三江平原植被净初级生产力时空变化及其影响因素分析

发布时间：2018-05-06 20:53

本文选题：初级净生产力NPP + 土地利用/覆被变化　；参考：《中国科学院大学(中国科学院东北地理与农业生态研究所)》2017年博士论文

【摘要】：作为全球碳循环中最重要的环节之一,陆地碳循环最复杂,涉及问题也最多。作为最可能的碳源/汇所在地,陆地生态系统已成为目前研究的热点区域,它同时也是目前研究中不确定性最大的生态系统之一。净初级生产力是生态系统可持续性及生态系统功能的重要表征,研究净初级生产力及其对全球变化的响应,在整个陆地生态系统碳循环研究中具有举足轻重的作用。三江平原是我国淡水沼泽湿地分布最为广泛的地区。由于地处中高纬度地区,三江平原对全球气候变化十分敏感。同时,三江平原受人类干扰十分严重:自二十世纪五十年代以来,大量的沼泽湿地被开垦为农田。揭示该区域长时间序列植被净初级生产力时空变化并定量分析各影响因素对植被净初级生产力变化的影响,不仅为区域尺度的全球变化研究提供典型案例,而且对准确地理解碳循环的过程和相关政策的制定具有重要的指导意义。本文以三江平原为研究对象,获取了1950s以来近十期三江平原土地利用/覆被数据,同时获取了1950s以来的三江平原气候变化(气温,降水),大气环境变化(CO2浓度,N沉降等)和土地管理数据(N施肥,灌溉数据等),并据此发展了模型输入数据集。在分析三江平原地理环境要素变化的基础上,构建碳循环驱动因子数据集,利用陆地生态系统动态模型(Dynamic Land Ecosystem Model,DLEM)模拟了气候变化和人类活动双重胁迫下,三江平原陆地生态系统NPP的时空变化。同时,利用单因子实验法定量分析了各影响因子变化对三江平原NPP变化的影响。本文的主要结论如下:(一)在全球变暖大背景下,三江平原1954年至2014年间的年平均气温呈上升趋势,最高年年均温出现在2007年(4.78℃),最低温出现在1969年(1.03℃)。年均最低温的增长速度远远高于年均最高温的增长速度,尤其是1980s以来,年均最低温的增长对三江平原近60年来年平均气温增长的贡献更大。1954-2014年期间,三江平原年均降水量为577.41mm/年。最大年降水量可达810.52mm(1994年),最小降水量达396.94 mm(1976年)。(二)在过去60年间,三江平原土地利用变化比较剧烈:水田、旱地和建设用地面积呈增加趋势,而林地、草地和沼泽大面积下降。在过去60年间,旱地面积增长最大,其次是水田,而沼泽和草地面积下降最为严重。沼泽与草地主要转化为耕地(水田与旱地)。土地利用变化轨迹分析表明人为因素是三江平原土地利用变化的主要驱动力,同时自然因素变化也发挥着一定作用。人类活动在三江平原沼泽湿地变化起主导作用。洛伦兹曲线、基尼系数和土地利用适宜性指数分析表明三江平原的土地利用结构相对合理。研究区生态系统服务价值(ESV)下降比较严重,1980s之后下降趋势减缓。沼泽面积的锐减是ESV下降的主要原因之一。ESV及其结构变化的分析表明:在继续保护林地和沼泽的基础上,决策者还应注意草地的保护与恢复工作以实现可持续发展。(三)在构建1950s以来的DLEM模型碳循环驱动因子数据集的基础上,本文基于站点数据,对DLEM模型进行参数本地化和模型验证,并估算和分析了三江平原1954-2014年间NPP的时空变化。在1950s-2014年间,三江平原植被净初级生产力NPP总量呈现不断上升的趋势,年均值由1950s的43.8 Tg Cyr~(-1)的上升到2010s的48.0 Tg Cyr~(-1)。此外,本文对三江平原沼泽湿地区(包括沼泽及已转化为其他土地利用类型的原沼泽区域)的NPP进行了分析:在研究时间段内NPP总量的年均值由1950s的28.7 Tg Cyr~(-1)的上升到2010s的30.8Tg Cyr~(-1)。(四)通过设置“单因子试验”,本文对各影响因子对过去60年三江平原NPP变化的影响进行定量分析。结果表明:在过去的60年间,气候变化因素对三江平原NPP增长的促进作用最大,其次是N沉降的变化和CO2浓度的变化。土地利用/覆被变化大大降低了研究区NPP的增长。同时,本文还对不同时期各因子的贡献率进行分析。结果表明:1950s,1980s,1990s,2000s,2010s对三江平原NPP增长贡献率最大的是气候变化,而在1960s和1970s氮沉降变化对NPP变化的贡献率最大。在1960s-2000s期间,土地利用/覆被变化对三江平原NPP的增长为负效应。分离气温变化与降雨变化的试验表明:降雨变化对研究区NPP变化的影响大于气温变化。(五)在过去的60年间,三江平原氮沉降呈现逐步增长的趋势,NHx_N增长的速度远远大于Noy_N。三江平原氮沉降的增长主要源于NHx_N的增长;同时,三江平原氮施肥量在过去的60年间不断增加。在1954-2014年间,三江平原氮沉降与氮施肥的增加均促进了研究区NPP的增长。研究区CO2浓度呈现不断增长的趋势,并在过去60年间促进了研究区NPP的增长。
[Abstract]:As one of the most important links in the global carbon cycle, the land carbon cycle is the most complex and most involved. As the most likely source of carbon source / sink, the terrestrial ecosystem has become a hot area of current research. It is also one of the most uncertain ecosystems in the present study. The net primary productivity is an ecological system. The important characterization of sustainability and ecosystem function, the study of net primary productivity and its response to global changes play an important role in the study of carbon cycle in the whole terrestrial ecosystem. The Sanjiang plain is the most widely distributed freshwater marsh in China. The Sanjiang plain is in the middle and high latitudes to the global climate change. At the same time, the Sanjiang plain is seriously disturbed by human beings. Since 1950s, a large number of marshes have been reclaimed as farmland. The spatial and temporal changes in net primary productivity of vegetation in this region are revealed and the effects of various factors on the changes of net primary productivity of vegetation are quantitatively analyzed, not only for regional scale. The study of global change provides typical cases, and has important guiding significance for the accurate understanding of the process of carbon cycle and the formulation of relevant policies. In this paper, the land use / cover data of nearly ten periods of Sanjiang Plain since 1950s were obtained, and the climate change of the Sanjiang Plain since 1950s (temperature, temperature, Precipitation), the change of atmospheric environment (CO2 concentration, N settlement, and so on) and land management data (N fertilization, irrigation data etc.), and then developed the model input data set. Based on the analysis of the changes in the geographical environment factors of Sanjiang plain, the data set of the carbon cycle driving factor is constructed, and the land ecosystem dynamic model (Dynamic Land Ecosystem Model, DLE) is used. M) simulated the spatio-temporal changes of the terrestrial ecosystem NPP in the Sanjiang plain under the dual coercion of climate change and human activity. At the same time, the influence of the change of the influence factors on the changes of the NPP in the Sanjiang plain was quantitatively analyzed by the single factor experiment method. The main conclusions of this paper are as follows: (1) from 1954 to 2014 of Sanjiang plain in the background of global warming. The annual average temperature showed an upward trend, the highest annual average temperature appeared in 2007 (4.78 degrees C) and the lowest temperature appeared in 1969 (1.03 degrees C). The annual average temperature growth rate was far higher than the average annual maximum temperature, especially since 1980s, the annual average temperature increase contributed to the average annual temperature growth of Sanjiang plain for 60 years more.1954- During 2014, the annual average precipitation in Sanjiang plain was 577.41mm/ years. The maximum annual precipitation could reach 810.52mm (1994), the minimum precipitation was 396.94 mm (1976). (two) in the past 60 years, the land use changes in the Sanjiang plain were more severe: the paddy field, the dry land and the construction ground have increased, while the woodlands, grassland and swamps have fallen in large areas. During the last 60 years, the area of dry land increased most, followed by the paddy field, and the area of swamps and meadows decreased most seriously. The swamps and meadows were mainly converted into cultivated land (paddy fields and dryland). The analysis of the change of land use changes showed that human factors were the main driving force of land use change in Sanjiang plain, while the change of natural factors also played a certain role. The Lorenz curve, Gini coefficient and land use suitability index show that the land use structure of the Sanjiang plain is relatively reasonable. The ecosystem service value (ESV) of the study area is relatively serious, and the decline trend after 1980s is slowed down. The sharp decrease of the marsh area is ESV decline. One of the main reasons,.ESV and its structural changes, shows that on the basis of continuing protection of woodland and swamps, decision-makers should also pay attention to the conservation and recovery of grassland to achieve sustainable development. (three) based on the data set of the carbon cycle driving factor of the DLEM model since the construction of 1950s, this paper is based on the site data, and the DLEM model is based on the site data. The spatio-temporal changes of NPP in the Sanjiang plain during 1954-2014 years were estimated and analyzed. During 1950s-2014, the net primary productivity of the vegetation in the Sanjiang plain showed a rising trend, the annual average value increased from 43.8 Tg C? Yr~ (-1) to 2010s 48 Tg C? Yr~. In addition, this paper was flat to Sanjiang. The NPP of the original swamp wet areas (including swamps and the original swamps that have been converted to other land use types) has been analyzed: the annual average value of the total NPP in the period of study is increased from 28.7 Tg C? Yr~ (-1) to 2010s's 30.8Tg C? Yr~ (-1). (four) by setting a "single factor test", the impact factors of the past 60 years are three The quantitative analysis of the influence of Jiangping original NPP change shows that in the past 60 years, climate change factors have the greatest promotion effect on the growth of NPP in Sanjiang plain, followed by the change of N settlement and the change of CO2 concentration. The land use / cover change greatly reduces the growth of NPP in the study area. Meanwhile, this paper also gives tribute to the various factors in different periods. The results showed that the largest contribution of 1950s, 1980s, 1990s, 2000s, 2010s to the NPP growth in Sanjiang plain was climate change, while the contribution rate of 1960s and 1970s to the variation of NPP was the largest. During the 1960s-2000s, the land use / cover change was negative to the growth of NPP in the Sanjiang plain. The change test showed that the influence of rainfall on the change of NPP in the study area was greater than the temperature change. (five) in the past 60 years, the nitrogen deposition in the Sanjiang plain showed a gradual increase trend, and the growth rate of NHx_N was far greater than the growth of nitrogen deposition in the Sanjiang plain of Noy_N.. At the same time, the nitrogen fertilization rate in the Sanjiang plain was 60 in the past. During the 1954-2014 years, the increase in nitrogen deposition and nitrogen fertilization in the Sanjiang plain both promoted the growth of NPP in the research area. The CO2 concentration in the study area showed a growing trend and promoted the growth of NPP in the research area over the past 60 years.

【学位授予单位】：中国科学院大学(中国科学院东北地理与农业生态研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：Q948

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