水青冈林中两种鹅耳枥种子萌发和幼苗的生存与生长（英文）

 千金榆(Carpinus cordata var．chinensis)和千筋树(Carpinus fargesiana)是四川省北部山地水青冈林中的两种主要落叶阔叶树。两种植物种子萌发和幼苗生存与生长的实验研究结果显示：千金榆种子秋季成熟落地后有一年多的休眠期，种子主要在落地后的第二和第三个生长季萌发；千筋树种子成熟落地后有的可在来年萌发，但大部分是在第二个生长季萌发；由于每2～3年两种树就有一个较大的结实年，每年都会有一些新的幼苗在林中出土；尽管两种树是耐荫的，但幼苗在较好光照条件下(如林窗)生存和生长明显好于在林冠遮荫的地方；施肥会加速幼苗的死亡，特别是在阴暗的林下，但在光照较好的条件下能促进幼苗的生长。结果说明两种鹅耳枥的幼苗可以在林下持续存在，但只有在较好的光照条件下，如稀疏的林冠下或林窗下才会有明显的净生长。

GERMINATION, SEEDLING SURVIVAL AND GROWTH OF TWO CARPINU S SPECIES FROM A CHINESE BEECH FOREST

Carpinus cordata var. chinensis and Carpinus fargesiana are two comm on shade tolerant species of beech forests in Daba Mountains, China. Seed germin ation, seedling survival and growth under field experimental conditions were stu died in relation to the regeneration. C. cordata var. chinensis seeds ha ve a distinct dormancy of more than one year and mainly germinate in the second and third growing seasons after seed fall.Some of C. fargesiana seeds germin ate in the first growing season after seed fall, but most germinate in the secon d. As the two species often produce seeds in the same mast year every two or thr ee years, emergence of some seedlings in the forest occurs every year. Seedlings survive and grow significantly better under better-lit conditions than in the shady understorey. Fertilization can hasten seedling death especially in the und erstorey, but can enhance seedling growth in better-lit conditions. Results sug gest that the seedlings of both species can persist in the shade of the beech fo rest canopy, but substantial net growth occurs only under better-lit conditions , such as beneath a sparse canopy or in canopy gaps.