典型草原冷蒿小禾草群落实生苗动态的研究

从实生苗的出现和死亡情况研究了冷蒿 ( Artemisia communtata)小禾草群落的实生苗动态 ,发现实生苗出现时间和数量均受水分条件的制约。而不同植物的种子萌发特性不同是造成实生苗出现时间产生差异的主要原因。自然条件下由于水分的限制这种差异并不明显 ,浇水后显出规律性的变化 ,出现两个明显的高峰期。种子萌发后并不意味着完成了实生苗的补充 ,大部分实生苗会在各个阶段死亡。造成死亡的外因主要有三个 :干旱、竞争及家蓄和野生动物的采食、践踏。但在放牧条件下 ,实生苗死亡率的变化仍有较一致的趋势 ,即随着牧压增加实生苗死亡率增加。

Studies on the Dynamics of Seedlings in Community of Artemisia Communtata-Short-Grasses in Typical Steppe

The dynamics of seedlings were studied in the aspects of seedling emergence and mortality in the community of the Artemisia communtata-Short-grasses in typical steppe. The results showed that the quantities and the time of seedling emergences were restricted by soil moisture condition. The differences of the characteristics of seed germination may be the key reason resulting in the differences in the time of seedling emergences. Under the natural condition, the differences weren't distinct due to moisture stress. Under the condition of sufficient water supply, seed germination went through a regular cycle, with two peaks of emergence occurrenecs. Drought, competition, and browsing or trampling of animals were the main reasons resulting in high mortality. The influence of grazing on seedling mortality had the trend that mortality of seedling increased with the stocking rate increasing.