Strydom Matthys, Veldtman Ruan, Ngwenya Mzabalazo Z, Esler Karen J
Department of Conservation Ecology and Entomology, Stellenbosch University, Matieland, South Africa.
Centre of Excellence for Invasion Biology, Stellenbosch University, Matieland, South Africa.
PLoS One. 2017 Aug 16;12(8):e0181763. doi: 10.1371/journal.pone.0181763. eCollection 2017.
Australian Acacia are invasive in many parts of the world. Despite significant mechanical and biological efforts to control their invasion and spread, soil-stored seed banks prevent their effective and sustained removal. In response South Africa has had a strong focus on employing seed reducing biological control agents to deal with Australian Acacia invasion, a programme that is considered as being successful. To provide a predictive understanding for their management, seed banks of four invasive Australian acacia species (Acacia longifolia, A. mearnsii, A. pycnantha and A. saligna) were studied in the Western Cape of South Africa. Across six to seven sites for each species, seed bank sizes were estimated from dense, monospecific stands by collecting 30 litter and soil samples. Average estimated seed bank size was large (1017 to 17261 seed m-2) as was annual input into the seed bank, suggesting that these seed banks are not residual but are replenished in size annually. A clear relationship between seed bank size and stem diameter was established indicating that mechanical clearing should be conducted shortly after fire-stimulated recruitment events or within old populations when seed banks are small. In dense, monospecific stands seed-feeding biological control agents are not effective in reducing seed bank size.
澳大利亚金合欢在世界许多地方都具有入侵性。尽管在控制其入侵和扩散方面付出了巨大的机械和生物防治努力，但土壤种子库阻碍了它们的有效和持续清除。作为应对措施，南非一直高度重视使用减少种子数量的生物防治剂来应对澳大利亚金合欢的入侵，该计划被认为是成功的。为了对其管理提供预测性理解，在南非西开普省对四种入侵性澳大利亚金合欢物种（长叶金合欢、黑荆、密花金合欢和银荆）的种子库进行了研究。对于每个物种，在六到七个地点，通过收集30份凋落物和土壤样本，从密集的单一种植林中估计种子库大小。估计的平均种子库大小很大（每平方米1017至17261粒种子），种子库的年输入量也是如此，这表明这些种子库不是残余的，而是每年在大小上得到补充。种子库大小与茎直径之间建立了明确的关系，这表明机械清理应在火灾刺激的更新事件后不久进行，或者在种子库较小时在老龄种群中进行。在密集的单一种植林中，以种子为食的生物防治剂在减少种子库大小方面无效。
