Abstract Encroachment into the moist coastal grasslands within eThekwini Municipality by Dalbergia obovata, an indigenous forest liana that forms dense monospecific stands, poses a potential biodiversity threat. Identification of the mechanisms of D. obovata diaspore dispersal from neighbouring adjacent forests, and subsequent patterns of propagation within the grasslands, was required to understand how D. obovata encroached into the grasslands. A simple wind dispersal model for D. obovata diaspores was developed to determine potential dispersal distances under different wind conditions. Field surveys were undertaken to map the distribution of plants within stands of D. obovata in the grasslands of two urban nature reserves and these were compared against historic orthophoto records to determine when establishment occurred. Stands were excavated to investigate the primary method of propagation by D. obovata once it had become established. The results of the wind dispersal modelling and field surveys showed that D. obovata dispersal was a product of the height of diaspore release and wind velocity. For successful dispersal to occur, diaspores would have to occupy positions close to the forest margin. Successful establishment of D. obovata was infrequent, and likely associated with extreme weather events, but once established, clonal propagation via roots and lateral branches resulted in expansion of the stands. The progressive expansion of the stands in the grasslands represents a threat to the grasslands.

中文翻译：

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将森林藤本植物散播到草原和建立后的林分扩张

摘要 Dalbergia obovata 侵入 eThekwini 市内潮湿的沿海草原，这是一种形成密集单种林的原生林藤本植物，构成了潜在的生物多样性威胁。需要确定 D. obovata 水硬石从邻近森林扩散的机制，以及随后在草原内的繁殖模式，以了解 D. obovata 如何侵入草原。开发了一个简单的 D. obovata 硬水散风散布模型，以确定不同风况下的潜在散布距离。进行了实地调查以绘制两个城市自然保护区草原中 D. obovata 林分内的植物分布图，并将这些与历史正射影像记录进行比较，以确定何时建立。在 D. obovata 建立后，他们挖掘了林分以研究其主要繁殖方法。风扩散模型和实地调查的结果表明，D. obovata 的扩散是硬水铝石释放高度和风速的产物。为了成功扩散，水铝石必须占据靠近森林边缘的位置。D. obovata 的成功建立并不常见，并且可能与极端天气事件有关，但一旦建立，通过根和侧枝的克隆繁殖导致林分扩大。草原上林分的逐步扩大对草原构成了威胁。风扩散模型和实地调查的结果表明，D. obovata 的扩散是硬水铝石释放高度和风速的产物。为了成功扩散，水铝石必须占据靠近林缘的位置。D. obovata 的成功建立并不常见，并且可能与极端天气事件有关，但一旦建立，通过根和侧枝的克隆繁殖导致林分扩大。草原上林分的逐步扩大对草原构成了威胁。风扩散模型和实地调查的结果表明，D. obovata 的扩散是硬水铝石释放高度和风速的产物。为了成功扩散，水铝石必须占据靠近森林边缘的位置。D. obovata 的成功建立并不常见，并且可能与极端天气事件有关，但一旦建立，通过根和侧枝的克隆繁殖导致林分扩大。草原上林分的逐步扩大对草原构成了威胁。并且可能与极端天气事件有关，但一旦建立，通过根和侧枝的克隆繁殖导致林分扩大。草原上林分的逐步扩大对草原构成了威胁。并且可能与极端天气事件有关，但一旦建立，通过根和侧枝的克隆繁殖导致林分扩大。草原上林分的逐步扩大对草原构成了威胁。