Impacts of drought and nitrogen enrichment on leaf nutrient resorption and root nutrient allocation in four Tibetan plant species
Impacts of drought and nitrogen enrichment on leaf nutrient resorption and root nutrient allocation in four Tibetan plant species
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干旱和富氮对四种西藏植物叶片养分吸收和根系养分分配的影响
DOI：
10.1016/j.scitotenv.2020.138106
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发表时间：
2020
影响因子：
9.8
通讯作者：
Hu Shuijin
中科院分区：
文献类型：
--
作者：
Zhao Qingzhou;Guo Jin;Shu Meng;Wang Peng;Hu Shuijin
植物养分再吸收是植物将衰老结构中的养分吸收到发育组织中的过程，对植物生长、凋落物分解和养分循环具有重要影响。全球变化因素，如氮（N）沉降和降水量的变化，可以介导植物养分吸收和分配。全球气候变化的同时，许多地区的氮素输入增加，干旱频率增加。然而，氮素供应量增加和干旱对植物养分响应的相互作用在很大程度上仍不清楚。通过盆栽试验，研究了氮素营养和干旱胁迫对青藏高原4种禾本科植物（细叶嵩草（Kobresia capillifolia）和垂穗嵩草（E. nutans））和2种杂类植物（高山翠雀（Delphinium kamaonense）和二倍叶紫菀（Aster diplostephioides））叶片N、P吸收和根系养分分配的影响。我们的研究结果表明，不同的吸收模式内的两个功能组。nutans和D. kamaonen对N的吸收强于K。capillifoliaandA. diplostephioides。氮的添加并没有改变它们的氮再吸收效率，但降低了前两个物种的氮再吸收效率。干旱不影响氮、磷吸收效率，但降低钾的氮吸收效率。毛叶。此外，氮素还促进了钾对磷素的再吸收。capillifolia和D. kamaonense，干旱对A. diplostephioides，表明P吸收在这些物种的营养保护中起着重要的作用。此外，氮吸收能力强的树种在氮富集条件下将更多的生物量C或N分配到地上部分，提高了凋落物质量，而氮吸收能力弱的树种在干旱条件下将更多的生物量C和/或N分配到地下部分。总之，这些结果表明，营养吸收和分配的反应，氮富集和干旱是高度物种特异性。未来的研究应考虑这些差异的反应，以更好地预测凋落物分解和生态系统养分循环。
Plant nutrient resorption, a process by which plant withdraws nutrients from senescing structures to developing tissues, can significantly affect plant growth, litter decomposition and nutrient cycling. Global change factors, such as nitrogen (N) deposition and altered precipitation, may mediate plant nutrient resorption and allocation. The ongoing global change is accompanied with increased N inputs and drought frequency in many regions. However, the interactive effects of increased N availability and drought on plant nutrient-responses remain largely unclear. In a pot experiment, we examined the impacts of N enrichment and drought on leaf N and phosphorous (P) resorption and root nutrient allocation in four species from the Qinghai-Tibet Plateau, including two graminoid species (Kobresia capillifoliaandElymus nutans) and two forb species (Delphinium kamaonenseandAster diplostephioides). Our results showed divergent resorption patterns within the two functional groups.E. nutansandD. kamaonenseshowed stronger N resorption thanK. capillifoliaandA. diplostephioides. N addition did not alter their N resorption efficiencies, but decreased the N resorption proficiencies of the former two species. In contrast, drought did not affect N or P resorption proficiencies, but decreased N resorption efficiency ofK. capillifolia. Besides, N addition facilitated P resorption inK. capillifoliaandD. kamaonense, and drought did the same inA. diplostephioides, suggesting that P resorption plays an important role in nutrient conservation in these species. Moreover, species with stronger N resorption allocated more biomass C or N to aboveground and enhanced their litter quality under N enrichment, while species with weaker resorption allocated more biomass C and/or N to belowground part under drought. Together, these results show that the responses of nutrient resorption and allocation to N enrichment and drought are highly species-specific. Future studies should take these differential responses into consideration to better predict litter decomposition and ecosystem nutrient cycling.