动物在大别山五针松种群天然更新中的作用

大别山五针松(Pinus dabeshanensis)为我国特有树种,其天然植株较少且分布范围狭窄,种群更新困难,已被列为国家二级重点保护野生植物。分别于2015年和2016年的10—12月,在目前已知最大天然种群所在地安徽岳西县河图镇大王沟,研究了大别山五针松球果与种子特征、种子雨与土壤种子库、动物对种子的取食和搬运,幼苗分布格局及其与鼠穴分布的关系,以期探明动物在其天然更新中的作用,分析其天然更新不力的原因。结果显示:大别山五针松种子败育率较高,阳坡个体球果发育情况好于阴坡;种子成熟期间没有明显的种子雨,土壤种子库也未调查到完整种子。共记录到母树与球果的访问动物6目11科16种,其中7种动物确定取食种子;地面种子摆放实验显示超过95%以上的种子被啮齿动物捕食或搬运至他处取食或贮藏,不同的摆放处理对啮齿动物的捕食、搬运没有显著影响;小林姬鼠(Apodemus sylvaticus)盗食现象严重,埋藏实验中人工贮点当夜被发现的概率在90%左右,岩松鼠(Sciurotamias davidianus)和小林姬鼠是其种子主要捕食者。研究地的大别山五针松种群于2015年和2016年分别新增一年生幼苗5株和7株,这表明大别山五针松在当地存在天然更新。幼苗多单独生长在母树周围,点格局分析显示在0—0.6 m的尺度范围内呈随机分布;在0.6 m尺度呈聚集分布。大别山五针松幼苗在小林姬鼠巢穴周边分布,其更新格局受到小林姬鼠贮点位置分布情况影响,小林姬鼠极有很可能为大别山五针松的传播者,啮齿动物对大别山五针松种子的捕食与搬运影响了大别山五针松的天然种群更新。

Role of animals in the natural population regeneration of Pinus dabeshanensis

Pinus dabeshanensis is listed as a national second-class protected wild plant species. Because of its rarity and narrow distribution, regeneration of its population is difficult. To determine the role of animals in natural population regeneration of P. dabeshanensis and causes of difficulties with natural regeneration of a P. dabeshanensis population, we studied P. dabeshanensis cone and seed traits, seed rain and soil seed banks, seed predation and removal by animals, spatial distribution patterns of seedlings and their relationships with the distribution of rat nests in the Ta-pieh Mountains, Yuexi County, Anhui Province during the period from November to December in the years 2015 and 2016. The results showed that P. dabeshanensis possessed a high rate of seed abortion, and cones grown on a sunny slope were better developed than those grown on a shady slope. We did not find seed rain or soil seed banks during seed maturation. Sixteen species of animals, belonging to 11 families and 6 orders, visited trees and cones. Seven species were identified as seed predators. A ground seed placement experiment showed that more than 95% of the seeds were preyed upon or removed to other places to be preyed upon or stored. The fates of P. dabeshanensis seeds among different placement locations were not significantly different. Apodemus sylvaticus was a good pilferer in our experiment; the seed discovery and storage rate was about 90% on the first night. Two species of rodents, Sciurotamias davidianus and A. sylvaticus, were the main seed predators. At the study site, we found 5 established seedlings in 2015 and 7 established seedlings in 2016. This indicated that there is a natural regeneration in the local area. The seedings mostly established around the seed tree independently, in a random distribution within 0-0.6 m and a clumped distribution at distances over 0.6 m. The natural regeneration pattern of P. dabeshanensis seedlings was affected by the location of A. sylvaticus nests, and the seedings established for the most part near the nests of A. sylvaticus. In summary, A. sylvaticus may be a seed disperser, and P. dabeshanensis seed predation and removal by rodents could affect P. dabeshanensis natural population regeneration.