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南非外来入侵物种 Metrosideros excelsa 的种子库和

花匠小妙招
2025-01-24 23:15

摘要

20 世纪 40 年代，新西兰瓶子草（Metrosideros excelsa，桃金娘科）作为观赏植物被引入南非，随后在开普花卉区的沿海地区归化。了解M. excelsa在南非的繁殖压力和对火灾的反应可以为评估该物种的入侵潜力和管理提供信息。我们评估了M. excelsa在烧毁和未烧毁林分中的树冠和土壤种子库；以及火灾后通过与火灾严重程度和树木大小相关的重新播种和重新发芽进行的再生。采用萌发技术对土壤种子库进行了评估，但从烧毁或未烧毁植物下采集的土壤中均未发现幼苗萌发，这表明该物种没有保持一个可行的土壤储存种子库，或者没有满足萌发触发条件（但可能性不大）。未烧毁树木树冠中的年种子量约为每棵树 50-2300 万粒。通过四氮唑染色测试评估，未燃烧树木树冠上的种子存活率为 18%，而树冠火灾（严重程度从低到极严重不等）会杀死所有树冠上的种子。火灾后 15 个月，幼苗与火灾前（活体）树木的比率为 0.01，而 43% 的被烧毁树木通过基部重生存活下来。火灾严重程度对树木存活率有非线性影响（中度和高度火灾严重程度后存活率最高，低度和极端火灾严重程度后存活率最低），而较大的树木更有可能在火灾中存活。这些结果表明，即使是低强度（安全）燃烧也可能是一种有用的控制措施，因为它可以杀死树冠上的种子，并造成大量死亡，尤其是较小的树木。对火灾后重新萌发的个体施用叶面除草剂的机会性评估（未与未施用除草剂的个体进行比较）也显示了相当高的死亡率（91%）。不过，还需要进行严格的除草剂试验（除草剂与焚烧同时使用），以便为 M. excelsa 的管理提供信息。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

摘要图片

Seed banks and post-fire recovery of invasive alien Metrosideros excelsa in South Africa: Implications for control

The New Zealand bottlebrush, Metrosideros excelsa (Myrtaceae), was introduced into South Africa in the 1940s as an ornamental plant and subsequently naturalized in coastal parts of the Cape Floristic Region. Knowledge of M. excelsa's propagule pressure and response to fire in South Africa can inform evaluation of the species' invasion potential and management. We assessed M. excelsa's canopy and soil seed banks in burnt and unburnt stands; and post-fire regeneration via reseeding and resprouting in relation to fire severity and tree size. Soil seed banks were assessed using an emergence technique, but no seedlings emerged from soil collected under burnt or unburnt plants suggesting that the species does not maintain a viable soil-stored seed bank or germination triggers were not met (though unlikely). The annual seed crop in the canopies of unburnt trees was approximately 0.5–23 million seeds per tree. Viability, assessed through tetrazolium stain testing, of canopy-borne seeds on unburnt trees was 18%, whereas a canopy fire, ranging in severity from low to extreme, killed all canopy-borne seeds. Fifteen months post-fire, the seedling to pre-fire (live) tree ratio was 0.01, whereas 43% of burnt trees survived via basal resprouting. Fire severity had a non-linear effect on tree survival (survival was highest after medium and high fire severity and lowest after low and extreme fire severity), while larger trees were more likely to survive fire. These results suggest that even low-severity (safe) burning may be a useful control measure as it kills canopy-borne seeds and causes substantial mortality, particularly of smaller trees. An opportunistic evaluation of an uncontrolled (no comparison with untreated individuals) foliar herbicide application to post-fire resprouting individuals also showed considerable (91%) mortality. However, rigorous herbicide trials (also with herbicide in conjunction with burning) are required to inform the management of M. excelsa.

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来源期刊

Austral Ecology

期刊介绍： Austral Ecology is the premier journal for basic and applied ecology in the Southern Hemisphere. As the official Journal of The Ecological Society of Australia (ESA), Austral Ecology addresses the commonality between ecosystems in Australia and many parts of southern Africa, South America, New Zealand and Oceania. For example many species in the unique biotas of these regions share common Gondwana ancestors. ESA''s aim is to publish innovative research to encourage the sharing of information and experiences that enrich the understanding of the ecology of the Southern Hemisphere. Austral Ecology involves an editorial board with representatives from Australia, South Africa, New Zealand, Brazil and Argentina. These representatives provide expert opinions, access to qualified reviewers and act as a focus for attracting a wide range of contributions from countries across the region. Austral Ecology publishes original papers describing experimental, observational or theoretical studies on terrestrial, marine or freshwater systems, which are considered without taxonomic bias. Special thematic issues are published regularly, including symposia on the ecology of estuaries and soft sediment habitats, freshwater systems and coral reef fish.

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