Biospheric primary production during an ENSO transition

The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) provides global monthly measurements of both oceanic phytoplankton chlorophyll biomass and light harvesting by land plants. These measurements allowed the comparison of simultaneous ocean and land net primary production (NPP) responses to a major El Ni?o to La Ni?a transition. Between September 1997 and August 2000, biospheric NPP varied by 6 petagrams of carbon per year (from 111 to 117 petagrams of carbon per year). Increases in ocean NPP were pronounced in tropical regions where El Ni?o-Southern Oscillation (ENSO) impacts on upwelling and nutrient availability were greatest. Globally, land NPP did not exhibit a clear ENSO response, although regional changes were substantial.     

中国北方森林和草地生态系统碳氮耦合循环与碳源汇效应研究

全球变化自20世纪80年代以来作为一个科学问题开始出现,现今已超越科学领域,成为影响当今世界发展的重大政治、经济和外交问题。在科技部的 “十三五”期间“全球变化及应对”重点研发计划专项支持下,来自中国科学院沈阳应用生态研究所、西北农林科技大学、中国科学院植物研究所等6个单位31位科学家于2016年7月开始承担“中国北方森林和草地生态系统碳氮耦合循环与碳源汇效应研究”项目。该项目旨在:1)凸显中国北方植物群落演替在温室气体吸收和排放平衡,特别是在我国未来碳汇中的作用;2)绘制森林和草地碳源汇转变的敏感区、脆弱区;3)建立和发展稳定同位素技术研究碳氮循环的多时间序列历史变化及其对全球氮沉降、大气CO2浓度上升和气候变化的响应;4)揭示氮沉降、升温、火干扰和植被演替驱动的碳氮耦合循环生物学机制及其碳源汇响应。通过该项目5年的实施,预期能增加我国北方森林和草地生态系统碳氮耦合循环生物学机制的认识,增强对北方森林和草地生态系统对全球变化响应的预测能力和减少预测的不确定性。      

Global warming and marine carbon cycle feedbacks on future atmospheric CO2

A low-order physical-biogeochemical climate model was used to project atmospheric carbon dioxide and global warming for scenarios developed by the Intergovernmental Panel on Climate Change. The North Atlantic thermohaline circulation weakens in all global warming simulations and collapses at high levels of carbon dioxide. Projected changes in the marine carbon cycle have a modest impact on atmospheric carbon dioxide. Compared with the control, atmospheric carbon dioxide increased by 4 percent at year 2100 and 20 percent at year 2500. The reduction in ocean carbon uptake can be mainly explained by sea surface warming. The projected changes of the marine biological cycle compensate the reduction in downward mixing of anthropogenic carbon, except when the North Atlantic thermohaline circulation collapses.     

Primary production of the biosphere: integrating terrestrial and oceanic components

Integrating conceptually similar models of the growth of marine and terrestrial primary producers yielded an estimated global net primary production (NPP) of 104.9 petagrams of carbon per year, with roughly equal contributions from land and oceans. Approaches based on satellite indices of absorbed solar radiation indicate marked heterogeneity in NPP for both land and oceans, reflecting the influence of physical and ecological processes. The spatial and temporal distributions of ocean NPP are consistent with primary limitation by light, nutrients, and temperature. On land, water limitation imposes additional constraints. On land and ocean, progressive changes in NPP can result in altered carbon storage, although contrasts in mechanisms of carbon storage and rates of organic matter turnover result in a range of relations between carbon storage and changes in NPP.     

陆地生态系统土壤呼吸研究进展

陆地土壤呼吸是碳从土壤进入大气的主要途径,与全球变化密切相关。土壤呼吸具有明显的季节和日变化动态,其季节动态与温度变化特征密切相关,还与各个地区降水量的变化趋势有关,一年中一般在7～8月份达到最高值,以后逐渐下降,从11月～翌年4月份最低且相对稳定。土壤呼吸的日变化与温度尤其是表层5～20cm地温的日变化相一致,表现为上午明显高于下午,而在早晨和傍晚时较低。不同生态系统的土壤呼吸作用存在很大的差别。一般地,森林土壤>农田土壤>草地。影响土壤呼吸的因素很多,除了土壤的通透性等物理特性和土壤微生物特征外,气温、土温、湿度、大气CO2浓度、土壤无机养分和有机质的含量与组成等都会影响土壤呼吸。大多数情况下,土壤呼吸速率是土壤一定深度地温或土壤含水量的函数。土壤呼吸随CO2浓度的升高而加强。施有机肥、N沉降和灌溉通常会使土壤呼吸增强;而施加矿质肥对土壤呼吸的影响不明显。     

气候变化对北京山区华北落叶松林NPP影响研究

应用BIOME-BGC模型模拟估算了1974—2010年间北京百花山华北落叶松林的净初级生产力(NPP),并分析了不同CO2浓度和气候变化情景对NPP的影响。结果表明:模型模拟出的NPP总体上高于样地实际的测定值,平均值相差范围为-13.61%～23.55%,表现出数值的波浪形年际变化,年际变动率达4.65%;相对于温度变化,降水量是控制华北落叶松林NPP年际变化的主要气候因子;华北落叶松林NPP对单独的CO2浓度加倍、降水增加表现出正向响应,而单独的温度增加不利于华北落叶松林NPP的积累;CO2浓度加倍、降水增加和温度增加三因子共同作用有促进华北落叶松NPP增加的作用,各因子之间表现出较强的交互作用。     

北京房山区8月份净第一性生产力变化分析

净第一性生产力是评价地表植被状况的重要指标之一,对分析和评价全球和区域生态环境、碳循环等变化具有重要作用.该文借助在CASA模型机理以及区域太阳辐射估算模型基础上建立的区域净第一性生产力估算模型,以房山区为例,分析了北京市郊区19922、001、2004年3年间8月份净第一性生产力的变化.分析结果表明,研究区3年间8月份的NPP分别为152.01、142.83、96.32 g/(m2.月);由于受到各种因素的影响,3年间8月份NPP结构构成不同,1992和2001年均以较高产区的NPP产量最高,其次是高产区和中产区,而2004年则以中产区的NPP产量最高,其次是高产区和低产区,而较高产区的NPP产量最低;1992和2001年各产量水平区的NPP总量在全区NPP总量中的比重,随NPP分区产量水平的提高而逐步提高,较高产区的NPP产量比重分别为:1992年42.26%,2001年37.54%;2004年各产量水平区所占比重变化较大,以中产区最高,占全区NPP总量的42.39%,其次是高产区和低产区,而以较高产区的NPP产量比重最低;通过逐步回归分析可知,在影响研究区NPP变化的各气候因素中,以平均风速、降雨量和实际日照时数影响最为显著,其中尤以降雨量的影响最大.     

South asian summer monsoon variability in a model with doubled atmospheric carbon dioxide concentration

Doubled atmospheric carbon dioxide concentration in a global coupled ocean-atmosphere climate model produced increased surface temperatures and evaporation and greater mean precipitation in the south Asian summer monsoon region. As a partial consequence, interannual variability of area-averaged monsoon rainfall was enhanced. Consistent with the climate sensitivity results from the model, observations showed a trend of increased interannual variability of Indian monsoon precipitation associated with warmer land and ocean temperatures in the monsoon region.     

氮、水交互对长白山阔叶红松林细根形态及生产量的影响

土壤养分和水分的变化深刻影响着森林生态系统的碳分配,进而影响树木细根形态结构和生产量。本文以我国长白山阔叶红松林为研究对象,研究氮沉降增加(50 kg/(hm·a))和降雨量减少(30%穿透雨,约210 mm/a)情形下,细根形态结构和生产量的时空响应特征。结果表明,细根形态结构和生产量受多种因素(处理、取样时间、取样层次)的共同影响。施氮样地(N)显著降低了0~10 cm土壤层细根直径,从而增加了比根长, 减少降雨样地(D)细根根长密度增加了1.55~3.24倍,细根生产量增加了104 g/(m·a), 减少降雨同时施氮样地(DN)10~20 cm土壤层细根直径和生产量显著增加。因此,长白山阔叶红松林不同土壤层细根在氮和水分吸收功能上可能存在分化,氮沉降增加、降雨格局变化及其交互作用在不同程度上驱动着细根形态和生产量的时空变化。      

石河子绿洲植被净第一性生产力遥感估算研究

[目的]探索适合西北绿洲区的NPP遥感模型,估算石河子绿洲区植被净第一性生产力.[方法]在GIS的支持下,利用卫星遥感数据和气象数据,以光能利用率模型为基础进行研究.[结果]构建了绿洲区植被净第一性生产力NPP估算模型,以1989～2001年的石河子绿洲区植被为例,对13年间的植被净初级生产力进行了估算,得到石河子绿洲区植被净第一性生产力13年平均值为2.086 TgC/a,其年均变化量为0.049 TgC/a,绿洲植被碳密度在237.3～309.3 gC/m2变化.[结论]研究时段内NPP总体呈现增长的趋势,这主要是近年来该区降水、气温以及土地利用方式改变的影响结果.     

Advances on the Responses of Root Dynamics to Increased Atmospheric CO2 and Global Climate Change

Plant roots dynamics responses to elevated atmospheric CO2 concentration, increased temperature and changed precipitation can be a key link between plant growth and long-term changes in soil organic matter and ecosystem carbon balance. This paper reviews some experiments and hypotheses developed in this area, which mainly include plant fine roots growth, root turnover, root respiration and other root dynamics responses to elevated CO2 and global climate change. Some recent new methods of studying root systems were also discussed and summarized. It holds herein that the assemblage of information about root turnover patterns, root respiration and other dynamic responses to elevated atmospheric CO2 and global climatic change can help to better understand and explore some new research areas. In this paper, some research challenges in the plant root responses to the elevated CO2 and other environmental factors during global climate change were also demonstrated.     

Efficient atmospheric cleansing of oxidized organic trace gases by vegetation

The biosphere is the major source and sink of nonmethane volatile organic compounds (VOCs) in the atmosphere. Gas-phase chemical reactions initiate the removal of these compounds from the atmosphere, which ultimately proceeds via deposition at the surface or direct oxidation to carbon monoxide or carbon dioxide. We performed ecosystem-scale flux measurements that show that the removal of oxygenated VOC via dry deposition is substantially larger than is currently assumed for deciduous ecosystems. Laboratory experiments indicate efficient enzymatic conversion and potential up-regulation of various stress-related genes, leading to enhanced uptake rates as a response to ozone and methyl vinyl ketone exposure or mechanical wounding. A revised scheme for the uptake of oxygenated VOCs, incorporated into a global chemistry-transport model, predicts appreciable regional changes in annual dry deposition fluxes.     

Global biodiversity scenarios for the year 2100

Scenarios of changes in biodiversity for the year 2100 can now be developed based on scenarios of changes in atmospheric carbon dioxide, climate, vegetation, and land use and the known sensitivity of biodiversity to these changes. This study identified a ranking of the importance of drivers of change, a ranking of the biomes with respect to expected changes, and the major sources of uncertainties. For terrestrial ecosystems, land-use change probably will have the largest effect, followed by climate change, nitrogen deposition, biotic exchange, and elevated carbon dioxide concentration. For freshwater ecosystems, biotic exchange is much more important. Mediterranean climate and grassland ecosystems likely will experience the greatest proportional change in biodiversity because of the substantial influence of all drivers of biodiversity change. Northern temperate ecosystems are estimated to experience the least biodiversity change because major land-use change has already occurred. Plausible changes in biodiversity in other biomes depend on interactions among the causes of biodiversity change. These interactions represent one of the largest uncertainties in projections of future biodiversity change.     

全球气候变化下中国农田土壤碳库未来变化

农田土壤碳库对缓解气候变化、保证粮食安全具有重要作用。日益加剧的气候变化对农田土壤有机碳库演变的潜在影响受到广泛关注。全球气候变化所带来的温度、降雨和大气二氧化碳（CO₂）浓度的改变,会通过影响净初级生产力（NPP）、外源碳投入和有机碳分解速率等因素改变生态系统碳循环过程。另外,气候变化也会通过改变土地利用方式和种植制度等农业措施改变生态系统碳循环。综述国内外农田土壤碳库演变对气候变化影响的研究成果表明,到21世纪末,中国气温将会升高3.9-6.0℃,降水有望增加9%-11%。至2050年,气温和降水的变化会造成中国农田系统碳投入相比1980年降低2.3%-10%（小麦、玉米和水稻平均值）。相反,在综合考虑CO₂浓度升高的协同作用后,2050年中国农田系统碳投入相比1990年前将会增加13%-22%（平均年增长率0.2%-0.4%）。模型预测显示,至2020、2050和2080年,中国旱地0-30 cm土层有机碳在CO₂低排放情景下分别会损失2.7、6.0和 7.8 tC·hm^-2,在CO₂高排放情景下分别会损失2.9、6.8和8.2 tC·hm^-2,大概占1980年农田土壤碳的4.5%、10.5%和12.7%。综合碳投入和排放对农田土壤碳库的整体影响来看,21世纪末期中国农田土壤有机碳库含量较1980年会下降10%左右,但如果采取相应的管理措施,可有效抑制农田土壤碳库的降低甚至提高,如农田系统碳投入以每年1%的速度增加时,土壤碳库会在21世纪末增加两倍。目前的研究结果显示,气候变化是否会强烈影响农田土壤碳库依然有很大的不确定因素,其对固碳效应正面和负面影响相互抵消后成为碳源还是碳汇说法不一。因此,在采取缓解气候变化、增加农田土壤固碳的措施的同时,还需加强农田土壤碳库未来变化趋势的研究和探索,为中国政策框架的决定以及未来气候变化谈判提供可靠的科学依据。     

氮沉降对森林土壤有机质和凋落物分解的影响及其微生物学机制

氮沉降持续增加背景下土壤C∶N∶P化学计量比和pH环境等的改变及其可能的土壤微生物学机制已经成为陆地生态系统与全球变化研究的新生长点和科学研究前沿.以生态化学计量学和土壤微生物生态学为理论基础,综述了氮沉降对森林土壤有机质和凋落物分解的影响及其微生物学机制的基本理论、最新进展、研究热点与难点,旨在促进全球变化背景下陆地生态系统地下生态学的研究.氮沉降持续增加会导致森林生态系统磷循环加速,导致磷限制.氮沉降不但改变森林土壤有机质和凋落物的C∶N∶P化学计量比和降低土壤pH值,而且改变土壤微生物生物量碳氮磷、细菌、真菌和放线菌的组成以及影响碳氮磷分解的关键酶活性.氮沉降对森林土壤有机质和凋落物分解的影响表现为促进、抑制和无影响,其影响的差异可能来源于微生物效应的不同.叶片在凋落前有显著的氮磷养分回收,但是根无明显的养分回收,造成土壤有机质和凋落物的C∶N∶P化学计量比存在明显差异.基于DNA/RNA等分子生物学方法为土壤微生物生态学研究提供了强有力的手段,将促进氮沉降对森林土壤有机质和凋落物化学计量比改变的微生物学机制研究.     

基于Biome-BGC模型的千烟洲森林水分利用效率研究

目的为了探究全球气候变化背景下森林生态系统水分利用效率的影响因子及其对气候变化的响应。方法本文利用经PEST模型参数优化后的Biome-BGC模型,对千烟洲森林生态系统2000—2014（CK）年以及不同气候情景变化模式下的水分利用效率及其影响因子进行了探究。结果（1）千烟洲的年均温和最大叶面积指数同水分利用效率呈显著正相关关系（P < 0.01）,降水同水分利用效率间的相关性不显著（P > 0.05）。（2）千烟洲不同情景模式水分利用效率的取值区间是2.09 ~ 3.71 g/kg、均值2.90 g/kg。（3）同CK（2.18 ~ 2.57 g/kg、均值2.38 g/kg）相比,千烟洲各情景模式下大气CO₂浓度增加情景（2.38 ~ 3.41 g/kg、均值2.90 g/kg）、降水和大气CO₂浓度同时增加情景（2.38 ~ 3.33 g/kg、均值2.86 g/kg）、气温和大气CO₂浓度同时增加情景（2.58 ~ 3.71 g/kg、均值3.15 g/kg）、降水和气温同时增加（2.30 ~ 2.84 g/kg、均值2.57 g/kg）及降水、气温和大气CO₂浓度同时增加情景（2.70 ~ 3.60 g/kg、均值3.15 g/kg）的水分利用效率差异显著。但是,降水增加情景（2.09 ~ 2.68 g/kg、均值2.39 g/kg）和气温增加情景（2.13 ~ 2.81 g/kg、均值2.47 g/kg）对水分利用效率的影响不显著。（4）降水和大气CO₂浓度同时增加情景与大气CO₂浓度增加情景的水分利用效率差异不显著,气温和大气CO₂浓度同时增加情景与大气CO₂浓度增加情景的水分利用效率差异显著。结论（1）千烟洲森林生态系统的水分利用效率受到气温和叶面积指数的影响,情景分析表明水分利用效率能很好的对气候变化做出响应。（2）降水、气温和大气CO₂浓度对水分利用效率的影响存在耦合效应。（3）增温对水分利用效率的影响要大于降水。      

青藏高原氮沉降研究现状及草地生态系统响应研究进展

为了解青藏高原氮沉降的时空差异特征及对高原生态系统的影响,对青藏高原不同区域大气活性氮沉降定量研究的相关结果进行总结分析,对大气活性氮沉降对草地生态系统的影响并与青藏高原现阶段相关研究进行综述与比较。研究表明:青藏高原氮沉降通量定量研究较少,且局限于短期监测或仅定量雨水活性氮含量,长期性的定点原位监测、大气活性氮的组成特征、城乡差异及变化趋势均未见报道;同时,大气氮沉降对青藏高原草地生态系统植物多样性的影响,植物化学计量特征变化趋势及物候相应等均报道较少,仅局限于现象的解释,并未对变化机理进行阐述。氮沉降作为全球变化的主要驱动因子,青藏高原氮沉降通量及其对生态环境的影响有待进一步加强。     

小麦籽粒氨基酸碳氮稳定同位素的测定与分析

 【目的】利用气相色谱-燃烧-同位素比值质谱仪（gas chromatography-combustion-isotope ratio mass spectrometry,GC-C-IRMS）测定小麦籽粒氨基酸碳氮稳定同位素组成。【方法】以小麦临汾50744为材料,水解得到其籽粒蛋白质氨基酸,将氨基酸标准样品以及小麦籽粒氨基酸衍生化为N-新戊酰基,O-异丙醇（N-pivaloyl-isopropyl,NPP）氨基酸酯,利用GC-C-IRMS测定其碳氮稳定同位素组成。【结果】氨基酸标准样品的碳氮同位素组成分析表明,NPP氨基酸酯的平均重现性δ13C为0.47‰,δ15N为0.28‰,并没有产生大的同位素分馏,因此δ13C和δ15N都能得到满意的测定结果。运用GC-C-IRMS测定了小麦临汾50744籽粒蛋白质氨基酸的稳定碳氮同位素的自然丰度,其中δ13C的变化范围在-28.7‰到-34.7‰,δ15N的变化范围为-6.2‰到9.5‰。采用系统聚类分析进行分类,根据δ13C可以将氨基酸分为两类;根据δ15N可以将氨基酸分为三类。【结论】运用GC-C-IRMS结合NPP氨基酸酯衍生物可以测定小麦籽粒氨基酸的稳定碳氮同位素,这对于揭示氨基酸代谢途径的差异以及逆境胁迫下氨基酸的合成差异具有重要的意义。     

Increasing atmospheric carbon dioxide: tree ring evidence for growth enhancement in natural vegetation

A response of plant growth to increased atmospheric carbon dioxide, which has been anticipated from laboratory data, may now have been detected in the annual rings of subalpine conifers growing in the western United States. Experimental evidence shows that carbon dioxide can be an important limiting factor in the growth of plants in this high-altitude environment. The greatly increased tree growth rates observed since the mid-l9th century exceed those expected from climatic trends but are consistent in magnitude with global trends in carbon dioxide, especially in recent decades. If correctly interpreted, these findings have important implications for climate studies involving tree ring observations and for models of the global carbon dioxide budget.     

A neoproterozoic snowball earth

Negative carbon isotope anomalies in carbonate rocks bracketing Neoproterozoic glacial deposits in Namibia, combined with estimates of thermal subsidence history, suggest that biological productivity in the surface ocean collapsed for millions of years. This collapse can be explained by a global glaciation (that is, a snowball Earth), which ended abruptly when subaerial volcanic outgassing raised atmospheric carbon dioxide to about 350 times the modern level. The rapid termination would have resulted in a warming of the snowball Earth to extreme greenhouse conditions. The transfer of atmospheric carbon dioxide to the ocean would result in the rapid precipitation of calcium carbonate in warm surface waters, producing the cap carbonate rocks observed globally.