大气中O3与CO2浓度升高对植物影响研究进展

由于工业的快速发展,大气中的O₃和CO₂浓度有逐年上升的趋势,对植物产生了很大的影响。目前,植物对O₃和CO₂浓度变化的复合作用的响应机制研究已经成为生态学研究的热点问题。文中阐述了O₃和CO₂浓度升高及其复合作用对植物的形态特征、光合作用、抗氧化系统及生物量等生理生化机制的影响,指出目前研究中存在并有待进一步研究的问题,以期为进一步开展高浓度O₃和CO₂对植物生理生态学影响研究提供科学参考和理论依据。     

大气CO2浓度增加对不同层次生物组织结构与功能的可能影响

本文系统地综述了国际上开展与全球气候变化有关的大气CO₂浓度增加对植物和生态系统影响研究的实验技术方法和细胞、叶片和个体水平对CO₂反应的最新研究成果,人工气候模拟装置和测定技术;大气CO₂浓度增加对细胞、叶片及个体植物生长的影响;主要的研究结论。     

全球[CO2]变化与植物水分关系

业已发现增加环境[CO₂]可以改善大多数植物的水分胁迫。许多研究结果表明,较低的蒸腾速率（Tr）与[CO₂]增加导致气孔关闭有关。由于[CO₂]增加引起蒸腾速率的下降和净光合速率（Pn）的提高,因此,生长在高于环境[CO₂]下的植物常常能够保持较高的水分利用效率（WUE）.也发现生长在高于环境[CO₂]下的植物能够保持较高的总水势（Ψ）,增加叶面积和生物量,有较大的根/茎比率（R/S）,因而通常比生长在正常环境[CO₂]下的植物更耐干旱。[CO₂]增加诱导产生的植物结构的变化（比如导管或管胞的解剖结构、叶比导度等）,可能与木质部空穴脆弱性的变化有关,也可能与栓塞逃逸的环境条件相联系。这些重要的问题需要进一步的研究。     

CO2浓度升高处理下宁夏枸杞糖代谢相关酶及基因表达分析

【目的】探究CO₂浓度升高对宁夏枸杞果实发育过程中碳水化合物积累的影响,为揭示枸杞果实品质形成对气候变化的响应提供参考。【方法】以宁夏枸杞‘宁杞1号’为试验材料,采用开顶气室模拟控制系统进行CO₂浓度升高处理(800±20μmol·mol^-1),以自然环境CO₂浓度(400±20μmol·mol^-1)为对照,处理60天后收集幼果期、青果期、转色期、红果期的根、茎、叶和果实样品,测定其糖组分含量及糖代谢相关酶活性和基因表达。【结果】1) CO₂浓度升高处理可促进果实发育过程中半乳糖、蔗糖和总糖的积累,红果期半乳糖、果糖、蔗糖、总糖含量较对照分别提升35.71%、23.18%、19.57%和12.23%(P<0.05)。2) CO₂浓度升高处理下,宁夏枸杞发育期根、茎、叶和果实组织中苹果酸合成酶(LbMS)、中性转化酶(LbAI)、蔗糖磷酸合成酶(LbSPS)及蔗糖合成酶(LbSS)活性均显著升高(P<0.05),α-半乳糖苷...     

群众杨幼苗叶光合特性与碳氮分配对CO2浓度和气温升高的响应

【目的】研究杨树光合作用和碳氮分配对CO₂浓度和温度升高的响应，探讨气候变化下杨树的生理生态适应机制，以期为我国北方杨树人工林生产力和生态效益的长期提升提供理论依据。【方法】以盆栽群众杨当年生扦插幼苗为试验材料，在开顶式生长室内模拟研究了空气CO₂浓度和气温升高(分别比室外大气升高200μmol mol^-1和2℃)及其共同作用下的功能叶光合特性、叶解剖结构、器官间干物质和碳氮分配的响应，并探讨了苗期群众杨对CO₂浓度和气温升高的生理生态响应。【结果】1)在CO₂浓度升高处理下，群众杨叶片气孔密度降低，蒸腾速率减弱，瞬时水分利用效率显著提高；光合潜力和氮利用效率增加，并通过叶肉组织增厚、叶和根碳氮比增加、比叶重增大以及根冠比增加等途径维持单位叶面积氮含量、瞬时光合特性和叶绿素荧光特性不变，而单位质量暗呼吸速率降低，并使单株总干质量和总碳量显著增加。2)增温2℃下的群众杨叶气孔密度显著增加，但瞬时气体交换和荧光参数、光合特性变化不显著，株高和单株总氮量略低，器官间的干物质和碳氮分配...     

稳定碳同位素在森林植物水分利用效率研究中的应用

介绍了植物水分利用效率与稳定碳同位素的相关性,以及影响植物碳同位素丰度值δ13C的主要因子,重点分析几种重要环境因子对林木δ13C的影响,表明降雨量、土壤水分状况、温度、光照和CO₂浓度等因素都会在不同程度上影响植物叶片气孔导度和CO₂的固定,导致植物δ13C发生变化;并从森林抚育间伐措施对δ13C的影响,水分胁迫条件下δ13C的变化,以及δ13C的替代测定方法等方面提出了研究展望。     

浅析陆地生态系统水分利用效率对气候因子的响应

气候变化对陆地生态系统水分利用格局影响显著。水分利用效率作为陆地生态系统碳水耦合的关键指标,反映了植物抗旱能力和生态系统的生产力水平。探究水分利用效率对CO₂、水分、温度以及太阳辐射等气候因子的响应情况,为探究气候变化对陆地生态系统的影响提供理论参考。     

兴安落叶松生态系统CO2浓度及其δ13C动态对环境因子的响应

【目的】探明环境因子对兴安落叶松原始林生态系统CO₂浓度及其δ¹³C动态的影响,深入理解生态系统的碳交换过程,为模拟和预测全球变化与生态系统之间的互馈机制以及科学评估寒温带森林生态系统碳汇能力提供参考。【方法】采用离轴积分腔输出光谱技术对兴安落叶松生态系统不同物候期、不同高度的CO₂浓度及其δ¹³C进行连续高频观测,并分析环境因子与CO₂浓度变化的关系。【结果】1)兴安落叶松生态系统不同高度的CO₂浓度在生长季和日尺度上均呈单峰变化,峰值分别出现在展叶期(522.34μmol·mol^-1)和凌晨(782.81μmol·mol^-1),谷值分别出现在落叶期(406.07μmol·mol^-1)和中午(379.72μmol·mol^-1);δ¹³C变化趋势与CO₂浓度相反;2)CO₂浓度随垂直高度升高而减小,δ     

氮沉降对凋落物分解的影响研究进展

过去几十年的人类活动增加了陆地生态系统的氮输入量,对凋落物分解的影响有促进、抑制和没有影响3种情况。凋落物的基质质量影响凋落物的分解,其中木质素、纤维素、酚类物质、N浓度、P浓度、C/N比、C/P比、木质素/N比具有重要作用。人类活动引起的全球变化,如CO₂增加、温度上升和降水变化,影响了氮沉降的速率和凋落物分解。未来氮沉降对凋落物分解的研究热点包括加强氮沉降对热带与亚热带森林凋落物和阔叶树种凋落物分解影响的研究,氮沉降对凋落物分解影响研究的长期化,采用13C同位素研究凋落物分解,注重凋落物分解对氮沉降与大气CO₂浓度升高、气候变暖、降水变化、紫外线辐射增强、P沉降交互作用响应的研究。     

气候变化与树木年轮结构关系研究进展

气候变化与树木年轮结构之间存在着紧密的联系。近年来,由于气候变迁、大气CO₂浓度增加和空气污染不断加重,对该领域的研究越来越引起人们的关注。对气候变化和年轮结构的关系研究作一总结和介绍,着重突出该领域的发展进程、研究方法、研究手段和发展前景,希望加快这一边缘学科的发展。     

大气CO2增长和气候变化对森林的影响研究进展

本文概述了过去１０多年中，国内外大气ＣＯ２增长对林木影响及气候变化对森林影响方面的研究结果。内容包括：在大气ＣＯ２倍增的情况下，净光合作用和生物产量、气孔的水气传导率及水分利用效率的变化；ＣＯ２与温度的共同影响及与养分供应的共同影响；暗呼吸，根茎比，光合适应现象。本文还介绍了气候变化对植被带、个别森林影响的宏观研究情况，以及古气候与古植被相互关系的研究。     

CO_2和O_3浓度升高对森林生态系统影响的研究进展

系统收集和整理了国内外关于CO2和O3复合胁迫对森林影响的研究,从两者的复合胁迫对森林树木的光合作用、地上部分生长、根系生长、土壤环境、种间竞争的影响等方面进行了阐述,并对该领域有待深入研究的方向进行了展望;提出应深入开展对植物地下水平和分子水平的研究,为解决全球气候变化对森林造成的影响提供借鉴,同时为生态系统的管理提供依据。     

Family Variation in the Morphology and Physiology of White Spruce (Picea glauca) Seedlings in Response to Elevated CO2 and Temperature

Tree improvement programs aim to develop families that are well-adapted to future growing conditions. To gain insight into the stability of the family genetic response to climate change, white spruce (Picea glauca) seedlings from 60 full-sib families were subjected to a combination of two temperature regimes and two levels of CO₂ over two growing seasons. There was positive effect of warmer temperatures and higher CO₂ on some growth variables but no significant family × treatment interactions. Instantaneous water use efficiency was the only physiological trait that was affected positively by the CO₂ treatment, showing a 51% increase that was consistent across families.     

The climate change and forestry of Heilongjiang Province in 1990’s

The background of global climate change was briefly summarized. The comprehensive effects of various factors, including seawater temperature, sunspots’ activities, volcanic explosion, CO₂ concentration change, O₃ concentration change and characteristics of atmospheric circulation index, on the climate change of Heilongjiang Province were analyzed. The tendency of climate change of Heilongjiang in the next 10 years was predicted according to the data of historical climate collected form passed 100 years and the above analysis. The climate of Heilongjiang Province in the next 10 years will be mainly wann and dry. There will be still annual fluctuation. Although the general tendency of climate change accords with global climate change, the regional characteristic is also distinctive. The probable influence of climate change on forestry was put forward and forestry response strategy was elementary discussed.     

Projections of regional changes in forest net primary productivity for different tree species in Europe driven by climate change and carbon dioxide

? Context

Projecting changes in forest productivity in Europe is crucial for adapting forest management to changing environmental conditions.

? Aims

The objective of this paper is to project forest productivity changes under different climate change scenarios at a large number of sites in Europe with a stand-scale process-based model.

? Methods

We applied the process-based forest growth model 4C at 132 typical forest sites of important European tree species in ten environmental zones using climate change scenarios from three different climate models and two different assumptions about CO₂ effects on productivity.

? Results

This paper shows that future forest productivity will be affected by climate change and that these effects depend strongly on the climate scenario used and the persistence of CO₂ effects. We find that productivity increases in Northern Europe, increases or decreases in Central Europe, and decreases in Southern Europe. This geographical pattern is mirrored by the responses of the individual tree species. The productivity of Scots pine and Norway spruce, mostly located in central and northern Europe, increases while the productivity of Common beech and oak in southern regions decreases. It is important to note that we consider the physiological response to climate change excluding disturbances or management.

? Conclusions

Different climate change scenarios and assumptions about the persistence of CO₂ effects lead to uncertain projections of future forest productivity. These uncertainties need to be integrated into forest management planning and adaptation of forest management to climate change using adaptive management frameworks.     

The impacts of climate change on potential natural vegetation distribution

Change in potential natural vegetation (PNV) distribution associated with climate change due to the doubling atmospheric carbon dioxide (2×CO₂) was estimated with a global natural vegetation mapping system based on the modified Kira scheme to the globe and the continents. With an input of widely-distributed global climate data, the system interpolates data onto a 1° latitude by 1° longitude grid over the globe, generates estimates of vegetation type, and produces a composite PNV map. The input climate data corresponding to the 1×CO₂ and 2×CO₂ consists of observations prior to AD 1958 at 2,001 weather stations worldwide and the 2×CO₂ simulation output from the Japan Meteorological Research Institue's General Circulation Model, respectively. As a result of the simulated global warming, the vegetation zones expanded mostly from the tropics toward the poles. PNV area changed by 6.98 billion (G) ha of the total land area (15.04 Gha) and potential forest area corresponding to the closed forest and open forest (woodland) reached 9.74 Gha with the increase of 1.29 Gha. The potential forest area in Europe had obvious advantages to the climate change accompanied with the increase of actual forest area. Although the actual forest area has decreased in North America and Asia, the potential forest area in these continents also benefitted from the climate change. In the end, the remaining continents tended to bear the brunt of the climate change.     

Separating effects of changes in atmospheric composition,climate and land-use on carbon sequestration of U.S. Mid-Atlantic temperate forests

Terrestrial carbon dynamics have been vastly modified because of changes in atmospheric composition, climate, and land-use. However, few studies provide a complete analysis of the factors and interactions that affect carbon dynamics over a large landscape. This study examines how changes in atmospheric composition (CO₂, O₃ and N deposition), climate and land-use affected carbon dynamics and sequestration in Mid-Atlantic temperate forests during the 20th century. We modified and applied the PnET-CN model, a well established process-based ecosystem model with a strong foundation of ecosystem knowledge from experimental studies. We validated the model results using the U.S. Forest Inventory and Analysis (FIA) data. Our results suggest that chronic changes in atmospheric chemistry over the past century markedly affected carbon dynamics and sequestration in Mid-Atlantic temperate forests, while climate change only had a minor impact although inter-annual climatic variability had a far more substantial effect. The NPP response to a century of chronic change in atmospheric composition at the regional scale was an increase of 29%, of which, 14% was from elevated CO₂, 17% from N deposition, 6% from the interaction between CO₂ and N deposition, and minus 8% from tropospheric ozone. Climate change increased NPP by only 4%. Disturbed forests had 6% lower NPP than undisturbed forests after seven decades. Regrowing forests after harvesting and natural disturbances had much greater capacity for sequestering carbon than undisturbed old-growth forests even though the newer forests had slightly lower net primary production (NPP). The modeling results indicated that N deposition was a stronger force than elevated CO₂ for increasing NPP and fast turnover tissues, while elevated CO₂ favored more sustainable carbon storage and sequestration. The model results are consistent with various experiments and observations and demonstrate a powerful approach to integrate and expand our knowledge of complex interactive effects of multiple environmental changes on forest carbon dynamics.     

Soil CO2 concentration,efflux, and partitioning in a recently afforested grassland

Relatively few studies have documented the impacts of afforestation, particularly production forestry, on belowground carbon dioxide (CO₂) effluxes to the atmosphere. We evaluated the changes in the soil CO₂ efflux—a proxy for soil respiration (Rs)—for three years following a native grassland conversion to eucalypt plantations in southern Brazil where minimum tillage during site preparation created two distinct soil zones, within planting row (W) and between-row (B). We used root-exclusion and carbon (C)- isotopic approaches to distinguish Rs components (heterotrophic-Rh and autotrophic-Ra respirations), and a CO₂ profile tube (1-m deep) to determine the concentration ([CO₂]) and isotopic C signature of soil CO₂ (δ¹³[CO₂]). The soil CO₂ efflux in the afforested site averaged 0.37 g CO₂ m^?2 h^?1, which was 56% lower than the soil CO₂ efflux in the grassland. The δ¹³CO₂ in the afforested site ranged from ? 14.1‰ to ? 29.4‰, indicating a greater contribution of eucalypt-derived respiration (both Rh and Ra) over time. Higher soil CO₂ efflux and lower [CO₂] were observed in W than B, indicating that soil preparation creates two distinct soil functional zones with respect to C cycling. The [CO₂] and δ¹³[CO₂] decreased in both zonal positions with eucalypt stand development. Although the equilibrium in C fluxes and pools across multiple rotations is needed to fully account for the feedback of eucalypt planted forests to climate change, we provide quantitative information on soil CO₂ dynamics after afforestation and show how soil preparation can leverage the feedback of planted forests to climate change.