摘要
啮齿动物对辽东栎(Quercus wutaishanica)种子的侵袭取决于种子的大小及其捕食频率。然而,啮齿动物对幼苗的捕食是否具有频率依赖性还不清楚。本研究在宁夏六盘山区辽东栎次生林内,选取林窗和林下两种生境,按5个种子大小频率(9:1,7:3,5:5,3:7和1:9)移栽萌发生根的辽东栎幼苗,探究啮齿动物对幼苗子叶的频率依赖性捕食及其对幼苗生长与存活的影响。研究结果表明:(i)幼苗移栽初期(1-7天),啮齿动物更偏好大种子建立幼苗的子叶。然而,移栽后8-60天,啮齿动物更偏好小种子建立幼苗的子叶,即表现为正频率依赖性捕食。(ii)尽管幼苗捕食率在林下高于林窗,但经过一个生长周期后,林窗内幼苗存活率高于林下(分别为5.40%和2.00%)。(iii)捕食子叶对辽东栎幼苗生长无显著影响,但顶芽被咬掉后幼苗各生长参数均显著降低(P<0.05)。这些结果不仅为啮齿动物和不同表型辽东栎幼苗的共存提供了新的见解,还揭示了栎树幼苗的更新策略。
Rodents attack oak(Quercus wutaishanica)seeds based on their sizes and frequencies before germination.However,the predation of oak seeds post-germination(seedling cotyledons)is not well studied.Here,we not only tested the preference of rodents for Q.wutaishanica seedling cotyledons based on the frequency of large-versus small-seeded(FLS),but also evaluated the effects of predation on seedlings growth and survival in different habitats.We transplanted seedlings with the FLS set as 9:1,7:3,5:5,3:7 and 1:9,respectively,in the forest gap and under the canopy in the Liupan Mountains National Nature Reserve in Ningxia Hui Autonomous Region,Northwest China.The results showed that:(i)in 1-7 days after transplanting seedlings,rodents prefer the cotyledon of large-seeded seedings while small-seeded seedlings were preferred in 8-60 days,and the positive frequency-dependent predation was observed.(ii)The cotyledons were preyed on,the apical buds were bitted off,and the whole seedlings were uprooted,which mostly occurred under the forest canopy.At the end of a growing season,the survival rate of seedlings in the forest gaps was more than twice that under forest canopies.(iii)If cotyledons were preyed on,the growth of Q.wutaishanica seedlings would not be affected,but the seedlings growth was severely inhibited when the apical bud was bitten off.These results not only provide new insights into the coexistence between rodents and seedlings of different phenotypes,but also reveal the ecological characteristics of deciduous Quercus regeneration.
基金
funded by the National Science and Technology Basic Resources Survey Project(SQ2019FY101602)
the National Natural Science Foundation of China(31660195).
