Facelli José M, Ladd Brenton
Department of Botany, The University of Adelaide, 5005, Adelaide, SA, Australia.
Oecologia. 1996 Sep;107(4):441-445. doi: 10.1007/BF00333933.
We studied how the responses of four species of eucalypt to leaf litter related to their germination responses to light and water availability. Two of the species (Eucalyptus obliqua and E. baxteri) have a mesic distribution, while the other two (E. oleosa, and E. incrassata) are more xerophytic. We studied the effect of litter on emergence of the four species in a glasshouse experiment. Litter did not affect the emergence of E. incrassata and E. oleosa, but enhanced the emergence of E. obliqua and E. baxteri. Litter increased the seedling mortality of all four species. Germination responses to light and water availability were studied in growth cabinets under controlled conditions. The germination of E. obliqua and E. baxteri was substantially lower under fluorescent light than in darkness, but that of E. oleosa and E. incrassata was not affected by the light environment. The germination of E. obliqua and E. baxteri was significantly reduced by reduced water potential (ψa). Substantial germination of E. oleosa and E. incrassata occurred even at very low ψa (less than -1.05 MPa). We conclude that both the shade and the humid micro-environment provided by litter may have contributed to the emergence responses of the four species to litter, and these responses may correspond to ecological adaptations to the different environments in which they live.
我们研究了四种桉树对落叶的反应如何与其对光照和水分可利用性的萌发反应相关。其中两个物种（斜叶桉和巴氏桉）具有中生分布，而另外两个（油桉和厚皮桉）则更为耐旱。我们在温室实验中研究了落叶对这四个物种出苗的影响。落叶对厚皮桉和油桉的出苗没有影响，但促进了斜叶桉和巴氏桉的出苗。落叶增加了所有四个物种的幼苗死亡率。在可控条件下的生长箱中研究了对光照和水分可利用性的萌发反应。斜叶桉和巴氏桉在荧光灯下的萌发率明显低于黑暗中，但油桉和厚皮桉的萌发不受光照环境的影响。降低水势（ψa）显著降低了斜叶桉和巴氏桉的萌发率。即使在非常低的ψa（低于-1.05 MPa）下，油桉和厚皮桉仍有大量萌发。我们得出结论，落叶提供的遮荫和潮湿微环境可能都促成了这四个物种对落叶的出苗反应，并且这些反应可能对应于它们所生活的不同环境的生态适应。
