Are differences in seed mass among species important in structuring plant communities? Evidence from analyses of spatial and temporal variation in dune-annual populations
Are differences in seed mass among species important in structuring plant communities? Evidence from analyses of spatial and temporal variation in dune-annual populations
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DOI：
10.1034/j.1600-0706.2002.960304.x
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发表时间：
2002-03-01
期刊：
影响因子：
3.4
通讯作者：
Turnbull, L
中科院分区：
文献类型：
--
作者：
Coomes, DA;Rees, M;Turnbull, L
我们分析了沿海一年生植物群落的种群和空间结构。跨越十个沙丘和三年，探索种子质量在构建这些社区中的作用。一个建议是，一年生植物群落结构的竞争殖民权衡驱动的种子分配策略的物种之间的差异，而另一种观点是，种子质量影响的方式，物种对环境变化的反应。以支持竞争与殖民的权衡。1995年，在沙丘上发现的两个种子最大的物种（Erodium circutarium和Geraniam molle）与10 mm尺度的其他行会成员呈负相关，表明它们在当年（种群密度高时）局部排除了种子较小的物种。在支持的环境响应假说，人口的一年生植物下降1995年和1996年之间的10个沙丘上的8个。强调每年的环境波动在确定种群规模方面的重要性。变得相对罕见的物种在空间上也变得更加聚集，这种影响在小种子物种中最为明显。因此，小种子的物种可能被迫撤退到避难所时，条件是不利的，在那里减少种间接触的频率可能会增加他们的持久性的机会。我们还表明，小种子的物种有时达到更高的人口密度比大种子的物种。与早期的研究结果一致，但原因是，这种丰度种子质量的关系可能是由于竞争殖民权衡或从不同的反应小，大种子物种对环境变化。我们的结论是，沙丘一年生物种与对比种子质量不同的环境变化的反应，而竞争殖民权衡起着较小的作用，在社区动态比以前认为的。
We analyse the population and spatial structures of coastal annual-plant communities. across ten dunes and three years, to explore the role of seed mass in structuring these communities. One suggestion is that annual-plant communities are Structured by competition-colonization trade-offs driven by difference among species in seed-allocation strategies, while another perspective is that seed mass influences the ways in which species respond to environmental variation. In support of the competition-colonization trade-off. the two largest-seeded species found on the dunes (Erodium circutarium and Geraniam molle) were negatively associated with the other guild members at the 10-mm scale in 1995, suggesting they locally excluded smaller-seeded species in that year (when population densities were high). In support of the environmental response hypothesis, populations of annual plants declined between 1995 and 1996 on eight of the ten dunes. underscoring the importance of year-to-year environmental fluctuations in determining population sizes. The species that became relatively uncommon also became more aggregated in space, and this effect was most pronounced among the small-seeded species. Thus, small-seeded species may be forced to retreat into refuges hen conditions are unfavourable, where reduced frequencies of interspecific contacts may increase their chances of persistence. We also show that small-seeded species sometimes reach much higher population densities than larger-seeded species. consistent with earlier findings, but reason that this abundance seed mass relationship could have resulted from either a competition-colonization trade-off or from different responses of small- and large-seeded species to environmental variation. We conclude that dune-annual species with contrasting seed masses respond differently to environmental variation, while the competition-colonization trade-off plays a lesser role in community dynamics than previously considered.