Bookman Peter A
Department of Botany, Washington State University, 99164, Pullman, Wash, USA.
Oecologia. 1983 Feb;56(2-3):413-418. doi: 10.1007/BF00379721.
Emergence of Bromus tectorum L. and Poa pratensis L., two dominant alien grasses in eastern Washington, from 24 microsites was monitored in spring and autumn 1979. Spring emergence of B. tectorum reached a maximum on north-facing slopes of artificially constructed pocket gopher mounds and burrows while spring emergence of P. pratensis was maximized on both north-and southfacing slopes of mounds. Earliest autumn emergence of B. tectorum seedlings was in fissures of 0.5 cm, 1 cm, and 2 cm depth while earliest emergence of P. pratensis was 24 days later in fissures of 0.5 cm, 1 cm, 2 cm, and 5 cm depth. All B. tectorum seedlings had emerged within 44 days after first emergence on north-facing slopes of artificially constructed mounds. Maximum emergence of P. pratensis (37%) seedlings occurred on the same north-facing positions of mound slopes and also on the north-facing slope of the burrow, 24 days after first emergence. Both species exhibit broad microsite tolerance and are found on similar but temporally separated microsites.
1979年春、秋两季监测了华盛顿东部两种优势外来禾本科植物——雀麦（Bromus tectorum L.）和草地早熟禾（Poa pratensis L.）在24个微生境中的出苗情况。雀麦在人工建造的囊鼠土堆和洞穴的北坡春季出苗量最大，而草地早熟禾在土堆的北坡和南坡春季出苗量均达到最大值。雀麦幼苗最早在秋季出现在深度为0.5厘米、1厘米和2厘米的裂缝中，而草地早熟禾最早出苗时间比雀麦晚24天，出现在深度为0.5厘米、1厘米、2厘米和5厘米的裂缝中。在人工建造土堆的北坡首次出苗后的44天内，所有雀麦幼苗均已出苗。草地早熟禾幼苗最大出苗率（37%）出现在土堆北坡相同位置以及洞穴的北坡，首次出苗24天后出现。这两个物种都表现出对微生境的广泛耐受性，并且出现在相似但时间上不同的微生境中。
