinements et al 2014 New Phytologist.
Light dependent acclimation of photosynthetic capacity per area is surprisingly similar across PFTs, the underlying traits enabling acllimation differ. For example, species with high leaf turnover and canopy development with highly dynamic light environments can adjust photosynthetic capacity by reallocating N among leaves. In contrast, plants that have low leaf turnover are predominately constrainted by leaf structure which stabilizes after 30-60 days after leaf out. Niinements et al 2014 New Phytologist.
