Plant-soil links of N and P resorption across contrasting parent materials from similar climates

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Ecological theory suggests that plant nutrient resorption should be higher in sites with lower soil nutrient availability. However, plant resorption responses to variation in soil nutrient availability remain poorly understood. We examined leaf nitrogen (N) and phosphorus (P) resorption patterns for 69 native plant species across four climatically similar pair of sites in eastern Australia, but contrasting in parent materials: nutrient-rich, basalt vs. nutrient-poor, sandstone and rhyolite soils. We expected that senesced leaf nutrient concentration/resorption proficiency would vary with parent material, but the relative resorption efficiency would remain invariant. We also examined the dependence of P resorption proficiency on leaf N status as a way to keep N:P ratios constant. Consistent with our expectations, green and senesced N and P concentrations were significantly higher on nutrient-rich basalt-derived soils than on nutrient-poor sandstone and rhyolite soils. Resorption efficiency was 69% for P across sites and varied little across these contrasting soil types within the same geographical area, suggesting that plants primarily conserve nutrients through P proficiency rather than efficiency. Contrary to our expectation, P resorption proficiency was regulated according to green leaf P concentrations and not linked to leaf N status. Widespread P-limitation to plants was indicated by low leaf concentrations, high P resorption efficiency, and higher N:P ratios across species and sites. Importantly, P resorption efficiency was positively associated with the proportion of P in labile, soluble forms, highlighting a biochemical basis for variation in resorption efficiency. By linking site geology, soil nutrients, and leaf nutrient dynamics, this study distinguishes resorption proficiency and resorption efficiency as functionally distinct components of nutrient conservation, shaped by different ecological and physiological drivers. This dataset contains one text file (csv format) containing data for 36 parameters measured for altogether 79 species at the four-different site pairs across Eastern Australia.