van Ulft L H
Department of Plant Biology, Utrecht University, Utrecht, The Netherlands.
Plant Biol (Stuttg). 2004 Mar-Apr;6(2):214-21. doi: 10.1055/s-2004-815736.
For eleven tree species, differing in seed mass, germination success (emergence success for two small-seeded species) and the causes of failure to germinate were studied in the forest understorey and in logging gaps in the tropical rain forests of Guyana. In the forest understorey, germination success increased with seed mass. However, as gap size increased the difference between smaller and larger seeded species diminished because germination success of smaller-seeded species increased slightly, while that of larger-seeded species decreased dramatically. The negative effect of gap size on germination success of larger-seeded species was caused by an increased risk of desiccation with gap size, which was a far more important seed mortality agent for larger than for smaller-seeded species. Generally, seeds of smaller-seeded species suffered more from insect predation and were removed at higher rates than larger-seeded species. On the other hand, larger-seeded species were eaten more by mammals than smaller-seeded species. It is concluded that logging can result in shifts in the species composition in the tropical rain forests of Guyana which are dominated by species with large seeds, since germination success of larger-seeded species is dramatically reduced in large logging gaps.
对圭亚那热带雨林林下层和采伐林隙中11种种子质量、萌发成功率（两种小种子物种为出土成功率）不同的树种以及种子不萌发的原因进行了研究。在林下层，萌发成功率随种子质量增加而提高。然而，随着林隙面积增大，小种子和大种子物种之间的差异减小，因为小种子物种的萌发成功率略有增加，而大种子物种的萌发成功率则大幅下降。林隙面积对大种子物种萌发成功率的负面影响是由随着林隙面积增大干燥风险增加导致的，对于大种子物种而言，干燥是比小种子物种更重要的种子死亡因素。一般来说，小种子物种的种子比大种子物种更容易遭受昆虫捕食，被移除的速率也更高。另一方面，大种子物种被哺乳动物吃掉的比小种子物种更多。得出的结论是，采伐会导致圭亚那以大种子物种为主的热带雨林物种组成发生变化，因为大种子物种在大面积采伐林隙中的萌发成功率会大幅降低。
