Rygiewicz P T, Martin K J, Tuininga A R
US Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, 200 SW 35th Street, Corvallis, OR 97333, USA e-mail:
Dynamac Corporation, National Health and Environmental Effects Research Laboratory, 200 SW 35th Street, Corvallis, OR 97333, USA, , , , , , US.
Oecologia. 2000 Aug;124(2):299-308. doi: 10.1007/s004420000385.
Mycorrhizas alter the acquisition of carbon and nutrients, thereby affecting numerous plant and ecosystem processes. It is important, therefore, to determine how mycorrhizal populations will change under possible future climate conditions. Individual and interactive effects of elevated atmospheric CO concentration and atmospheric temperature were assessed in a 2×2 factorial design [ambient and elevated (200 ppm above ambient) CO concentrations, and ambient and elevated (4°C above ambient) temperatures]. In June 1993, 2-year-old Douglas fir (Pseudotsuga menziesii Mirb. Franco) seedlings were planted in 12 environment-tracking chambers (n=3) containing reconstructed, low-nitrogen, native forest soil. Climate treatments were imposed shortly thereafter, and the seedlings grew until June 1997. Soil cores were taken twice per year during the exposure period. We present findings on changes in the community structure of ectomycorrhizal (ECM) root tips, categorized into morphotypes using gross morphological traits. A diverse and stable community of morphotypes (a total of 40) was encountered; no more than 30 of which were seen at any sampling time. In the first sample, there were only 15 morphotypes found in the 12 chambers. Morphotype numbers increased during the first half of the experiment, remaining fairly constant thereafter. Near the end of the exposure, elevated-temperature treatments maintained more morphotypes than ambient treatments. However, overall, absolute measures (number of ECM tips) were affected primarily by CO treatment, whereas proportional measures (e.g., Simpson's index) were affected primarily by temperature. While some morphotypes were negatively affected seasonally by higher temperatures (putative Rhizopogon group), others (Cenococcum) seemed to thrive. Underlying the dominant patterns of change in diversity, driven by the Rhizopogon group, subdominant populations responded slightly differently. Community diversity through time tended to increase at a greater rate for all subdominant populations compared with the rate when dominant populations were included.
菌根会改变碳和养分的获取，从而影响众多植物和生态系统过程。因此，确定未来可能的气候条件下菌根种群将如何变化很重要。在一个2×2析因设计中评估了大气CO浓度升高和大气温度的单独及交互作用[环境CO浓度和升高（比环境浓度高200 ppm）的CO浓度，以及环境温度和升高（比环境温度高4°C）的温度]。1993年6月，将2年生花旗松（Pseudotsuga menziesii Mirb. Franco）幼苗种植在12个环境跟踪室（n = 3）中，这些室装有重建的、低氮的原生森林土壤。此后不久施加气候处理，幼苗一直生长到1997年6月。在暴露期每年取两次土壤芯。我们展示了外生菌根（ECM）根尖群落结构变化的研究结果，这些根尖根据总体形态特征被分类为形态型。遇到了一个多样且稳定的形态型群落（总共40种）；在任何采样时间观察到的形态型不超过30种。在第一个样本中，12个室中仅发现15种形态型。形态型数量在实验的前半段增加，此后保持相当稳定。在暴露接近尾声时，高温处理比环境处理维持了更多的形态型。然而，总体而言，绝对指标（ECM根尖数量）主要受CO处理影响，而比例指标（例如辛普森指数）主要受温度影响。虽然一些形态型在季节上受到较高温度的负面影响（假定的须腹菌属组），但其他形态型（土生空团菌）似乎茁壮成长。在由须腹菌属组驱动的多样性变化主导模式之下，次优势种群的反应略有不同。与包含优势种群时相比，所有次优势种群随时间的群落多样性趋于以更快的速度增加。
