Chin J Plant Ecol ›› 2007, Vol. 31 ›› Issue (5): 883-891.DOI: 10.17521/cjpe.2007.0111

• Research Articles • Previous Articles     Next Articles


QIU Juan1, TAN Dun-Yan1, FAN Da-Yong2,*()   

  1. 1College of Forestry Sciences, Xinjiang Agricultural University, Urumqi 830052, China
    2Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
  • Received:2006-11-14 Accepted:2007-02-08 Online:2007-11-14 Published:2007-09-30
  • Contact: FAN Da-Yong


Aims Spring ephemerals characterized by very short-term growth rhythm and specific biological traits in the Junggar Desert of China play an important role in succession of the desert plant community, maintenance of the desert biological diversity and conservation of water and soil in desert. The main aim of the present study was to address: 1) the photosynthetic characteristics and the biomass allocation traits of spring ephemerals and 2) the relationship between these traits and unique growth pattern of these spring ephemerals.

Methods In vivo photosynthetic traits of 16 spring ephemerals at their growth stages were measured by an open gas-exchange measurement system (Li-6400) and biomass allocation patterns were measured in seven species.

Important findings Maximum net photosynthesis rate (Pnmax),maximum transpiration rate (Trmax) and water use efficiency (WUE) of 16 species were 8.07~35.96 μmol CO2·m-2·s-1, 3.16~29.64 mmol H2O·m-2·s-1 and 0.54~ 4.26 μmol CO2·mmol-1H2O, respectively. Pnmax was positively correlated with maximum stomatal conductance, the correlation coefficient was 0.77 (p<0.05) and the slope in the linear region was 26.36 μmol·mmol-1. Based on analysis for the response of Pn to internal CO2 concentration and to photosynthetic photon flux density, apparent CO2 compensation point are in the range of 4 to 5 Pa (ambient air temperature of 28~30 ℃ during the measurement), apparent carboxylation efficiency ranged from 0.64 to 1.86 μmol CO2·m-2·s-1·Pa-1, and apparent quantum yield ranged from 0.05 to 0.06. Biomass allocation data analysis showed that individual biomass of spring ephemerals were very low (0.05~0.39 g). Total leaf area ranged from 3.24 to 51.40 cm2, leaf mass per unit leaf area ranged from 0.40 to 0.77 g·m-2, root/total biomass ratio was 5.72%~19.43%, and leaf area ratio was 2.92~9.00 m2·kg-1. The percentage of total biomass allocated to roots was positively correlated with WUE for the seven investigated species (r=0.93, p<0.01). Results indicate that the species investigated are typical C3 plants. These spring ephemerals are characterized by higher Pn, Tr and lower WUE in comparison with other desert species. The unique biomass allocation of low root/aboveground biomass ratio, higher leaf area ratio, higher leaf mass per unit leaf area, and photosynthetic traits are involved in the physiological mechanisms that contributed to the rapid growth of desert spring ephemerals.

Key words: Junggar Desert, spring ephemerals, photosynthesis rate, transpiration rate, water use efficiency, biomass allocation