Lauenroth W K, Dodd J L, Sims P L
Natural Resource Ecology Laboratory, Colorado State University, 80523, Fort Collins, CO, USA.
Department of Range Science, Colorado State University, 80523, Fort Collins, CO, USA.
Oecologia. 1978 Jan;36(2):211-222. doi: 10.1007/BF00349810.
A replicated factorial experiment was designed to test the hypothesis that manipulating inputs of water and mineral nitrogen to a semiarid grassland would disrupt existing interactions resulting in alteration of the structure of the primary producer community. Alteration of community structure was measured as either changes in growing season average biomass of 6 functional groups of plants or their relative contribution to total biomass.Additions of water greatly increased total biomass and resulted in the replacement of one of the dominant functional groups by a subordinate group. The water plus nitrogen treatment resulted in large biomass increases in two of the dominant functional groups, elimination of succulents as an important component of community structure, and establishment of several introduced weedy species. Continuation of the experiment will likely result in complete dominance of the water plus nitrogen treatment by these introduced species.Despite the large changes in community structure observed as a result of water- and nitrogen-induced stresses we conclude that the shortgrass prairie in northcentral Colorado is asymptotically stable with respect to these influences.
设计了一项重复析因实验，以检验以下假设：对半干旱草原的水分和矿质氮输入进行调控会破坏现有的相互作用，从而导致初级生产者群落结构发生改变。群落结构的改变通过6个植物功能群生长季平均生物量的变化或它们对总生物量的相对贡献来衡量。添加水分极大地增加了总生物量，并导致一个优势功能群被一个从属功能群取代。水分加氮处理使两个优势功能群的生物量大幅增加，消除了肉质植物作为群落结构的一个重要组成部分，并使几种外来杂草物种得以建立。继续进行该实验可能会导致这些外来物种在水分加氮处理中完全占据主导地位。尽管由于水分和氮胁迫导致群落结构发生了巨大变化，但我们得出结论，科罗拉多州中北部的矮草草原在这些影响方面是渐近稳定的。
