Peatlands In China Research Articles

Distribution and key influential factors of comammox in drained and waterlogged soils of zoige plateau peatland

Peatlands are important carbon and nitrogen reservoirs, playing crucial roles in nitrogen cycling. During microbially-driven nitrogen cycling, nitrous oxide (N2O, 298 times global warming potential of CO2) can be emitted, exacerbating global warming. Complete ammonia-oxidizing bacteria (comammox), a newly discovered group of prokaryotes, can independently oxidize ammonia directly to nitrate, bypassing the nitrite stage, and thereby reducing N2O production associated with the traditional two-step nitrification process. However, information on comammox distribution and its key influential factors in plateau peatlands remains scarce. Thus, this study chose Zoige plateau peatland in China to collect soil samples from different soil types (drained and waterlogged), across different seasons (non-growing and growing), and at various depth (0–100 cm) to assess comammox abundance and community composition. Additionally, soil properties were analyzed and correlated with comammox abundance and community composition to identify the key factors affecting comammox distribution. Comammox abundance varied significantly across soil types, depth, and sampling seasons. Waterlogged soils demonstrated higher comammox abundance than drained soils. In waterlogged soils, comammox abundance showed higher during growing season than non-growing season, while the opposite trend was observed in drained soils. Regardless of soil types, comammox abundance decreased with increasing soil depth. In soils of Zoige plateau peatland, comammox clades A.1, A.2, A.3 and B.1 were identified, with clade B.1 dominating the comammox community. Both Nitrospira sp. CG24A (clade B.1) and Candidatus Nitrospira nitrificans (clade A.1) showed great seasonal variations. Soil properties, including moisture, pH, carbon, and nutrients, collectively influenced comammox abundance and diversity. Among these factors, NH4+-N was the main factor affecting comammox abundance, while moisture primarily drove community distribution. These findings provide valuable insights into comammox distribution, enhancing our understanding of its potential role in mitigating N2O emissions and thus nitrogen cycling in plateau peatland soils.

Phenolic compounds weaken the impact of drought on soil enzyme activity in global wetlands.

Soil enzymes play a central role in carbon and nutrient cycling, and their activities can be affected by drought-induced oxygen exposure. However, a systematic global estimate of enzyme sensitivity to drought in wetlands is still lacking. Through a meta-analysis of 55 studies comprising 761 paired observations, this study found that phosphorus-related enzyme activity increased by 38% as result of drought in wetlands, while the majority of other soil enzyme activities remained stable. The expansion of vascular plants under long-term drought significantly promoted the accumulation of phenolic compounds. Using a 2-week incubation experiment with phenol supplementation, we found that phosphorus-related enzyme could tolerate higher biotoxicity of phenolic compounds than other enzymes. Moreover, a long-term (35 years) drainage experiment in a northern peatland in China confirmed that the increased phenolic concentration in surface layer resulting from a shift in vegetation composition inhibited the increase in enzyme activities caused by rising oxygen availability, except for phosphorus-related enzyme. Overall, these results demonstrate the complex and resilient nature of wetland ecosystems, with soil enzymes showing a high degree of adaptation to drought conditions. These new insights could help evaluate the impact of drought on future wetland ecosystem services and provide a theoretical foundation for the remediation of degraded wetlands.

Variations in the archaeal community and associated methanogenesis in peat profiles of three typical peatland types in China

BackgroundPeatlands contain about 500 Pg of carbon worldwide and play a dual role as both a carbon sink and an important methane (CH4) source, thereby potentially influencing climate change. However, systematic studies on peat properties, microorganisms, methanogenesis, and their interrelations in peatlands remain limited, especially in China. Therefore, the present study aims to investigate the physicochemical properties, archaeal community, and predominant methanogenesis pathways in three typical peatlands in China, namely Hani (H), Taishanmiao (T), and Ruokeba (R) peatlands, and quantitively determine their CH4 production potentials.ResultsThese peatlands exhibited high water content (WC) and total carbon content (TC), as well as low pH values. In addition, R exhibited a lower dissolved organic carbon concentration (DOC), as well as higher total iron content (TFe) and pH values compared to those observed in T. There were also clear differences in the archaeal community between the three peatlands, especially in the deep peat layers. The average relative abundance of the total methanogens ranged from 10 to 12%, of which Methanosarcinales and Methanomicrobiales were the most abundant in peat samples (8%). In contrast, Methanobacteriales were mainly distributed in the upper peat layer (0–40 cm). Besides methanogens, Marine Benthic Group D/Deep-Sea Hydrothermal Vent Euryarchaeotic Group 1 (MBG–D/DHVEG–1), Nitrosotaleales, and several other orders of Bathyarchaeota also exhibited high relative abundances, especially in T. This finding might be due to the unique geological conditions, suggesting high archaeal diversity in peatlands. In addition, the highest and lowest CH4 production potentials were 2.38 and 0.22 μg g−1 d−1 in H and R, respectively. The distributions of the dominant methanogens were consistent with the respective methanogenesis pathways in the three peatlands. The pH, DOC, and WC were strongly correlated with CH4 production potentials. However, no relationship was found between CH4 production potential and methanogens, suggesting that CH4 production in peatlands may not be controlled by the relative abundance of methanogens.ConclusionsThe results of the present study provide further insights into CH4 production in peatlands in China, highlighting the importance of the archaeal community and peat physicochemical properties for studies on methanogenesis in distinct types of peatlands.

The importance of moisture in regulating soil organic carbon content based on a comparison of “enzymic latch” and “iron gate” in Zoige Plateau peatland

Due to the enormous amount of carbon (C) stored in peatlands, understanding the regulator of soil organic carbon (SOC) in peatlands is critical for global C cycling. Currently, “enzymic latch” and “iron gate” are the frequently debated mechanisms that propose phenol oxidase (PHO) and Fe2+ as important regulators driving SOC cycling in peatland. Therefore, this study compared “enzymic latch” and “iron gate” in the same peatland (Zoige Plateau, the largest peatland in China) to figure out the crucial regulator of SOC content via investigating the interrelationships among soil properties, C-related enzymes, phenolics, and iron (Fe) oxides. Moreover, waterlogged and non-waterlogged soils were chosen to take samples in both dry and wet season to understand the potential role of moisture in regulating SOC content. It was found that the contents of dissolved organic C, phenolics, SOC, Fe oxides, and β-glucosidase (BG) activities in waterlogged soils were higher than those in non-waterlogged soils. Compared to the dry season, soils in the wet season had higher phenolics, SOC, and Fe oxides contents. Also, this study observed an insignificant relationship between PHO and SOC (p > 0.05) and the small amounts of Fe2+ to total Fe (<2‰) in soils. Meanwhile, the highest effect of moisture (0.89) and negligible effect of PHO (0.04) and Fe2+ (-0.08) on SOC based on pathway analysis suggested that moisture might be the crucial regulator of SOC. Furthermore, pathway analysis implied that moisture could indirectly affect SOC by adjusting BG (p < 0.05) and soluble phenolics (p < 0.05). This study provided valuable information for understanding the importance of moisture in driving C cycling and helping against soil C loss by moisture management in Zoige Plateau.

Nitrogen addition may promote soil organic carbon storage and CO2 emission but reduce dissolved organic carbon in Zoige peatland

With the increase of nitrogen (N) deposition, N input can affect soil C cycling since microbes may trigger a series of activities to balance the supply and demand of nutrients. However, as one of the largest C sinks on earth, the role of extra N addition in affecting peatland soil C and its potential mechanism remains unclear and debated. Therefore, this study chose the largest peatland in China (i.e., Zoige, mostly N-limited) to systematically explore the potential changes of soil C, microbes, and ecoenzymes caused by extra N input at the lab scale incubation. Three different types of soils were collected and incubated with different levels of NH4NO3 solution for 45 days. After incubation, N input generally increased soil organic C (SOC) but decreased dissolved organic carbon (DOC) in Zoige peatland soils. Moreover, CO2 and CH4 emissions were significantly increased after high N input (equal to 5 mg NH4NO3 g−1 dry soils). Through a series of analyses, it was observed that microbial communities and ecoenzyme activities mainly influenced the changes of different C components. Collectively, this study implied that the increasing N deposition might help C sequestration in N-limited peatland soils; simultaneously, the risk of increased CO2 and CH4 by N input in global warming should not be ignored.

The dynamics of phosphorus fractions and the factors driving phosphorus cycle in Zoige Plateau peatland soil

Phosphorus (P) is an essential nutrient, limiting plant growth and microbial activity in many ecosystems. However, a few studies have been conducted to investigate P dynamics and the factors driving P dynamics in peatland soils. Therefore, this study chose Zoige Plateau peatland (the largest peatland in China) to reveal P dynamics and the possible driving factors through fractionating soil P and investigating a series of abiotic and biotic factors. It is found that season, peatland type, and soil depth could strongly affect P dynamics. H2O–P and NaHCO3–P (labile P) had lower content, while NaOH–P, HCl–P, Mix-P, and Residual-P (non-labile P) were the dominant fractions. Besides, the sum of P fractions was higher than the traditional measurement of total P, suggesting P storage might be underestimated in peatland soils. Moreover, it is observed that biotic factors affected P fractions more than abiotic factors, and fungi affected refractory P more than bacteria. This study provides essential information for understanding P cycling in peatland soils and emphasizes specific microbes related to P cycling, which should be paid more attention to in the future.

Iron-bound organic carbon and their determinants in peatlands of China

There is a strong correlation between iron oxide mineral and organic carbon (OC) concentrations. However, the role of iron oxide minerals in the preservation of OC in peatlands is poorly understood. In this study, we collected soil samples from 10 peatlands in central and west China to comprehensively investigate the concentration, characteristics, and spatial variability of iron oxide-bound OC (Fe-bound OC) concentrations and determine the impact of climatic factors and soil physicochemical properties on the correlation between OC and iron oxides. Our results showed that the concentration of Fe-bound OC ranged from 3.91 to 18.79 g kg−1. On average, Fe-bound OC accounted for 3.42 ± 1.32% of soil OC. The molar ratio of OC: Fe ranged from 2.17 to 12.18, indicating that coprecipitation was the dominant mechanism affecting the binding of OC to reactive iron oxides in peatlands. δ13C isotope analyses revealed that Fe-bound OC was relatively enriched in 13C in peatlands. Iron mineral sources, local vegetation, and the water table were responsible for differences in the concentration of Fe-bound OC identified among the 10 sites. Correlation analysis results indicated that total organic carbon (TOC) was the main determinant factor for the concentration of Fe-bound OC (r = 0.549, p < 0.01), and the binding mechanism was jointly regulated by TOC and reactive Fe content. The proportion of Fe-bound OC to TOC (fFe-bound OC) was positively correlated with the reactive Fe (r = 0.457, p < 0.05), indicating that the importance of binding with iron minerals in OC accumulation is regulated by the concentration of reactive Fe in peatlands. This study highlights the quantitative characteristics and spatial variability of Fe-bound OC in peatlands, providing important information for assessing and managing the carbon cycle in peatland ecosystems.

A 13,000-year peatland palaeohydrological response to the ENSO-related Asian monsoon precipitation changes in the middle Yangtze Valley

Quantitative reconstructions of the depth to water table (DWT) of ombrotrophic (rain-fed) peatlands are important for understanding the palaeohydrological responses of peatlands to past climate changes. This understanding can provide insights into projecting peatlands future variability and evolution. However, the postglacial DWT reconstruction of peatlands in China is challenging due to complications of the atmospheric circulation system, the scarcity of hydrological proxies, and the site-specific nature of hydrological signals. Here we present a postglacial quantitative DWT reconstruction based on the analysis of fossil phytoliths from the Dajiuhu Peatland, central China. The reconstructions were based on a phytolith-DWT calibration model using a weighted averaging partial least-squares regression analysis of peatland topsoil calibration datasets. Three shallow DWT (wet) periods at 13,000–11,500 cal yr BP, 9,600–7,500 cal yr BP, and 3,000 cal yr BP-present, and two extended deep DWT (dry) periods at 11,500–9600 cal yr BP and at 7,500–3,000 cal yr BP are found based on the cluster analysis of phytolith assemblages and reconstructed DWT changes. These five documented hydrological periods are consistent with regional precipitation reconstructions from independent records in the middle Yangtze Valley (MYV). We interpret these changes as mostly reflecting changes in ENSO at various timescales. An amplified ENSO forced a southward Western Pacific Subtropical High and caused the persistence of the Meiyu Front in the mid-lower Yangtze Valley, consistent with the intense rainfall periods in our study region. Our results indicate that phytolith records are a reliable and sensitive proxy for the calibration of water table models and the quantitatively palaeo-DWT reconstruction of peatlands and reveal a remarkable link between the local hydrological variations and the coupled atmospheric-oceanic circulation, which is significant for the prediction of future hydrological changes in the Asian monsoon region under the background of global warming.

Holocene peatland development and carbon stock of Zoige peatlands, Tibetan Plateau: a modeling approach

Despite the many studies about peatland development and carbon dynamics in China, especially for Zoige peatlands on the eastern edge of the Tibetan Plateau, few apply modeling as an effective approach to study peatland development. In order to fill up the knowledge gaps of China alpine peatland development and to provide a comparison with previous research, we studied the Zoige peatlands in Holocene with a modeling approach. Simulated results were obtained by the Holocene peatland model (HPM). Driving data was reconstructed based on paleoclimate studies. Model calibration and performance index validation were done by comparing the model output with literature data about peat age depth. Based on our results, the peat cohort mass mean accumulation rate was 0.45 mm year(-1) (ranging from 0.38 to 0.50 mm year(-1)). The mean C accumulation rate was about 0.026 kg C m(-2) year(-1) (ranging from 0.023 to 0.029 kg C m(-2) year(-1)), with a peak accumulation rate around 7 ka to 6 ka BP during the Holocene. The peat depth was 5.38 m (ranging from 4.6 to 5.99 m). The total peat storage in Zoige was about 1.76 Pg (ranging from 1.58 to 2.29 pg), and the carbon stock was estimated as 0.432 pg C (ranging from 0.348 to 0.479 pg C) in Zoige peatlands during the Holocene. After model calibration and validation, simulated results indicated that peat development and carbon accumulation were controlled by variation of water table depth (WTD). Simulated results indicated that the Zoige peatlands are the most important component of peatlands in China in terms of carbon stock. Though HPM lacks in driving data of temperature and incomplete climate factors, its limitations in the parameter setting should not offset the added value of the modeling approach in improving our understanding of peatland carbon and their controlling factor dynamics at the long-term scales in the Zoige region where there are very few studies so far.

15000年以来若尔盖高原泥炭地发育及其碳动态

PDF HTML阅读 XML下载 导出引用 引用提醒 15000年以来若尔盖高原泥炭地发育及其碳动态 DOI: 10.5846/stxb201804240932 作者: 作者单位: 中国科学院成都生物研究所,中国科学院成都生物研究所,中国科学院成都生物研究所,中国科学院成都生物研究所,中国科学院成都生物研究所,中国科学院成都生物研究所,中国科学院成都生物研究所,中国科学院成都生物研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划项目（2016YFC0501804）；中国科学院前沿科学重点研究项目（QYZDB-SW-DQC007）；国家自然科学基金项目（31570480，41571220） Peatland development and carbon dynamics histories of Zoige peatlands for 15000 years Author: Affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences,,,,,,,Chengdu Institute of Biology, Chinese Academy of Sciences Fund Project: The National Key Research and Development Program of China (2016YFC0501804), the Key Research Program of Frontier Sciences, the Chinese Academy of Sciences (QYZDB-SSW-DQC007) and the National Natural Science Foundation of China (31570480, 41571220). 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:高海拔泥炭地是维护高原气候环境稳定的重要生态系统，由于其兼具高海拔和高寒的特点，对气候变化尤为敏感。若尔盖高原泥炭地是中国高海拔泥炭地集中分布区，碳储量丰富，由于方法学差异及数据缺乏，其碳储量估算仍存在一定程度的不确定性，对长时间尺度碳通量的模拟研究还较为匮乏。因此，以若尔盖高原泥炭地为研究对象，基于若尔盖高原泥炭地每千年的面积变化和碳累积速率重新评估若尔盖高原泥炭地碳储量，并利用泥炭分解模型和碳通量重建模型探讨了15000年以来若尔盖高原泥炭地碳通量动态。研究结果表明，若尔盖高原泥炭地约从15000年开始发育，发育高峰期在12000-10000年和7000-5000年，泥炭累积速率范围为0.22-1.31 mm/a，平均值为0.56 mm/a；碳累积速率范围为13.4-77.2 g C m-2 a-1，平均碳累积速率为33.5 g C m-2 a-1，3000年至今碳累积速率最高，7000-6000年是碳累积速率次峰值时期；15000年以来若尔盖高原泥炭地碳储存量达1.4 Pg（1 Pg=1015 g），碳累积输入和碳累积释放分别为5.6 Pg和4.2 Pg；净碳平衡平均值为0.087 Tg（1 Tg=1012 g）C/a，峰值出现在11000-10000年为0.295 Pg；在6000-2000年若尔盖泥炭地出现微弱碳源，最大值出现在5000-4000年，约为-0.034 Pg，净碳平衡在15000-11000年和4000年至今呈现上升趋势，而10000-4000年整体呈现下降趋势。总体而言，若尔盖高原泥炭地碳储量丰富，是青藏高原东部重要的陆地生态系统碳库和碳汇，本研究将为我国高海拔泥炭地碳库保育提供一定的理论和数据支撑。 Abstract:Peatlands are carbon-rich wetlands that have acted as globally important carbon pools by affecting the atmospheric CO2 over long timescales. Knowledge of peatland initiation and carbon dynamics can help predict peat carbon fate in the future. Also, understanding relative changes in carbon flux processes will contribute to a more comprehensive understanding of carbon cycles and the interaction between peatland and climate. The Zoige peatlands are the most representative peatlands in China. This study presents a data synthesis of peatland basal ages, area changes, carbon accumulation rate variations, and, furthermore, analyzed and separated carbon uptake and release, two important carbon flux processes from the observed peat carbon data in Zoige peatlands during the Holocene. The Zoige peatlands showed initiation peaks at 12000-10000 a and 7000-5000 a. The peat accumulation rates ranged from 0.22 to 1.31 mm/a with a mean value of 0.56 g C m-2 a-1. Carbon accumulation rates in Zoige ranged from 13.4 to 77.2 g C m-2 a-1, with a mean value of 33.5 g C m-2 a-1. The carbon pools were estimated to be 1.4 Pg over the entire Zoige peatlands, with results circumventing the uncertainties of previous studies due to peat sampling depth. The long-term decomposition rate for the Zoige peatlands was 0.00024038/a, which is comparable to the long-term decomposition rate of tropical peatlands, and higher than in northern and southern peatlands. The net carbon balance (NCB) rate of Zoige peatlands had a mean value of 0.087 Tg C/a with a maximum of 0.295 Pg. The Zoige peatlands functioned as a carbon source during 6000-2000 a with a minimum NCB value of -0.034 Pg at 5000-4000 a. Overall, the Zoige peatlands were an important carbon pool, however, with some variability. Our results in this study highlighted the importance of carbon cycle research in the Zoige peatlands, and also provided reference values to guide future studies. 参考文献 相似文献 引证文献

Scaling of soil carbon, nitrogen, phosphorus and C:N:P ratio patterns in peatlands of China

Inspired by the importance of Redfield-type C:N:P ratios in global soils, we looked for analogous patterns in peatlands and aimed at deciphering the potential affecting factors. By analyzing a suite of peatlands soil data (n = 1031), mean soil organic carbon (SOC), total nitrogen (TN) and total phosphorous (TP) contents were 50.51%, 1.45% and 0.13%, respectively, while average C:N, C:P and N:P ratios were 26.72, 1186.00 and 46.58, respectively. C:N ratios showed smaller variations across different vegetation coverage and had less spatial heterogeneity than C:P and N:P ratios. No consistent C:N:P ratio, though with a general value of 1245:47:1, was found for entire peatland soils in China. The Northeast China, Tibet, Zoige Plateau and parts of Xinjiang had high soil SOC, TN, TP, and C:P ratio. Qinghai, parts of the lower reaches of the Yangtze River, and the coast zones have low TP and N:P ratio. Significant differences for SOC, TN, TP, C:N, C:P and N:P ratios were observed across groups categorized by predominant vegetation. Moisture, temperature and precipitation all closely related to SOC, TN, TP and their pairwise ratios. The hydrothermal coefficient (RH), defined as annual average precipitation divided by temperature, positively and significantly related to C:N, C:P and N:P ratios, implying that ongoing climate change may prejudice peatlands as carbon sinks during the past 50 years in China.

Natural succession is a feasible approach for cultivated peatland restoration in Northeast China

Peatland restoration has been attracting increasing attention and implementation since large areas of peatlands in China have been degraded or reclaimed to cropland in recent decades. However, the length of time for cultivated peatland to be restored to natural climax level in terms of vegetation remained unknown. A field experiment was conducted to investigate the characteristics of hydrology, plant community, and soil in abandoned 0-, 2-, 15-, and 30-year-old paddy lands and a natural peatland. The results showed a long-term rise in water level after restoration. Similarity indexes between restored sites and natural peatland also increased with the extension of restoration time. During the first three years after abandonment, weeds grew vigorously and almost overtook the entire experimental site. However, the plant community was dominated by a Carex schmidtii–Phragmites australis–Thelypteris palustris community, where similarity increased to 64% and vegetation succession approached a natural climax community after 15 years of restoration. Compared with the paddy field, total nitrogen (TN), total phosphorus (TP), total organic matter (TOM) in the soil at 0–30cm depth and soil bulk density at 0–60cm showed no significant change after 2 years of restoration. In the 15-year restoration site, however, TN and TOM at 0–30cm increased by 108% and 86%, respectively (P<0.01), and soil bulk density at 0–60cm decreased by 40% compared with the paddy field (P<0.05), and the values were already similar to the 30-year site and the natural peatland. Those findings indicate that the cultivated peatland could be restored effectively through natural succession.

Effects of hydrologic mediation and plantation of Carex schmidtii Meinsh on peatland restoration in China's Changbai Mountain region

Since large areas of peatlands in China have been degraded or reclaimed to cropland in recent decades, the conversion of these croplands to wetlands and the restoration of degraded peatlands by means of engineering have been attracting increasing attention. Hydrologic mediation and plantation of dominant peatland species were implemented to determine the effects of these two artificial measures on revegetation and soil property improvement in paddy fields in the Changbai Mountains in Northeast China. The results showed that after a three-year restoration, compared to natural restoration treatment, planting of Carex schmidtii significantly reduced aboveground biomass by 45% (P<0.05), increased root biomass by 53% (P<0.05), increased the Shannon–Wiener Index by 17%, enhanced concentrations of total soil organic matter by 28% (P<0.05), reduced topsoil bulk density by 40% (P<0.05), and improved water retention capacity of the topsoil. These results demonstrate the ability of C. schmidtii to inhibit the growth of weeds and other nontarget species through competition, and to increase the amount of residual roots in soil due to its well-developed rhizomes. Aboveground biomass and total organic matter in hydrologic mediation were 38% lower and 37% higher than in the natural restoration treatment, respectively. However, annual precipitation in this area is 704.2mm, higher than most other area in Northeast China, and the Shannon–Wiener Index and soil bulk density were 4% and 29% lower than in the natural restoration treatment, respectively. Furthermore, the combined application of these two measures resulted in 35% lower aboveground biomass, 22% higher Shannon–Wiener Index, 16% higher topsoil organic matter, and 27% lower bulk density than in the natural restoration treatment. However, the growth of C. schmidtii was inhibited due to the reduction in its survival rate and basal width growth rate. Our results suggest that planting C. schmidtii is an effective way to promote the restoration of degraded peatland and enhance its carbon sink function in the Changbai Mountains. On the other hand, implementation of hydrologic mediation is not recommended for this rain-rich region.

Effects of soil warming, rainfall reduction and water table level on CH4 emissions from the Zoige peatland in China

The Zoige Plateau features approximately 4605 km2 of peatlands, making it the largest peatland area in China. This area stored 2.9 Pg peat during the Holocene, yet little is known about methane (CH4) emissions from this region. In this study, we designed a mesocosm experiment to measure CH4 emissions during the growing seasons of 2009–2010 under different scenarios involving soil warming, 20% reduction in rainfall and changes in the water table level. Our results showed that CH4 emissions were higher in 2009 than in 2010 under all experimental conditions. Average soil temperature was approximately 11.4 °C under control conditions, 13.3 °C under soil warming conditions, 12.7 °C with 20% rainfall reduction, and 13.4 °C under combined conditions of soil warming and 20% reduced rainfall. For the single factor effect, soil warming treatment increased average CH4 emissions by 28%, while rainfall reduction increased it by 30%; however, neither increase was statistically significant. In contrast, the combined effect of soil warming and rainfall reduction significantly decreased CH4 emissions by an average of 58%. Extending this result across the entire peatland area in the Zoige Plateau translates into approximately 5.3 Gg of CH4 uptake per year. These results suggest that a drier and warmer Zoige Plateau will become a CH4 sink. Our study also found a positive relationship between water table level and CH4 emissions. Average CH4 emissions decreased by approximately 82% as water drawdown varied from 0 (0.94 mg CH4 m−2 h−1) to −50 cm (0.17 mg CH4 m−2 h−1). When we simultaneously examined the effect of all three factors of water table level, soil warming and rainfall reduction on CH4 emissions, we found soil warming and rainfall effect on CH4 emissions varied with water table levels. However, none of the three factors significantly affected CH4 emissions at a water table depth of 30 cm below peat depth.

Remotely sensing the ecological influences of ditches in Zoige Peatland, eastern Tibetan Plateau

Zoige Peatland in the eastern Tibetan Plateau, the largest alpine peatland in China, was widely ditched in 1970s for pasture expansion. The ditching is believed to have caused peatland degradation, but there is still no widespread agreement on this due to the absence of essential regional and temporal information about ditch drainage. Therefore, this study used both remote-sensing observations and field surveys to examine the ecological influences of ditching for this alpine peatland. In the study, ditch distribution was interpreted with remote-sensing imagery and the ecological responses were investigated with temporal observation by Moderate Resolution Imaging Spectroradiometer (MODIS) and field surveys. The results showed that there were ~1200 km ditches interpreted, mainly in three spatial patterns depending on hydro-geomorphologies. The MODIS enhanced vegetation index (EVI) was more sensitive to peatland surface water depth (R2 = 0.678, P < 0.001) than the normalized difference water index (NDWI) (R2 = 0.583, P < 0.001), because the latter would become saturated at a certain surface water depth (~50 cm in Zoige). The temporal MODIS imagery reflected the ecological responses of ditched peatland to drainage in terms of vegetation density and water conditions. This study indicated that ditching depressed the surface water depth of the Zoige Peatland in summer, but not to the extent of completely transforming peatland into steppe due to the recharging of local beneficial hydro-geomorphologies. The MODIS indices investigated in the study could be used to monitor the annual regional status of vegetation cover and surface water for Zoige peatland.

Carbon dynamics of peatlands in China during the Holocene

Understanding the responses of the carbon-rich peatland ecosystems to past climate change is crucial for predicting peat carbon fate in the future. Here we presented a data synthesis of peatland initiation ages, area changes, and peat carbon (C) accumulation rate variations in China since the Holocene, along with total C pool estimates. The data showed different controls of peatland expansion and C accumulation in different regions. The peat C accumulation rates were 32.3 (ranging from 20.7 to 50.2) g C m−2 yr−1 in the Qinghai-Tibetan Plateau (QTP) and 14.7 (ranging from 7.4 to 36.5) g C m−2 yr−1 in the Northeast China (NEC). The peaks of peatland expansion and C accumulation in the QTP occurred in the early Holocene in response to high summer insolation and strong summer-winter climate seasonality. The rapid peatland expansion and maximum C accumulation rate in the NEC occurred in the middle-late Holocene. Peatlands scattered in the coastal and lakeside regions of China expanded rapidly at the onset of the Holocene due to large transgression, consistent with the stronger summer insolation and monsoon, and during the middle and late Holocene, as a response to the high and stable sea level and the strong summer monsoon. The carbon storage of peatlands in China was estimated as 2.17 (ranging from 1.16 to 3.18) Pg, among which 1.49 (ranging from 0.58 to 2.40) Pg was contributed by peatlands in the QTP, 0.21 (ranging from 0.11 to 0.31) Pg by those in the NEC, and 0.47 Pg by those scattered in other regions of China. Our comparison of peatlands dynamics among regions in China showed that climate and monsoon are the essential factors in determining the expansion and carbon accumulation patterns of peatlands, although their effects on peatland formation and C accumulation is complex owing to land availability in peatland basins and regional moisture conditions.

Holocene peatland initiation, lateral expansion, and carbon dynamics in the Zoige Basin of the eastern Tibetan Plateau

The Zoige Basin on the eastern Tibetan Plateau has the largest area of highland peatlands in China. However, the development history of these peatlands is still poorly understood. Understanding how these carbon-rich ecosystems responded to change in the Asian summer monsoons during the Holocene will provide insight into the peatland carbon accumulation processes under different climate boundary conditions. Here, we document the timing of initiation and expansion histories of these peatlands using 59 new basal peat ages across the Zoige Basin, with 29 ages for initiation analysis and 30 additional ages for lateral expansion analysis. Also, we synthesized basal ages from 26 sites and carbon accumulation records at four sites from previous studies in this region. The results show that the peatland initiation is widespread at 11.5–10 and 7–6 kyr (1 kyr = 1000 cal. yr BP) and the minimum initiation periods occurred after 5 kyr. Our multiple basal ages along eight transects show that slopes are a dominant control on peatland lateral expansion rates, with very slow and less variable rates at slopes &gt;0.4°. Furthermore, we found a significant relationship between peatland basal ages and peat depths from 85 sites, suggesting relatively uniform peat properties. Carbon accumulation rates from detailed downcore analysis at four sites and on the basis of peat depth–basal age relationship show similar patterns with a peak carbon accumulation at 10–8 kyr. On the basis of estimated mean values of bulk density and carbon content from the region, the Holocene average C accumulation for the Zoige Basin is 31.1 g C/m2/yr. The widespread peatland initiation and rapid accumulation in the early Holocene were likely in response to higher temperature and stronger summer monsoon intensity, while the slowdown of peatland development during the late Holocene might have been caused by climate cooling and drying.

Estimation of storage and density of organic carbon in peatlands of China

Based on the results of the National Survey of Peat Resources (1983–1985) and the investigation results on the peatlands of China, the storage and density of the organic carbon in the peatlands of China were estimated. The total organic carbon storage (OCS) of the peatlands in China, including bare peatlands and buried peatlands, are 1.503 × 109 t, unevenly distributed over 30 provincial level administrative units and 16 climatic zones. Peatland organic carbon storage (POCS) in Sichuan (6.45 × 108 t) and Yunnan provinces (2.91 × 108 t) is the highest, accounting for 62.29% of the total POCS. Humid zone of plateau has the highest POCS of 7.14 × 108 t, especially in the Zoige Plateau, where the POCS is 6.30 × 108 t, accounting for 41.92% of the total POCS of China. The organic carbon density (OCD) of the peatlands in China mostly ranges from 80 kg/m3 to 140 kg/m3, and the range of the maximum is 270–360 kg/m3, and the minimum is less than 80 kg/m3. Divided by the Yanshan Mountain, Taihang Mountains and Hengduan Mountains, the peatland oganic carbon density (POCD) is lower on the northwestern side than that on the southeastern side. Jiangxi Province has the highest POCD due to the ancient buried peatlands. The OCD of the bare peatlands is mostly in the range of 60–150 kg/m3, and that of the buried peatlands is more than 100 kg/m3. In the bare peatlands, the OCD generally increases from the surface layer to the below surface layer, and then decreases with the depth. Although the peatlands area in China is small, the OCS per unit area is far higher than the other soil types, so peatlands protection can effectively mitigate climate change.

Ecology of testate amoebae in Dajiuhu peatland of Shennongjia Mountains, China, in relation to hydrology

This study investigates the testate amoeba communities of a large peatland in Central China. The ecology and seasonal variability of testate amoeba communities were studied during 2009–2010. Investigation of environmental controls using ordination showed that the relationship between testate amoeba communities and depth to water table (DWT) and pH are extremely weak. The small proportion of variance explained by water table depth here (only 1.9% in the full data) shows that the hydrological control is weaker than we expected in this peatland, and weaker than any study we are aware of using a similar methodology. Attempts to develop species-environment (transfer function) models or identify indicator species for future palaeoecological studies were unsuccessful. Previous large-scale studies of peatland testate amoeba ecology have been largely restricted to Europe and North America and results have been relatively consistent among studies. Our results contrast with this consensus and suggest that at least in minerotrophic peatlands in China testate amoeba communities may be primarily controlled by different environmental variables. In China, testate amoebae have been relatively little studied but may prove to be valuable for a variety of applications in palaeoecology and biomonitoring and much further work is required.

Effects of temperature, soil moisture, soil type and their interactions on soil carbon mineralization in Zoigê alpine wetland, Qinghai-Tibet Plateau

Wetland stores substantial amount of carbon and may contribute greatly to global climate change debate. However, few researches have focused on the effects of global climate change on carbon mineralization in Zoige al- pine wetland, Qinghai-Tibet Plateau, which is one of the most important peatlands in China. Through incubation ex- periment, this paper studied the effects of temperature, soil moisture, soil type (marsh soil and peat soil) and their in- teractions on CO2 and CH4 emission rates in Zoige alpine wetland. Results show that when the temperature rises from 5℃ to 35℃, CO2 emission rates increase by 3.3-3.7 times and 2.4-2.6 times under non-inundation treatment, and by 2.2-2.3 times and 4.1-4.3 times under inundation treatment in marsh soil and peat soil, respectively. Compared with non-inundation treatment, CO2 emission rates decrease by 6%-44%, 20%-60% in marsh soil and peat soil, respec- tively, under inundation treatment. CO2 emission rate is significantly affected by the combined effects of the tempera- ture and soil type (p < 0.001), and soil moisture and soil type (p < 0.001), and CH4 emission rate was significantly af- fected by the interaction of the temperature and soil moisture (p < 0.001). Q10 values for CO2 emission rate are higher at the range of 5℃-25℃ than 25℃-35 , ℃ indicating that carbon mineralization is more sensitive at low temperature in