State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, People's Republic of China.
Department of Biology, University of Kentucky, Lexington, Kentucky, USA.
Ecol Appl. 2024 Jul;34(5):e2984. doi: 10.1002/eap.2984. Epub 2024 May 16.
Seed rain and the soil seed bank represent the dispersal of seeds in space and time, respectively, and can be important sources of recruitment of new individuals during plant community regeneration. However, the temporal dynamics of seed rain and the mechanisms by which the seed rain and soil seed bank may play a role in plant community regeneration with increased grazing disturbance remain unclear. Seed rain, soil seed bank, aboveground vegetation, and rodent density were sampled along a grazing gradient in an alpine marsh on the eastern Tibetan Plateau. We described the temporal dynamics of seed dispersal using Bayesian generalized mixed models, and nonmetric multidimensional scaling and the structural equation model were used to examine the effects of grazing disturbance on the relative role of seed rain and soil seed bank on aboveground plant community regeneration. The temporal dynamics of seed rain changed from a unimodal to a bimodal pattern with increased grazing disturbance. Both species diversity and seed density of the seed rain and seed bank increased significantly with increased grazing disturbance. Increased grazing disturbance indirectly increased the similarity of composition between seed rain, seed bank, and aboveground plant community by directly increasing species diversity and abundance of aboveground plant community. However, increased grazing disturbance also indirectly decreased the similarity of seed rain, soil seed bank, and aboveground plant community by directly increasing rodent density. The similarity between seed rain and aboveground plant community was greater than that of the soil seed bank and aboveground plant community with increased grazing disturbance. Grazing disturbance spreads the risk of seed germination and seedling establishment by changing the temporal dynamics of seed dispersal. Plants (positive) and rodents (negative) mediated the role of seed rain and soil seed bank in plant community regeneration. The role of seed rain in plant community regeneration is higher than the seed bank in disturbed alpine marshes. Our findings increase our understanding of the regeneration process of the plant community, and they provide valuable information for the conservation and restoration of alpine marsh ecosystems.
种子雨和土壤种子库分别代表种子在空间和时间上的扩散，它们可以成为植物群落再生过程中新个体补充的重要来源。然而，种子雨的时间动态以及种子雨和土壤种子库如何在增加放牧干扰的情况下在植物群落再生中发挥作用的机制尚不清楚。在青藏高原东部的一个高山沼泽地的放牧梯度上，我们沿放牧梯度采样了种子雨、土壤种子库、地上植被和鼠密度。我们使用贝叶斯广义混合模型描述了种子扩散的时间动态，使用非度量多维标度和结构方程模型检验了放牧干扰对种子雨和土壤种子库在地上植物群落再生中的相对作用的影响。随着放牧干扰的增加，种子雨的时间动态从单峰模式转变为双峰模式。种子雨和种子库的物种多样性和种子密度都随着放牧干扰的增加而显著增加。增加的放牧干扰通过直接增加地上植物群落的物种多样性和丰度，间接增加了种子雨、种子库和地上植物群落之间组成的相似性。然而，增加的放牧干扰也通过直接增加鼠密度，间接降低了种子雨、土壤种子库和地上植物群落之间的相似性。随着放牧干扰的增加，种子雨与地上植物群落之间的相似性大于土壤种子库与地上植物群落之间的相似性。放牧干扰通过改变种子扩散的时间动态来分散种子萌发和幼苗建立的风险。植物（正）和啮齿动物（负）调节了种子雨和土壤种子库在植物群落再生中的作用。在受干扰的高山沼泽中，种子雨在植物群落再生中的作用高于种子库。我们的研究结果增加了我们对植物群落再生过程的理解，并为高山沼泽生态系统的保护和恢复提供了有价值的信息。
