Litter accumulation and biomass dynamics in riparian zones in tropical South America of the Asian invasive plant <i>Hedychium coronarium</i> J. König (Zingiberaceae)

<b>Background</b>: Promoting changes in abiotic conditions and ecosystem processes, such as decomposition, is a mechanism by which some exotic plant species displace native plants and become invasive. <b>Aims</b>: We monitored ramets of Hedychium coronarium over 30 months to estimate the litter decay rate, biomass dynamics and litter accumulation over time in riparian sites invaded by the species in southeastern Brazil. <b>Methods</b>: We measured the number, height, emergence and mortality of ramets in three environments invaded by H. coronarium (natural, rural and urban). We also measured litter decay in situ and in in vitro experiments. We used sinusoidal models to describe height fluctuation and exponential models to simulate litter decay and litter accumulation. <b>Results</b>: Ramets of H. coronarium showed high seasonal variation in terms of height and emergence, as well as low litter decay. Accordingly, our models predicted high litter production and a seasonal pattern of litter accumulation in invaded sites. <b>Conclusions</b>: H. coronarium produces a great amount of litter, which shows slow decay and hence seems to affect decomposition processes. Investigating seasonal variation on the effects of invasive species on ecosystem functioning shed light on the factors driving the success and impact of invasive plants.**背景**：部分外来植物物种可通过改变非生物环境与生态系统过程（如分解作用）排挤本土植物，进而实现入侵。 **研究目标**：我们针对巴西东南部被姜花（Hedychium coronarium）入侵的河岸生境，对该物种的分株（ramet）开展了为期30个月的监测，以估算其枯落物分解速率、生物量动态及随时间变化的枯落物积累量。 **研究方法**：我们在姜花（H. coronarium）入侵的三类生境（自然、乡村与城市生境）中，监测了分株的数量、株高、萌发率与死亡率。同时分别开展原位枯落物分解实验与离体枯落物分解实验。我们采用正弦模型描述株高波动规律，使用指数模型模拟枯落物分解与积累过程。 **研究结果**：姜花分株的株高与萌发率存在显著季节波动，且枯落物分解速率较低。据此，我们的模型预测入侵生境中将产生大量枯落物，并呈现出季节性的枯落物积累模式。 **研究结论**：姜花可产生大量枯落物，且其枯落物分解缓慢，因此可能对生态系统分解过程产生影响。探究入侵物种对生态系统功能的季节影响效应，有助于阐明驱动入侵植物成功定植与产生危害的关键因素。