School of Geosciences, University of Edinburgh, Crew Building, Kings Buildings, Edinburgh, EH9 3FF, United Kingdom.
Smithsonian Tropical Research Institute, 0843-03092, Balboa, Ancon, Panama.
Glob Chang Biol. 2019 Mar;25(3):827-838. doi: 10.1111/gcb.14502. Epub 2019 Jan 6.
Terrestrial biogeochemical feedbacks to the climate are strongly modulated by the temperature response of soil microorganisms. Tropical forests, in particular, exert a major influence on global climate because they are the most productive terrestrial ecosystem. We used an elevation gradient across tropical forest in the Andes (a gradient of 20°C mean annual temperature, MAT), to test whether soil bacterial and fungal community growth responses are adapted to long-term temperature differences. We evaluated the temperature dependency of soil bacterial and fungal growth using the leucine- and acetate-incorporation methods, respectively, and determined indices for the temperature response of growth: Q (temperature sensitivity over a given 10oC range) and T (the minimum temperature for growth). For both bacterial and fungal communities, increased MAT (decreased elevation) resulted in increases in Q and T of growth. Across a MAT range from 6°C to 26°C, the Q and T varied for bacterial growth (Q = 2.4 to 3.5; T = -8°C to -1.5°C) and fungal growth (Q = 2.6 to 3.6; T = -6°C to -1°C). Thus, bacteria and fungi did not differ significantly in their growth temperature responses with changes in MAT. Our findings indicate that across natural temperature gradients, each increase in MAT by 1°C results in increases in T of microbial growth by approximately 0.3°C and Q by 0.05, consistent with long-term temperature adaptation of soil microbial communities. A 2°C warming would increase microbial activity across a MAT gradient of 6°C to 26°C by 28% to 15%, respectively, and temperature adaptation of microbial communities would further increase activity by 1.2% to 0.3%. The impact of warming on microbial activity, and the related impact on soil carbon cycling, is thus greater in regions with lower MAT. These results can be used to predict future changes in the temperature response of microbial activity over different levels of warming and over large temperature ranges, extending to tropical regions.
陆地生物地球化学反馈对气候的影响强烈受到土壤微生物温度响应的调节。特别是热带森林，由于它们是最具生产力的陆地生态系统，因此对全球气候产生了重大影响。我们利用安第斯山脉热带森林的海拔梯度（平均年气温 MAT 梯度为 20°C），测试了土壤细菌和真菌群落的生长响应是否适应长期的温度差异。我们分别使用亮氨酸和乙酸盐掺入方法来评估土壤细菌和真菌生长的温度依赖性，并确定了生长温度响应的指标：Q（给定 10°C 范围内的温度敏感性）和 T（生长的最低温度）。对于细菌和真菌群落，MAT 的增加（海拔的降低）导致生长的 Q 和 T 增加。在 MAT 范围从 6°C 到 26°C 时，细菌生长的 Q 和 T 变化（Q = 2.4 到 3.5；T = -8°C 到 -1.5°C）和真菌生长的 Q 和 T 变化（Q = 2.6 到 3.6；T = -6°C 到 -1°C）。因此，随着 MAT 的变化，细菌和真菌在其生长温度响应方面没有显著差异。我们的研究结果表明，在自然温度梯度中，MAT 每增加 1°C，微生物生长的 T 值增加约 0.3°C，Q 值增加 0.05，这与土壤微生物群落的长期温度适应一致。在 6°C 到 26°C 的 MAT 梯度范围内，2°C 的变暖将分别使微生物活性增加 28%到 15%，而微生物群落的温度适应将进一步使活性增加 1.2%到 0.3%。因此，在 MAT 较低的地区，变暖对微生物活性以及相关的土壤碳循环的影响更大。这些结果可用于预测在不同程度的变暖以及在较大温度范围内微生物活性的温度响应的未来变化，扩展到热带地区。
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