比较了内蒙古锡林郭勒草原坡地地形中坡底和坡顶大针茅的营养生物量与生殖生物量，并采用关联度法与因子分析法分析了影响种子生物量的因子.结果表明：坡底与坡顶大针茅营养生长和生殖生长之间差异均显著.与坡顶相比，坡底大针茅种群未结实子株高和数目分别增加24.69%和35.37%，已结实子株数增加102.97%，其营养生物量、生殖生物量和总生物量分别增加44.14%、95.59%和47.45%，种子百粒重增加25.00%.坡顶大针茅种子生物量受土壤含水量的影响较大，而坡底受土壤pH的影响较大.坡地地形使土壤水分和土壤氮含量发生分异，坡底大针茅将更多的能量分配给有性生殖.
An investigation was conducted on the vegetative and reproductive biom
ass allocation of Stipa grandis at the hill-top and hill-foot of Xilingol
grassland, and relatedness- and factor analyses were made to study the effects
of hill position on the S. grandis seed biomass. Significant differences were ob
served in the vegetative and reproductive growth of S. grandis plants at the
hill-top and hill-foot. At hill-foot, the height and number of non-flowerin
g S. grandis ramets increased by 2469% and 3537%, respectively, the number o
f flowering ramets increased by 10297%, the vegetative, reproductive, and tota
l biomass increased by 4414%, 9559% and 4745%, respectively, and the
100-grain mass increased by 2500%, as compared with those at hill-top. The
seed biomass of S. grandis at hill-top was mainly affected by soil moistur
e content, while that at hill-foot was mainly affected by soil pH. Hill positio
n induced the differentiation of soil moisture and N contents, and made the
S. grandis at the fertile hill-foot allocating more energy to its sexual re
production.