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牦牛粪便碎化对藏北高寒草原土壤温室气体排放影响研究
Alternative TitleEffects of yak dung fragmentation on alpine steppe soil greenhouse gas emissions
杜子银
Subtype博士
Thesis Advisor王小丹
2017
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline自然地理
Keyword牛粪 斑块破碎化 降水淋溶 DOC DON NH4+-N NO3?-N 植被生物量 N2O排放
Abstract为了阐明不同碎化程度牦牛粪便斑块在自然降解过程中的养分动态变化及其对土壤养分含量、植被生长和温室气体排放的影响和可能作用机制,以中国科学院申扎高寒草原与湿地生态系统观测试验站(30°57' N, 88°42' E, 4,675 m a.s.l.)高寒草原观测场为研究基地,开展了以原状(ODP)、1/4碎化(FDP)、1/8碎化(EDP)和1/16碎化(SDP)牦牛粪便斑块为处理的PVC板框试验,监测了各处理牛粪碳(C)、氮(N)主要养分和主要温室气体(N2O、CH4和CO2)的排放通量;同时开展了不施粪便(对照)、ODP、FDP、EDP和SDP为处理(分别记为CK、ODP-S、FDP-S、EDP-S和SDP-S)的牛粪-土壤-植被体系试验,原位测定了土壤温湿度和碳氮养分变化、植被生物量响应和温室气体排放通量等,得到以下主要的研究结果:(1)在PVC板框试验中,斑块碎化促进了牛粪活性碳氮的淋溶,但对其自身总碳和全氮含量影响不大。经过72 d降解过后,各处理牛粪NH4+-N和NO3?-N显著降低,而总碳和全氮无显著变化;牛粪碎化显著增加了可溶性有机碳(DOC)和有机氮(DON)的淋溶,ODP处理DOC和DON累积淋溶量(65.8 kg C/ha和4.01 kg N/ha)显著低于(P < 0.05)FDP,EDP和SDP处理的DOC(分别为98.3,114和140 kg C/ha)和DON累积淋溶量(分别为5.44,5.73和6.54 kg N/ha),且碎化程度越大累积淋溶量也越大。不过,一定程度的斑块碎化增加牛粪NH4+-N淋溶,但会持续减少NO3?-N淋溶。总体而言,降水导致的各处理以DOC形式损失的碳占牛粪总碳损失量的2.99%-7.27%,而以DON、NH4+-N和NO3?-N形式损失的氮占牛粪总氮损失量的5.72%-11.7%、2.08%-2.91%和0.60%-0.80%。(2)在牛粪-土壤-植被体系试验中,牛粪施加总体上增加了土壤有机碳(SOC)和全氮(TN)含量,而且随着降解时间的增长还会持续增加土壤NO3?-N含量。持续的降水淋溶致使牛粪施加后的30 d和72 d较CK显著增加了土壤DOC含量,而且碎化程度越大增幅越大。ODP-S处理受降水淋溶的DOC损失缓慢,从而使得其对增加土壤DOC含量的持续时间较长,并导致在1-30,31-72和73-120 d三个降解时期内的土壤DOC含量表现出显著差异(P< 0.05)。与之不同的是,牛粪施加可能通过刺激土壤微生物和植被对DON的需求,而表现为较CK显著降低了土壤DON含量(P < 0.05)。(3)就整个生长季而言,牛粪施加总体上较对照增加了高寒草原植被地上和0-10 cm根系生物量。斑块碎化在试验1-30 d和31-72 d并未较原状牛粪和对照显著增加植被地上和地下生物量,而到生长季末期原状牛粪处理则表现出显著增加的效应。表明牛粪斑块碎化在增加NH4+-N淋溶而减少NO3?-N淋溶的情形下并未能迅速促进植被生长,这可能与高原草原植被本身具有不同的氮素吸收偏好有关。而原状牛粪斑块对促进植被生长具有一定的滞后性。(4)牦牛粪便碎化促进了粪便自身N2O和CO2排放,但显著减少了CH4排放。在70 d观测期内,ODP处理N2O累积排放量为-29.2 g N2O-N/ha,显著低于(P < 0.05)FDP、EDP和SDP处理的40.3,24.0和25.9 g N2O-N/ha;而ODP处理CH4累积排放量685 g CH4-C/ha则显著高于(P < 0.05)FDP、EDP和SDP处理的231,271和357 g CH4-C/ha。1/4碎化牛粪斑块可能具有更适宜有机碳矿化和微生物厌氧反硝化等条件,从而使得其具有最高的CO2和N2O累积排放量。(5)牛粪返还较对照增加了高寒草原土壤N2O、CH4和CO2排放,而且排放通量与斑块大小有密切的关系。在120 d试验期内,ODP-S和FDP-S处理显著增加了(P < 0.05)高寒草原土壤N2O累积排放(50.4和58.9 g N/ha),而碎化程度更大时则与CK无显著差异。相比之下,ODP-S通过增加CH4排放而显著减少了(P < 0.05)草原土壤对CH4的吸收,而斑块碎化则对CH4排放无显著影响;总体而言,一定程度的牛粪碎化增大了N2O和CO2的排放系数,但无论碎化程度如何都能显著减小CH4的排放系数。这能为未来气候变化环境下,厘清牦牛粪便碎化导致的高寒草原温室气体排放组分的差异并合理管理放牧牦牛粪便等提供科学的理论参考。
Other AbstractTo understand the effects of yak dung fragmentation on major nutrients dynamics of dung itself and soil, and explore the effects on vegetation growth and greenhouse gas emissions, field experiments were conducted at the Xainza Alpine Steppe and Wetland Ecosystem Observation Station in Northern Tibet, China (30°57' N, 88°42' E, 4,675 m a.s.l.). The PVC experiment had four treatments that included four treatments such as the original dung patch (ODP) and fragmentizing the original dung into 4 (FDP), 8 (EDP) and 16 (SDP) pats in the four identical leaching devices. Dung carbon (C) and nitrogen (N) nutrients and greenhouse gas (GHG) include N2O, CH4 and CO2 fluxes were measured during the natural decomposition of dung patches. Besides, yak dung-soil-vegetation experiment was conducted at the alpine steppe observation field, and treatments such as no fertilization (CK), one original dung patch (ODP-S) and fragmentizing the original dung into 4 (FDP-S), 8 (EDP-S) and 16 (SDP-S) pats were included. Soil moisture, temperature, major C and N nutrients, vegetation biomasses and GHG emissions were simultaneously detected and the results as follows:(1) Yak dung fragmentation promoted activated C and N leaching, while had no significant impacts on dung total C and N contents. Dung ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3--N) significantly decreased, but no such properties in total C and N contents were detected across the 72 d decomposition period. Patch fragmentation accelerated dung dissolved organic carbon (DOC) and nitrogen (DON) leaching, with the cumulative DOC and DON leaching amounts for ODP treatment (65.8 kg C/ha and 4.01 kg N/ha) significantly lower (P< 0.05) than those at FDP, EDP and SDP treatments (98.3, 114 and 140 kg C/ha; 5.44, 5.73 and 6.54 kg N/ha). Moreover, the increase of dung fragmentation resulted in the enlarge of cumulative DOC and DON leaching. Patch fragmentation could increase dung NH4+-N leaching to some extent, but would decrease NO3--N leaching with the increase of fragmentation degrees. Cumulative DOC leaching amounts that derived from rainfall erosion for the four treatments accounted for 2.99%-7.27% of the total C losses during the 72 d decomposition period, while cumulative DON, NH4+-N and NO3--N leaching amounts respectively accounted for 5.72%-11.7%, 2.08%-2.91% and 0.60%-0.80% of the toal N losses.(2) Yak dung application generally increased soil organic carbon (SOC) and total nitrogen (TN) compared to the control, and tend to increase soil NO3--N content as the increase of dung ages. Rainfall erosion promoted dung DOC leaching and resulted in the significant increase of soil DOC content at 30 and 72 d contrast to the control, and patch fragmentation tend to accelerate the increase of soil DOC content. Compared to the fragmented dung patches, the ODP-S treatment had a slower DOC leaching rate, which lead to the prolong of dung effects on increasing soil DOC and therefore result in the significant differences (P< 0.05) of soil DOC contents among the three decomposition periods. Differently, yak dung application probably stimulate the microorganisms and vegetation demands to DON, and therefore result in the significantly lower soil DON content than the control (P< 0.05).(3) Yak dung return generally increase the vegetation aboveground and 0-10 cm root biomasses of alpine steppe in the whole growing season. Fresh dung fragmentation failed to quickly increase vegetation above- and belowground biomass, while the ODP-S treatment exhibited significantly increased vegetation biomass at the end of growing season. This might attribute to plants in alpine steppe ecosystem had different nitrogen absorption preference, and dung fragmentation increase NH4+-N leaching but decrease NO3--N leaching into soil failed to quickly promote vegetation growth, implying NO3--N was probably the key factor that would control vegetation growth demands. In contrast, original yak dung patch prolonged the time in increasing vegetation biomass.(4) Patch fragmentation increase dung N2O and CO2 emission, but significantly decrease CH4 emission. Cumulative N2O emission at ODP treatment (-29.2 g N2O-N/ha) significantly lower (P< 0.05) than that at FDP, EDP and SDP treatments (40.3, 24.0 and 25.9 g N2O-N/ha), while the CH4 emission at ODP treatment (685 g CH4-C/ha) significantly greater (P< 0.05) than that at the corresponding fragmented treatments (231, 271 and 357 g CH4-C/ha). The orginal dung that was fragmentized into four small pats probably had the suitable conditions for organic C mineralization and microorganism anaerobic denitrification and therefore significantly promoted dung N2O and CO2 emission.(5) Yak dung application increase alpine steppe soil N2O, CH4 and CO2 emission, and the fluxes related to the size of patches. Original dung patch and fragmentize it into four small pats siginificantly increased (P< 0.05) cumulative N2O emission (50.4 and 58.9 g N/ha) compared to the control, while the enlarge of fragmentation on the basis of four pats had no marked impacts on soil N2O emission. By contrast, The return of typical dung patch increase CH4 emission and significantly decrease (P< 0.05) the ability of CH4 absorption for steppe soil. Generally, yak dung fragmentation, for instance, fragmented from original status to four small pats could increase the N2O and CO2 emission factors, while once the fragmentation occurrence the CH4 emission factor would significantly decreased. These findings will help to understand the variation of GHG components during the emission processes that derived from yak dung fragmentation in the alpine steppe ecosystem under the condition of climate change, and will provide theoretical references for the scientifical management of yak dung patches. 
Pages129
Language中文
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/24599
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
First Author Affilication中国科学院水利部成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
杜子银. 牦牛粪便碎化对藏北高寒草原土壤温室气体排放影响研究[D]. 北京. 中国科学院大学,2017.
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