How close are we to a predictive science of the biosphere?

In just 20 years, the field of biosphere-atmosphere interactions has gone from a nascent discipline to a central area of modern climate change research. The development of terrestrial biosphere models that predict the responses of ecosystems to climate and increasing CO2 levels has highlighted several mechanisms by which changes in ecosystem composition and function might alter regional and global climate. However, results from empirical studies suggest that ecosystem responses can differ markedly from the predictions of terrestrial biosphere models. As I discuss here, the challenge now is to connect terrestrial biosphere models to empirical ecosystem measurements. Only by systematically evaluating the predictions of terrestrial biosphere models against suites of ecosystem observations and experiments measurements will a true predictive science of the biosphere be achieved.     

Impacts of recent climate change on terrestrial flora and fauna: Some emerging Australian examples

The effects of anthropogenic climate change on biodiversity are well known for some high‐profile Australian marine systems, including coral bleaching and kelp forest devastation. Less well‐published are the impacts of climate change being observed in terrestrial ecosystems, although ecological models have predicted substantial changes are likely. Detecting and attributing terrestrial changes to anthropogenic factors is difficult due to the ecological importance of extreme conditions, the noisy nature of short‐term data collected with limited resources, and complexities introduced by biotic interactions. Here, we provide a suite of case studies that have considered possible impacts of anthropogenic climate change on Australian terrestrial systems. Our intention is to provide a diverse collection of stories illustrating how Australian flora and fauna are likely responding to direct and indirect effects of anthropogenic climate change. We aim to raise awareness rather than be comprehensive. We include case studies covering canopy dieback in forests, compositional shifts in vegetation, positive feedbacks between climate, vegetation and disturbance regimes, local extinctions in plants, size changes in birds, phenological shifts in reproduction and shifting biotic interactions that threaten communities and endangered species. Some of these changes are direct and clear cut, others are indirect and less clearly connected to climate change; however, all are important in providing insights into the future state of terrestrial ecosystems. We also highlight some of the management issues relevant to conserving terrestrial communities and ecosystems in the face of anthropogenic climate change.     

Microorganisms and climate change: terrestrial feedbacks and mitigation options

Microbial processes have a central role in the global fluxes of the key biogenic greenhouse gases (carbon dioxide, methane and nitrous oxide) and are likely to respond rapidly to climate change. Whether changes in microbial processes lead to a net positive or negative feedback for greenhouse gas emissions is unclear. To improve the prediction of climate models, it is important to understand the mechanisms by which microorganisms regulate terrestrial greenhouse gas flux. This involves consideration of the complex interactions that occur between microorganisms and other biotic and abiotic factors. The potential to mitigate climate change by reducing greenhouse gas emissions through managing terrestrial microbial processes is a tantalizing prospect for the future.     

Means and extremes: building variability into community‐level climate change experiments

Experimental studies assessing climatic effects on ecological communities have typically applied static warming treatments. Although these studies have been informative, they have usually failed to incorporate either current or predicted future, patterns of variability. Future climates are likely to include extreme events which have greater impacts on ecological systems than changes in means alone. Here, we review the studies which have used experiments to assess impacts of temperature on marine, freshwater and terrestrial communities, and classify them into a set of ‘generations’ based on how they incorporate variability. The majority of studies have failed to incorporate extreme events. In terrestrial ecosystems in particular, experimental treatments have reduced temperature variability, when most climate models predict increased variability. Marine studies have tended to not concentrate on changes in variability, likely in part because the thermal mass of oceans will moderate variation. In freshwaters, climate change experiments have a much shorter history than in the other ecosystems, and have tended to take a relatively simple approach. We propose a new ‘generation’ of climate change experiments using down‐scaled climate models which incorporate predicted changes in climatic variability, and describe a process for generating data which can be applied as experimental climate change treatments.     

陆地生态系统过程对气候变暖的响应与适应

陆地生态系统包含一系列时空连续、尺度多元且互相联系的生态学过程。由于大部分生态学过程都受到温度调控, 因此气候变暖会对全球陆地生态系统产生深远的影响。近年来, 全球变化生态学的基本科学问题之一是陆地生态系统的关键过程如何响应与适应全球气候变暖。围绕该问题, 该文梳理了近年来的研究进展, 重点关注植物生理生态过程、物候期、群落动态、生产力及其分配、凋落物与土壤有机质分解、养分循环等过程对温度升高的响应与适应机理。通过定量分析近20年来发表于主流期刊的相关论文, 展望了该领域的前沿方向, 包括物种性状对生态系统过程的预测能力, 生物地球化学循环的耦合过程, 极端高温与低温事件的响应与适应机理, 不对称气候变暖的影响机理和基于过程的生态系统模拟预测等。基于这些研究进展, 该文建议进一步研究陆地生态系统如何适应气候变暖, 更多关注我国的特色生态系统类型, 并整合实验、观测或模型等研究手段开展跨尺度的合作研究。     

大气CO2升高及气候变化对中国陆地生态系统结构与功能的制约和影响（英文）

在本顶研究中,我们探讨了大气CO2加倍和气候变化条件下,中国陆地生态系统的结构与功能的变化。与多数研究不同的是,我们耦合了两个以地理空间为参照的生态系统模型,即生物地理模型（KBIOME）和生物地球化学模型（TEM）,用此研究现状和未来的环境下,中国的植被分布和年净初级生产力（NPP）的状况,我们采用3个大气环流模型,（GFDL－Q,GISS和OSU）预测的结果代表潜在气候变化。3个气候模型的预测都煌中国将变得更温暖并总体上更湿润。耦合的模型预测中国陆地生态系统的结构与功能都将产生十分显著的变化。植被的变迁表现为：1）中国东部森林带北移,温带常绿阔叶林面积扩大,较南的森林取代较北的类型;2）森林和草地的总面积增加,这是作为取代干旱藻木林、沙漠和高山苔原的结果。年净初级生产力在大气CO2加倍和气候变化条件下,增加30％左右,与其它研究不同的另一点是,我们可能进一步区分生产力变化的原因,在所增加的生产力中,12％－21％是源于生态系统的取代较低产的生态系统的结果。这项研究预测了未来中国植被和生产力潜在的变化并给出了变化的范围,为同类的研究以及有关的政策评估提供了有用的参考信息。     

Climate change and the future distributions of aquatic macrophytes across boreal catchments

Aim Aquatic–terrestrial ecotones are vulnerable to climate change, and degradation of the emergent aquatic macrophyte zone would have severe ecological consequences for freshwater, wetland and terrestrial ecosystems. Our aim was to uncover future changes in boreal emergent aquatic macrophyte zones by modelling the occurrence and percentage cover of emergent aquatic vegetation under different climate scenarios in Finland by the 2050s. Location Finland, northern Europe. Methods Data derived from different GIS sources were used to estimate future emergent aquatic macrophyte distributions in all catchments in Finland (848 in total). We used generalized additive models (GAM) with a full stepwise selection algorithm and Akaike information criterion to explore the main environmental determinates (climate and geomorphology) of emergent aquatic macrophyte distributions, which were derived from the national subclass of CORINE land‐cover classification. The accuracy of the distribution models (GAMs) was cross‐validated, using percentage of explained deviance and the area under the curve derived from the receiver‐operating characteristic plots. Results Our results indicated that emergent aquatic macrophytes will expand their distributions northwards from the current catchments and percentage cover will increase in all of the catchments in all climate scenarios. Growing degree‐days was the primary determinant affecting distributions of emergent aquatic macrophytes. Inclusion of geomorphological variables clearly improved model performance in both model exercises compared with pure climate variables. Main conclusions Emergent aquatic macrophyte distributions will expand due to climate change. Many emergent aquatic plant species have already expanded their distributions during the past decades, and this process will continue in the years 2051–80. Emergent aquatic macrophytes pose an increasing overgrowth risk for sensitive macrophyte species in boreal freshwater ecosystems, which should be acknowledged in management and conservation actions. We conclude that predictions based on GIS data can provide useful ‘first‐filter’ estimates of changes in aquatic–terrestrial ecotones.     

2020—2050年CO2施肥效应促进全球陆地生态系统碳吸收

CO₂施肥效应是全球变绿的主要原因,随着大气中CO₂浓度的持续增加,预估未来气候变化条件下,CO₂施肥效应对陆地生态系统的影响对减缓全球气候变化具有重大意义。基于未来气候情景数据和Farquhar模型,并结合生态过程模型BEPS(Boreal Ecosystem Productivity Simulator),定量化研究2020—2050年CO₂施肥效应对全球叶面积指数(LAI)和总初级生产力(GPP)的影响。研究结果显示2020—2050年,在RCP2.6、RCP4.5和RCP8.5气候情景下,CO₂施肥效应导致的LAI年际变化趋势分别为0.002、0.003和0.005 m^-2m^-2a^-1;三个气候情景下CO₂施肥效应对LAI的影响为CO₂每增加0.1%,LAI平均增加约8.1%—9.2%,由此导致GPP对应增加7.9%—14.6%;由CO₂施...     

How uncertainties in future climate change predictions translate into future terrestrial carbon fluxes

We forced a global terrestrial carbon cycle model by climate fields of 14 ocean and atmosphere general circulation models (OAGCMs) to simulate the response of terrestrial carbon pools and fluxes to climate change over the next century. These models participated in the second phase of the Coupled Model Intercomparison Project (CMIP2), where a 1% per year increase of atmospheric CO₂ was prescribed. We obtain a reduction in net land uptake because of climate change ranging between 1.4 and 5.7 Gt C yr^?1 at the time of atmospheric CO₂ doubling. Such a reduction in terrestrial carbon sinks is largely dominated by the response of tropical ecosystems, where soil water stress occurs. The uncertainty in the simulated land carbon cycle response is the consequence of discrepancies in land temperature and precipitation changes simulated by the OAGCMs. We use a statistical approach to assess the coherence of the land carbon fluxes response to climate change. The biospheric carbon fluxes and pools changes have a coherent response in the tropics, in the Mediterranean region and in high latitudes of the Northern Hemisphere. This is because of a good coherence of soil water content change in the first two regions and of temperature change in the high latitudes of the Northern Hemisphere. Then we evaluate the carbon uptake uncertainties to the assumptions on plant productivity sensitivity to atmospheric CO₂ and on decomposition rate sensitivity to temperature. We show that these uncertainties are on the same order of magnitude than the uncertainty because of climate change. Finally, we find that the OAGCMs having the largest climate sensitivities to CO₂ are the ones with the largest soil drying in the tropics, and therefore with the largest reduction of carbon uptake.     

Projected Changes in Terrestrial Carbon Storage in Europe under Climate and Land-use Change, 1990–2100

Changes in climate and land use, caused by socio-economic changes, greenhouse gas emissions, agricultural policies and other factors, are known to affect both natural and managed ecosystems, and will likely impact on the European terrestrial carbon balance during the coming decades. This study presents a comprehensive European Union wide (EU15 plus Norway and Switzerland, EU*) assessment of potential future changes in terrestrial carbon storage considering these effects based on four illustrative IPCC-SRES storylines (A1FI, A2, B1, B2). A process-based land vegetation model (LPJ-DGVM), adapted to include a generic representation of managed ecosystems, is forced with changing fields of land-use patterns from 1901 to 2100 to assess the effect of land-use and cover changes on the terrestrial carbon balance of Europe. The uncertainty in the future carbon balance associated with the choice of a climate change scenario is assessed by forcing LPJ-DGVM with output from four different climate models (GCMs: CGCM2, CSIRO2, HadCM3, PCM2) for the same SRES storyline. Decrease in agricultural areas and afforestation leads to simulated carbon sequestration for all land-use change scenarios with an average net uptake of 17–38 Tg C/year between 1990 and 2100, corresponding to 1.9–2.9% of the EU*s CO₂ emissions over the same period. Soil carbon losses resulting from climate warming reduce or even offset carbon sequestration resulting from growth enhancement induced by climate change and increasing atmospheric CO₂ concentrations in the second half of the twenty-first century. Differences in future climate change projections among GCMs are the main cause for uncertainty in the cumulative European terrestrial carbon uptake of 4.4–10.1 Pg C between 1990 and 2100.