Department of Forest Sciences, University of British Columbia Vancouver, BC, V6T 1Z4, Canada.
Ecol Evol. 2011 Nov;1(3):306-16. doi: 10.1002/ece3.24.
Facilitation of tree establishment by ectomycorrhizal (EM) networks (MNs) may become increasingly important as drought stress increases with climate change in some forested regions of North America. The objective of this study was to determine (1) whether temperature, CO(2) concentration ([CO(2)]), soil moisture, and MNs interact to affect plant establishment success, such that MNs facilitate establishment when plants are the most water stressed, and (2) whether transfer of C and water between plants through MNs plays a role in this. We established interior Douglas-fir (Pseudotsuga menziesiivar.glauca) seedlings in root boxes with and without the potential to form MNs with nearby conspecific seedlings that had consistent access to water via their taproots. We varied temperature, [CO(2)], and soil moisture in growth chambers. Douglas-fir seedling survival increased when the potential existed to form an MN. Growth increased with MN potential under the driest soil conditions, but decreased with temperature at 800 ppm [CO(2)]. Transfer of (13)C to receiver seedlings was unaffected by potential to form an MN with donor seedlings, but deuterated water (D(2)O) transfer increased with MN potential under ambient [CO(2)]. Chlorophyll fluorescence was reduced when seedlings had the potential to form an MN under high [CO(2)] and cool temperatures. We conclude that Douglas-fir seedling establishment in laboratory conditions is facilitated by MN potential where Douglas-fir seedlings have consistent access to water. Moreover, this facilitation appears to increase as water stress potential increases and water transfer via networks may play a role in this. These results suggest that conservation of MN potential may be important to forest regeneration where drought stress increases with climate change.
外生菌根网络 (MNs) 促进树木的建立可能变得越来越重要，因为在北美的一些森林地区，随着气候变化，干旱胁迫加剧。本研究的目的是确定：(1) 温度、CO(2) 浓度 ([CO(2)])、土壤水分和 MNs 是否相互作用影响植物的建立成功率，使得 MNs 在植物水分胁迫最大时促进建立；(2) 通过 MNs 在植物之间转移 C 和水是否在其中发挥作用。我们在根箱中建立了内部道格拉斯冷杉 (Pseudotsuga menziesiivar. glauca) 幼苗，这些根箱具有与附近同种幼苗形成 MN 的潜力，这些幼苗通过主根持续获得水分。我们在生长室中改变温度、[CO(2)] 和土壤水分。当存在形成 MN 的潜力时，冷杉幼苗的存活率增加。在最干燥的土壤条件下，具有 MN 潜力的情况下，生长增加，但在 800 ppm [CO(2)] 下，温度会降低。与具有供体幼苗形成 MN 的潜力无关，但在环境 [CO(2)] 下，与 MN 潜力相关的向受体幼苗的 (13)C 转移增加。当幼苗在高 [CO(2)] 和凉爽温度下有形成 MN 的潜力时，叶绿素荧光减少。我们得出的结论是，在实验室条件下，当冷杉幼苗持续获得水分时，外生菌根网络的潜力促进了冷杉幼苗的建立。此外，随着水分胁迫潜力的增加，这种促进作用似乎会增加，并且通过网络进行水分转移可能在其中发挥作用。这些结果表明，在气候变化导致干旱胁迫增加的情况下，外生菌根网络潜力的保护可能对森林再生很重要。
