Phosphorus resorption by young beech trees and soil phosphatase activity as dependent on phosphorus availability

Area of Science:

• Forest Ecology
• Plant Physiology
• Soil Science

Background:

• Decreasing foliar phosphorus (P) concentrations in Fagus sylvatica L. forests indicate potential P limitation.
• Understanding P recycling is crucial for forest health and sustainable management.

Purpose of the Study:

• To investigate phosphorus (P) recycling mechanisms in Fagus sylvatica L. forests with contrasting soil P availability.
• To assess the impact of P fertilization on P resorption and phosphatase activity.

Main Methods:

• Mesocosm experiment using juvenile Fagus sylvatica L. trees and soils from P-poor and P-rich forest sites.
• Measurement of P resorption efficiency from senesced leaves.
• Assay of acid and alkaline phosphatase activity in rhizosphere and bulk soil.

Main Results:

• P resorption efficiency was significantly higher (70%) in P-poor sites compared to P-rich sites (48%).
• P fertilization reduced P resorption efficiency in P-poor sites but not in P-rich sites.
• Acid and alkaline phosphatase activities were higher in the rhizosphere of P-poor soils. Acid phosphatase activity was concentrated in the rhizosphere in P-poor soils, and in bulk soil in P-rich soils.

Conclusions:

• Fagus sylvatica demonstrates enhanced P resorption efficiency under low soil P availability.
• Acid phosphatase activity in the rhizosphere is a key indicator of P limitation in Fagus sylvatica forests.
• Microbial phosphatases play a more significant role in P cycling in P-rich soils compared to P-poor soils.