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- Nottingham, Andrew T., et al.
(författare)
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Adaptation of soil microbial growth to temperature : Using a tropical elevation gradient to predict future changes
- 2019
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 25:3, s. 827-838
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Tidskriftsartikel (refereegranskat)abstract
- 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: Q10 (temperature sensitivity over a given 10oC range) and Tmin(the minimum temperature for growth). For both bacterial and fungal communities, increased MAT (decreased elevation) resulted in increases in Q10and Tmin of growth. Across a MAT range from 6°C to 26°C, the Q10and Tmin varied for bacterial growth (Q10–20 = 2.4 to 3.5; Tmin = −8°C to −1.5°C) and fungal growth (Q10–20 = 2.6 to 3.6; Tmin = −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 Tmin of microbial growth by approximately 0.3°C and Q10–20by 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.
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| 2. |
- Nottingham, Andrew T., et al.
(författare)
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Microbial diversity declines in warmed tropical soil and respiration rise exceed predictions as communities adapt
- 2022
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Ingår i: Nature Microbiology. - : Springer Science and Business Media LLC. - 2058-5276. ; 7:10, s. 1650-1660
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Tidskriftsartikel (refereegranskat)abstract
- Perturbation of soil microbial communities by rising temperatures could have important consequences for biodiversity and future climate, particularly in tropical forests where high biological diversity coincides with a vast store of soil carbon. We carried out a 2-year in situ soil warming experiment in a tropical forest in Panama and found large changes in the soil microbial community and its growth sensitivity, which did not fully explain observed large increases in CO2 emission. Microbial diversity, especially of bacteria, declined markedly with 3 to 8 °C warming, demonstrating a breakdown in the positive temperature-diversity relationship observed elsewhere. The microbial community composition shifted with warming, with many taxa no longer detected and others enriched, including thermophilic taxa. This community shift resulted in community adaptation of growth to warmer temperatures, which we used to predict changes in soil CO2 emissions. However, the in situ CO2 emissions exceeded our model predictions threefold, potentially driven by abiotic acceleration of enzymatic activity. Our results suggest that warming of tropical forests will have rapid, detrimental consequences both for soil microbial biodiversity and future climate.
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| 3. |
- Nottingham, Andrew T., et al.
(författare)
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Nutrient limitations to bacterial and fungal growth during cellulose decomposition in tropical forest soils
- 2018
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Ingår i: Biology and Fertility of Soils. - : Springer Science and Business Media LLC. - 0178-2762 .- 1432-0789. ; 54:2, s. 219-228
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Tidskriftsartikel (refereegranskat)abstract
- Nutrients constrain the soil carbon cycle in tropical forests, but we lack knowledge on how these constraints vary within the soil microbial community. Here, we used in situ fertilization in a montane tropical forest and in two lowland tropical forests on contrasting soil types to test the principal hypothesis that there are different nutrient constraints to different groups of microorganisms during the decomposition of cellulose. We also tested the hypotheses that decomposers shift from nitrogen to phosphorus constraints from montane to lowland forests, respectively, and are further constrained by potassium and sodium deficiency in the western Amazon. Cellulose and nutrients (nitrogen, phosphorus, potassium, sodium, and combined) were added to soils in situ, and microbial growth on cellulose (phospholipid fatty acids and ergosterol) and respiration were measured. Microbial growth on cellulose after single nutrient additions was highest following nitrogen addition for fungi, suggesting nitrogen as the primary limiting nutrient for cellulose decomposition. This was observed at all sites, with no clear shift in nutrient constraints to decomposition between lowland and montane sites. We also observed positive respiration and fungal growth responses to sodium and potassium addition at one of the lowland sites. However, when phosphorus was added, and especially when added in combination with other nutrients, bacterial growth was highest, suggesting that bacteria out-compete fungi for nitrogen where phosphorus is abundant. In summary, nitrogen constrains fungal growth and cellulose decomposition in both lowland and montane tropical forest soils, but additional nutrients may also be of critical importance in determining the balance between fungal and bacterial decomposition of cellulose.
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| 4. |
- Nottingham, Andrew T., et al.
(författare)
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Soil carbon and microbes in the warming tropics
- 2022
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 36:6, s. 1338-1354
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Forskningsöversikt (refereegranskat)abstract
- Climate warming could destabilise the Earth's largest terrestrial store of reactive carbon (C), by accelerating the decomposition of soil organic matter. A third of that C store resides in the tropics. The potential for tropical soils to sequester C, or to act as an additional source of CO2, will depend on the balance of C inputs and outputs, mediated by the response of soil microbial communities and their activity to perturbation. We review the impact of warming on microbial communities and C storage in humid tropical forest soils over multiple time-scales. Recent in situ experiments indicate high sensitivity of tropical forest soil C mineralisation to warming in the short term. However, whether this will translate into long-term soil C decline remains unclear. At decadal time-scales, high sensitivity of soil C mineralisation to warming is consistent with the correlation between the inter-annual variation in the tropical land surface temperature and atmospheric CO2 growth rate, and with simulations using the Carnegie-Ames-Stanford Approach biosphere model. This observed sensitivity may further contribute to climatic change over millennial time-scales, suggested by radiocarbon dating of organic matter in river basins showing a twofold acceleration in tropical soil C release during the late-glacial warming period. However, counter to this evidence, long-term stability of tropical soil C is suggested by observed steady-state soil C turnover across temperature gradients with elevation, and by the presence of C in tropical soils that pre-dates the Holocene Thermal Maximum and late-glacial warming periods. To help reconcile these recent experimental findings and long-term observations, we propose mechanisms to explain tropical soil C and microbial responses to warming across multiple time-scales. Combined in situ experimental and monitoring approaches—large-scale and cross-site—are urgently needed to resolve the interplay of these mechanisms across spatial and temporal scales, to shape a better understanding of the relationship between soil microbes and C storage in tropical soils. Read the free Plain Language Summary for this article on the Journal blog.
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