不同轮割制度对典型草原主要种群的影响

选择12个具有代表性的种群,研究不同轮割制度对其地上现存生物量的影响.结果表明,12个种群可以分为3种类型:1)生物量下降型,羊草、米氏冰草、小叶锦鸡儿和黄囊苔草,尤以羊草和小叶锦鸡儿具有代表性.羊草地上生物量的平均值以一年割两次、一年割一次、割一年休一年和割两年休一年依次较对照下降了3.37%、4.9%、45.4%和34.18%;小叶锦鸡儿地上生物量分别较对照下降了81.79%、3.33%、40.29%和2.30%.2)生物量增加型,(艹)/(洽)草、黄蒿、冷蒿和猪毛菜,尤以(艹)/(洽)草和冷蒿具有代表性.(艹)/(洽)草生物量依次较对照增加了94.84%、287.79%、132.8%和211.74%,其中以一年割一次和割一年休一年的增加幅度较大;冷蒿生物量分别较对照增加了193.02%、210.47%、154.5%和10.47%.究其原因,(艹)/(洽)草和冷蒿地上生物量增加是通过种群自身的变化;而黄蒿和猪毛菜则是通过群落密度的下降和适宜的种子萌发条件.3)生物量波动型,大针茅、西伯利亚羽茅、变蒿和麻花头,介于前两种类型之间.

Effects of different cutting system on main typical steppe populations in Inner Mongolia

Twelve main typical steppe populations in Inner Mongolia were selected to investigate the effects of different cutting system on their aboveground standing biomass.The results showed that the test populations could be categorized into 3 groups,i.e.,1) group with decreasing biomass,which included Leymus chinensis,Agropyron michnoi,Caragana microphylla and Carex korshinskyi,with L.chinensis and C.microphylla as the representatives.The average aboveground standing biomass of L.chinensis was decreased by 63.37%,64.96%,45.64% and 34.18% after 2 cuttings a year,1 cutting a year,1 year cutting and 1 year resting,and 2 years cutting and 1 year resting,while that of C.microphylla decreased by 81.79%,63.33%,40.29% and 26.30%,respectively,compared with the control; 2) group with increasing biomass,which included Koeleria cristata,Artemisia scoparia,A.frigida,and Salsola collina,and K.cristata and A.frigida were the representatives.The biomass of K.cristata was increased by 94.84%,287.79%,132.86% and 211.74%,while that of A.frigida was increased by 193.02%,210.47%,154.65% and 160.47%,respectively.The biomass increase of K.cristata and A.frigida was derived from their population changes,while that of A.scoparia and S.collina was come from the decrease of community densities and the more suitable conditions for seed germination; 3) group with fluctuated biomass,which included Stipa grandis,Achnatherum sibiricum,Artemisia commutata and Serratula centauroides,and the change patterns of their biomass were between those of the former 2 groups.