Du Yanjun, Queenborough Simon A, Chen Lei, Wang Yunquan, Mi Xiangcheng, Ma Keping, Comita Liza S
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
School of Forestry and Environmental Studies, Yale University, New Haven, CT, 06511, USA.
Oecologia. 2017 May;184(1):193-203. doi: 10.1007/s00442-017-3842-3. Epub 2017 Feb 25.
Recent evidence suggests that plant performance can be influenced by the phylogenetic diversity of neighboring plants. However, no study to date has examined the effect of such phylogenetic density dependence on the transition from seed to seedling. Using 6 years of data on seedling recruitment and seed rain of 13 species from 130 stations (one 0.5 m seed trap and three adjacent 1 m seedling plots) in a subtropical evergreen forest, we asked: (1) Does negative density dependence act across seed to seedling stages? (2) Is there evidence for phylogenetic density dependence during the seed to seedling transition? (3) Does the strength of density dependence vary among years? Generalized linear mixed-effects models were used to model seed to seedling transition as a function of conspecific seed and seedling densities, heterospecific seed and seedling densities, and mean phylogenetic distance of heterospecific seeds and seedling. Conspecific seed density had a significant negative effect on seedling transition rates for 12 of 13 focal species. In contrast, conspecific seedling density had a positive effect for 7 species, suggesting species-specific habitat preferences. Few species were significantly affected by the density or phylogenetic relatedness of heterospecific seeds and seedlings. Only conspecific seed density effects varied among years for most focal species. Overall, our results reveal that conspecific seed and seedling densities play a more important role than the density or relatedness of heterospecific seeds and seedlings during the seed to seedling stage, suggesting that species-specific seed predators, along with habitat preferences, may contribute to diversity maintenance in this forest.
最近的证据表明，植物的表现可能会受到邻近植物系统发育多样性的影响。然而，迄今为止尚无研究考察这种系统发育密度依赖性对从种子到幼苗转变的影响。利用亚热带常绿林中130个站点（一个0.5米的种子陷阱和三个相邻的1米幼苗样地）的13个物种6年的幼苗更新和种子雨数据，我们提出以下问题：（1）负密度依赖性是否在从种子到幼苗的阶段起作用？（2）在种子到幼苗的转变过程中是否存在系统发育密度依赖性的证据？（3）密度依赖性的强度在不同年份是否有所变化？我们使用广义线性混合效应模型将种子到幼苗的转变建模为同种种子和幼苗密度、异种种子和幼苗密度以及异种种子和幼苗的平均系统发育距离的函数。对于13个重点物种中的12个，同种种子密度对幼苗转变率有显著的负面影响。相比之下，同种幼苗密度对7个物种有积极影响，这表明了物种特定的栖息地偏好。很少有物种受到异种种子和幼苗的密度或系统发育相关性的显著影响。对于大多数重点物种，只有同种种子密度效应在不同年份有所变化。总体而言，我们的结果表明，在从种子到幼苗的阶段，同种种子和幼苗密度比异种种子和幼苗的密度或相关性发挥更重要的作用，这表明特定物种的种子捕食者以及栖息地偏好可能有助于维持这片森林的多样性。
