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Climate change is having a significant impact on ecosystem services and is likely to become increasingly important as this phenomenon intensifies. Future impacts can be difficult to assess as they often involve long timescales, dynamic systems with high uncertainties, and are typically confounded by other drivers of change. Despite a growing literature on climate change impacts on ecosystem services, no quantitative syntheses exist. Hence, we lack an overarching understanding of the impacts of climate change, how they are being assessed, and the extent to which other drivers, uncertainties, and decision making are incorporated. To address this, we systematically reviewed the peer-reviewed literature that assesses climate change impacts on ecosystem services at subglobal scales. We found that the impact of climate change on most types of services was predominantly negative (59% negative, 24% mixed, 4% neutral, 13% positive), but varied across services, drivers, and assessment methods. Although uncertainty was usually incorporated, there were substantial gaps in the sources of uncertainty included, along with the methods used to incorporate them. We found that relatively few studies integrated decision making, and even fewer studies aimed to identify solutions that were robust to uncertainty. For management or policy to ensure the delivery of ecosystem services, integrated approaches that incorporate multiple drivers of change and account for multiple sources of uncertainty are needed. This is undoubtedly a challenging task, but ignoring these complexities can result in misleading assessments of the impacts of climate change, suboptimal management outcomes, and the inefficient allocation of resources for climate adaptation. [ABSTRACT FROM AUTHOR]

The southeastern Australian climate and climate variability is driven primarily by large-scale climate dynamics. How these dynamics translate into local effects is influenced by the nature of the landscape, the vegetation, soil moisture, fire, snow, irrigation and orography. This local land-atmosphere coupling can enhance or moderate the large-scale dynamics and have significant influences locally and regionally. This paper reviews the state of knowledge of the coupled land-atmosphere dynamics over southeast Australia and identifies the challenges for future research. Relevant processes are investigated and if possible their importance to regional climate is identified. Many coupled land-atmosphere dynamic processes, identified as important in the Northern Hemisphere studies, remain to be studied in southeast Australia. This represents an important priority for Australian research because this will establish their role in future changes in regional climate over Australia. However, this also represents a significant international priority because the very high natural climate variability in the region provides a laboratory to examine how coupled land-atmosphere dynamic processes may change in other regions if global warming increases the range of natural variability. Copyright © 2010 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Global climate change is the major and most urgent global environmental issue. Australia is already experiencing climate change as evidenced by higher temperatures and more frequent and severe droughts. These impacts are compounded by increasing land use pressures on natural resources and native ecosystems. This paper provides a synthesis of the interactions, feedbacks and risks of natural climate variability, climate change and land use/land cover change (LUCC) impacting on the Australian continent and how they vary regionally. We review evidence of climate change and underlying processes resulting from interactions between global warming caused by increased concentration of atmospheric greenhouse gases and modification of the land surface. The consequences of ignoring the effect of LUCC on current and future droughts in Australia could have catastrophic consequences for the nation's environment, economy and communities. We highlight the need for more integrated, long-term and adaptive policies and regional natural resource management strategies that restore the beneficial feedbacks between native vegetation cover and local-regional climate, to help ameliorate the impact of global warming. [ABSTRACT FROM AUTHOR]

Aim The assumedly anomalous occurrence of savannas and forest–savanna mosaics in the Gran Sabana – a neotropical region under a climate more suitable for tropical rain forests – has been attributed to a variety of historical, climatic, and anthropogenic factors. This paper describes a previously undocumented shift in vegetation and climate that occurred during the early Holocene, and evaluates its significance for the understanding of the origin of the Gran Sabana vegetation. Location A treeless savanna locality of the Gran Sabana (4°30′–6°45′ N and 60°34′–62°50′ W), in the Venezuelan Guayana of northern South America, at the headwaters of the Caroní river, one of the major tributaries of the Orinoco river. Methods Pollen and charcoal analysis of a previously dated peat section spanning from about the Pleistocene/Holocene boundary until the present. Results Mesothermic cloud forests dominated by Catostemma (Bombacaceae) occupied the site around the Pleistocene/Holocene boundary. During the early Holocene, a progressive but relatively rapid trend towards savanna vegetation occurred, and eventually the former cloud forests were replaced by a treeless savanna. Some time after the establishment of savannas, a marked increase in charcoal particles indicates the occurrence of the first local fires. Main conclusions The occurrence of cloud forests at the Pleistocene/Holocene boundary contradicts the historical hypothesis according to which the Gran Sabana is a relict of the hypothetical widespread savannas that have been assumed to have dominated the region during the last glaciation. The first local fires recorded in the Holocene were on savanna vegetation, which is against the hypothesis of fire as the triggering factor for the establishment of these savannas. Climate change, in the form of global warming and a persistently drier climate, emerges as the most probable cause for the forest–savanna turnover. [ABSTRACT FROM AUTHOR]

As anthropogenic carbon emissions continue, it is important to predict how vegetation will change due to the warming climate, increasing atmospheric CO2, and changing precipitation patterns. Some projections show decreases in vegetation either regionally in the tropics (e.g., Falloon et al., 2012; Port et al., 2012) or globally (e.g., Bastin et al., 2019) due to high temperatures and drying, and there is large uncertainty surrounding the response of global vegetation to climate change (Arora et al., 2020; Friedlingstein et al., 2006; Walker et al., 2020). Here we use simulations with the NCAR Community Earth System Model (CESM) with dynamic vegetation to explore how increasing CO2 may affect vegetation and, through feedbacks, the climate. We find that globally, warming only decreases vegetation, but when we include the effects of CO2 on plant physiology, vegetated area increases by ∼23% relative to the preindustrial simulation. This greening occurs even without significant increases in precipitation, as high CO2 increases plant water use efficiency, allowing for more vegetation in arid and hot regions. Our results show that CO2‐induced vegetation changes affect climate by amplifying high latitude warming, cooling some areas of the tropics, and shifting global precipitation patterns. Our results highlight the importance of including climate‐vegetation feedbacks in Earth system modeling. Plain Language Summary: As anthropogenic carbon emissions continue to increase, it is important to learn how vegetation will respond and how, in turn, changes in vegetation may affect climate through various feedbacks. Here, we use an Earth system model with dynamic vegetation to compare the vegetation and climate responses to warming scenarios with and without CO2‐induced changes to plant physiology. We find that increased CO2 and vegetation responses expand where plants can grow. Increased water use efficiency allows vegetation to increase in dry regions and also in hot regions, and a longer growing season allows vegetation to expand poleward. While global vegetated area decreases with warming only, relative to the preindustrial simulation, it is increased ∼23% over the preindustrial simulation when plant responses to high CO2 are included in the model. The expanded vegetation affects climate by amplifying Arctic warming, cooling some areas of the tropics, and shifting the equatorial rain belt northward. Our results are of interest both for understanding our future climate under anthropogenic climate change and for understanding past warm, high CO2 periods. Key Points: High CO2 allows plants to increase water use efficiency, permitting more vegetation in arid and hot regionsGreening affects climate by amplifying high latitude warming, cooling some areas in the tropics, and shifting global precipitation patternsPlant responses to high CO2 shift climate‐vegetation relationships in biome space, relative to model scenarios with warming only [ABSTRACT FROM AUTHOR]

This study quantifies the influences of climate variation and vegetation greening on the changes in evapotranspiration (ET) over 110 humid catchments of China from 1982 to 2016. A process‐based model considering climate and vegetation changes is employed to estimate ET. The simulated ET compared well with the observed values based on the flux measurements and water balance equation, with the coefficients of determination above 0.62. During the study period, environmental change of the study area was characterized by the increases in air temperature and leaf area index, that is, climate warming and vegetation greening. Annual ET increased at 104 catchments with the trends ranging from 0.01 to 6.2 mm yr−2. The numerical experiment approach and sensitivity method are used to attribute ET changes to climate variation and vegetation greening. The results show that the contributions of climate variation to ET changes estimated by the two methods are 90.6% and 91.3%, respectively, whereas the contributions of vegetation greening to ET changes are only 9.4% and 8.7%, indicating that climate variation controls ET changes in the study area. However, vegetation greening alters the proportions of ET components, which contributes 59.0%–62.0% to the increase in the ratio of transpiration to ET. This study quantifies the roles of climate and vegetation changes in the dynamics of ET, suggesting that more concerns should be paid on the interactions between ecological processes and hydrological cycle in humid regions. Key Points: Evapotranspiration changes are attributed to climate variation and vegetation greening over 110 humid catchments in ChinaClimate variation controls the dynamics of evapotranspiration over the humid regionVegetation greening has limited influences on evapotranspiration but mainly alters evapotranspiration partitioning [ABSTRACT FROM AUTHOR]

This study compares two ensemble methods, pseudo global warming (PGW) and multimodel ensemble (MME) mean in evaluating future vegetation‐climate changes and feedback over East Asia using a regional model driven with boundary conditions derived from historical and RCP8.5 runs of four global models. Over most of the domain, MME and PGW produce similar future climate changes, except for two regions: over Northeast Asia, MME projects less winter warming and less increase of summer precipitation than PGW, and over North China Plain, MME projects greater increase of summer precipitation than PGW. Both PGW and MME project greater leaf area index (LAI) and expansion of tree coverage at the expense of grass over most of the domain due to elevated CO2 concentration and climate change. However, over Northeast China, PGW and three ensemble members project an increase of temperate trees at the expense of boreal trees or grass and a decrease of LAI, and one ensemble member projects a loss of forest to grassland. Both PGW and MME identify two hotspots of vegetation‐temperature feedback, including the Northeast China where the projected loss of boreal evergreen forest causes a significant winter cooling (which offsets a major portion of greenhouse gas‐induced warming) and the Tibetan Plateau where the projected LAI increase and vegetation expansion lead to a significant winter warming through reduced albedo. The vegetation feedback impact on precipitation is similar between the two approaches, including a significant wet signal in a belt between 30°N and 40°N during winter and over the Tibetan Plateau during summer. Plain Language Summary: Climate is undergoing severe changes. Climate simulation and projections from global climate models suffer from coarse resolution and model dependence, especially for the East Asia region. In this study, we assess multimodel ensemble (MME) projections of the East Asian vegetation‐climate changes using a regional model driven with boundary conditions from multiple global models. Two ensemble approaches are used, the traditional MME mean that is based on unweighted average of the four runs driven with individual global models and the reanalysis‐based pseudo global warming (PGW) that derives the regional model's boundary conditions by adding the four‐model average of future changes to the boundary conditions from the reanalysis data. PGW and MME produce a similar future climate change signals over most of the model domain except for the Northeast China, North China, and India regions. Both PGW and MME identify two hotspots of vegetation‐temperature feedback, including the Northeast China with significant winter cooling due to forest loss and the Tibetan Plateau with significant winter warming due to LAI increase and vegetation cover expansion. Key Points: Two ensemble approaches are used to project the future vegetation‐climate changes over East AsiaProjected changes over Northeast China are highly sensitive to the GCM‐derived boundary conditionsVegetation feedback has significant impacts on winter temperature over Northeast China and Tibetan Plateau due to albedo effects [ABSTRACT FROM AUTHOR]

As the climate changes, increasing variations in environmental factors directly influence crop cultivation at different magnitudes over a broad range of local communities worldwide. As a result, there is an urgent need to develop local impact assessments and adaptation strategies for use at local, rather than national or global, levels. In this study, we predicted the future frost damage of kiwifruit in the Jeonnam province, Korea, as a case study for the local impact assessment of climate change. This study included a series of models that integrated both the biological responses of plants and the physical influences of climatic factors. First, potential changes in the suitable area for kiwifruit cultivation under a changing climate were simulated using downscaled high resolution (1 km) climate data. Through the development of a frost‐forecasting model and linking it to a kiwifruit phenology model, we also assessed the interaction of plant and climatic factors. Because of the warming climate, the last frost date in spring occurred 13.7 days earlier in average under climate change. Nevertheless, the potential risk of spring frost damage of kiwifruit continued to exist at a similar magnitude in the future. Additional study at the county level indicated that the date of bud burst is advancing even faster than the last frost date (approximately 1 day per every decade), resulting in the increasing risk of spring frost damage for kiwifruit through 2100. In this study, the local impacts of climate change on kiwifruit frost damage were assessed using the integrated modelling approach. As such, local policy makers and stakeholders will be able to prepare more realistic adaptation strategies to cope with upcoming threats in a changing climate. In this study, the local impacts of climate change on kiwifruit frost damage in the Jeonnam Province, Korea were assessed using an integrated modelling approach. First, optimal areas for kiwifruit cultivation under a changing climate were simulated, resulting in almost 98% of lands becoming "Highly suitable" in the 2080s. In addition, through the development of a frost‐forecasting model and linking it to a kiwifruit phenology model, we found that the potential risk of spring frost damage of kiwifruit continued to exist at a similar magnitude as shown in the figure below. [ABSTRACT FROM AUTHOR]

Abstract: Aim: Reconstruct the long‐term ecosystem dynamics of the region across an elevational gradient as they relate to climate and local controls. In particular, we (1) describe the dominant conifers' history; (2) assess changes in vegetation composition and distribution; and (3) note periods of abrupt change versus stability as means of better understanding vegetation responses to environmental variability. Location: Greater Yellowstone Ecosystem (GYE; USA). Time period: 16.5 ka bp‐present. Major taxa studied: Juniperus, Picea, Abies, Pinus, Pseudotsuga. Methods: The vegetation reconstruction was developed from 15 pollen records. Results were interpreted based on modern pollen–vegetation relationships estimated from a suite of regression‐based approaches. Results: Calibrated pollen data suggest that late‐glacial vegetation, dominated by shrubs and Juniperus, lacks a modern counterpart in the area. Picea, Abies and Pinus expanded at 16 ka bp in association with postglacial warming and co‐occurred in mixed‐conifer parkland/forest after 12 ka bp. This association along with Pinus contorta forest, which was present after 9 ka bp, has persisted with little change at middle and high elevations to the present day. This stability contrasts with the dynamic history of plant communities at low elevations, where shifts between parkland, steppe and forest over the last 8,000 years were likely driven by variations in effective moisture and fire. Main conclusions: The postglacial vegetation history of the GYE highlights the dynamic nature of mountain ecosystems and informs on their vulnerability to future climate change: (1) most of the conifers have been present in the area for >12,000 years and survived climate change by adjusting their elevational ranges; (2) some plant associations have exhibited stability over millennia as a result of nonclimatic controls; and (3) present‐day forest cover is elevationally more compressed than at any time in history, probably due to the legacy of the Medieval Climate Anomaly and the Little Ice Age. [ABSTRACT FROM AUTHOR]

Abstract: Aims: It has been assumed that montane species will undergo upslope shifts in response to climate warming and their range sizes are therefore predicted to decrease. However, this view has been challenged because a recent study (Elsen & Tingley, ) indicated that land surface area increases with increasing altitude in some mountains. To test this prediction, we used one of the world's biodiversity hotspots as a study system to examine overall patterns of plant distribution shift in response to climate warming. Location: The Hengduan Mountains and adjacent regions. Methods: Based on distribution data for 151 species at a resolution of 2.5 arc minutes, we employed ecological niche modelling to model their distributions under the climatic conditions of the Last Glacial Maximum, Current (2017), and 2050 separately. We examined the distributional shifts of these species, especially with respect to altitude and range size, in response to two periods of stepwise climate warming. Results: All the montane plants sampled shifted upward during the two warming stages, but not only northward, some shifted westward or in other directions. In contrast with the expected consistent loss of range when shifting upward, 63.6% of the plants expanded their range size continuously since the LGM. Only 11.9% of the plants contracted their range size continuously from the LGM to 2050. Estimates of species richness in the regions studied changed greatly, but in an unbalanced manner, from the LGM to the Current and from the Current to 2050. Main conclusions: Numerous montane plants in the Hengduan Mountains are predicted to expand their range sizes as they shift upslope in response to climate warming. Our results highlight the possibility that more available land surface area due to the heterogeneous topography along altitudinal gradients and the adjacent large Qinghai‐Tibet Plateau sensu stricto can mediate the range loss of the montane plants under climate warming. These findings are crucial for estimating the future range sizes of plants and planning biodiversity protection for mountain ecosystems under the anticipated warming of the world's climate. [ABSTRACT FROM AUTHOR]

Abstract: The vast expanses of rangeland on the Tibetan Plateau, which support the livelihood of c. 9.8 million local inhabitants, have experienced rapid climate warming over the past 50 years. At the same time, precipitation has increased in large parts of the Plateau but decreased in other parts, particularly in the northwest. These trends are predicted to continue into the future. However, their potential effects on rangeland quality remain unclear. We conducted a two‐factor field experiment in which we manipulated temperature (control or warming by 1.5–1.8°C) and precipitation (control or 50% reduction or increase in rainfall) in an alpine grassland on the northeastern Tibetan Plateau, starting in 2011. From 2014 to 2016, we measured forage production and community composition, and in 2015 forage quality (crude protein, cell‐soluble contents, hemicellulose, cellulose, lignin and digestibility) was represented by seven abundant species. Overall, warming did not change total forage production at plant community level, but increased legume production and decreased non‐legume forb production. Increased and reduced precipitation enhanced and decreased forage production by 18.2% and 12.9% respectively. Increased precipitation in particular increased grass and sedge production, but not legume production. Forage quality showed species‐specific responses to the simulated climate changes. At community level, warming and reduced precipitation improved forage quality, which were mainly caused by a shift in community composition towards more legumes, rather than the direct effects of simulated climate changes. Meanwhile, increased precipitation did not reduce forage quality, despite the precipitation‐induced increase in forage production. Integrating forage production and quality into nutrient production as a measure of rangeland quality, we found that warming and increased precipitation additively improved rangeland quality, while reduced precipitation decreased it. Synthesis and applications. Rangeland quality, an important ecosystem provisioning service, will benefit from a warmer climate on the Tibetan Plateau in the regions with a predicted increase in precipitation, but not in those regions where precipitation might be reduced in the future. We suggest management strategies, including reseeding native legumes, establishing sustainable pastures and assisting the exchange of harvested forage, to cope with the challenges posed by these different climate change scenarios. [ABSTRACT FROM AUTHOR]

Abstract: Warmer and drier conditions associated with ongoing climate change will increase abiotic stress for plants and mycorrhizal fungi in drylands world‐wide, thereby potentially reducing vegetation cover and productivity and increasing the risk of land degradation and desertification. Rhizosphere–microbial interactions and feedbacks are critical processes that could either mitigate or aggravate the vulnerability of dryland vegetation to forecasted climate change. We conducted a 4‐year manipulative study in a semi‐arid shrubland in the Iberian Peninsula to assess the effects of warming (c. 2.5°C; W), rainfall reduction (c. 30%; RR) and their combination (W+RR) on the performance of native shrubs (Helianthemum squamatum) and their associated mycorrhizal fungi. Warming (W and W+RR) decreased the net photosynthetic rates of H. squamatum shrubs by c. 31% despite concurrent increases in stomatal conductance (c. 33%), leading to sharp decreases (c. 50%) in water use efficiency. Warming also advanced growth phenology, decreased leaf nitrogen and phosphorus contents per unit area, reduced shoot biomass production by c. 36% and decreased survival during a dry year in both W and W+RR plants. Plants under RR showed more moderate decreases (c. 10%–20%) in photosynthesis, stomatal conductance and shoot growth. Warming, RR and W+RR altered ectomycorrhizal fungal (EMF) community structure and drastically reduced the relative abundance of EMF sequences obtained by high‐throughput sequencing, a response associated with decreases in the leaf nitrogen, phosphorus and dry matter contents of their host plants. In contrast to EMF, the community structure and relative sequence abundances of other non‐mycorrhizal fungal guilds were not significantly affected by the climate manipulation treatments. Synthesis. Our findings highlight the vulnerability of both native plants and their symbiotic mycorrhizal fungi to climate warming and drying in semi‐arid shrublands, and point to the importance of a deeper understanding of plant–soil feedbacks to predict dryland vegetation responses to forecasted aridification. The interdependent responses of plants and ectomycorrhizal fungi to warming and rainfall reduction may lead to a detrimental feedback loop on vegetation productivity and nutrient pool size, which could amplify the adverse impacts of forecasted climate change on ecosystem functioning in EMF‐dominated drylands. [ABSTRACT FROM AUTHOR]

Summary: Global warming and reduced precipitation may trigger large‐scale species losses and vegetation shifts in ecosystems around the world. However, currently lacking are practical ways to quantify the sensitivity of species and community composition to these often‐confounded climatic forces. Here we conducted long‐term (16 yr) nocturnal‐warming (+0.6°C) and reduced precipitation (−20% soil moisture) experiments in a Mediterranean shrubland. Climatic niche groups (CNGs) – species ranked or classified by similar temperature or precipitation distributions – informatively described community responses under experimental manipulations. Under warming, CNGs revealed that only those species distributed in cooler regions decreased. Correspondingly, under reduced precipitation, a U‐shaped treatment effect observed in the total community was the result of an abrupt decrease in wet‐distributed species, followed by a delayed increase in dry‐distributed species. Notably, while partially correlated, CNG explanations of community response were stronger for their respective climate parameter, suggesting some species possess specific adaptations to either warming or drought that may lead to independent selection to the two climatic variables. Our findings indicate that when climatic distributions are combined with experiments, the resulting incorporation of local plant evolutionary strategies and their changing dynamics over time leads to predictable and informative shifts in community structure under independent climate change scenarios. [ABSTRACT FROM AUTHOR]

Wildfire area is predicted to increase with global warming. Empirical statistical models and process-based simulations agree almost universally. The key relationship for this unanimity, observed at multiple spatial and temporal scales, is between drought and fire. Predictive models often focus on ecosystems in which this relationship appears to be particularly strong, such as mesic and arid forests and shrublands with substantial biomass such as chaparral. We examine the drought-fire relationship, specifically the correlations between water-balance deficit and annual area burned, across the full gradient of deficit in the western USA, from temperate rainforest to desert. In the middle of this gradient, conditional on vegetation (fuels), correlations are strong, but outside this range the equivalence hotter and drier equals more fire either breaks down or is contingent on other factors such as previous-year climate. This suggests that the regional drought-fire dynamic will not be stationary in future climate, nor will other more complex contingencies associated with the variation in fire extent. Predictions of future wildfire area therefore need to consider not only vegetation changes, as some dynamic vegetation models now do, but also potential changes in the drought-fire dynamic that will ensue in a warming climate. [ABSTRACT FROM AUTHOR]

Questions Which climatic variables are the main determinants of radial growth and to what extent does their effect on growth vary among species? What are the similarities between the temporal radial growth patterns of the two common shrub species, Alnus viridis and Salix glauca? Do changing growth conditions over the past 120 yr and their predicted impact on growth match shrub expansion observed in the region? Location Arsuk Fjord and Disko Bay regions, W Greenland. Methods Alnus viridis and S. glauca specimens were sampled in the field and radial growth was analysed using standard dendrochronological methods ('response functions'). The identified climatic variables were applied to model radial growth using a linear mixed model and predict the growth for 1890-2010. Results The main determinants of radial growth were summer temperatures and, although not significant in the final models, spring precipitation. The empirical chronologies showed only somewhat similar growth patterns. They responded to similar sets of climatic variables, but their similarity was weakened because of the low number of replicates and local differences in growth conditions. The similarity between predicted (modelled) chronologies was higher, which was related to the response to similar sets of climatic variables and high correlation between climatic variables across long distances. Conclusion Overall, estimated growth did not increase over the past 120 yr, but considerable variations in growth are conspicuous and match known historical patterns of the Atlantic Multidecadal Oscillation. Perspectives regarding the observed shrub expansion in W Greenland are discussed, and based on the estimated growth patterns, we consider it unlikely that the recent 10-15-yr period of favourable climate is the main responsible cause. [ABSTRACT FROM AUTHOR]

Climate warming is expected to increase respiration rates of tropical forest trees and lianas, which may negatively affect the carbon balance of tropical forests. Thermal acclimation could mitigate the expected respiration increase, but the thermal acclimation potential of tropical forests remains largely unknown. In a tropical forest in Panama, we experimentally increased nighttime temperatures of upper canopy leaves of three tree and two liana species by on average 3 °C for 1 week, and quantified temperature responses of leaf dark respiration. Respiration at 25 °C ( R25) decreased with increasing leaf temperature, but acclimation did not result in perfect homeostasis of respiration across temperatures. In contrast, Q10 of treatment and control leaves exhibited similarly high values (range 2.5-3.0) without evidence of acclimation. The decrease in R25 was not caused by respiratory substrate depletion, as warming did not reduce leaf carbohydrate concentration. To evaluate the wider implications of our experimental results, we simulated the carbon cycle of tropical latitudes (24 °S-24 °N) from 2000 to 2100 using a dynamic global vegetation model ( LM3 VN) modified to account for acclimation. Acclimation reduced the degree to which respiration increases with climate warming in the model relative to a no-acclimation scenario, leading to 21% greater increase in net primary productivity and 18% greater increase in biomass carbon storage over the 21st century. We conclude that leaf respiration of tropical forest plants can acclimate to nighttime warming, thereby reducing the magnitude of the positive feedback between climate change and the carbon cycle. [ABSTRACT FROM AUTHOR]

Ecology Letters (2011) Abstract Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation - and associated ecosystem consequences - have the potential to be much greater than we have observed to date. [ABSTRACT FROM AUTHOR]

In a spatially explicit climate change impact assessment, a Bayesian network (BN) model was implemented to probabilistically simulate future response of the four major vegetation types in Swaziland. Two emission scenarios (A2 and B2) from an ensemble of three statistically downscaled coupled atmosphere-ocean global circulation models (CSIRO-Mk3, CCCma-CGCM3 and UKMO-HadCM3) were used to simulate possible changes in BN-based environmental envelopes of major vegetation communities. Both physiographic and climatic data were used as predictors representing the 2020s, 2050s and the 2080s periods. A comparison of simulated vegetation distribution and the expert vegetation map under baseline conditions showed an overall correspondence of 97.7% and a Kappa coefficient of 0.966. Although the ensemble projections showed comparable trends during the 2020s, the results from the A2 storyline were more drastic indicating that grassland and the Lebombo bushveld will be impacted negatively as early as the 2020s with about 1 °C temperature increase. The bioclimatically suitable areas of all but one vegetation type decline drastically after about 2 °C warming, more so under the more severe A2 scenario and in particular during the 2080s. The sour bushveld is the only vegetation type that initially responds positively to warming by possibly encroaching to the highly vulnerable grassland areas. Vulnerability of vegetation is increased by the limited ability to migrate into suitable climates due to close affinity to certain geological formations and the fragmentation of the landscape by agriculture and other land uses. This is expected to have serious impacts on biodiversity in the country. Under warmer climates, the likely vegetation types to emerge are uncertain due to future novel combinations of climate and bedrock lithology. The strengths and limitations of the BN approach are also discussed. [ABSTRACT FROM AUTHOR]

The article reports on the study that explains the variations in flowering date using a statistical procedure. It states that the procedure can interpret two phenological parameters of species which are the thermal requirement and thermal threshold. It notes that researchers can determine which species can be considered as sensitive to temperature by using a statistical approach on empirical p-values. It adds that the procedure can predict the impact of global warming on spring flowering dates.

Climate change is expected to cause extensive vegetation changes in the Arctic: deciduous shrubs are already expanding, in response to climate warming. The results from transect studies suggest that increasing shrub cover will impact significantly on the surface energy balance. However, little is known about the direct effects of shrub cover on permafrost thaw during summer. We experimentally quantified the influence of Betula nana cover on permafrost thaw in a moist tundra site in northeast Siberia with continuous permafrost. We measured the thaw depth of the soil, also called the active layer thickness (ALT), ground heat flux and net radiation in 10 m diameter plots with natural B. nana cover (control plots) and in plots in which B. nana was removed (removal plots). Removal of B. nana increased ALT by 9% on average late in the growing season, compared with control plots. Differences in ALT correlated well with differences in ground heat flux between the control plots and B. nana removal plots. In the undisturbed control plots, we found an inverse correlation between B. nana cover and late growing season ALT. These results suggest that the expected expansion of deciduous shrubs in the Arctic region, triggered by climate warming, may reduce summer permafrost thaw. Increased shrub growth may thus partially offset further permafrost degradation by future temperature increases. Permafrost models need to include a dynamic vegetation component to accurately predict future permafrost thaw. [ABSTRACT FROM AUTHOR]

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The ongoing and projected warming in the northern high latitudes (NHL; poleward of 60 °N) may lead to dramatic changes in the terrestrial carbon cycle. On the one hand, warming and increasing atmospheric CO2 concentration stimulate vegetation productivity, taking up CO2. On the other hand, warming accelerates the decomposition of soil organic matter (SOM), releasing carbon into the atmosphere. Here, the NHL terrestrial carbon storage is investigated based on 10 models from the Coupled Carbon Cycle Climate Model Intercomparison Project. Our analysis suggests that the NHL will be a carbon sink of 0.3 ± 0.3 Pg C yr−1 by 2100. The cumulative land organic carbon storage is modeled to increase by 38 ± 20 Pg C over 1901 levels, of which 17 ± 8 Pg C comes from vegetation (43%) and 21 ± 16 Pg C from the soil (8%). Both CO2 fertilization and warming enhance vegetation growth in the NHL. Although the intense warming there enhances SOM decomposition, soil organic carbon (SOC) storage continues to increase in the 21st century. This is because higher vegetation productivity leads to more turnover (litterfall) into the soil, a process that has received relatively little attention. However, the projected growth rate of SOC begins to level off after 2060 when SOM decomposition accelerates at high temperature and then catches up with the increasing input from vegetation turnover. Such competing mechanisms may lead to a switch of the NHL SOC pool from a sink to a source after 2100 under more intense warming, but large uncertainty exists due to our incomplete understanding of processes such as the strength of the CO2 fertilization effect, permafrost, and the role of soil moisture. Unlike the CO2 fertilization effect that enhances vegetation productivity across the world, global warming increases the productivity at high latitudes but tends to reduce it in the tropics and mid-latitudes. These effects are further enhanced as a result of positive carbon cycle–climate feedbacks due to additional CO2 and warming. [ABSTRACT FROM AUTHOR]

Question: How did the vascular plant species composition of a nunatak in the alpine vegetation belt change over a time span of 100 years? Location: A 5.6-ha nunatak, Isla Persa in the Swiss Alps, that remained ice-free during the last maximum glacier advance in the 1850s and is today partly covered with climactic alpine grassland and dwarf heath shrubs. Methods: Floristic inventories in 1906, 1927, 1972, 1995, 2003 and 2004 and a comparative analysis of the species composition over the period 1906-2004. Results: 31 species that were not recorded in the first inventory were found in the following surveys. However, among them only six were common by 2004. Generally, the new species prefer warmer conditions than those previously present and most newcomers are associated with montane or sub-alpine grasslands and woodlands. In particular, the observed increase of Vaccinium myrtillus and the arrival of shrub and tree species further substantiate a trend towards vegetation composition of the lower altitudinal belt. Ferns represented 26% of the newcomers, probably due to the high dispersal ability of their lightweight spores. The observed species enrichment was globally small compared to previously inventoried summits. Conclusion: Floristic change strongly suggests warmer climatic conditions as the main factor contributing to species compositional change. The relative stability of species richness may be explained by several factors: the isolation of the nunatak and the difficulties for plants to reach the site, the colder local climate, a limited available species pool and interactions of established alpine plants with newly immigrating taxa. Supplementary data collected at a similar altitude would be necessary to better understand the influence of climate change on alpine grasslands. [ABSTRACT FROM AUTHOR]

1. The tree-ring growth response of stone pine ( Pinus cembra L.) to climatic variability was studied in the Alps. The aims were (i) to assess tree-ring growth patterns at different spatial-temporal scales; (ii) to identify the climate parameters that explain most of the variability in radial growth at different time domains; and (iii) to study past and current trends in radial growth and climate–growth relationships at different locations. 2. High- and low-frequency stone pine chronologies were compiled for 30 treeline sites on the French and Italian Alps. We used gridded climate data computed from 200 years of instrumental records from an extensive Alpine network. Climate–growth relationships were computed with bootstrap correlation functions and their stationarity and consistency over time assessed with moving correlation. 3. No spatial patterns were detected in stone pine chronology statistics despite the regional clustering observed in tree-ring series and climate responses. This can be attributed to (i) local weather variability; (ii) different biophysical conditions caused by soil moisture, solar radiation, snowmelt dynamics and growing season length; and (iii) forest stand history and age structure, the expression of long-term land use and disturbances. 4. The exceptionally long-term climate records allowed significant stone pine growth response changes to be assessed at both annual and decadal time scales. Winter conditions and spring–summer temperatures mainly affected the growing season length, in addition to site carbon and water balance. Most of these limiting factors varied spatially and temporally along the latitudinal and longitudinal gradients in response to the corresponding changes in local conditions. 5. Our results show evidence of a clear response variability of Pinus cembra to climate limiting factors, at both spatial and temporal scale. Such knowledge extended to other species and regions will provide better estimates of the effect of climate variability on species distribution and dynamics within global change scenarios and more accurate past climate reconstruction and forest ecosystem modelling. [ABSTRACT FROM AUTHOR]

Australian alpine ecosystems are expected to diminish in extent as global warming intensifies. Alpine vegetation patterns are influenced by the duration of snow cover including the presence of snowdrifts in summer, but there is little quantitative information on landscape-scale relationships between vegetation patterns and the frequency of occurrence of persistent summer snowdrifts in the Australian alps. We mapped annual changes in summer snowdrifts in the Kosciuszko alpine region, Australia, from Landsat TM images and modelled the frequency of occurrence of persistent summer snowdrifts from long-term records (1954–2003) of winter snow depth. We then compared vegetation composition and structure among four classes that differed in the frequency of occurrence of persistent summer snowdrifts. We found a curvilinear relationship between annual winter snow depth and the area occupied by persistent snowdrifts in the following summer ( r2 = 0.9756). Only 21 ha (0.42% of study area) was predicted to have supported summer snowdrifts in 80% of the past 50 years, while 440 ha supported persistent summer snow in 10% of years. Mean cover and species richness of vascular plants declined significantly, and species composition varied significantly, as the frequency of summer snow persistence increased. Cushion plants and rushes were most abundant where summer snowdrifts occurred most frequently, and shrubs, grasses and sedges were most abundant in areas that did not support snowdrifts in summer. The results demonstrate strong regional relationships between vegetation composition and structure and the frequency of occurrence of persistent summer snowdrifts. Reductions in winter snow depth due to global warming are expected to lead to substantial reductions in the extent of persistent summer snowdrifts. As a consequence, shrubs, grasses and sedges are predicted to expand at the expense of cushion plants and rushes, reducing landscape vegetation diversity. Fortunately, few vascular plant species (e.g. Ranunculus niphophilus) appear to be totally restricted to areas where summer snow occurs most frequently. The results from this study highlight potential indicator species that could be monitored to assess the effects of global warming on Australian alpine environments. [ABSTRACT FROM AUTHOR]

Increasing atmospheric CO2 and surface temperatures should increase carbonate and silicate weathering rates, directly via warming, and indirectly via the CO2 fertilization effect enhancing plant productivity. Enhanced weathering should in turn increase alkalinity input to the ocean and accelerate long-term CO2 uptake. We added silicate and carbonate weathering and carbonate sediments to an existing global carbon cycle and surface temperature model and subjected it to a range of long-term fossil fuel emissions scenarios, spanning 1100-15,000 GtC in total. Emissions of ≥7350 GtC dissolve all carbonate sediments, and enhanced carbonate and silicate weathering accelerate subsequent CO2 removal from the atmosphere by up to a factor of 4. For 1100-4000 GtC emissions, enhanced weathering accelerates CO2 removal by a factor of 1.5-2.5. However, it takes >1 Myr for silicate weathering to stabilize atmospheric CO2. If land use tends to suppress vegetation and weathering rates on this timescale, then CO2 will stabilize above preindustrial levels. [ABSTRACT FROM AUTHOR]

Dynamic global vegetation models (DGVMs) have been shown to broadly reproduce seasonal and interannual patterns of carbon exchange, as well as realistic vegetation dynamics. To assess the uncertainties in these results associated with model parameterization, the Lund-Potsdam-Jena-DGVM (LPJ-DGVM) is analyzed in terms of model robustness and key sensitive parameters. Present-day global land-atmosphere carbon fluxes are relatively well constrained, despite considerable uncertainty in global net primary production mainly propagating from uncertainty in parameters controlling assimilation rate, plant respiration and plant water balance. In response to climate change, water-use efficiency driven increases in net carbon assimilation by plants, transient changes in vegetation composition and global warming effects on soil organic matter dynamics are robust model results. As a consequence, long-term trends in land-atmosphere fluxes are consistently modeled despite an uncertainty range of -3.35 ± 1.45 PgC yr-1 at the end of the twenty-first century for the specific scenario used. [ABSTRACT FROM AUTHOR]

Global climate models predict continued rapid warming for most of the Arctic throughout the next century. To further understand the response of arctic tundra to climate warming, four sites in northern Alaska were warmed for five to seven consecutive growing seasons using open-top chambers. Sites were located in dry heath and wet meadow communities near Barrow (71°18′N, 156°40′W) and Atqasuk (70°29′N, 157°25′W). Change in plant community composition was measured using a point frame method. During the period of observation, species richness declined in control plots by up to 2.7 species plot−1. Responses to warming varied by site but similar trends included increased canopy height (−0.1 to 2.3 cm) and relative cover of standing dead plant matter (1.5–6.0%) and graminoids (1.8–5.8%) and decreased species diversity (0.1–1.7 species plot−1) and relative cover of lichens (0.2–9.1%) and bryophytes (1.4–4.6%) (parentheses enclose the range of average values for the sites). The response to warming was separated into an initial short-term response assessed after two growing seasons of warming and a secondary longer-term response assessed after an additional three to five growing seasons of warming. The initial responses to warming were similar in the four sites, while the secondary responses varied by site. The response to warming was greater at Barrow than Atqasuk because of a greater initial response at Barrow. However, the long-term response to warming was projected to be greater at Atqasuk because of a greater secondary response at Atqasuk. These findings show that predictions of vegetation change due to climate warming based on manipulative experiments will differ depending on both the duration and plant community on which the study focuses. [ABSTRACT FROM AUTHOR]

Question: Have recent increases in temperature caused a decline in arctic-alpine plants at the southern margin of their range? Location: Above tree line; Glacier National Park, Montana, western USA. Methods: We monitored the abundance of seven arctic-alpine vascular plants at or near the southern limits of their ranges at three sites in Glacier National Park, Montana from 1989 through 2002. In addition we recorded canopy cover of all plant species in sample plots once at the beginning and again at the end of the study. Results: Mean summer temperature during this period averaged 0.6 °C higher than the previous four decades. Results of ordinations with non-metric multidimensional scaling suggested that vegetation moved toward the dry end of a moisture gradient at two sites during the course of the study. At the same time four of the peripheral arctic-alpine indicator species demonstrated 31-65% declines in abundance, while none increased. Conclusions: We cannot rigorously infer causality from our descriptive study; however, changes in both indicator species and the vegetation matrix were consistent with predictions of climate-induced extirpation of high-elevation species and the northern migration of floras. Our results also suggest that species responded to the decade of warming individualistically with little relationship to growth form. [ABSTRACT FROM AUTHOR]

Detecting the response of vegetation to climate forcing as distinct from spatial and temporal variability may be difficult, if not impossible, over the typical duration of most field studies. We analyzed the spatial and interannual variability of plant functional type biomass from field studies in low arctic tussock tundra and compared these to climate change simulations of plant community composition using a dynamic tundra vegetation model (ArcVeg). Spatial heterogeneity of peak season live aboveground biomass was estimated using field samples taken from low arctic tundra at Ivotuk, Alaska (68.5°N, 155.7°W) in 1999. Coefficients of variation for live aboveground biomass at the 1 m2 scale ranged from 14.6% for deciduous shrubs, 18.5% for graminoids and 25.3% for mosses to over 57% for forbs and lichens. Spatial heterogeneity in the ArcVeg dynamic vegetation model was simulated to be greater than the field data, ranging from 37.1% for deciduous shrubs to 107.9% for forbs. Disturbances in the model, such as caribou grazing and freezing–thawing of soil, as well as demographic stochasticity, led to the greater variability in the simulated results. Temporal variances of aboveground live biomass over a 19-year period using data from Toolik Lake, AK fell within the range of field and simulation spatial variances. However, simulations using ArcVeg suggest that temporal variability can be substantially less than site-scale spatial variability. Field data coupled with ArcVeg simulations of climate change scenarios indicate that some changes in plant community composition may be detectable within two decades following the onset of warming, and shrubs and mosses might be the key indicators of community change. Model simulations also project increasing landscape scale spatial heterogeneity (particularly of shrubs) with increasing temperatures. [ABSTRACT FROM AUTHOR]

Aim Predictions of vegetation change with global warming require models that accurately reflect physiological processes underlying growth limitations and species distributions. However, information about environmental controls on physiology and consequent effects on species boundaries and ecosystem functions such as production is limited, especially for forested wetlands that are potentially important carbon sinks. Location The bald cypress ( Taxodium distichum) region of the south-eastern United States was studied to examine how production of an important forested wetland varies with latitude and temperature as well as local hydrology. Methods We used published data to analyse litter production across a latitudinal gradient from 26.2 to 37.8° N to determine how bald cypress swamps might respond to alternate climate conditions and what changes might occur throughout the distributional range. Results Litterfall rates followed a bell shaped curve, indicating that production was more limited at the distributional boundaries ( c. 225 g/m² year-1) compared to the mid-range (795-1126 g/m² year-1). This pattern suggests that conditions are suboptimal near both boundaries and that the absence of populations outside this latitudinal range may be largely due to physiological constraints on the carbon balance of dominant species. While dispersal limitations cannot be totally discounted, competition with other wetland types at the extremes of the range does not seem likely to be important because the relative basal area of bald cypress does not decrease near the edges of the range. Impaired hydrology depressed production across the entire range, but more in the south than the north. Main conclusions Our findings suggest that (1) physiological limitations constrain biotic boundaries of bald cypress swamps; (2) future changes in global temperature would affect litter production in a nonlinear manner across the distributional range; (3) local changes in hydrology may interact with climate to further reduce litter production, particularly at lower latitudes; and (4) southernmost forests could be extirpated if environmental conditions compromise carbon balance and water-use efficiency of trees. [ABSTRACT FROM AUTHOR]

Feedback interactions between terrestrial vegetation and climate could alter predictions of the responses of both systems to a doubling of atmospheric CO2. Most previous analyses of biosphere responses to global warming have used output from equilibrium simulations of current and future climate, as compared to more recently available transient GCM simulations. We compared the vegetation responses to these two different classes of GCM simulation (equilibrium and transient) using an equilibrium vegetation distribution model, MAPSS. Average climatologies were extracted from the transient GCM simulations for current and doubled (2×) CO2 concentrations (taken to be 2070–2099) for use by the equilibrium vegetation model. However, the 2 × CO2 climates extracted from the transient GCM simulations were not in equilibrium, having attained only about 65% of their eventual 2 × CO2 equilibrium temperature change. Most of the differences in global vegetation response appeared to be related to a very different simulated change in the pole to tropic temperature gradient. Also, the transient scenarios produced much larger increases of precipitation in temperate latitudes, commensurate with a minimum in the latitudinal temperature change. Thus, the (equilibrium) global vegetation response, under the transient scenarios, tends more to a greening than a decline in vegetation density, as often previously simulated. It may be that much of the world could become greener during the early phases of global warming, only to reverse in later, more equilibrial stages. However, whether or not the world’s vegetation experiences large drought-induced declines or perhaps large vegetation expansions in early stages could be determined by the degree to which elevated CO2 will actually benefit natural vegetation, an issue still under debate. There may occur oscillations, perhaps on long timescales, between greener... [ABSTRACT FROM AUTHOR]