A COMPARATIVE STUDY ON REPRODUCTIVE ALLOCATION OF MUTUAL SPECIES IN MODERATE-TEMPERATE AND WARM-TEMPERATE STEPPE

A comparative study of the reproductive allocation of above ground biomass, nutrient elements (total C, total N, total P) and energy (calorific value) in mutual species such as Stipa grandis, Leymus chinensis, Cleistogenes squarrosa, Lespedeza dahurica and Heteropappus altaicus was carried out in the last stage growth seasons during 1999-2000, using two stations of Warm_temperate Steppe and Moderate_temperate Steppe in the Inner Mongolia Steppe Region. Results demonstrate that the reproductive allocation of biomass, nutrient elements (total C) and energy (caloric value) of these species in the two stations is close, but the reproductive allocation of total N and total P is remarkably higher, reflecting the characteristic concentration of the elements N and P in the reproductive organs. Meanwhile, the reproductive allocation proportion of the biomass, the elements and energy of these species are larger in Warm_temperate Steppe than in Moderate_temperate Steppe, except in Leymus chinensis. The findings show one aspect of adaptation to circumstances of extreme fluctuation among different years and extremely uneven well_distribution of precipitation during the growth seasons by the higher reproductive allocation of these species in Warm_temperate Steppe; and reflect that these species adapt themselves to a shorter growth season and unfavourable effects by increasing the allocation proportion of assimilation organs in Moderate_temperate Steppe.