食种子动物对三种锦鸡儿属植物繁殖更新的影响

Influence of seed predation on regeneration of three Caragana species

锦鸡儿属(Caragana)植物是黄土高原植被的重要组分,具有固氮、耐旱的特性,对黄土丘陵沟壑区的植被恢复具有重要意义。作者于2002–2003年对该属本地种白毛锦鸡儿(C.licentiana)和甘蒙锦鸡儿(C.opulens)及外来种中间锦鸡儿(C.intermedia)种子被动物取食情况进行了比较研究。2003年白毛锦鸡儿种子散落前的虫害率为88.2%,甘蒙锦鸡儿为29.7%±1.7%,中间锦鸡儿为43.2%±4.8%。种子落地后,白毛锦鸡儿和甘蒙锦鸡儿的种子被小啮齿动物取食的比例在各种微生境下均为100%,且取食速度很快,在种子放置后4d内即全部被取食。中间锦鸡儿种子被取食率则因微生境的不同而不同:在灌丛下被取食率为100%,在半阳坡的开阔草地上为85.0%±10.0%,在种植植物未成功的水平阶地上为31.0%±8.7%,且取食速度相对较慢。研究结果表明,食种子动物的取食大大减少了白毛锦鸡儿和甘蒙锦鸡儿的种子量以及种子传播萌发的机会。但食种子动物可能充当了白毛锦鸡儿4.0%硬实种子的传播者,从而有助于白毛锦鸡儿实现种子途径的更新;中间锦鸡儿种子无论在散落前还是散落后受食种子动物的影响均很小。

The leguminous Caragana species are important vegetation components, which are useful for rehabilitation of degraded ecosystems on the Loess Plateau, China. We studied the influence of seed predation by frugivores on the regeneration of two native leguminous species, C. licentiana and C. opulens, and one exotic species, C. intermedia. The results showed that before dispersal, 88.2% of the seeds of C. licentiana, 29.7%± 1.7% of C. opulens, and 43.2%±4.8% of C. interrnedia were infected by insects. After dispersal, 100% of the seeds of C. licentiana and C. opulens in all microhabitat were completely predated by seed predators in one to tour days. Seed predation rate of C. intermedia was relatively low and differed with microhabitats： 100% in shrub lands, 85.0%± 10.0 in grasslands, and 31.0%± 8.7% in open land. Seed predators greatly reduce seed quantity, seed dispersal and germination rate of C. licentiana and C. opulens. On the other hand, seed predators may effectively disperse the hard-coated seeds of C. licentiana, which may explain why C. licentiana has become a dominant shrub species in Dingxi County, Gansu Province. Seed predators have little influence on the seeds of C. interrnedia.