Zhou Xiaolong, Duan Ronghua, Long Jian, Bu Haiyan
College of Ecology and Environment, Xinjiang University, Urumqi 830046, China.
Key Laboratory of Oasis Ecology, Xinjiang University, Urumqi 830046, China.
Plants (Basel). 2025 Sep 2;14(17):2730. doi: 10.3390/plants14172730.
Seed size and number are two important components of plant reproductive traits. Previous theoretical studies have suggested that resource limitations lead to a strong trade-off between seed size and seed number. However, empirical evidence from natural communities remains scarce. In this study, the relationship between seed size and seed number was tested at the community level and in three functional groups-graminoids, forbs, and legumes-in a natural alpine steppe community in the Tianshan Mountains. The role of limiting resources in reproduction and in determining trade-off patterns was also examined by treating the reproductive biomass and allocation of each species as a resource pool for producing seeds. Our results showed a significant negative relationship between seed size and seed number at the community level, which indicated that a trade-off between seed size and number existed and that the species that produced large seeds produced fewer seeds and vice versa. This trade-off was detected for the graminoid group but not for the forb or legume group, so the trade-off at the community level was determined primarily by graminoid species. Moreover, the graminoid group had lower reproductive biomass and allocation than the forb and legume groups, indicating that the graminoid species were more strictly limited by reproductive resources. Our study provides evidence of a seed size-number trade-off in a natural alpine steppe community, especially among graminoid species, and the important role of reproductive resources in determining the trade-off.
种子大小和数量是植物繁殖性状的两个重要组成部分。先前的理论研究表明，资源限制导致种子大小和种子数量之间存在强烈的权衡。然而，来自自然群落的实证证据仍然稀缺。在本研究中，我们在天山自然高寒草原群落的群落水平以及三个功能组（禾本科植物、草本植物和豆科植物）中测试了种子大小和种子数量之间的关系。通过将每个物种的繁殖生物量和分配视为产生种子的资源库，还研究了限制资源在繁殖和决定权衡模式中的作用。我们的结果表明，在群落水平上种子大小和种子数量之间存在显著的负相关关系，这表明种子大小和数量之间存在权衡，即产生大种子的物种产生的种子较少，反之亦然。这种权衡在禾本科植物组中被检测到，但在草本植物或豆科植物组中未被检测到，因此群落水平上的权衡主要由禾本科植物物种决定。此外，禾本科植物组的繁殖生物量和分配低于草本植物和豆科植物组，这表明禾本科植物物种受到繁殖资源的限制更为严格。我们的研究提供了自然高寒草原群落中种子大小 - 数量权衡的证据，特别是在禾本科植物物种之间，以及繁殖资源在决定这种权衡中的重要作用。
