Nutrient resorption is a crucial mechanism for plant nutrient conservation, but most previous studies did not consider the leaf-mass loss during senescence due to lack of measured data. This would lead to an underestimation of nutrient resorption efficiency (NuRE), or calculating NuRE of various species based on the average mass loss at plant-functional-group level in the literature, thus affecting its accuracy. Here we measured the leaf-mass loss to correct NuRE with the species-specific mass loss correction factor (MLCF), so as to foster a more accurate calculation of the nutrient fluxes within and between plants and the soil. Green leaves and senesced leaves were collected from 35 dominant woody plants in northern China. Mass of green and senesced leaves were measured to calculate the MLCF at species level. The MLCF was reported for each of the 35 dominant woody plants in northern China. These species averagely lost 17% of the green-leaf mass during leaf senescence, but varied greatly from 1.3% to 36.8% mass loss across the 35 species, or 11.7% to 19.6% loss across the functional types. Accordingly, the MLCF varied from 0.632 to 0.987 across the 35 species with an average value 0.832. The NuRE corrected with MLCF was remarkably increased on the whole (e.g. both the average nitrogen and phosphorus NuRE became about 9% higher, or more accurate), compared with the uncorrected ones, especially in the case of low resorption efficiencies. Our field data provide reliable references for the MLCF of plants in related regions at both species and functional-type levels, and are expected to promote more accurate calculations of NuRE.
摘要：
植物叶片养分重吸收效率的质量损失校正
养分重吸收是植物保持养分的关键机制，但以往多数研究未考虑叶片衰老过程中的质量损失，低估了植物的叶片养分重吸收效率(NuRE)；或只能基于文献中植物功能群水平的平均质量损失，校正所研究的不同物种的叶片NuRE，从而影响了该参数的精确性。本研究通过采集中国北方地区35种常见木本植物的绿色叶片和凋落叶片样本，测量绿色叶片和凋落叶片的质量，计算了叶片衰老过程中的质量损失，并给出了这些物种凋落叶片的质量损失校正系数(MLCF)。总体而言，植物凋落叶片的质量比成熟绿 色叶片平均损失17%，物种水平质量损失变化范围为1.3%–36.8%，功能群水平为11.7%–19.6%。相 应地，这35种木本植物的凋落叶片的MLCF值平均为0.832，变化范围为0.632–0.987。与校正前相 比，用MLCF校正后的NuRE总体上显著增加。例如，校正后氮和磷的平均NuRE皆增高约9%，即比其校正前(低估)更接近真实值；当植物NuRE较低时，这种校正作用(改善)表现得尤为明显。本研究基于物种水平的野外实测数据，报道了中国北方部分常见木本植物的MLCF参考值，研究结果将有助于更准确地计算此类植物的养分重吸收效率，提升本地区植物-土壤系统中养分流通评估的精准度。
关键词:
绿色叶片,
凋落叶片,
质量损失校正系数,
养分重吸收,
衰老叶片,
木本植物
