目的:变化的降水机制可以影响陆地植物和生态系统。然而,植物物候对降水时间模式变化的响应和潜在机制尚不清楚。本研究旨在探讨季节性降水再分配对温带草原植物生殖物候的影响。
方法:具有对照(C)的现场实验,提前(AP)和延迟(DP)生长季降水峰值,并采用AP和DP(ADP)的组合。选择了七个优势植物物种,并将其分为两个功能组(早期与中间开花的物种,浅层-vs.根深蒂固的物种)监测生殖物候,包括出芽,开花,和结果日期,以及2015年至2017年和2022年四个生长季节的繁殖持续时间。
结果:AP,但不是DP治疗促进了物候(即,萌芽,开花,和结果)日期,并延长了4个生长季节和7个受监测物种的生殖持续时间。此外,物候响应在不同植物功能群之间表现出不同的模式,这可以归因于土壤水分的变化及其在不同月份和土壤深度的变化。此外,繁殖持续时间延长的物种增加了与其他物种的物候重叠,这可能会对他们在AP治疗下的优势产生负面影响。
结论:我们的发现表明,降水季节性变化可能通过影响土壤水分有效性和变异性对植物物候产生相当大的影响。将这两个因素同时纳入物候模型将有助于我们了解植物物候在加剧的降水变化情景下的响应。此外,对生殖持续时间延长的物种的优势度下降的观察表明,在全球变化下,生殖物候变化可能会影响草原的群落组成。
OBJECTIVE: Changing precipitation regimes can influence terrestrial plants and ecosystems. However, plant phenological responses to changing precipitation temporal patterns and the underlying mechanisms are largely unclear. This study was conducted to explore the effects of seasonal precipitation redistribution on plant reproductive phenology in a temperate steppe.
METHODS: A field experiment with control (C), advanced (AP) and delayed (DP) growing-season precipitation peaks, and the combination of AP and DP (ADP) were employed. Seven dominant plant species were selected and divided into two functional groups (early- vs. middle-
flowering species, shallow- vs. deep-rooted species) to monitor reproductive phenology including budding,
flowering, and fruiting date, as well as reproductive duration for four growing seasons from 2015 to 2017, and 2022.
RESULTS: The AP, but not DP treatment advanced the phenological (i.e., budding,
flowering, and fruiting) dates and lengthened the reproductive duration across the 4 growing seasons and 7 monitored species. In addition, the phenological responses showed divergent patterns among different plant functional groups, which could be attributed to shifts in soil moisture and its variability in different months and soil depths. Moreover, species with lengthened reproductive duration increased phenological overlap with other species, which could have a negative impact on their dominance under the AP treatment.
CONCLUSIONS: Our findings reveal that changing precipitation seasonality could have considerable impacts on plant phenology by affecting soil water availability and variability. Incorporating these two factors simultaneously in the phenology models will help us understand the response of plant phenology under intensified changing precipitation scenarios. In addition, the observations of decreased dominance for the species with lengthened reproductive duration suggest that changing reproductive phenology can have a potential to affect community composition in grasslands under global change.