scholarly journals Effects of long-term warming on microbial nutrient limitation of soil aggregates on the Qinghai-Tibet Plateau

2021 ◽  
Author(s):  
Wenjing Chen ◽  
Huakun Zhou ◽  
Leilei Qiao ◽  
Yuanze Li ◽  
Yang Wu ◽  
...  
Keyword(s):  
Soil Aggregates ◽  
Aggregate Size ◽  
Soil Aggregate ◽  
Tibet Plateau ◽  
Alpine Meadows ◽  
P Limitation ◽  
Microbial Nutrient Limitation ◽  
Qinghai Tibet Plateau ◽  
C Limitation

Abstract Background and aims Global warming has increasingly serious impacts on the structure and function of the Tibetan Plateau ecosystem. However, the mechanism by which warming affects the biogeochemical processes, and consequently the microbial nutrient limitation in soil aggregates, is not clear. Methods In the present study, we used open-top chamber experiments to simulate warming in an alpine meadow and an alpine shrubland on the Qinghai-Tibet Plateau, and we measured the C, N, and P-acquiring enzyme (β-1, 4-glucosidase, BG; leucine aminopeptidase, LAP; β-N-acetylglucosaminidase, NAG; alkali phosphatase, AP) activities and their stoichiometry to understand how warming affects microorganism-limiting mechanisms in soil aggregates. Results The results showed that long-term warming treatment significantly decreased soil organic carbon (SOC) and total nitrogen (TN) concentrations of large macroaggregates (LMGA) and small macroaggregates (SMGA) in alpine meadows, but significantly increased SOC concentration of LMGA in alpine shrubland. The SOC and TN concentrations of alpine meadows increased with the decrease of soil aggregate size and the concentrations in microaggregate (MIGA) were significantly higher than those LMGA. Soil enzyme activity increased with the decrease in aggregate size and was not significantly affected by warming treatment. Enzyme stoichiometry results demonstrated that soil microbes in alpine meadows and shrubland were limited by nutrient P relative to nitrogen; moreover, the long-term warming treatment aggravated the P limitation of soil microorganisms in the shrubland, and it had significant differences in LMGA and MIGA. At the same time, the long-term warming treatment had no significant effect on C limitation in the alpine shrubland and alpine meadows, but soil aggregate size affected the C limitation patterns of microorganisms and showed the greatest limitations in MIGA. Conclusions The microbial P limitation in shrubland is more sensitive to warming than that in meadow. Soil aggregates mediate the acquisition of C by microorganisms, and the C limitation in MIGA is the greatest. By providing a new perspective on this topic, our study increased our understanding of the effects of warming on microbial nutrient utilization and restriction patterns in soil aggregates.

scholarly journals Effects of Long-Term Warming on Microbial Nutrient Limitation of Soil Aggregates on the Qinghai-Tibet Plateau

2021 ◽  
Author(s):  
Wenjing Chen ◽  
Huakun Zhou ◽  
Leilei Qiao ◽  
Yuanze Li ◽  
Yang Wu ◽  
...  
Keyword(s):  
Alpine Meadow ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Nutrient Utilization ◽  
Tibet Plateau ◽  
The Tibetan Plateau ◽  
P Limitation ◽  
Microbial P ◽  
Microbial Nutrient Limitation

Abstract Background and aims Global warming has increasingly serious impacts on the structure and function of the Tibetan Plateau ecosystem. However, the mechanism by which warming affects the biogeochemical processes and consequently the microbial nutrient limitation in soil aggregates is not clear. Methods In the present study, we used open-top chamber experiments to simulate warming in an alpine meadow and an alpine shrubland on the Qinghai-Tibet Plateau to understand how warming affects nutrient utilization and microorganism-limiting mechanisms in soil aggregates. Results The results showed that long-term warming treatment had contrasting effects on soil organic carbon (SOC) content of the alpine meadow and that of the shrubland. This difference was more pronounced with the increase in soil aggregate size, and the SOC content in microaggregates (MIGA) was significantly higher than that in large macroaggregates (LMGA). Soil enzyme activity increased with the decrease in aggregate size and was not significantly affected by warming treatment. Enzyme stoichiometry demonstrated that microbial P limitation is widespread on the Tibetan Plateau, and the long-term warming treatment exacerbated it, which has significant differences in shrubland. At the same time, the long-term warming treatment had no significant effect on C limitation in the alpine shrubland and the alpine meadow, but soil aggregate size affected the C limitation patterns of microorganisms and showed strong limitations in MIGA. Conclusions The microbial P limitation in shrubland is more sensitive to warming than that of grassland. Soil aggregates mediate the acquisition of carbon by microorganisms, and the carbon limitation in MIGA is the greatest. By providing a new perspective on this topic, our study increased our understanding of the effects of warming on microbial nutrient utilization and restriction patterns in soil aggregates.

scholarly journals Soil aggregate size influences the impact of inorganic nitrogen deposition on soil nitrification in an alpine meadow of the Qinghai–Tibet Plateau

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8230 ◽  
Author(s):  
Jingjing Li ◽  
Chao Yang ◽  
Xiaoli Liu ◽  
Hanzhong Ji ◽  
Xinqing Shao
Keyword(s):  
Alpine Meadow ◽  
Inorganic Nitrogen ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Bulk Soil ◽  
Tibet Plateau ◽  
Nitrification Rate ◽  
Soil N ◽  
Soil Nitrification ◽  
Qinghai Tibet Plateau

Background Ammonium (NH4+) and nitrate (NO3−) are two inorganic forms of nitrogen (N) that are deposited from the atmosphere into soil systems. As the substrate and product of soil nitrification, these two forms of inorganic nitrogen will affect or be affected by the soil net nitrification rate (Nr). Our knowledge regarding soil nitrification is mainly derived from studies with bulk soil. However, soil is composed of different aggregate fractions, which may have an important impact on Nr. Methods In 2017, we collected soil samples from an alpine meadow of the Qinghai–Tibet Plateau and separated them into four soil aggregates (2–4, 1–2, 0.25–1, and <0.25 mm) using the dry sieving method. The four soil aggregate sizes amended with the 2 N deposition forms (NH4+-N and NO3−-N) were then incubated at 25 °C for 28 days, and the soil aggregates for each treatment were collected on day 0, 7, 14, 21, and 28 to determine the NO3−-N concentration. The soil Nr and contribution of soil aggregates to the nitrification rate in the bulk soil were calculated. Results There were differences in the physicochemical properties of the soil aggregates. The addition of N and aggregate size had strong effects on soil Nr, which were significantly increased under high levels of NH4+ addition across all soil aggregates. The Nr during the 4 week incubation period differed among aggregate sizes. Nr in the 2–4 mm aggregates was higher than in the other aggregates, which was correlated with the maximum values of the soil porosity observed in the 2–4 mm aggregates. Furthermore, almost half of the soil was composed of aggregates of <0.25 mm, indicating that the <0.25 mm aggregates made a higher contribution to the nitrification rate in the bulk soil than the other aggregates, even though these aggregates had a lower nitrification ability. Overall, our study revealed that the soil nitrification rate was influenced by both the N addition and soil aggregates, and that the 2–4 mm aggregates had a dominant effect on the response of soil N transformation processes to future nitrogen deposition in the alpine meadow.

Response of phosphorus fractions to land-use change followed by long-term fertilization in a sub-alpine humid soil of Qinghai–Tibet plateau

2018 ◽  
Vol 19 (3) ◽  
pp. 1109-1119 ◽  
Author(s):  
Xiaolei Sun ◽  
Meng Li ◽  
Guoxi Wang ◽  
Marios Drosos ◽  
Fulai Liu ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Phosphorus Fractions ◽  
Tibet Plateau ◽  
Qinghai Tibet Plateau

Aggregate size distribution and stability of an oxisol under legume-based and pure grass pastures in the eastern Colombian savannas

Soil Research ◽  
1995 ◽  
Vol 33 (1) ◽  
pp. 153 ◽  
Author(s):  
AJ Gijsman ◽  
RJ Thomas
Keyword(s):  
Size Distribution ◽  
Soil Aggregates ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Soil Aggregate ◽  
Hot Water ◽  
Aggregate Size Distribution ◽  
Carbohydrate Concentration ◽  
Stability Measurement ◽  
Water Extractable

This study evaluated soil aggregate size distribution and stability of an Oxisol under improved grass-only or grass-legume pastures, established in previously native savanna. Three grass-legume combinations were included at various stocking rates. In all treatments and soil layers, soils were well aggregated, having more than 90% of their weight in macroaggregates (>250 �m). The addition of legumes to pastures did not affect the soil aggregate size distribution, although aggregates showed somewhat more stability against slaking. An increase in stocking rate negatively affected both average aggregate size and aggregate stability. Aggregates showed little or no dispersion of clay particles in any treatment. A positive correlation was found between wet aggregate stability and hot-water extractable carbohydrate concentration, supporting the hypothesis that these carbohydrates equate with plant-derived or microbial polysaccharides which glue soil aggregates together. It is suggested that determination of hot-water extractable carbohydrates may serve as a useful indicator of small differences in aggregate stability, even when these differences are not evident in the stability measurement itself.

Soil aggregate size and long-term fertilization effects on the function and community of ammonia oxidizers

Geoderma ◽  
2019 ◽  
Vol 338 ◽  
pp. 107-117 ◽  
Author(s):  
Pei-Pei Li ◽  
Yan-Lai Han ◽  
Ji-Zheng He ◽  
Shui-Qing Zhang ◽  
Li-Mei Zhang
Keyword(s):  
Aggregate Size ◽  
Soil Aggregate ◽  
Ammonia Oxidizers ◽  
Fertilization Effects

scholarly journals Factors Determining Soil Water Repellency in Two Coniferous Plantations on a Hillslope

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 730 ◽  
Author(s):  
Moein Farahnak ◽  
Keiji Mitsuyasu ◽  
Kyoichi Otsuki ◽  
Kuniyoshi Shimizu ◽  
Atsushi Kume
Keyword(s):  
Soil Water ◽  
Overland Flow ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Water Repellency ◽  
Soil Aggregate ◽  
Water Infiltration ◽  
Soil Water Repellency ◽  
Tree Cutting ◽  
Coniferous Plantations

Soil water repellency (SWR) is a cause of low water infiltration, overland flow and soil erosion in mountainous coniferous plantations in Japan. The factors determining SWR intensity were investigated in two coniferous plantations of Chamaecyparis obtusa (Siebold et Zucc.) Endl. and Cryptomeria japonica (L.f.) D. Don, using intact tree plots and cut tree plots on the same hillslope. The SWR of Ch. obtusa plots was stronger than that of Cr. japonica plots. SWR intensity decreased after tree cutting. There were no significant differences in SWR upslope and downslope of individual trees/stumps for both tree species, though areas downslope of individual Ch. obtusa trees had higher SWR intensity than those upslope. SWR intensity and soil aggregate stability were positively correlated in the Ch. obtusa intact tree plot (r = 0.88, p < 0.01), whereas in the cut tree plot, this correlation was weak with no significance (r = 0.29, p = 0.41). Soil aggregate size had a non-significant influence on SWR intensity. These findings suggest that SWR intensity was not related to the soil aggregate size, but SWR intensity seemed have a role in soil aggregation in the Ch. obtusa intact tree plot. Destruction of soil aggregates could occur after tree cutting because of physical disturbances or increased input of different types of organic matter from other vegetation into soil. The presence of Ch. obtusa introduces a source of SWR, although uncertainty remains about how water repellency is distributed around soil aggregates. The distribution pattern of soil water content and soil hydraulic conductivity around Cr. japonica was related to other factors such as the litter layer and non-water-repellant soil.

Sign in / Sign up

Export Citation Format

Share Document