红树植物功能性状对盐和铜胁迫的响应

目前,室内通过人工控制方式开展红树林对环境胁迫的响应研究,忽视了不同红树植物物种的生长习性,且以单一胁迫为主。通过野外生长与人工控制相结合方式,研究5个时期(2018.6-2020.8)盐和铜胁迫对3种红树植物(秋茄、拉关木和木榄)11种功能性状的影响,使用单因素和双因素方差分析研究不同时期不同树种下盐和铜胁迫对叶片功能性状的影响,回答红树植物功能性状对盐和铜单一及复合胁迫响应的科学问题。结果表明,不同时期下,三种红树植物功能性状具有明显差异。随着时间增长,三种植物的碳含量和冠层高度均呈升高趋势,其他功能性状因物种不同而表现出不同趋势;与乡土红树植物(秋茄和木榄)相比,外来入侵物种(拉关木)具有更快的生长速度。不同时期下,拉关木比秋茄和木榄具有更好耐盐性,三个物种的植物生长发育对铜胁迫的响应均不敏感。大部分时期下,单一盐胁迫对拉关木的植物功能性状无显著影响(P < 0.05),对秋茄和木榄的碳含量、冠层高度和比叶面积有显著影响(P < 0.05);单一铜胁迫对三个物种的绝大多数功能性状无显著影响。另外,盐-铜复合胁迫对秋茄叶片碳、磷、氮磷比及冠层高度有显著影响(P < 0.05),对拉关木叶片碳、铜含量、冠层高度、比叶面积有显著影响(P < 0.05),仅对木榄SPAD值有显著影响(P < 0.05)。在红树林保护修复工作中,研究成果可为红树林退化原因和机理阐释、红树林生长监测评估、生境治理以及树种选择提供一定的理论依据。

Response of leaf functional traits of mangrove plants to single and combined stress of salt and copper

Mangrove is a wetland woody plant community growing in the Intertidal zone of tropical and subtropical beaches. It plays an important role in purifying seawater, preventing waves and protecting embankments, fixing carbon and storing carbon, promoting siltation and land formation, and maintaining biodiversity.At present, the indoor laboratory research on the response of mangroves to environmental stress is carried out by artificial control, which ignores the growth habits of different mangrove species, and most studies focus on single stress. Through the combination of field growth and manual control, this paper aims to study the effects of salt and copper stress on 11 functional traits of three mangrove plants (Kandelia candel, Laguncularia racemosa and Bruguiear gymnorrhiza) in five periods (from June 2018 to August 2020). The effects of salt and copper stress on leaf functional traits of different tree species in different periods were studied by single factor and two-factor variance analysis, which could further answer the scientific problem of mangrove plant functional traits in response to single and combined stress of salt and copper. The results showed that the functional traits of the three mangrove plants were significantly different in different periods. With the increase of time, the carbon content and canopy height of the three plants showed an increasing trend, and other functional traits showed different trends due to different species. Compared with native mangrove plants (Kandelia candel and Bruguiear gymnorrhiza), the invasive alien species (Laguncularia racemosa) had a faster growth rate. Under different periods, Laguncularia racemosa had better salt tolerance than Kandelia candel and Bruguiear gymnorrhiza. The growth and development of the three species were not sensitive to copper stress. In most periods, the single salt stress had no significant effect on plant functional traits (P < 0.05), but had significant effects on carbon content, canopy height, and specific leaf area (P < 0.05). Single copper stress had no significant effect on most functional traits of the three species. In addition, salt-copper combined stress had significant effects on leaf carbon, phosphorus, nitrogen-phosphorus ratio, and canopy height of Kandelia candel (P < 0.05), and had significant effects on leaf carbon, copper content, canopy height, and specific leaf area of Laguncularia racemosa (P < 0.05 ), while the salt-copper combined stress only had significant effects on SPAD value of Bruguiear gymnorrhiza (P < 0.05 ). In the protection and restoration of mangroves, the research results can provide a theoretical basis for interpretation of the causes and mechanisms of mangrove degradation, the monitoring and evaluation of mangrove growth, habitat management, and tree species selection.