Nutrient resorption of two evergreen shrubs in response to long‑term fertilization in a bog.
Plant resorption of multiple nutrients during leaf senescence has been established but stoichiometric changes among N, P and K during resorption and after fertilization are poorly understood. We anticipated that increased N supply would lead to further P limitation or co-limitation with N or K [i.e. P-(co)limitation], decrease N resorption and increase P and K resorption, while P and K addition would decrease P and K resorption and increase N resorption. Furthermore, Ca would accumulate while Mg would be resorbed during leaf senescence, irrespective of fertilization. We investigated the effect of N, P and K addition on resorption in two evergreen shrubs (Chamaedaphne calyculata and Rhododendron groenlandicum) in a long-term fertilization experiment at Mer Bleue bog, Ontario, Canada. In general, N addition caused further P-(co)limitation, increased P and K resorption efficiency but did not affect N resorption. P and K addition did not shift the system to N limitation and affect K resorption, but reduced P resorption proficiency. C. calyculata resorbed both Ca and Mg while R. groenlandicum resorbed neither. C. calyculata showed a higher resorption than R. groenlandicum, suggesting it is better adapted to nutrient deficiency than R. groenlandicum. Resorption during leaf senescence decreased N:P, N:K and K:P ratios. The limited response of N and K and the response of P resorption to fertilization reflect the stoichiometric coupling of nutrient cycling, which varies among the two shrub species; changes in species composition may affect nutrient cycling in bogs.
Meng
M
Wang
Meaghan T
MT
Murphy
Tim R
TR
Moore
D002118:Calcium / Q000378:metabolism; D029791:Ericaceae / Q000378:metabolism*; D005308:Fertilizers; D008274:Magnesium / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D009864:Ontario; D010758:Phosphorus / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D053833:Wetlands
D005308:Fertilizers; D010758:Phosphorus; D008274:Magnesium; D009584:Nitrogen; D011188:Potassium; D002118:Calcium