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青藏高原土壤有机碳储量与密度分布 总被引:13,自引:0,他引:13
采用全国第二次土壤普查数据结合作者的实测数据,利用1∶100万土壤数据库对青藏高原土壤有机质层、土壤矿质层及整个剖面的土壤有机碳密度和土壤有机碳储量分别进行了估算。结果表明:青藏高原的平均土壤有机碳密度约为C 7.2 kg m-2,较前人的C 8.01~19.05 kg m-2全国平均土壤有机碳密度偏低。青藏高原总的土壤有机碳储量约为18.37 Pg,其中有机质层土壤有机碳储量约占38.14%,矿质层土壤有机碳储量则占61.86%。 相似文献
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火干扰对森林生态系统土壤有机碳影响研究进展 总被引:1,自引:0,他引:1
森林生态系统土壤有机碳作为陆地碳循环研究的重要内容,在全球变化和全球碳收支的研究中占据了重要地位。火干扰能改变森林生态系统中土壤与大气的碳素交换,是森林生态系统碳循环的重要影响因子。为此,加强火干扰下森林生态系统土壤有机碳循环研究,了解火干扰与森林生态系统土壤有机碳循环之间的交互关系,有助于揭示火干扰下土壤碳库动态机理。本研究简要综述了火干扰对森林生态系统土壤有机碳影响研究进展,探讨了不同强度林火对土壤有机碳的影响,分析了其产生机理;阐述了火干扰不同时间后土壤有机碳变化、火干扰对不同土层土壤有机碳的影响,并分析了其原因。最后讨论了火干扰对森林土壤有机碳影响研究中存在的相关问题,提出了在今后研究中应关注的问题,并对未来的研究方向进行了展望。 相似文献
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不同地形条件下青藏高原农田土壤有机碳的分布特征 总被引:1,自引:0,他引:1
西北高寒地区农田土壤有机碳(SOC)储量的变化研究,可为东部农田SOC对气候和管理措施的响应提供预警信息。针对西部高原县域尺度上典型的地貌类型和土壤类型,对其耕层和剖面SOC进行了分析。结果表明, 青海省乐都县农田耕层(020 cm)SOC的变化范围为4.38 g/kg~20.81 g/kg,均值为11.29 g/kg,且不同土壤类型上表现出黑钙土(16.15 g/kg)>栗钙土(10.53 g/kg)>灰钙土(9.50 g/kg)的趋势。地形对耕层(020 cm)SOC含量没有显著影响,但深层(20100 cm)SOC因地形存在显著差异,在峁坡上,黑钙土、 栗钙土和灰钙土的深层(20100 cm)SOC分别比同种土壤类型的谷底深层土壤提高了111.5%、 62.5%和66.3%。农田SOC的垂直分布也因地形存在差异,同一种土壤类型在谷底其耕层(020 cm)SOC含量均比深层(20100 cm)高,峁坡上其深层(20100 cm)比耕层(020 cm)高,黑钙土、 栗钙土和灰钙土在谷底其耕层(020 cm)SOC含量分别比同一土壤类型的深层(20100 cm)土壤提高18.7%、 24.3%和153.5%,黑钙土、 栗钙土和灰钙土在峁坡上其深层(20100 cm)SOC含量分别比同一土壤类型耕层(020 cm)提高46.9%、 8.0%和1.0%。这一结果可为准确估算青藏高原农田SOC的变化提供参考。 相似文献
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侵蚀条件下土壤有机碳流失研究进展 总被引:3,自引:0,他引:3
全球土壤有机碳库储量丰富且活跃,而作为碳流失主要驱动力的土壤侵蚀对陆地碳循环影响巨大,揭示其影响将对气候变化背景下深刻理解碳收支过程和相关政策的制定具有重要意义。该文主要介绍了近年来国内外关于水蚀和风蚀影响土壤有机碳流失过程的研究进展,分析了侵蚀条件下土壤碳的源汇争议,简述了土壤有机碳流失的原位和异位环境效应,并提出了相关研究的主要现实问题和未来发展方向。在侵蚀进程中,土壤有机碳的固定与流失并存,流失部分主要包括在地表径流泥沙和土壤呼吸过程中,当前相关研究多集中于侵蚀有机碳的去向问题。在一定的景观范围内,定量刻画侵蚀过程中土壤碳输入输出关系是今后区域碳循环研究领域亟待解决的关键科学问题。 相似文献
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人为活动影响下陆地生态系统退化对于土壤碳库损失的影响规模是当前全球变化研究的热点。在青海省三江源区选择了8个高寒草甸典型样区,划分4种不同退化程度样地(原生植被、轻度退化、重度退化、极度退化),收割法采集地上部植物生物量,10cm等深度采集表土土壤样品,分析了地上生物量、可食牧草生物量以及土壤有机碳含量变化。结果表明,随着退化程度的加剧,地上生物量和饲草生物量均表现强烈下降的趋势,但后者的下降幅度更大,在极度退化下损失达99%。研究区内高寒湿地土壤的表土有机碳含量出现极大的变异性,随退化程度的加剧而呈显著下降。与原生植被下相比,轻度退化、重度退化和极度退化下0-30cm土壤有机碳含量分别平均降低了25%、44%和52%。这种损失固然与地上部生物量下降有关,有机碳分层系数显示土壤侵蚀也是重要因素。估计退化下土壤有机碳平均下降36tC·hm^-2,累积退化下表土有机碳损失可能在200TgC以上,保护高寒草甸生态系统,对于三江源区土壤的畜牧业可持续发展和我国陆地生态系统碳库具有极重要的意义。 相似文献
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高寒草原土壤有机碳与腐殖质碳变化及其微生物效应 总被引:4,自引:1,他引:4
基于多区域重复采样,研究了藏北高原不同状态(正常、轻度和严重退化)高寒草原表层(0~10 cm)、亚表层(10~20 cm)土壤有机碳(Soil organic carbon,SOC)、腐殖质碳(Humus carbon,HC)、胡敏酸碳(Humic acid carbon,HAC)和富里酸碳(Fulvic acid carbon,FAC)的变化,以及土壤微生物群落、微生物生物量碳(Microbial biomass carbon,MBC)、纤维素分解酶活性(Cellulolytic enzyme activity,CEA)对其产生的影响与作用。结果表明:高原寒旱环境中土壤的HC/SOC比例过低,但PQ值(HAC/HC)很高。随土层加深,不同状态草地SOC、HC、HAC含量、HC/SOC比例在总体上趋于不同程度的下降,PQ值则均呈一定程度的提高。相对于正常草地,随草地退化加剧,表层SOC、HC(HAC、FAC)增幅分别表现出略呈下降、大幅提高,亚表层降幅则均呈大幅下降。反映到0~20 cm土层,SOC、HC、HAC含量均表现出正常草地严重退化草地轻度退化草地,HC/SOC比例、PQ值则分别呈严重退化草地正常草地轻度退化草地、正常草地轻度退化草地严重退化草地,说明草地退化在促进表层SOC、HC(HAC、FAC)形成与积累的同时,更"激发"了亚表层的矿化,尤其是严重退化草地有机残体的分解过程,但腐殖质品质并未随土壤腐殖化程度的提高而得到相应改善。MBC、CEA与SOC、HC及组分高度一致的土体分布格局影响并决定了上述过程,草地退化有利于真菌、放线菌对土壤、尤其是亚表层土壤有机残体的分解与转化。 相似文献
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念青唐古拉山东南坡高寒草原生态系统表层土壤活性有机碳的影响因素研究 总被引:1,自引:0,他引:1
高寒草原是青藏高原广泛分布的植被类型。本文以念青唐古拉山东南坡高寒草原生态系统为对象,采用野外调查与室内分析相结合的方法,对影响高寒草原生态系统表层(0~20cm)土壤活性有机碳分布的因素进行了研究。结果表明:念青唐古拉山东南坡高寒草原生态系统表层(0~20cm)土壤活性有机碳平均含量为2.61±0.31g·kg?1;影响表层土壤活性有机碳分布的地形因子是海拔和坡度,植被因子是0~10cm、10~20cm土层地下生物量,物理因子是0~10cm、10~20cm土壤含水量和0~20cm土壤容重,化学因子是土壤全钾含量。其中0~10cm、10~20cm土壤含水量和0~20cm土壤容重影响达显著水平。在海拔4421~4598m范围内,随着海拔升高,表层土壤活性有机碳含量表现出增加→减少→增加→减少的分布特征。 相似文献
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Soil organic carbon distribution in relation to land use and its storage in a small watershed of the Loess Plateau, China 总被引:2,自引:0,他引:2
Soil organic carbon (SOC) is an important component in agricultural soil, and its stock is a major part of global carbon stocks. Estimating the SOC distribution and storage is important for improving soil quality and SOC sequestration. This study evaluated the SOC distribution different land uses and estimated the SOC storage by classifying the study area by land use in a small watershed on the Loess Plateau. The results showed that the SOC content and density were affected by land use. The SOC content for shrubland and natural grassland was significantly higher than for other land uses, and cropland had the lowest SOC content. The effect of land use on the SOC content was more significant in the 0-10 cm soil layer than in other soil layers. For every type of land use, the SOC content decreased with soil depth. The highest SOC density (0-60 cm) in the study area was found in shrublandII (Hippophae rhamnoides), and the other land uses decreased in the SOC density as follows: natural grassland > shrublandI (Caragana korshinskii) > abandoned cropland > orchard > level ground cropland > terrace cropland > artificial grassland. Shrubland and natural grassland were the most efficient types for SOC sequestration, followed by abandoned cropland. The SOC stock (0-60 cm) in this study was 23,584.77 t with a mean SOC density of 4.64 (0-60 cm). 相似文献
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Dissolved organic matter (DOM) plays a central role in driving biogeochemical processes in soils, but little information is available on the relation of soil DOM dynamics to microbial activity. The effects of NO3− and NH4+ deposition in grasslands on the amount and composition of soil DOM also remain largely unclear. In this study, a multi-form, low-dose N addition experiment was conducted in an alpine meadow on the Qinghai–Tibetan Plateau in 2007. Three N fertilizers, NH4Cl, (NH4)2SO4 and KNO3, were applied at four rates: 0, 10, 20 and 40 kg N ha−1 yr−1. Soil samples from surface (0–10 cm) and subsurface layers (10–20 cm) were collected in 2011. Excitation/emission matrix fluorescence spectroscopy (EEM) was used to assess the composition and stability of soil DOM. Community-level physiological profile (CLPP, basing on the BIOLOG Ecoplate technique) was measured to evaluate the relationship between soil DOC dynamics and microbial utilization of C resources. Nitrogen (N) dose rather than N form significantly increased soil DOC contents in surface layer by 23.5%–35.1%, whereas it significantly decreased soil DOC contents in subsurface layer by 10.4%–23.8%. Continuous five-year N addition significantly increased the labile components and decreased recalcitrant components of soil DOM in surface layer, while an opposite pattern was observed in subsurface layer; however, the humification indices (HIX) of soil DOM was unaltered by various N treatments. Furthermore, N addition changed the amount and biodegradability of soil DOM through stimulating microbial metabolic activity and preferentially utilizing organic acids. These results suggest that microbial metabolic processes dominate the dynamics of soil DOC, and increasing atmospheric N deposition could be adverse to the accumulation of soil organic carbon pool in the alpine meadow on the Qinghai-Tibetan Plateau. 相似文献
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Alpine ecosystems are quite sensitive to global climatic changes. Drawing from two sets of remote sensing data (1986 and 2000) and field investigations, the ecological index method was used to document ecosystem changes in the Yangtze and Yellow River source regions of central Qinghai–Tibet. Although crucial to understanding alpine ecosystem responses to global climatic changes, and in assessing the potential for their rehabilitation, the impact of such changes on alpine soil characteristics, including structure, composition, water retention, as well as chemical and nutrient contents, is poorly understood. Over a 15-year period (1986–2000), climatic changes led to considerable degradation of alpine meadows and steppes. In the meadows, the surface layers of the soil became coarser, bulk density, porosity and saturated hydraulic conductivity rose, while water-holding capacity decreased. In comparison, steppe soils showed little changes in soil physical properties. Degradation of alpine ecosystems led to large losses in soil available Fe, Mn and Zn. Important losses in soil organic matter (SOM) and total nitrogen (TN) occurred in badly degraded ecosystems. Climate warming in the Qinghai–Tibet Plateau, caused by the impact of greenhouse gas, has resulted in changes of cold alpine ecosystem such as the significant alteration of the soil C and N cycles. 相似文献
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The aim of this study was to assess initial effects of warming on the nutrient pools of carbon and nitrogen of two most widespread ecosystem types, swamp meadow and alpine meadow, in the Qinghai-Tibet Plateau, China. The temperature of the air and upper-soil layer was passively increased using open-top chambers (OTCs) with two different temperature elevations. We analyzed air and soil temperature, soil moisture, biomass, microbial biomass, and nutrient dynamics after 2 years of warming. The use of OTCs clearly raised temperature and decreased soil moisture. The aboveground plant and root biomass increased in all OTCs in two meadows. A small temperature increase in OTCs resulted in swamp meadow acting as a net carbon sink and alpine meadow as a net source, and further warming intensified this processes, at least in a short term. On balance, the alpine ecosystems in the Fenghuoshan region acted as a carbon source. 相似文献
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生物质改良剂对川西北地区高寒草地沙化土壤有机碳特征的影响 总被引:1,自引:0,他引:1
川西北高寒草原特殊的地理环境、气候条件以及过度人为放牧导致草地沙化问题突出。为了探讨不同生物质改良剂对高寒草地沙化土壤有机碳特征的影响,采用随机区组试验设计方法,设置3种生物质改良剂[秸秆类(JG)、菌渣类(JZ)、生物炭类(SWT)], 2个施用水平(6 t·hm?2和18 t·hm?2),以空白处理(CK)为对照,研究高寒草地沙化土壤总有机碳、活性有机碳和呼吸特征的变化。结果表明:1)施用生物质改良剂显著提高了土壤有机碳(TOC)、微生物量碳(MBC)和易氧化有机碳(EOC)含量,且提高效果随改良剂施用量的增加而增强。与CK相比,JG、JZ、SWT处理0~10 cm TOC含量分别平均提高60.66%、39.22%、34.99%,且JG处理显著高于JZ和SWT处理; MBC含量在0~10 cm则表现为JZJGSWTCK,且处理间差异达显著水平; EOC含量表现为JG处理最高,在0~10 cm、10~20 cm土层处分别比对照提高108.82%、79.26%。2)不同生物质改良剂处理中, EOC/TOC表现为JGJZSWTCK,MBC/TOC表现为JZJGSWTCK,且不同处理间差异显著。3)施用不同改良剂均显著提高了土壤呼吸速率,且随改良剂施用量的增加,土壤呼吸速率显著增加。与CK相比,施用6 t·hm?2的JG、JZ、SWT的土壤呼吸速率平均提高103.42%、86.31%、18.83%, JZ和JG处理的土壤呼吸速率显著高于SWT和CK处理。相关性分析表明,土壤水分与土壤呼吸速率呈显著正相关关系, TOC、MBC以及EOC与土壤呼吸速率呈极显著正相关关系。4)施入不同改良剂均显著提高了土壤呼吸总量、土壤微生物呼吸总量和净生态系统生产力(NEP值),均表现出较强的碳汇潜力, JG处理的NEP值较JZ和SWT处理分别显著提高56.45%和122.12%,且各处理间差异显著,说明秸秆改良剂具有较高的碳汇强度。该研究可为川西北藏区补充完善高寒草地沙化土壤制定科学有效的土壤碳调控管理措施提供依据。 相似文献
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Mountainous peatlands are one of the most important terrestrial ecosystems for carbon storage and play an important role in the global carbon cycle. An insight into the carbon cycle of peat swamps located in mountainous regions can be obtained by studying the distribution of soil organic carbon (SOC) and its relationships with environmental factors. This study focused on the development conditions of peat swamps in the Gahai wetlands, located on the Zoigê Plateau, China, with four different altitudinal gradients as experimental sample sites. The distribution of SOC and its relationship with environmental factors were analysed through vegetation surveys and a generalized additive model (GAM). The results show that with increasing altitude, soil temperature decreased while the soil pH and bulk density initially decreased then increased. On the contrary, the topographic wetness index (TWI), SOC content, above-ground biomass and litter count initially increased then decreased. The SOC content of the 0–30 cm soil layer was in the range 226–330 g·kg−1 (coefficient of variation (CV) = 21.4%), and the 30–60 cm layer was 178–257 g·kg−1 (CV = 17.5%) and was significantly correlated (p < .05) with above-ground biomass and litter count. Meanwhile, the SOC content in the 60–90 cm soil layer was in the range 132–167 g·kg−1 (CV = 9.2%) with a significant correlation (p < .05) with soil temperature, pH, bulk density and topographic moisture index. The study showed that the SOC content exhibited more pronounced spatial patterns with increasing altitude, with the peak value in the shallow soil layer appearing in lower elevation areas compared with the deep soil layer. The level of variation changed from medium to low, reflecting the stable mechanism for maintaining SOC within the heterogeneous peat swamp environment. 相似文献
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氮素富集对青藏高原高寒草甸土壤有机碳迁移和累积过程的影响 总被引:3,自引:0,他引:3
为深入揭示陆地生态系统碳固定对大气氮沉降增加的响应机理,基于海北高寒草甸多形态(NH4Cl、(NH4)2SO4、KNO3)、低剂量(N 0、10、20、40 kg hm-2a-1)的增氮控制试验平台,采集各处理水平下不同深度土壤样品,利用颗粒分组法分离测定总土壤有机碳(SOC)以及各粒径组分的碳含量和δ13C值。研究结果表明:低氮显著增加了土壤粗颗粒态有机碳(Macro POC)和矿质结合态有机碳(MAOC)的含量,而高氮处理正好相反。施氮一致降低土壤细颗粒态有机碳(Micro POC)含量。此外,添加硝态氮肥对SOC各组分含量和δ13C值的影响显著高于铵态氮肥。总体而言,低氮导致地表30 cm层SOC储量增加了4.5%,而中氮和高氮导致SOC储量分别下降了5.4%和8.8%。低氮处理时新增的碳以Macro POC为主,而高氮处理时损失的碳主要是Micro POC。连续5 a施氮促进了颗粒态有机碳(POC)组分的分解,进而导致SOC稳定组分的比例增加。可以认为,大气氮沉降或低剂量施氮(10 kg hm-2a-1)短期内有利于青藏高原高寒草甸土壤碳截留,硝态氮较铵态氮输入对土壤碳储量增加更为有益。 相似文献