Treseder Kathleen K, Allen Michael F
Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
Center for Conservation Biology, University of California, Riverside, CA 92521, USA.
New Phytol. 2002 Sep;155(3):507-515. doi: 10.1046/j.1469-8137.2002.00470.x.
• Since mycorrhizal fungi constitute an important component of the soil-plant interface, their responses to changes in nutrient availability may mediate shifts in ecosystem function. We tested the hypothesis that initial soil nutrient availability may determine effects of nitrogen (N) and phosphorus (P) additions on the growth and community of arbuscular mycorrhizal (AM) fungi. • Extraradical hyphal lengths and degree of root colonization of AM fungi were measured in control and fertilized plots along a soil fertility gradient in Hawaii. Responses of individual AM genera were assessed through immunofluorescent labeling. • The AM biomass was increased by N and P additions in the N- and P-limited sites, respectively, and reduced by P fertilization in the fertile site only. The abundance of Scutellospora was lower under N than under P fertilization, whereas the incidence of Glomus was higher in the fertile site than the N-limited site. Gigaspora and Acaulospora did not vary among sites or treatments. • Our results indicate that a decrease in AM abundance following nutrient additions cannot be assumed to occur and the effects may differ among AM genera and ecosystems with varying soil nutrients. Limitation of N and P may be one possible explanation.
• 由于菌根真菌是土壤-植物界面的重要组成部分，它们对养分有效性变化的响应可能会介导生态系统功能的转变。我们检验了这样一个假设，即初始土壤养分有效性可能决定氮（N）和磷（P）添加对丛枝菌根（AM）真菌生长和群落的影响。
• 在夏威夷沿着土壤肥力梯度的对照和施肥地块中，测量了AM真菌的根外菌丝长度和根定殖程度。通过免疫荧光标记评估了各个AM属的响应。
• 在N和P受限的地块中，N和P添加分别增加了AM生物量，而仅在肥沃地块中P施肥降低了AM生物量。N施肥下盾巨孢囊霉的丰度低于P施肥，而球囊霉在肥沃地块中的发生率高于N受限地块。巨孢囊霉和无梗囊霉在不同地块或处理之间没有差异。
• 我们的结果表明，不能假定养分添加后AM丰度会降低，并且其影响可能因AM属和土壤养分不同的生态系统而异。N和P的限制可能是一种可能的解释。
