부산대학교 도서관

Background: Tropical tree species can maintain high growth rates on low-phosphorus (P) soils. However, the physiological basis of the high growth rates of tropical tree species remains unknown. Scope: Here, we examine how traits related to P uptake and use efficiency might account for this phenomenon. Based on a comparison of plant physiological responses to P and nitrogen (N) limitation, we hypothesize that distinct evolutionary processes have occurred on strongly weathered tropical soils characterized by low P availability relative to weakly and moderately weathered temperate soils characterized by low N availability. Efficient P-use arises through the synthesis of galactolipids rather than phospholipids, small genome size, preferential and flexible P allocation to leaves, efficient P resorption from wood and leaves, tissue longevity, and a decrease in P allocation to reproduction. Efficient P uptake mechanisms include synthesis of phosphatase in roots to acquire organic P from phosphodiesters and phytate, association with mycorrhizal fungi efficient at acquiring P, secretion of organic anions from roots to mobilize soil P, increased mass flow, and modifications of root depth distribution and structure. Conclusions: Despite the prevalence of low P soils throughout the tropics, few studies have explored P-use efficiency and acquisition mechanisms in tropical trees. We predict that the wide range of mechanisms by which plants can efficiently acquire and use P maintains productivity and promotes species diversity on low P soils in the tropics and elsewhere. [ABSTRACT FROM AUTHOR]