Lindig-Cisneros Roberto, Zedler Joy B
Department of Botany and Arboretum, University of Wisconsin-Madison, 430 Lincoln Dr., Madison, WI, 53706, USA.
Oecologia. 2002 Oct;133(2):159-167. doi: 10.1007/s00442-002-1020-7. Epub 2002 Oct 1.
Microsites that prevent seed germination are critical for slowing the invasion of native plant communities by aggressive, clonal species. A suitable model for study is the clonal grass, Phalaris arundinacea, which reproduces prolifically from seed and is spreading into wetlands across temperate North America. Knowing that light conditions control its seed germination in the laboratory and that light varies with canopy complexity in a Wisconsin fen, we tested multiple attributes of microsites under spatially and temporally dynamic canopies (namely, presence/absence of a matrix species, number of species in the canopy, plus indirect effects of three soil water levels) for their control of germination in microcosms. Our 6-species canopies + the matrix of Glyceria striata had the densest cover and reduced P. arundinacea germination to 1.9%, compared to 7.3% for 1-species canopies + the matrix. After selectively removing canopy components, germination increased to 36.1% for 6-species and 33.0% for 1-species canopies. Comparing canopies with each of the six species, germination declined in relation to increasing leaf width. Given moist soil, P. arundinacea germination microsites are determined by canopy complexity, which affects light penetration, which in turn determines germination rate.
阻止种子萌发的微生境对于减缓侵略性克隆物种对本地植物群落的入侵至关重要。一个合适的研究模型是克隆性禾本科植物——虉草，它通过种子大量繁殖，并正在扩散到北美洲温带的湿地中。鉴于在实验室中光照条件可控制其种子萌发，且在威斯康星州的一个沼泽中光照会随冠层复杂程度而变化，我们在空间和时间动态变化的冠层下测试了微生境的多个属性（即是否存在基质物种、冠层中的物种数量，以及三种土壤水位的间接影响）对微观世界中种子萌发的控制作用。我们的6物种冠层 + 条纹甘油草基质具有最密集的覆盖度，并将虉草的萌发率降低至1.9%，相比之下，1物种冠层 + 基质的萌发率为7.3%。选择性去除冠层成分后，6物种冠层的萌发率增加到了36.1%，1物种冠层的萌发率增加到了33.0%。将冠层与六种物种中的每一种进行比较，萌发率随着叶片宽度的增加而下降。在土壤湿润的情况下，虉草种子萌发的微生境由冠层复杂程度决定，冠层复杂程度影响光照穿透，进而决定萌发率。
