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作 者 ：张文标

期 刊 ：生态学报 2008年 28卷 8期 页码：4037~4046

关键词：夏蜡梅(Sinocalycanthus chinensis)；开花物候；传粉成功；大明山；

Keywords:Daming mountain, flowering phenology, pollination success, Sinocalycanthus chinensis,

摘 要 ：野外定点观测了夏蜡梅在3个群体的开花物候进程，分别计算了结实率和结籽率，并分析了始花日和开花同步性等开花物候指数对其传粉成功的影响，还进一步从个体水平分析了开花时间对传粉成功的影响。结果如下：夏蜡梅的花期在5月上旬到6月下旬，开花物候参数在不同群体间存在较明显的差异，而各群体的开花进程均呈明显的“单峰型”，且开花同步性高，为“大量开花模式”。群体内各开花物候参数与传粉成功相关性不明显；群体间开花物候参数中的始花日和开花中值日与结实率呈极显著的负相关，终花日与结实率和结籽率分别呈极显著和显著的负相关。个体水平不同开花时间对结实率有着显著影响（F=15.960，df=3，P＜0.01），而对结籽率影响不大（F=2.358，df=3，P=0.073）。相同海拔高度小生境不同对夏蜡梅的传粉成功影响不大，但不同海拔高度对夏蜡梅的传粉成功影响显著。作为一种濒危物种，夏蜡梅这种“集中开花模式”可以吸引更多的传粉昆虫，有助于其获得更多的传粉成功，但增加了其花粉在个体内及邻近个体间的传递，不利于花粉在群体间的扩散，而导致了一定程度的自交和近交衰退，这可能是夏蜡梅群体遗传变异性低、遗传分化明显及濒危的一个原因。

Abstract:The variations in flowering phenology and pollination success of Sinocalycanthus chinensis were investigated in a field survey, which was carried out on the Daming Mountain, Zhejiang Province, China. Three populations of S. chinensis were chosen. Population A (523 m a.s.l.) was in the edges of broad-leaved forests. Population B (520 m a.s.l.) and population C (840 m a.s.l.) were located in the broad-leaved forest. For these three populations, 26, 21 and 25 individuals were randomly marked in 2006 before flowering, respectively. Flowering and fruiting per plant were monitored weekly. Flowering onset, median flowering date, and ending flowering date were recorded. Then phenology index and synchrony index were calculated. We analyzed the difference in flowering phenology between three populations, the correlation matrix between phenological parameters, the effect of flowering time on the pollination success, the correlation between phenological parameter and pollination success, and the difference in pollination success between three populations. The results were as follows: The flowering duration of S. chinensis populations spanned from early May to late June. Temporal patterns of flowering of S. chinensis were very similar at the population level, with a well-defined peak and marked synchrony. Within each population, the phenological parameters showed no correlation with fruit set and seed set. But among populations, onset and median flowering date had significantly negative correlation with fruit set. Ending flowering date had significantly negative correlation with fruit set and the correlation was extremely significant for seed set. Flowering time conferred a marked impact on fruit set (F=15.960, df=3, P＜0.01) at the individual level of S. chinensis, but not on the seed set (F=2.358, df=3, P=0.073). Although population A and population B appeared at similar altitudes, habitat types had different effects on flowering phenology but not on pollination success. Population C from the higher altitude had significantly lower pollination success, as compared with populations A and B from lower altitude. As an endangered species, S. chinensis exhibited a so-called “Mass-flowering” pattern, thereby increasing the pollination success of individuals and the dispersal of pollens within and/or among individuals. This phenomenon does not seem to facilitate to disperse pollens among populations and would pose, to some extent, self-mating and inbreeding depression, thereby leading to low genetic variability, high genetic differentiation. These traits may, to a larger extent, explain why S. chinensis is readily endangered.

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