本文選題：松嫩草地 + 地下凈生產(chǎn)力(BNPP)��； 參考：《東北師范大學》2016年博士論文

【摘要】：草地生態(tài)系統(tǒng)作為重要的地下碳儲存庫,在地球上廣泛分布著。地下碳存儲是草地生態(tài)系統(tǒng)碳循環(huán)以及分配的核心部分。了解草地中地下碳過程(尤其是根周轉(zhuǎn)過程)可以幫助我們更好地認識陸地生態(tài)系統(tǒng)的碳循環(huán)。然而,大面積草地由于自然因素以及人類過度開墾、刈割、放牧以及農(nóng)場管理方式等人為因素而受到嚴重破壞。在中國,過度開墾導致的草地退化已經(jīng)成為嚴重的環(huán)境生態(tài)問題,退化草地的恢復顯得十分緊迫。為此,有必要考慮地下部分對不同草地管理措施的響應,以及考慮這些措施對植物整體恢復效果(包括地上和地下部分)。松嫩草地作為中國的主要草地,位于吉林省,是一個典型的草甸草原。目前關于不同草地管理措施,尤其是枯落物播種、耕作、地上生物量割取等措施對地下凈初級生產(chǎn)力(BNPP)、地下生物量分配率(f_(BNPP))、細根動態(tài)(根生產(chǎn)、根死亡、現(xiàn)存量以及根周轉(zhuǎn))和細根壽命的影響研究還未見報道。因此,研究不同草地管理措施對BNPP、f_(BNPP)、細根動態(tài)、根壽命的影響能增強人們對松嫩草地地下生態(tài)過程的了解,研究結果可填補和豐富該領域研究空白。此外,結合地上、地下生物量數(shù)據(jù),能夠評估不同草地管理措施對松嫩草地恢復的效果,為合理的開發(fā)以及有效的恢復草地生態(tài)系統(tǒng)提供科學依據(jù)。為了研究不同草地管理措施對BNPP、f_(BNPP)、根生產(chǎn)、死亡、周轉(zhuǎn)以及細根壽命的影響,于2012-2014年選擇二處主要樣地,采用不同的生態(tài)管理措施,樣地1：枯落物與播種結合樣地。措施包括向退化的棄耕地中分別添加不同量的枯落物(0g m~(-2),200 gm~(-2),400 g m~(-2)和600 g m~(-2)),然后隨機分隔成播種和未播種兩種處理。每個處理中設置4個子處理：未播種的保留枯落物(NSKL);未播種的去除枯落物(NSML);播種的保留枯落物(SKL)；播種的去除枯落物(SML)。樣地2：對退化草地采用7種不同的管理措施：玉米耕作(MT)、玉米免耕并保持殘留(MNTKR)、玉米免耕并去除殘留(MNTMR)、人工草地未去除枯落物(AGNCL)、人工草地去除枯落物(AGCL)、自然草地未去除枯落物(NGNCL)和自然草地去除枯落物(NGCL)。此外,為了了解退化的棄耕地在自然植被恢復階段物種分布格局與土壤鹽分梯度的關系,選取3處代表性的植被斑塊,分析土壤電導率(EC)、土壤pH、土壤有機質(zhì)(SOM)以及土壤氮(N)與植被分布的對應關系。根據(jù)斑塊不同的外觀情況和物種分布,將取樣斑塊分為中心區(qū)(CS)、中間區(qū)(MS)和外圍區(qū)(OS)進行取樣。在農(nóng)業(yè)耕地、人工草地、天然草地和枯落物管理樣地的3年研究期間,土壤含水量有明顯的季節(jié)性動態(tài)變化,且在植物生長季達到峰值。由于2012年降水較豐富,BNPP在2012年高于2013年和2014年。在枯落物和播種管理樣地,BNPP為53-301 gm~(-2),播種管理主要通過提高羊草(Leymus chinensis)產(chǎn)量,使BNPP提高了34%。相比于未播種處理,播種處理下去除每年的枯落物對BNPP的提高更明顯,尤其是在2012年和2014年。播種處理下,相比于保留枯落物,BNPP在去除每年枯落物處理下提高了18.19%,表明播種和去除每年枯落物增強了對BNPP的影響。同樣,玉米和草地管理樣地的BNPP為220-1331 g m~(-2),而且玉米管理的高于人工和自然草地管理。耕作和去除枯落物顯著提高了BNPPL。然而,由于當?shù)啬敛菸锓N(羊草)的添加,人工草地BNPP(280gm~(-2))相比于自然草地BNPP(240gm~(-2))提高了更多。與BNPP類似,枯落物和播種管理樣地中f_(BNPP)為0.28-0.42,且由于地下生物量分配的提高,f_(BNPP)隨著枯落物量的增加而增加,進而提高全球碳封存。此外,在玉米、人工草地和天然草地管理樣地,f_(BNPP)為0.25-0.54,且在2014年顯著地高于2012、2013年。特別的是,在自然草地管理下,去除枯落物提高了f_(BNPP),這可能是由于干旱導致更多的生物量向地下分配。細根動態(tài)(根生產(chǎn)、死亡、現(xiàn)存量和根周轉(zhuǎn))貫穿于植物的整個生長季,且在土壤0-10cm層和10-20cm層的細根動態(tài)隨著時間波動,與土壤含水量密切相關,峰值出現(xiàn)在7月和9月。土壤表層20cm根周轉(zhuǎn)率為1.9-2.9 yr~(-1),且在人工草地和自然草地中,去除枯落物顯著提高了根的周轉(zhuǎn)率。此外,不同處理的根壽命存在顯著差異,0-10cm土層和10-20cm土層的中位壽命分別在364-785天和380-786天,且差異在去除枯落物處理下更顯著。通過調(diào)查物種分布格局與土壤鹽分梯度的相關關系得到,與土壤EC相反,SOM從中央到外圍區(qū)域都顯著提高。地上生物量和物種分布格局均與SOM顯著相關,這與土壤EC形成對比。在中心部分,一年生物種地膚(Kochia scoparia (L.) Schrad)占總生物量的90%以上,然而作為外圍區(qū)域最占優(yōu)勢的多年生物種羊草(Leymus chinensis (Trin.) Tzvel)和蘆葦(Phragmites australis (Cav.) Trin. ex Steud)的生物量占總生物量的90%以上。在中間部分,大多數(shù)物種能夠很好地共存,多年生物種體現(xiàn)出從相鄰植物種間關系獲利�？偨Y而言,我們的結果表明結合枯落物和播種,去除枯落物,耕作實踐可提高BNPP,細根動態(tài)和壽命,進而會提高全球C存儲。因此,對將來模擬預測氣候與碳的反饋具有重要借鑒價值�？沙掷m(xù)且有效的草地恢復意味著地上、地下生產(chǎn)力的提高,相關人員應考慮利用目前研究的方法措施來開展恢復,并通過制訂提高草地生產(chǎn)力的協(xié)議呈現(xiàn)恰當?shù)倪x擇。此外,由于植被對土壤生物化學參數(shù)響應敏感,對這一區(qū)域的恢復研究應重在提高SOM含量,減小鹽分脅迫,恢復頂級物種群落。因此,建議今后的研究應考慮可降低土壤鹽分和pH值,以及提高SOM和N含量的技術方法來實現(xiàn)松嫩草地棄耕地的持續(xù)、有效的恢復。
[Abstract]:As an important underground carbon repository, grassland ecosystem is widely distributed on the earth. Underground carbon storage is the core part of the carbon cycle and distribution of grassland ecosystem. Understanding the process of underground carbon (especially root turnover) can help us to better understand the carbon cycle of terrestrial ecosystems. Natural factors and human overland reclamation, mowing, grazing and farm management have been severely damaged. In China, grassland degradation caused by overland reclamation has become a serious environmental ecological problem, and the restoration of degraded grassland is very urgent. Therefore, it is necessary to consider the management measures for different grasslands in the underground part. Response and consideration of the overall recovery effect of these measures (including ground and underground). The Songnen grassland, as the main grassland in China, is a typical meadow grassland in Jilin province. At present, measures for different grassland management, especially litter sowing, tillage, and aboveground biomass cutting, are applied to the net primary primary plant. The effects of BNPP, f_ (BNPP), fine root dynamics (root production, root death, existing quantity and root turnover) and fine root life have not yet been reported. Therefore, the study of the effects of different grassland management measures on BNPP, f_ (BNPP), fine root dynamics and root life can enhance people's understanding of the underground ecological process of the Songnen grassland. The results can fill and enrich the research gap in this field. In addition, underground biomass data can assess the effect of different grassland management measures on the restoration of the Songnen grassland, provide a scientific basis for rational development and effective restoration of grassland ecosystem. In order to study the management measures for different grassland, BNPP, f_ (BNPP), root production, The effects of death, turnover and fine root life were selected in two major plots in 2012-2014 years, using different ecological management measures, sample plots 1: litter and sowing binding plots. The measures included adding different amounts of litter (0g m~ (-2), 200 gm~ (-2), 400 g m~ (-2) and 600 g m~ (-2) into degraded abandoned farmland, and then randomly divided into two parts. Two treatments were sowing and not sowing. 4 sub treatments were set in each treatment: NSKL, NSML, non seeded litter (SKL); sowing retention litter (SKL); sowing and dropping litter (SML). Sample plot 2: 7 different management measures for degraded grassland: corn tillage (MT), maize no tillage and residue residue MNTKR, maize no tillage and removal of residual (MNTMR), artificial grassland did not remove litter (AGNCL), artificial grassland was removed from litter (AGCL), natural grassland did not remove litter (NGNCL) and natural grassland to remove litter (NGCL). In addition, in order to understand the species distribution pattern and soil salinity gradient in the natural vegetation recovery stage of degraded land. Relationship, select 3 representative vegetation patches, analyze the corresponding relationship between soil conductivity (EC), soil pH, soil organic matter (SOM) and soil nitrogen (N) and vegetation distribution. According to the different appearance and species distribution of the plaque, the sampling patches are divided into central region (CS), the middle region (MS) and the peripheral region (OS) are sampled. In agricultural land, artificial grass During the 3 year study of natural grassland and litter management plots, the soil moisture content had obvious seasonal dynamic changes and reached the peak in the plant growth season. Due to the rich precipitation in 2012, BNPP was higher in 2012 than 2013 and 2014. In the litter and sowing management plots, BNPP was 53-301 gm~ (-2), and sowing management mainly through raising sheep. The yield of Leymus chinensis makes the BNPP increase 34%. compared to the non sowing treatment. The removal of BNPP is more obvious by removing the annual litter under sowing treatment, especially in 2012 and 2014. Under sowing treatment, compared to the retention of the litter, BNPP increased by 18.19% under the removal of the litter each year, indicating sowing and removal of the litter each year. The effect on BNPP was enhanced. Similarly, the BNPP of corn and grassland management plots was 220-1331 g m~ (-2), and maize management was higher than artificial and natural grassland management. Cultivation and removal of litter significantly increased BNPPL., however, due to the addition of local herbage species (Leymus chinensis), artificial grassland BNPP (280gm~ (-2)) compared to BNPP (240gm~) of natural grassland (240gm~ (-) 2) increased. Similar to BNPP, f_ (BNPP) was 0.28-0.42 in the litter and sowing management plots, and f_ (BNPP) increased as the amount of litter increased, and then increased global carbon sequestration. In addition, f_ (BNPP) was 0.25-0.54 in corn, artificial grassland and natural grassland, and was significant in 2014. The ground is more than 20122013 years. Especially in natural grassland management, the removal of litter increases f_ (BNPP), which may be due to the drought that causes more biomass to be distributed to the ground. Fine root dynamics (root production, death, existing quantities and root turnover) run through the entire growing season of the plant, along with the fine roots of the soil 0-10cm and 10-20cm layers. The time fluctuation is closely related to the soil water content, the peak value appears in July and September. The turnover rate of 20cm root in the soil surface is 1.9-2.9 yr~ (-1). In the artificial and natural grassland, the removal of litter significantly improves the turnover rate of root. In addition, there are significant differences in the root life of different treatments, and the middle life span of the 0-10cm soil layer and the 10-20cm soil layer. The difference between the 364-785 days and the 380-786 days is more significant. By investigating the relationship between the distribution pattern of the species and the soil salinity gradient, the SOM from the central to the peripheral area is significantly higher than the soil EC. The aboveground biomass and the species distribution pattern are all significantly related to the SOM, which is compared with the soil EC. In the central part, Kochia scoparia (L.) Schrad accounts for more than 90% of the total biomass in a year. However, the biomass of Leymus chinensis (Leymus chinensis (Trin.) Tzvel) and reed (Phragmites australis (Cav.) Trin.) account for more than 90% of the total biomass, which are the most dominant in the peripheral areas. Several species can coexist well, and years of biological species represent a profit from interspecies relationships in adjacent plants. In summary, our results show that the combination of litter and sowing, removal of litter, and cultivation practices can improve BNPP, fine root dynamics and life, and then increase global C storage. Therefore, feedback on climate and carbon simulation is heavy in the future. For reference, sustainable and effective grassland restoration means the improvement of ground productivity and the improvement of underground productivity. The relevant personnel should consider using the current methods and measures to carry out recovery and make appropriate choices by formulating a protocol to improve grassland productivity. In addition, the vegetation is sensitive to the soil biochemical parameters, for this area. The study of domain recovery should focus on increasing the content of SOM, reducing salt stress and restoring the community of top species. Therefore, it is suggested that future research should consider the technical methods that can reduce soil salinity and pH, and improve the content of SOM and N to achieve the sustainable and effective recovery of the abandoned land of the Songnen grassland.

【學位授予單位】：東北師范大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：S812

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