Biodiv Sci ›› 2001, Vol. 09 ›› Issue (4): 373-381.  DOI: 10.17520/biods.2001055

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Seed bank and the factors influencing it for three Fagaceae species in Dujiangyan Region, Sichuan

XIAO Zhi-Shu, WANG Yu-Shan, ZHANG Zhi-Bin   

  1. Institute of Zoology , Chinese Academy of Sciences , Beijing 100080
  • Received:2001-02-21 Revised:2001-09-26 Online:2001-11-20 Published:2001-11-20
  • Contact: ZHANG ZhiBin

Abstract: Fagaceae is one of the most important families in subt ropical evergreen broad-leaved forest sin the Yangtse River Valley. However , studies on its natural regeneration are lacking. In this paper ,the seed rain , soil seed bank and factors influencing seed survival of three Fagaceae species , Quercus variabilis , Q. serrata and Castanopsis fargesii , were studied in Dujiangyan Region of the upper Yangt se River Valley , China. A method for estimating the proportion of insect-damaged seeds , surviving seeds , predated seeds and decayed seeds , was developed. Result s showed that : 1) the seed rain of three Fagaceae species lasted from the end of September to the beginning of December in the year 2000. The peaks of seed rain were slightly different in primary forest and in secondary forest . 2) The acorn crops of three Fagaceae species were all very small , and the mean density of seed rain were very low. In primary forest , the mean acorn density of Q. variabilis , Q. serrata and C. fargesii was 2.3 ±3. 85/ m2 , 6.5 ±17.43/ m2 and 1.9 ±5.21/ m2 ,respectively ; while in secondary forest , the mean density of the three species was 2.4±3.47/ m2 , 6.5 ±13.55/ m2 and 0.3 ±1.35/ m2 . 3) At the end of the seed rain , the number of acorns or their debris were thoroughly investigated at different depths in the soil : litter layer , 0~2 cm underground and 2~10 cm underground. The investigation of soilseed bank of two Fagaceae species showed that no Q. variabilis acorns remained in primary forest , while a few acorns (0.15 ±0.37 / m2) remained only in the litter of secondary forest . A few acorns of Q. serrata remained in both primary forest and secondary forest (0.20 ±0.70/ m2 and 0.10 ±0.31/m2 , respectively) , and also a few germinated (0.50 ±1.82/ m2 and 0.20 ±0.89/ m2 , respectively) ;but no acorns of C. fargesii were found. Most acorns remained in the litter , while few acorns stayed underground ; 4) The role of decay , insect-damage , predation and removal by vertebrates in the fates of acorns of the three plant species were quantitatively measured. Vertebrate predation was the key factor ; insect-damage increased the proportion of decay but decreased predation by vertebrates. The survival of acorns of Q. variabilis was lower than that of the smaller acorns of Q. serrata.