松嫩草地地下净生产力和细根动态对不同的管理实践的响应

发布时间：2018-04-25 16:59

本文选题：松嫩草地 + 地下净生产力(BNPP)　；参考：《东北师范大学》2016年博士论文

【摘要】：草地生态系统作为重要的地下碳储存库,在地球上广泛分布着。地下碳存储是草地生态系统碳循环以及分配的核心部分。了解草地中地下碳过程(尤其是根周转过程)可以帮助我们更好地认识陆地生态系统的碳循环。然而,大面积草地由于自然因素以及人类过度开垦、刈割、放牧以及农场管理方式等人为因素而受到严重破坏。在中国,过度开垦导致的草地退化已经成为严重的环境生态问题,退化草地的恢复显得十分紧迫。为此,有必要考虑地下部分对不同草地管理措施的响应,以及考虑这些措施对植物整体恢复效果(包括地上和地下部分)。松嫩草地作为中国的主要草地,位于吉林省,是一个典型的草甸草原。目前关于不同草地管理措施,尤其是枯落物播种、耕作、地上生物量割取等措施对地下净初级生产力(BNPP)、地下生物量分配率(f_(BNPP))、细根动态(根生产、根死亡、现存量以及根周转)和细根寿命的影响研究还未见报道。因此,研究不同草地管理措施对BNPP、f_(BNPP)、细根动态、根寿命的影响能增强人们对松嫩草地地下生态过程的了解,研究结果可填补和丰富该领域研究空白。此外,结合地上、地下生物量数据,能够评估不同草地管理措施对松嫩草地恢复的效果,为合理的开发以及有效的恢复草地生态系统提供科学依据。为了研究不同草地管理措施对BNPP、f_(BNPP)、根生产、死亡、周转以及细根寿命的影响,于2012-2014年选择二处主要样地,采用不同的生态管理措施,样地1：枯落物与播种结合样地。措施包括向退化的弃耕地中分别添加不同量的枯落物(0g m~(-2),200 gm~(-2),400 g m~(-2)和600 g m~(-2)),然后随机分隔成播种和未播种两种处理。每个处理中设置4个子处理：未播种的保留枯落物(NSKL);未播种的去除枯落物(NSML);播种的保留枯落物(SKL)；播种的去除枯落物(SML)。样地2：对退化草地采用7种不同的管理措施：玉米耕作(MT)、玉米免耕并保持残留(MNTKR)、玉米免耕并去除残留(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,为了了解退化的弃耕地在自然植被恢复阶段物种分布格局与土壤盐分梯度的关系,选取3处代表性的植被斑块,分析土壤电导率(EC)、土壤pH、土壤有机质(SOM)以及土壤氮(N)与植被分布的对应关系。根据斑块不同的外观情况和物种分布,将取样斑块分为中心区(CS)、中间区(MS)和外围区(OS)进行取样。在农业耕地、人工草地、天然草地和枯落物管理样地的3年研究期间,土壤含水量有明显的季节性动态变化,且在植物生长季达到峰值。由于2012年降水较丰富,BNPP在2012年高于2013年和2014年。在枯落物和播种管理样地,BNPP为53-301 gm~(-2),播种管理主要通过提高羊草(Leymus chinensis)产量,使BNPP提高了34%。相比于未播种处理,播种处理下去除每年的枯落物对BNPP的提高更明显,尤其是在2012年和2014年。播种处理下,相比于保留枯落物,BNPP在去除每年枯落物处理下提高了18.19%,表明播种和去除每年枯落物增强了对BNPP的影响。同样,玉米和草地管理样地的BNPP为220-1331 g m~(-2),而且玉米管理的高于人工和自然草地管理。耕作和去除枯落物显著提高了BNPPL。然而,由于当地牧草物种(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。与BNPP类似,枯落物和播种管理样地中f_(BNPP)为0.28-0.42,且由于地下生物量分配的提高,f_(BNPP)随着枯落物量的增加而增加,进而提高全球碳封存。此外,在玉米、人工草地和天然草地管理样地,f_(BNPP)为0.25-0.54,且在2014年显著地高于2012、2013年。特别的是,在自然草地管理下,去除枯落物提高了f_(BNPP),这可能是由于干旱导致更多的生物量向地下分配。细根动态(根生产、死亡、现存量和根周转)贯穿于植物的整个生长季,且在土壤0-10cm层和10-20cm层的细根动态随着时间波动,与土壤含水量密切相关,峰值出现在7月和9月。土壤表层20cm根周转率为1.9-2.9 yr~(-1),且在人工草地和自然草地中,去除枯落物显著提高了根的周转率。此外,不同处理的根寿命存在显著差异,0-10cm土层和10-20cm土层的中位寿命分别在364-785天和380-786天,且差异在去除枯落物处理下更显著。通过调查物种分布格局与土壤盐分梯度的相关关系得到,与土壤EC相反,SOM从中央到外围区域都显著提高。地上生物量和物种分布格局均与SOM显著相关,这与土壤EC形成对比。在中心部分,一年生物种地肤(Kochia scoparia (L.) Schrad)占总生物量的90%以上,然而作为外围区域最占优势的多年生物种羊草(Leymus chinensis (Trin.) Tzvel)和芦苇(Phragmites australis (Cav.) Trin. ex Steud)的生物量占总生物量的90%以上。在中间部分,大多数物种能够很好地共存,多年生物种体现出从相邻植物种间关系获利。总结而言,我们的结果表明结合枯落物和播种,去除枯落物,耕作实践可提高BNPP,细根动态和寿命,进而会提高全球C存储。因此,对将来模拟预测气候与碳的反馈具有重要借鉴价值。可持续且有效的草地恢复意味着地上、地下生产力的提高,相关人员应考虑利用目前研究的方法措施来开展恢复,并通过制订提高草地生产力的协议呈现恰当的选择。此外,由于植被对土壤生物化学参数响应敏感,对这一区域的恢复研究应重在提高SOM含量,减小盐分胁迫,恢复顶级物种群落。因此,建议今后的研究应考虑可降低土壤盐分和pH值,以及提高SOM和N含量的技术方法来实现松嫩草地弃耕地的持续、有效的恢复。
[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.

【学位授予单位】：东北师范大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S812

【参考文献】