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Understanding the effects of simulated warming on photosynthetic performance of aquatic plants may provide strong supports for predicting future dynamics of wetland ecosystems in the context of climate change. The plateau wetlands located in Yunnan province are highly sensitive to climate warming due to their high altitude and cold temperature. Here, we conducted a temperaturecontrolled experiment using two temperature manipulations (ambient temperature as the control and 2°C higher than ambient temperature as the warmed treatment) to determine the photosynthetic characteristics of two lakeside dominant species (Scirpus validus Vahl and Typha orientalis C. Presl.) in Dianchi Lake. Net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate of S. validus that grew under warmed treatment were all significantly higher than those under the control. Gs and Ci of T. orientalis showed similar patterns as S. validus did. For the response curves of Pn to photosynthetic active radiation (Pn-PAR) and intercellular CO2 concentration (Pn-Ci), S. validus had higher Pn values under elevated temperatures than the control, while Pn-PAR and Pn-Ci curves of T. orientalis did not separate clearly under two temperature scenarios. Both S. validus and T. orientalis had higher maximum net photosynthetic rate, light saturation point, dark respiration rate, the maximum rate of RuBP carboxylation (Vcmax), maximum electron transport rate driving RuBP regeneration (Jmax), the ratio of Vcmax to Jmax, triosephosphate utilization, and 1, 5-bishosphate carboxylase ribulose content under warmed treatment than those under the control. This study provides a preliminary step for predicting the future primary production and vegetation dynamics of plateau wetlands in Yunnan province. [ABSTRACT FROM AUTHOR]

Soils contain more carbon than plants or the atmosphere, and sensitivities of soil organic carbon (SOC) stocks to changing climate and plant productivity are a major uncertainty in global carbon cycle projections. Despite a consensus that microbial degradation and mineral stabilization processes control SOC cycling, no systematic synthesis of long-term warming and litter addition experiments has been used to test process-based microbe-mineral SOC models. We explored SOC responses to warming and increased carbon inputs using a synthesis of 147 field manipulation experiments and five SOC models with different representations of microbial and mineral processes. Model projections diverged but encompassed a similar range of variability as the experimental results. Experimental measurements were insufficient to eliminate or validate individual model outcomes. While all models projected that CO2 efflux would increase and SOC stocks would decline under warming, nearly one-third of experiments observed decreases in CO2 flux and nearly half of experiments observed increases in SOC stocks under warming. Long-term measurements of C inputs to soil and their changes under warming are needed to reconcile modeled and observed patterns. Measurements separating the responses of mineral-protected and unprotected SOC fractions in manipulation experiments are needed to address key uncertainties in microbial degradation and mineral stabilization mechanisms. Integrating models with experimental design will allow targeting of these uncertainties and help to reconcile divergence among models to produce more confident projections of SOC responses to global changes. [ABSTRACT FROM AUTHOR]

Global change drivers (elevated atmospheric CO2, rising surface temperatures, and changes in resource availability) have significant consequences for global plant communities. In the northern sagebrush steppe of North America, the invasive annual grass Bromus tectorum (cheatgrass) is expected to benefit from projected warmer and drier conditions, as well as increased CO2 and nutrient availability. In growth chambers, we addressed this expectation using two replacement series experiments designed to test competition between B. tectorum and the native perennial bunchgrass Pseudoroegneria spicata. In the first experiment, we tested the effects of elevated temperature, decreased water and increased nutrient availability, on competition between the two species. In the second, we tested the effects of elevated atmospheric CO2 and decreased water availability on the competitive dynamic. In both experiments, under all conditions, P. spicata suppressed B. tectorum, though, in experiment one, warmer and drier conditions and elevated nutrient availability increased B. tectorum’s competitiveness. In experiment two, when grown in monoculture, both species responded positively to elevated CO2. However, when grown in competition, elevated CO2 increased P. spicata’s suppressive effect, and the combination of dry soil conditions and elevated CO2 enhanced this effect. Our findings demonstrate that B. tectorum competitiveness with P. spicata responds differently to global change drivers; thus, future conditions are unlikely to facilitate B. tectorum invasion into established P. spicata communities of the northern sagebrush steppe. However, disturbance (e.g., fire) to these communities, and the associated increase in soil nutrients, elevates the risk of B. tectorum invasion. [ABSTRACT FROM AUTHOR]

A number of modelling results suggested thermocline shifts as a consequence of global climate change in stratifying lakes. Abundance and composition of the phytoplankton assemblage is strongly affected by the stratification patterns, and therefore, change in the thermocline position might have a substantial effect on this community or even on the whole lake ecosystem. In this study, thermocline depths in large mesocosms installed in Lake Stechlin (Germany) were deepened by 2 meters and phytoplankton changes were analysed by comparing changes to untreated mesocosms. Higher amounts of SRP were registered in the hypolimnion of treatment mesocosms than in the controls, and there were no differences in the epilimnion. Small but significant changes were observed on the phytoplankton community composition related to the effect of deepening the thermocline; however, it was weaker than the yearly successional changes. The most remarkable differences were caused by Planktothrix rubescens and by chlorophytes. P. rubescens became strongly dominant at the end of the experiment in the mesocosms, and in the open lake as well. The results of the experiment cannot clearly support the proliferation of cyanobacteria in general; however, the deepened thermocline can modify the behaviour of some species, as was observed in case of P. rubescens. [ABSTRACT FROM AUTHOR]

Dryland shrub communities have been degraded by a range of disturbances and now face additional stress from global climate change. The spring/summer growing season of the North American sagebrush biome is projected to become warmer and drier, which is expected to facilitate the expansion of the invasive annual grass Bromus tectorum (cheatgrass) and alter its response to fire in the northern extent of the biome. We tested these predictions with a factorial experiment with two levels of burning (spring burn and none) and three climate treatments (warming, warming + drying, and control) that was repeated over 3 years in a Montana sagebrush steppe. We expected the climate treatments to make B. tectorum more competitive with the native perennial grass community, especially Pseudoroegneria spicata, and alter its response to fire. Experimental warming and warming + drying reduced B. tectorum cover, biomass, and fecundity, but there was no response to fire except for fecundity, which increased; the native grass community was the most significant factor that affected B. tectorum metrics. The experimental climate treatments also negatively affected P. spicata, total native grass cover, and community biodiversity, while fire negatively affected total native grass cover, particularly when climate conditions were warmer and drier. Our short-term results indicate that without sufficient antecedent moisture and a significant disruption to the native perennial grass community, a change in climate to a warmer and drier spring/summer growing season in the northern sagebrush biome will not facilitate B. tectorum invasion or alter its response to fire. [ABSTRACT FROM AUTHOR]

European beech ( Fagus sylvatica L.) forests in the Iberian Peninsula are a clear example of a temperate forest tree species at the rear edge of its large distribution area in Europe. The expected drier and warmer climate may alter tree growth and species distribution. Consequently, the peripheral populations will most likely be the most threatened ones. Four peripheral beech forests in the Iberian Peninsula were studied in order to assess the climate factors influencing tree growth for the last six decades. The analyses included an individual tree approach in order to detect not only the changes in the sensitivity to climate but also the potential size-mediated sensitivity to climate. Our results revealed a dominant influence of previous and current year summer on tree growth during the last six decades, although the analysis in two equally long periods unveiled changes and shifts in tree sensitivity to climate. The individual tree approach showed that those changes in tree response to climate are not size dependent in most of the cases. We observed a reduced negative effect of warmer winter temperatures at some sites and a generalized increased influence of previous year climatic conditions on current year tree growth. These results highlight the crucial role played by carryover effects and stored carbohydrates for future tree growth and species persistence. [ABSTRACT FROM AUTHOR]

Since apple fruit skin reddens poorly under warmer climates, new apple cultivars are desired that are adapted to global warming in terms of bearing well-reddened fruit. We developed a simple sequence repeat marker, Mdo.chr9.4, which is suitable for red skin color selection. It amplified four alleles (Mdo.chr9.4-R, Mdo.chr9.4-Y, Mdo.chr9.4-Y, and Mdo.chr9.4-Y) distinguished by length. Mdo.chr9.4-R associated with MdMYB1- 1 which confers red fruit skin. The presence of Mdo.chr9.4-R was consistent with empirical skin color in all 160 tested accessions. Mdo.chr9.4 was identified as the only significant marker that contributed to red skin color intensity by a genome wide association study (GWAS), and it accounted for 52.0% of phenotypic variation, confirming that MdMYB1 was the major and principal determinant of fruit skin color in apples. Individuals with a homozygous state of Mdo.chr9.4-R (dose 2) were significantly redder than those showing a heterozygote state (dose 1) in both the accession set and full-sib families, indicating a partially dominant effect of MdMYB1- 1. Therefore, the selection of dose 2 individuals would target individuals with intensive red skin. We applied Mdo.chr9.4 to several application populations using a time and cost-efficient genotyping system developed in the present study. This system, along with Mdo.chr9.4, provide advanced marker-assisted breeding for intensive red skin color apples adapted to a global warming climate. [ABSTRACT FROM AUTHOR]

Tropical rainforest plays an important role in the global carbon cycle, accounting for a large part of global net primary productivity and contributing to CO sequestration. The objective of this work is to simulate potential changes in the rainforest biome in Central America subject to anthropogenic climate change under two emissions scenarios, RCP4.5 and RCP8.5. The use of a dynamic vegetation model and climate change scenarios is an approach to investigate, assess or anticipate how biomes respond to climate change. In this work, the Inland dynamic vegetation model was driven by the Eta regional climate model simulations. These simulations accept boundary conditions from HadGEM2-ES runs in the two emissions scenarios. The possible consequences of regional climate change on vegetation properties, such as biomass, net primary production and changes in forest extent and distribution, were investigated. The Inland model projections show reductions in tropical forest cover in both scenarios. The reduction of tropical forest cover is greater in RCP8.5. The Inland model projects biomass increases where tropical forest remains due to the CO fertilization effect. The future distribution of predominant vegetation shows that some areas of tropical rainforest in Central America are replaced by savannah and grassland in RCP4.5. Inland projections under both RCP4.5 and RCP8.5 show a net primary productivity reduction trend due to significant tropical forest reduction, temperature increase, precipitation reduction and dry spell increments, despite the biomass increases in some areas of Costa Rica and Panama. This study may provide guidance to adaptation studies of climate change impacts on the tropical rainforests in Central America. [ABSTRACT FROM AUTHOR]

Long-term measurements of ecological effects of warming are often not statistically significant because of annual variability or signal noise. These are reduced in indicators that filter or reduce the noise around the signal and allow effects of climate warming to emerge. In this way, certain indicators act as medium pass filters integrating the signal over years-to-decades. In the Alaskan Arctic, the 25-year record of warming of air temperature revealed no significant trend, yet environmental and ecological changes prove that warming is affecting the ecosystem. The useful indicators are deep permafrost temperatures, vegetation and shrub biomass, satellite measures of canopy reflectance (NDVI), and chemical measures of soil weathering. In contrast, the 18-year record in the Greenland Arctic revealed an extremely high summer air-warming of 1.3 °C/decade; the cover of some plant species increased while the cover of others decreased. Useful indicators of change are NDVI and the active layer thickness. [ABSTRACT FROM AUTHOR]

The abundance and diversity of soil bacterial and fungal communities in a wheat field under elevated atmospheric CO concentrations and increased air temperatures were investigated using qPCR and pyrosequencing. Elevated CO concentrations significantly increased the abundances of bacteria and fungi, and an increase of air temperatures significantly reduced fungal abundance. We found that Proteobacteria, Bacteroidetes, Chloroflexi, and Ascomycota were the most abundant bacterial and fungal phyla in the wheat field soil. Elevated CO concentrations and increased air temperatures had no significant effect on the bacterial alpha diversity, whereas fungal richness was reduced under warming treatments. Moreover, we note that certain bacterial and fungal groups responded differentially to elevated CO concentrations and increased air temperatures, and fungal species were highly sensitive to climatic changes. [ABSTRACT FROM AUTHOR]

Warming of the climate system is unequivocal, and the change of climate variables will eventually have a great impact on vegetation cover and agricultural practices, especially in the arid area Xinjiang in China, whose agriculture and ecosystems are heavily vulnerable to climate change. In this paper, normalized difference vegetation index (NDVI) was used to study the vegetation growth and its response to climate change in Xinjiang. Firstly, two NDVI datasets (Global Inventory Modeling and Mapping Studies (GIMMS) and Moderate Resolution Imaging Spectroradiometer (MODIS)) were merged through a pixel-wise regression analysis to obtain a long time series of NDVI data, and then, relationships between yearly NDVI and yearly climate variables, and monthly NDVI and monthly climate variables were extensively investigated for grassland and cropland in northern and southern Xinjiang, respectively. Results show the following: (1) there was an increasing trend in NDVI for both grassland and cropland in both northern and southern Xinjiang over the past decades and trends were significant except that for grassland in northern Xinjiang; (2) precipitation and evaporation were more important than temperature for grassland in northern Xinjiang, while precipitation and temperature were more important than evaporation for grassland in southern Xinjiang and cropland in both northern and southern Xinjiang; (3) NDVI was highly correlated with accumulated monthly precipitation instead of monthly precipitation, and there was a lagged effect of precipitation, temperature, and evaporation on NDVI change. However, lagged effects were only significant in specific months. The results could be helpful to agricultural practices; e.g., based on lagged effect of precipitation, irrigation in July is very important for crop growth. [ABSTRACT FROM AUTHOR]

Global warming is triggering some species to shift towards the poles or higher elevations, but spatial translocation is also influenced by land-use regime or intensity. The Himalayan climate is getting warmer and land use has changed, reducing in intensity in some areas. We estimated the upper species limit (USL) and tree limit of Abies spectabilis (D. Don) Spach and assessed whether these have changed over recent years. We hypothesise an upslope shift in response to enhanced temperature and changes in land-use intensity. Our four transects were located in treeline ecotones of two protected areas in Nepal, namely Manaslu Conservation Area (3 transects) and Gaurishankar Conservation Area (1 transect). Transects (20 m wide) ran from the USL of A. spectabilis down towards the treeline and beyond to the forest line. Length of each transect varied depending on local conditions. Co-ordinates, elevation, height and age of each A. spectabilis individual along the transects were recorded. We noted an upward shift of both the USL and the tree limit. The rate of shift was ca. 20 m per decade for the USL and 12 m per decade for the tree limit in the area of reduced land-use intensity and in the area with no change in land use, 5 m per decade for the USL, but almost nil for tree limit. The seedling density was higher below the treeline than above. Reduced intensity of land use was the dominant factor in upslope shift of A. spectabilis at both the USL and the tree limit. [ABSTRACT FROM AUTHOR]

Key message : Pollen heat acclimation. Abstract: As a consequence of global warming, plants have to face more severe and more frequently occurring periods of high temperature stress. While this affects the whole plant, development of the male gametophyte, the pollen, seems to be the most sensitive process. Given the great importance of functioning pollen for the plant life cycle and for agricultural production, it is necessary to understand this sensitivity. While changes in temperature affect different components of all cells and require a cellular response and acclimation, high temperature effects and responses in developing pollen are distinct from vegetative tissues at several points. This could be related to specific physiological characteristics of developing pollen and supporting tissues which make them vulnerable to high temperature, or its derived effects such as ROS accumulation and carbohydrate starvation. But also expression of heat stress-responsive genes shows unique patterns in developing pollen when compared to vegetative tissues that might explain the failure to withstand high temperatures. As an alternative to viewing pollen failure under high temperature as a result of inherent sensitivity of a specific developmental process, we end by discussing whether it might actually be an adaptation. [ABSTRACT FROM AUTHOR]

Current climate change affects the competitive ability and reproductive success of many species, leading to local extinctions, adjustment to novel local conditions by phenotypic plasticity or rapid adaptation, or tracking their optima through range shifts. However, many species have limited ability to expand to suitable areas. Altitudinal gradients, with abrupt changes in abiotic conditions over short distances, represent 'natural experiments' for the evaluation of ecological and evolutionary responses under scenarios of climate change. Nothofagus pumilio is the tree species which dominates as pure stands the montane forests of Patagonia. We evaluated the adaptive value of variation in quantitative traits of N. pumilio under contrasting conditions of the altitudinal gradient with a long-term reciprocal transplant experimental design. While high-elevation plants show little response in plant, leaf, and phenological traits to the experimental trials, low-elevation ones show greater plasticity in their responses to changing environments, particularly at high elevation. Our results suggest a relatively reduced potential for evolutionary adaptation of high-elevation genotypes, and a greater evolutionary potential of low-elevation ones. Under global warming scenarios of forest upslope migration, high-elevation variants may be outperformed by low-elevation ones during this process, leading to the local extinction and/or replacement of these genotypes. These results challenge previous models and predictions expected under global warming for altitudinal gradients, on which the leading edge is considered to be the upper treeline forests. [ABSTRACT FROM AUTHOR]

The article presents abstracts on topics related to phytopathology including the development of CRISPR/Cas9 genome editing technology, the potential impact of global warming on plants in Israel and the creation of anti-crop weapons based on plant pathogens.

In recent years, with the constant change in the global climate, the effect of climate factors on net primary productivity (NPP) has become a hot research topic. However, two opposing views have been presented in this research area: global NPP increases with global warming, and global NPP decreases with global warming. The main reasons for these two opposite results are the tremendous differences among seasonal and annual climate variables, and the growth of plants in accordance with these climate variables. Therefore, it will fail to fully clarify the relation between vegetation growth and climate changes by research that relies solely on annual data. With seasonal climate variables, we may clarify the relation between vegetation growth and climate changes more accurately. Our research examined the arid and semiarid areas in China (ASAC), which account for one quarter of the total area of China. The ecological environment of these areas is fragile and easily affected by human activities. We analyzed the influence of climate changes, especially the changes in seasonal climate variables, on NPP, with Climatic Research Unit (CRU) climatic data and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite remote data, for the years 2000-2010. The results indicate that: for annual climatic data, the percentage of the ASAC in which NPP is positively correlated with temperature is 66.11%, and 91.47% of the ASAC demonstrates a positive correlation between NPP and precipitation. Precipitation is more positively correlated with NPP than temperature in the ASAC. For seasonal climatic data, the correlation between NPP and spring temperature shows significant regional differences. Positive correlation areas are concentrated in the eastern portion of the ASAC, while the western section of the ASAC generally shows a negative correlation. However, in summer, most areas in the ASAC show a negative correlation between NPP and temperature. In autumn, precipitation is less important in the west, as opposed to the east, in which it is critically important. Temperatures in winter are a limiting factor for NPP throughout the region. The findings of this research not only underline the importance of seasonal climate variables for vegetation growth, but also suggest that the effects of seasonal climate variables on NPP should be explored further in related research in the future. [ABSTRACT FROM AUTHOR]

Change in plant phenology is one of the most sensitive ecological responses to climate warming. Little information is known about the effects of climate warming on phenology of urban tree species in the northern forest of China. In this study, we investigated the phenological characteristics of the main tree species in the urban forest of Shengyang City in China and the correlation between phenology and atmospheric temperature from the discontinuous data during past 42 years over three time periods (from 1962 to 1965, 1977 to 1978, and 2000 to 2005). The results showed that the annual average temperature in Shenyang City showed an increasing trend and increased by 0.96°C from 1962 to 2005 due to climate warming. The germination phenology of the urban trees was negatively correlated with the temperature in winter and early spring. The leafing phenology was mainly influenced by the temperature in spring before leafing. Influenced by climate warming, the germination, leafing, and flowering phenologies of this urban forest in 2005 were 14, 13, and 10 days earlier than those in 1962, respectively. We inferred that further warming in winter might prolong the growing season of urban trees in the northern forest of China. [ABSTRACT FROM AUTHOR]

Understanding spatial and temporal dynamics of land surface phenology (LSP) and its driving forces are critical for providing information relevant to short- and long-term decision making, particularly as it relates to climate response planning. With the third generation Global Inventory Monitoring and Modeling System (GIMMS3g) Normalized Difference Vegetation Index (NDVI) data and environmental data from multiple sources, we investigated the spatio-temporal changes in the start of the growing season (SOS) in southern African savannas from 1982 through 2010 and determined its linkage to environmental factors using spatial panel data models. Overall, the SOS occurs earlier in the north compared to the south. This relates in part to the differences in ecosystems, with northern areas representing high rainfall and dense tree cover (mainly tree savannas), whereas the south has lower rainfall and sparse tree cover (mainly bush and grass savannas). From 1982 to 2010, an advanced trend was observed predominantly in the tree savanna areas of the north, whereas a delayed trend was chiefly found in the floodplain of the north and bush/grass savannas of the south. Different environmental drivers were detected within tree- and grass-dominated savannas, with a critical division being represented by the 800 mm isohyet. Our results supported the importance of water as a driver in this water-limited system, specifically preseason soil moisture, in determining the SOS in these water-limited, grass-dominated savannas. In addition, the research pointed to other, often overlooked, effects of preseason maximum and minimum temperatures on the SOS across the entire region. Higher preseason maximum temperatures led to an advance of the SOS, whereas the opposite effects of preseason minimum temperature were observed. With the rapid increase in global change research, this work will prove helpful for managing savanna landscapes and key to predicting how projected climate changes will affect regional vegetation phenology and productivity. [ABSTRACT FROM AUTHOR]

Due to global warming since the Last Glacial Maximum, many plant populations have retreated to mountain tops, i.e., sky-islands, which are isolated by low-elevation barriers and inhospitable habitats. Under projected environmental changes, these populations may decline and face local extinction. Iris ensata Thunb. populations at the species' most southern distribution range are in this position. We used eight polymorphic nuclear microsatellite markers and three fragments of chloroplast genome to analyze population structure of six extant sky-island populations of I. ensata. A total of 83 alleles were found across 192 individuals from six populations. High levels of intra-population genetic diversity ( H = 0.578, H = 0.608) of I. ensata were detected. Moderate but significant levels of genetic differentiation were also found among the populations ( F = 0.133, P < 0.001). Mantel test showed no isolation-by-distance pattern ( r = 0.339, P = 0.161). Assignment analysis classified all individuals into five groups, and four populations were dominated by only one group. Five chloroplast DNA (cpDNA) haplotypes were found, and one was shared by all populations. Two populations contained a private haplotype. Long-term fragmentation, but relatively large population sizes and restricted gene flow among populations, contributed to the above patterns. Under projected habitat changes, the studied populations are at risk of local extinction. We identified three populations that had a high priority of ex situ conservation to be the source populations for the future assisted migration. Number of individuals, how to select individuals, and a potential recipient site were discussed. [ABSTRACT FROM AUTHOR]

Understanding how species respond to climate change is critical for forecasting the future dynamics and distribution of pests, diseases and biological diversity. Although ecologists have long acknowledged species' direct physiological and demographic responses to climate, more recent work suggests that these direct responses can be overwhelmed by indirect effects mediated via other interacting community members. Theory suggests that some of the most dramatic impacts of community change will probably arise through the assembly of novel species combinations after asynchronous migrations with climate. Empirical tests of this prediction are rare, as existing work focuses on the effects of changing interactions between competitors that co-occur today. To explore how species' responses to climate warming depend on how their competitors migrate to track climate, we transplanted alpine plant species and intact plant communities along a climate gradient in the Swiss Alps. Here we show that when alpine plants were transplanted to warmer climates to simulate a migration failure, their performance was strongly reduced by novel competitors that could migrate upwards from lower elevation; these effects generally exceeded the impact of warming on competition with current competitors. In contrast, when we grew the focal plants under their current climate to simulate climate tracking, a shift in the competitive environment to novel high-elevation competitors had little to no effect. This asymmetry in the importance of changing competitor identity at the leading versus trailing range edges is best explained by the degree of functional similarity between current and novel competitors. We conclude that accounting for novel competitive interactions may be essential to predict species' responses to climate change accurately. [ABSTRACT FROM AUTHOR]

In the tundra, mosses play an important functional role regulating belowground and ecosystem processes, but there is still considerable uncertainty about how tundra moss communities will respond to climate change. We examined the effects of 5 years of in situ air and soil warming on net primary productivity (NPP), carbon (C) and nitrogen (N) isotope signatures (δC and δN), and C:N in dominant Alaskan tundra mosses. Air warming increased mean air temperatures by up to 0.5°C and resulted in an 80-90% reduction in NPP in the feather moss Pleurozium and the peat moss Sphagnum. Soil warming increased permafrost thaw depth by 12-18%, upper soil water content by 23-27%, and resulted in a threefold increase in Sphagnum NPP. δC was positively correlated with moss NPP, and increased by 0.5-1‰ in all mosses under soil warming. C:N was reduced in Sphagnum and Pleurozium, due to increases in tissue %N in the soil warming treatment, suggesting that moss N availability could increase as temperatures increases. Higher N availability in warmer conditions, however, may be offset by unfavorable moisture conditions for moss growth. Similar to responses in tundra vascular plant communities, our results forecast interspecific differences in productivity among tundra mosses. Specifically, air warming may reduce productivity in Sphagnum and Pleurozium, but soil warming could offset this response in Sphagnum. Such responses may lead to changes in tundra moss community structure and function as temperatures increase that have the potential to alter tundra C and N cycling in a future climate. [ABSTRACT FROM AUTHOR]

For decades, ecosystem scientists have used global warming potentials (GWPs) to compare the radiative forcing of various greenhouse gases to determine if ecosystems have a net warming or cooling effect on climate. On a conceptual basis, the continued use of GWPs by the ecological community may be untenable because the use of GWPs requires the implicit assumption that greenhouse gas emissions occur as a single pulse; this assumption is rarely justified in ecosystem studies. We present two alternate metrics-the sustained-flux global warming potential (SGWP, for gas emissions) and the sustained-flux global cooling potential (SGCP, for gas uptake)-for use when gas fluxes persist over time. The SGWP is generally larger than the GWP (by up to ~40%) for both methane and nitrous oxide emissions, creating situations where the GWP and SGWP metrics could provide opposing interpretations about the climatic role of an ecosystem. Further, there is an asymmetry in methane and nitrous oxide dynamics between persistent emission and uptake situations, producing very different values for the SGWP vs. SGCP and leading to the conclusion that ecosystems that take up these gases are very effective at reducing radiative forcing. Although the new metrics are more realistic than the GWP for ecosystem fluxes, we further argue that even these metrics may be insufficient in the context of trying to understand the lifetime climatic role of an ecosystem. A dynamic modeling approach that has the flexibility to account for temporally variable rates of greenhouse gas exchange, and is not limited by a fixed time frame, may be more informative than the SGWP, SGCP, or GWP. Ultimately, we hope this article will stimulate discussion within the ecosystem science community about the most appropriate way(s) of assessing the role of ecosystems as regulators of global climate. [ABSTRACT FROM AUTHOR]

Key message: This study fine mapped and validated a QTL on rice chromosome 4 that increases spikelet fertility under high temperature (over 37 °C) at the flowering stage. Abstract: Climate change has a negative effect on crop production and food security. Understanding the genetic mechanism of heat tolerance and developing heat-tolerant varieties is essential to cope with future global warming. Previously, we reported on a QTL ( qHTSF4.1) from an IR64/N22 population responsible for rice spikelet fertility under high-temperature stress at the flowering stage. To further fine map and validate the effect of qHTSF4.1, PCR-based SNP markers were developed and used to genotype BCF, BCF, BCF, and BCF populations from the same cross. The interval of the QTL was narrowed down to about 1.2 Mb; however, further recombination was not identified even with a large BCF population that was subsequently developed and screened. The sequence in the QTL region is highly conserved and a large number of genes in the same gene family were observed to be clustered in the region. The QTL qHTSF4.1 consistently increased spikelet fertility in all of the backcross populations. This was confirmed using 24 rice varieties. Most of the rice varieties with the QTL showed a certain degree of heat tolerance under high-temperature conditions. In a BCF population with clean background of IR64, QTL qHTSF4.1 increased spikelet fertility by about 15 %. It could be an important source for enhancing heat tolerance in rice at the flowering stage. PCR-based SNP markers developed in this study can be used for QTL introgression and for pyramiding with other agronomically important QTLs/genes through marker-assisted selection. [ABSTRACT FROM AUTHOR]

There is growing recognition that changes in vegetation composition can strongly influence peatland carbon cycling, with potential feedbacks to future climate. Nevertheless, despite accelerated climate and vegetation change in this ecosystem, the growth responses of peatland plant species to combined warming and vegetation change are unknown. Here, we used a field warming and vegetation removal experiment to test the hypothesis that dominant species from the three plant functional types present (dwarf-shrubs: Calluna vulgaris; graminoids: Eriophorum vaginatum; bryophytes: Sphagnum capillifolium) contrast in their growth responses to warming and the presence or absence of other plant functional types. Warming was accomplished using open top chambers, which raised air temperature by approximately 0.35 °C, and we measured air and soil microclimate as potential mechanisms through which both experimental factors could influence growth. We found that only Calluna growth increased with experimental warming (by 20 %), whereas the presence of dwarf-shrubs and bryophytes increased growth of Sphagnum (46 %) and Eriophorum (20 %), respectively. Sphagnum growth was also negatively related to soil temperature, which was lower when dwarf-shrubs were present. Dwarf-shrubs may therefore promote Sphagnum growth by cooling the peat surface. Conversely, the effect of bryophyte presence on Eriophorum growth was not related to any change in microclimate, suggesting other factors play a role. In conclusion, our findings reveal contrasting abiotic and biotic controls over dominant peatland plant growth, suggesting that community composition and carbon cycling could be modified by simultaneous climate and vegetation change. [ABSTRACT FROM AUTHOR]

Connectivity between ecosystems is of ecological relevance, especially when adjacent areas of contrasting productivity are compared. High-productive rocky shores dominated by macroalgae are one of the most important sources of wrack subsidies linked to low-productive sandy beaches. Rocky bed communities from nearshore environments are affected by shifts in ultraviolet radiation (UVR) and temperature. Therefore, any alteration to macroalgal traits, in terms of nutritional quality, pigments, or phlorotannins, due to environmental stress could trigger cascading changes in the food web of recipient ecosystems. To examine the effects of climate-associated variables, we mimicked a rocky intertidal ecosystem by constructing a set of mesocosm tanks harboring two macroalgal species, the native Laminaria ochroleuca and the non-indigenous Sargassum muticum, subjected to a combination of UVR and temperatures. We used the manipulated macroalgae to explore the effects of climate stress variables on the wrack-reliant amphipod Talitrus saltator. The macroalgae displayed differential and variable responses to UVR and temperature manipulations. L. ochroleuca nutrient quality and phlorotannins decreased with elevated UVR and at warm temperatures. S. muticum seemed to be more tolerant to stress conditions, and phlorotannin production was induced by elevated UVB. We documented concomitant effects induced by the treated macroalgae on the food consumption of T. saltator. We suggest that macroalgae became less palatable to T. saltator because chemical defenses were gained rather than a significant change in the nutritive value occurring. We hypothesize that the effects of warming and enhanced UVR on macroalgae might shift source-sink dynamics between connected ecosystems. Understanding the way in which climate-associated variables interact and influence subsidies in recipient ecosystems is of paramount relevance to assess the broad consequences of climate change and its proper management. [ABSTRACT FROM AUTHOR]

Aims: We explored how climate warming and increased atmospheric nitrogen (N) deposition may influence grass litter decomposition over time, how litter quality versus environmental effects contribute to these responses, and the importance of these responses over winter. Methods: We used litter bags to examine decomposition over 2 years in a warming and N addition field experiment, and examined the contributions of litter quality and environment to these responses by transferring litter reciprocally between the treatment plots and a common garden. Results: Warming increased mass loss over the first year for Bromus inermis litter, which was consistent with the litter quality response, but by the second year there was no overall warming effect, and this change coincided with a negative environmental effect of warming. N addition increased mass loss and was more influential than warming in the early stages of Poa pratensis litter decomposition; the N effect appeared to be driven primarily by litter quality. Winter decomposition was not a substantial component of the treatment responses. Conclusions: Our results indicate that litter quality and environmental effects play different roles at different time scales in the decomposition responses of grass litter to warming and N addition, and these responses can be species specific. [ABSTRACT FROM AUTHOR]

Climate change is strong in the Amazon basin. Climate models consistently predict widespread warmer and drier conditions by the end of the 21st century. As a consequence, water stress will increase throughout the region. We here review current understanding of the impact of climate change on forests' distribution patterns, species diversity and ecosystem functioning of lowland rainforests in the Amazon basin. We reviewed 192 studies that provide empirical evidence, historical information and theoretical models. Over millions of years rainforests expansions and contractions have been accompanied by changes in the diversity and productivity of forests. In the future, drought will produce forest contractions along the forest edges and the savanna ecotone, causing an extensive savannization, particularly in the east. In terms of diversity, warming will reduce plant species survival by decreasing their productivity, but extinctions may also occur as a result of vegetation disequilibrium, as many plants, dispersal and pollinator species will fail to track changing climate; mild drought kills understory trees and severe drought may eliminate canopy trees as well. Severe droughts will thus produce directional changes in species composition, although these shifts may vary among forests on different soil types. In terms of ecosystem functioning, droughts will reduce root growth and standing biomass and may shift the Amazonian forest from being CO sinks to become CO sources. Physiological and ecological responses to warming and the feedback between vegetation and climate are still not completely understood. In particular, experimental assays that allow direct conclusions on the response of Amazonian plants to the predicted climatic conditions are needed. Such studies could make possible more reliable estimates of future climatic and vegetation responses. [ABSTRACT FROM AUTHOR]

Global warming is one of the gravest threats to crop production and environmental sustainability. Rice, the staple food of more than half of the world's population, is the most prominent cause of greenhouse gas (GHG) emissions in agriculture and gives way to global warming. The increasing demand for rice in the future has deployed tremendous concerns to reduce GHG emissions for minimizing the negative environmental impacts of rice cultivation. In this review, we presented a contemporary synthesis of existing data on how crop management practices influence emissions of GHGs in rice fields. We realized that modifications in traditional crop management regimes possess a huge potential to overcome GHG emissions. We examined and evaluated the different possible options and found that modifying tillage permutations and irrigation patterns, managing organic and fertilizer inputs, selecting suitable cultivar, and cropping regime can mitigate GHG emissions. Previously, many authors have discussed the feasibility principle and the influence of these practices on a single gas or, in particular, in the whole agricultural sector. Nonetheless, changes in management practices may influence more than one gas at the same time by different mechanisms or sometimes their effects may be antagonistic. Therefore, in the present attempt, we estimated the overall global warming potential of each approach to consider the magnitude of its effects on all gases and provided a comprehensive assessment of suitable crop management practices for reducing GHG emissions in rice culture. [ABSTRACT FROM AUTHOR]

This study examines climate change impacts (increased temperature and pCO) on canopy-forming Desmarestia anceps and D. menziesii from the western Antarctic Peninsula during the austral summer-winter of 2013. These are ecologically important species that play a role functionally equivalent to kelp forests in this region. Two-way factorial microcosm experiments with treatments reflecting near-future ocean conditions were run with these species and include increased temperature alone (3.5 °C × pH 8.0), reduced pH alone (1.5 °C × pH 7.6), and both factors combined (3.5 °C × pH 7.6). Phlorotannin concentration, chlorophyll a concentration, growth, and photosynthetic parameters (slope to saturation of photo centers ( α), saturating irradiance ( E), maximum electron transport rate (ETR), and maximum quantum yield of photosystem II ( F/ F)) were used to assess the physiological responses of the individuals to the different climate change treatments. Few significant impacts were observed: In D. menziesii, E at the midpoint (after 39 days) was significantly higher in the 3.5 °C × pH 7.6 treatment and phlorotannin concentration was significantly higher in the 1.5 °C × pH 7.6 treatment than others at the end point of the experiment (79 days). All individuals in the experiment grew quickly through the midpoint, but growth declined thereafter. The photosynthetic apparatus of these species acclimated to microcosm conditions, and photo-physiological parameters changed between initial, midpoint, and end point measurements. Results indicate that D. menziesii is the more sensitive of the two species and that climate change factors can have a synergistic effect on this species. However, neither species responds negatively to climate change factors at the level of change used in this study, though the observed shifts in phlorotannin concentration and photosynthetic characteristics may have an unforeseen impact on the community dynamics in this geographic area. [ABSTRACT FROM AUTHOR]

In southern England and northern France, pedunculate oak ( Quercus robur L.) and sessile oak ( Quercus petraea (Matt.) Liebl.) are keystone native species, supporting a substantial diversity of associated species, as well as being a valuable hardwood timber. Future environmental change may require modifications to the ways in which oaks are managed if they are to retain these important roles in forests. Such future management may be informed by past growth patterns using dendrochronological techniques. Oak radial growth between 1900 and 2010 was investigated in five regions in southern England and northern France, together with the impacts of past temperature and precipitation. Additionally, oak growth in monoculture stands and in stands where oak is mixed with Scots pine ( Pinus sylvestris L.) was assessed in two forested regions (the New Forest and Thetford Forest) in southern England. This study suggests that oaks in these areas of England and France have shown substantial resilience to past climatic and other environmental factors, with oak growth rates increasing significantly over the twentieth century. Oaks grown in monocultures appeared to grow better than those in mixed stands in the New Forest in southern England; there was no difference in Thetford Forest. Pointer years of unusually good or poor radial growth very rarely coincided between regions in the study area, suggesting that drivers of extreme growth are localised to the region and site-specific drivers, rather than climatic trends in common across the wider area. [ABSTRACT FROM AUTHOR]

Assessing the impact of climate change is important for ecosystem conservation and plant recovery, especially in climate sensitive regions. Various studies suggested that the Köppen classification is an effective method to depict climate change. However, these studies were restricted to large scales or of limited accuracy due to uncertainties in climate model projections. In addition, the impact of elevation on the shift of climate zones, as compared with other factors, is less emphasized. To address these issues we compiled the Köppen Climate Classification (period 1961-2010) for the study area, Sichuan Province, China. The spatial resolution was selected as 1 km × 1 km. Sichuan Province may be characterized by 3 main climate classes and 10 subtypes. The east-west gradient of the climatic regimes in Sichuan is represented by the main climate classes, warm temperate climates (C), snow climates (D) and polar climates (E), at which the most abundant class is C. The most abundant subtype is snow climate with dry winter and cool summer (Dwc). Shifts in Köppen climate classes reflect the observed trend of increasing temperature. Finally, the elevation showed an obvious impact on the distribution and the change of climate classes in Sichuan Province. The shift of areas covered by Köppen climate classes increases with elevation. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal (AM) fungi form mutualistic symbioses with most plant species and play important roles in ecosystems. Knowledge of the response of AM fungi to temperature change will improve our understanding of the function of AM fungal community under global climate change scenarios in ecosystems. The effects of constant warming on AM fungal communities have been investigated previously, but responses to asymmetrical warming over 24-h periods have never been documented in natural ecosystems. In this study, we examined AM fungal communities in a full factorial design including day-time and night-time warming in a semiarid steppe in northern China. Day-time and 24-h warming, but not night-time warming, significantly increased AM fungal spore density. In contrast, none of the three warming regimes had a significant effect on AM fungal extra radical hyphal density. A total of 161 operational taxonomic units (OTUs) of AM fungi were recovered by 454 pyrosequencing of 18S rDNA. Day-time, night-time, and 24-h warming all significantly increased AM fungal OTU richness. Some AM fungal OTUs showed a significant bias toward day-time, night-time or 24-h warming. The AM fungal community composition was significantly affected by night-time warming, but not by day-time and 24-h warming. Our finding highlighted different responses of AM fungal spore density and community composition to asymmetrical warming. This study might improve our understanding of ecosystem functioning of AM fungal community under global climate change scenarios in a semiarid steppe ecosystem. [ABSTRACT FROM AUTHOR]

Flowering dates and the timing of late season frost are both driven by local ambient temperatures. However, under climatic warming observed over the past century, it remains uncertain how such impacts affect frost risk associated with plant phenophase shifts. Any increase in frost frequency or severity has the potential to damage flowers and their resultant yields and, in more extreme cases, the survival of the plant. An accurate assessment of the relationship between the timing of last frost events and phenological shifts associated with warmer climate is thus imperative. We investigate spring advances in citrus flowering dates (orange, tangerine, sweet lemon, sour lemon and sour orange) for Kerman and Shiraz, Iran from 1960 to 2010. These cities have experienced increases in both T and T, advances in peak flowering dates and changes in last frost dates over the study period. Based on daily instrumental climate records, the last frost dates for each year are compared with the peak flowering dates. For both cities, the rate of last frost advance lags behind the phenological advance, thus increasing frost risk. Increased frost risk will likely have considerable direct impacts on crop yields and on the associated capacity to adapt, given future climatic uncertainty. [ABSTRACT FROM AUTHOR]

One of the ways to assess the impacts of climate change on plants is analysing their long-term phenological data. We studied phenological records of 18 common tree species and their 8 phenological phases, spanning 65 years (1946−2010) and covering the area of the Czech Republic. For each species and phenophase, we assessed the changes in its annual means (for detecting shifts in the timing of the event) and standard deviations (for detecting changes in duration of the phenophases). The prevailing pattern across tree species was that since around the year 1976, there has been a consistent advancement of the onset of spring phenophases (leaf unfolding and flowering) and subsequent acceleration of fruit ripening, and a delay of autumn phenophases (leaf colouring and leaf falling). The most considerable shifts in the timing of spring phenophases were displayed by early-successional short-lived tree species. The most pronounced temporal shifts were found for the beginning of seed ripening in conifers with an advancement in this phenophase of up to 2.2 days year in Scots Pine ( Pinus sylvestris). With regards to the change in duration of the phenophases, no consistent patterns were revealed. The growing season has extended on average by 23.8 days during the last 35 years. The most considerable prolongation was found in Pedunculate Oak ( Quercus robur): 31.6 days (1976−2010). Extended growing season lengths do have the potential to increase growth and seed productivity, but unequal shifts among species might alter competitive relationships within ecosystems. [ABSTRACT FROM AUTHOR]

A significant increase in summer temperatures has been observed for the period 1996-2011 in Poznań, Poland. The phenological response of four weed taxa, widely represented by anemophilous species ( Artemisia spp., Rumex spp. and Poaceae and Urticaceae species) to this recent climate warming has been analysed in Poznań by examining the variations in the course of airborne pollen seasons. Pollen data were collected by 7-day Hirst-type volumetric trap. Trends in pollen seasons were determined using Mann-Kendall test and Sen's slope estimator, whereas the relationships between meteorological and aerobiological data were established by Spearman's rank correlation coefficient. Significant trends in pollen data were detected. The duration of pollen seasons of all analysed taxa increased (from +2.0 days/year for Urticaceae to +3.8 days/year for Rumex), which can be attributed to a delay in pollen season end dates rather than earlier start dates. In addition, the intensity of Artemisia pollen seasons significantly decreased and correlates with mean July-September daily minimum temperatures ( r = −0.644, p < 0.01). In contrast, no significant correlations were found between temperature and characteristics of Rumex pollen seasons. The results of this study show that observed shifts in weed pollen seasons in Poznań, i.e. longer duration and later end dates, might be caused by the recorded increase in summer temperature. This influence was the strongest in relation to Artemisia, which is the taxon that flowers latest in the year. The general lack of significant correlations between Rumex and Urticaceae pollen seasons and spring and/or summer temperature suggests that other factors, e.g. land use practices, could also be partially responsible for the observed shifts in pollen seasons. [ABSTRACT FROM AUTHOR]

Global warming and enhanced nitrogen (N) inputs are two key global-change drivers affecting temperate forest ecosystems simultaneously. Interactive effects of multiple drivers might cause species responses to differ from those in single-factor experiments; therefore, there is an urgent need for more multi-factor studies. Here, we assessed the growth and reproductive performance of multiple populations of a widespread grass of deciduous forests ( Milium effusum) sampled along a latitudinal gradient and subjected to experimental manipulations of temperature and nitrogen availability. Common garden transplant experiments along the latitudinal gradient were used to manipulate temperatures and combined with experimental N addition to assess intraspecific responses of the study species to global-change drivers as well as to determine local adaptation. The total biomass, number of seeds and seedling emergence time of M. effusum increased when transplanted in the southern common garden. Apart from effects on the seed mass, the species did not respond to N addition alone. Yet, interactive effects between warming and N addition were found: N addition led to increased biomass growth but only in the northern common garden. Significant home-site advantages were apparent, most likely because of increased mycorrhizal colonization of roots of local transplants. We show that multiple global-change drivers may alter dynamics in understorey communities of temperate forests. Our study reinforces the need to increase our understanding of plant responses to future environmental changes by expanding the multi-factor research framework. [ABSTRACT FROM AUTHOR]

Observations of a longer growing season through earlier plant growth in temperate to polar regions have been thought to be a response to climate warming. However, data from experimental warming studies indicate that many species that initiate leaf growth and flowering earlier also reach seed maturation and senesce earlier, shortening their active and reproductive periods. A conceptual model to explain this apparent contradiction, and an analysis of the effect of elevated CO2-which can delay annual life cycle events-on changing season length, have not been tested. Here we show that experimental warming in a temperate grassland led to a longer growing season through earlier leaf emergence by the first species to leaf, often a grass, and constant or delayed senescence by other species that were the last to senesce, supporting the conceptual model. Elevated CO2 further extended growing, but not reproductive, season length in the warmed grassland by conserving water, which enabled most species to remain active longer. Our results suggest that a longer growing season, especially in years or biomes where water is a limiting factor, is not due to warming alone, but also to higher atmospheric CO2 concentrations that extend the active period of plant annual life cycles. [ABSTRACT FROM AUTHOR]

Tree mortality in response to climate change induced drought has emerged as a global concern. Small changes of tree mortality rates can profoundly affect forest structure, composition, dynamics and ecosystem services such as carbon sequestration. Our analyses of longitudinal data from natural stands (82 plots) in Beijing showed that tree mortality rates have increased significantly over the two decades from 1986 to 2006. In contrast, recruitment rates decreased significantly over this period. The increase in overall mortality rates resulted from an increase in tree deaths dominantly attributed to changes in temperature and precipitation resulting in drier conditions across latitudes, elevations, tree species, and tree sizes. In addition, the results showed that mortality rates of Chinese pine ( Pinus tabuliformis) ( β = 0.0874) as a result of climate change induce drought were much smaller than oak ( Quercus) ( β = 0.1583). [ABSTRACT FROM AUTHOR]

Due to global warming, species are expanding their range to higher latitudes. Some range expanding plants have become invasive in their new range. The Evolution of Increased Competitive Ability (EICA) hypothesis and the Shifting Defense Hypothesis (SDH) predict altered selection on plant defenses in the introduced range of invasive plants due to changes in herbivore pressures and communities. Here, we investigated chemical defenses (glucosinolates) of five native and seven invasive populations of the Eurasian invasive range expanding plant, Rorippa austriaca. Further, we studied feeding preferences of a generalist and a specialist herbivore among the populations. We detected eight glucosinolates in the leaves of R. austriaca. 8-Methylsulfinyloctyl glucosinolate was the most abundant glucosinolate in all plants. There were no overall differences between native and invasive plants in concentrations of glucosinolates. However, concentrations among populations within each range differed significantly. Feeding preference between the populations by a generalist herbivore was negatively correlated with glucosinolate concentrations. Feeding by a specialist did not differ between the populations and was not correlated with glucosinolates. Possibly, local differences in herbivore communities within each range may explain the differences in concentrations of glucosinolates among populations. Little support for the predictions of the EICA hypothesis or the SDH was found for the glucosinolate defenses of the studied native and invasive R. austriaca populations. [ABSTRACT FROM AUTHOR]

Plant sensitivity to warming can be expressed as β or the number of days of advance in leafing or flowering events per 1 °C of Mean Annual Temperature (MAT) change. Many local studies demonstrate that β estimates for spring flowering species are usually larger than estimates for plants flowering in summer or fall. Until now, however, neither observational nor experimental estimates of this parameter were considered to be climate or geographically dependent. Here we question this paradigm through reanalysis of observational β estimates and mathematical modeling of the seasonal warming signal. Statistical analysis of a large number of bulk (averaged over species) estimates of β derived from the Pan European Phenology Data network (PEP725) revealed a positive spatial correlation with MAT, as well as a negative correlation with the Seasonal Temperature Range (STR). These spatial correlations of bulk β values as well as interseasonal variability in β were explained using a simple deterministic model of the Thermal Growing Season (TGS). More specifically, we found that the geographic distribution of bulk plant sensitivity to warming as well as the seasonal decline of β were controlled by the seasonal patterns in the warming signal and by average soil thermal properties. Thus, until recently, plants managed to keep pace with climate warming by shifting their leafing and flowering events by the same number of days as the length of the period of weather suitable for their growth. Our model predicts, however, an even greater increase in the TGS for subsequent increases in MAT. Depending on how they interact with other factors such as changes in precipitation and increased temperature variability, these longer thermal growing seasons may not be beneficial for plant growth. [ABSTRACT FROM AUTHOR]

Alpine grassland soils store large amounts of soil organic carbon (SOC) and are susceptible to rising air temperature. Soil extracellular enzymes catalyze the rate-limiting step in SOC decomposition and their catalysis, production and degradation rates are regulated by temperature. Therefore, the responses of these enzymes to warming could have a profound impact on carbon cycling in the alpine grassland ecosystems. This study was conducted to measure the responses of soil extracellular enzyme activity and temperature sensitivity (Q) to experimental warming in samples from an alpine grassland ecosystem on the Tibetan Plateau. A free air-temperature enhancement system was set up in May 2006. We measured soil microbial biomass, nutrient availability and the activity of five extracellular enzymes in 2009 and 2010. The Q of each enzyme was calculated using a simple first-order exponential equation. We found that warming had no significant effects on soil microbial biomass C, the labile C or N content, or nutrient availability. Significant differences in the activity of most extracellular enzymes among sampling dates were found, with typically higher enzyme activity during the warm period of the year. The effects of warming on the activity of the five extracellular enzymes at 20 °C were not significant. Enzyme activity in vitro strongly increased with temperature up to 27 °C or over 30 °C (optimum temperature; T). Seasonal variations in the Q were found, but the effects of warming on Q were not significant. We conclude that soil extracellular enzymes adapted to seasonal temperature variations, but did not acclimate to the field experimental warming. [ABSTRACT FROM AUTHOR]

Adverse climate change attributed to elevated atmospheric carbon dioxide concentration (CO 2) and increased temperature components of global warming has been a central issue affecting economic and social development. Climate change, particularly global warming, imposes a severe impact on the terrestrial ecosystem. Elevated CO 2, drought, and high temperature have been extensively documented individually; however, relatively little is known about how plants respond to the interaction of these factors. To summarize current knowledge on the response of plants to global change factors, we focus on the interactive effects of CO 2 enrichment, warming, and drought on plant growth, carbon allocation, and photosynthesis. Stimulation due to elevated CO 2 might be suppressed under other negative climatic/environmental stresses such as drought, high temperature, and their combination. However, elevated CO 2 could alleviate deleterious effects of moderate drought via reducing stomatal conductance, altering leaf surface, and regulating gene expression. High CO 2 levels and rising temperatures may result in opposite responses in plant water use efficiency. Stimulation of plant growth due to elevated CO 2 for C 3 species occurs regardless of water conditions, but only under a water deficit for C 4 species. The positive effect of elevated CO 2 on C 4 species is derived mainly from the improved water status. Plant adaptive or maladaptive responses to multivariate environments are interactive; thus, researchers need to explore the ecological underpinnings involved in such responses to the multiple factors involved in climate change. [ABSTRACT FROM AUTHOR]

This paper studies the specific diversity and quantitative indicators of zooplankton of the Vasyugan River in the middle and lower reaches, as well as in the estuaries of major tributaries. The dominant zooplankton complex is noted to have changed according to 50- and 10-year-old data. The succession of the plankton community is taking place, which is possibly due to global warming and the restructuring of the entire Vasyuganye ecosystem. No oil pollution has been detected in the river by bioindication methods. [ABSTRACT FROM AUTHOR]

Global food security is threatened by the emergence and spread of crop pests and pathogens. Spread is facilitated primarily by human transportation, but there is increasing concern that climate change allows establishment in hitherto unsuitable regions. However, interactions between climate change, crops and pests are complex, and the extent to which crop pests and pathogens have altered their latitudinal ranges in response to global warming is largely unknown. Here, we demonstrate an average poleward shift of 2.7±0.8 km yr−1 since 1960, in observations of hundreds of pests and pathogens, but with significant variation in trends among taxonomic groups. Observational bias, where developed countries at high latitudes detect pests earlier than developing countries at low latitudes, would result in an apparent shift towards the Equator. The observed positive latitudinal trends in many taxa support the hypothesis of global warming-driven pest movement. [ABSTRACT FROM AUTHOR]

Climate change is likely to have a profound effect on many agricultural variables, although the extent of its influence will vary over the course of the annual farm management cycle. Consequently, the effect of different and interconnected physical, technical and economic factors must be modeled in order to estimate the effects of climate change on agricultural productivity. Such modeling commonly makes use of indicators that summarize the among environmental factors that are considered when farmers plan their activities. This study uses net evapotranspiration (ET), estimated using EPIC, as a proxy index for the physical factors considered by farmers when managing irrigation. Recent trends suggest that the probability distribution function of ET may continue to change in the near future due to changes in the irrigation needs of crops. Also, water availability may continue to vary due to changes in the rainfall regime. The impacts of the uncertainties related to these changes on costs are evaluated using a Discrete Stochastic Programming model representing an irrigable Mediterranean area where limited water is supplied from a reservoir. In this context, adaptation to climate change can be best supported by improvements to the collective irrigation systems, rather than by measures aimed at individual farms such as those contained within the rural development policy. [ABSTRACT FROM AUTHOR]

Advancing phenology in response to global warming has been reported across biomes, raising concerns about the temporal uncoupling of trophic interactions. Concurrently, widely reported flower visitor declines have been linked to resource limitations. Phenological responses in the Arctic have been shown to outpace responses from lower latitudes and recent studies suggest that differences between such responses for plants and their flower visitors could be particularly pronounced in the Arctic. The evidence for phenological uncoupling is scant because relevant data sets are lacking or not available at a relevant spatial scale. Here, we present evidence of a climate-associated shortening of the flowering season and a concomitant decline in flower visitor abundance based on a long-term, spatially replicated (1996-2009) data set from high-Arctic Greenland. A unique feature of the data set is the spatial and temporal overlap of independent observations of plant and insect phenology. The shortening of the flowering season arose through spatial variation in phenological responses to warming. The shorter flowering seasons may have played a role in the observed decline in flower visitor abundance. Our results demonstrate that the dramatic climatic changes currently taking place in the Arctic are strongly affecting individual species and ecological communities, with implications for trophic interactions. [ABSTRACT FROM AUTHOR]

Aims: Heat stress is a growing concern in crop production because of global warming. In many cropping systems heat stress often occurs simultaneously with other environmental stress factors such as mineral nutrient deficiencies. This study aimed to investigate the role of adequate magnesium (Mg) nutrition in mitigating the detrimental effects of heat stress on wheat ( Triticum aestivum) and maize ( Zea mays). Methods: Wheat and maize plants were grown in solution culture with low or adequate Mg supply at 25/22 °C (light/dark). Half of the plants were, then, exposed to heat stress at 35/28 °C (light/dark). Development of leaf chlorosis and changes in root and shoot growth, chlorophyll and Mg concentrations as well as the activities of major antioxidative enzymes were quantified in the experimental plants. Additionally, maize plants were analyzed for the specific weights (e.g., dry or fresh weight per a given leaf surface area) and soluble carbohydrate concentrations of sink and source leaves. Results: Visual leaf symptoms of Mg deficiency were aggravated in wheat and maize when exposed to heat stress. In both species, root growth was more sensitive to Mg deficiency than shoot growth, and the shoot-to-root ratios peaked when heat stress was combined with Mg deficiency. Magnesium deficiency markedly reduced soluble carbohydrate concentrations in young leaf; but resulted in substantial increase in source leaves. Magnesium deficiency also increased activities of antioxidative enzymes, especially when combined with heat stress. The highest activities of superoxide dismutase (up to 80 % above the control), glutathione reductase (up to 250 % above the control) and ascorbate peroxidase (up to 300 % above the control) were measured when Mg-deficient plants were subjected to heat, indicating stimulated formation of reactive oxygen species (ROS) in Mg deficient leaves under heat stress. Conclusions: Magnesium deficiency increases susceptibility of wheat and maize plants to heat stress, probably by increasing oxidative cellular damage caused by ROS. Ensuring a sufficiently high Mg supply for crop plants through Mg fertilization is a critical factor for minimizing heat-related losses in crop production. [ABSTRACT FROM AUTHOR]

Climate warming has led to changes in the composition, density and distribution of Arctic vegetation in recent decades. These changes cause multiple opposing feedbacks between the biosphere and atmosphere, the relative magnitudes of which will have globally significant consequences but are unknown at a pan-Arctic scale. The precise nature of Arctic vegetation change under future warming will strongly influence climate feedbacks, yet Earth system modelling studies have so far assumed arbitrary increases in shrubs (for example, +20%; refs , ), highlighting the need for predictions of future vegetation distribution shifts. Here we show, using climate scenarios for the 2050s and models that utilize statistical associations between vegetation and climate, the potential for extremely widespread redistribution of vegetation across the Arctic. We predict that at least half of vegetated areas will shift to a different physiognomic class, and woody cover will increase by as much as 52%. By incorporating observed relationships between vegetation and albedo, evapotranspiration and biomass, we show that vegetation distribution shifts will result in an overall positive feedback to climate that is likely to cause greater warming than has previously been predicted. Such extensive changes to Arctic vegetation will have implications for climate, wildlife and ecosystem services. [ABSTRACT FROM AUTHOR]

Global temperature is increasing, especially over northern lands (>50° N), owing to positive feedbacks. As this increase is most pronounced in winter, temperature seasonality (ST)-conventionally defined as the difference between summer and winter temperatures-is diminishing over time, a phenomenon that is analogous to its equatorward decline at an annual scale. The initiation, termination and performance of vegetation photosynthetic activity are tied to threshold temperatures. Trends in the timing of these thresholds and cumulative temperatures above them may alter vegetation productivity, or modify vegetation seasonality (SV), over time. The relationship between ST and SV is critically examined here with newly improved ground and satellite data sets. The observed diminishment of ST and SV is equivalent to 4° and 7° (5° and 6°) latitudinal shift equatorward during the past 30 years in the Arctic (boreal) region. Analysis of simulations from 17 state-of-the-art climate models indicates an additional STdiminishment equivalent to a 20° equatorward shift could occur this century. How SV will change in response to such large projected ST declines and the impact this will have on ecosystem services are not well understood. Hence the need for continued monitoring of northern lands as their seasonal temperature profiles evolve to resemble thosefurther south. [ABSTRACT FROM AUTHOR]

Changes in leaf phenology lengthen the growing season length (GSL, the days between leaf budburst and leaf fall) under the global warming. GSL and the leaf phenology response to climate change is one of the most important predictors of climate change effect on plants. Empirical evidence of climatic effects on GSL remains scarce, especially at a regional scale and the latitudinal pattern. This study analyzed the datasets of leaf budburst and fall phenology in Morus bombycis (Urticales), which were observed by the agency of the Japan Meteorological Agency (JMA) from 1953 to 2005 over a wide range of latitudes in Japan (31 to 44° N). In the present study, single regression slopes of leaf phenological timing and air temperature across Japan were calculated and their spatial patterns using general linear models were tested. The results showed that the GSL extension was caused mainly by a delay in leaf fall phenology. Relationships between latitude and leaf phenological and GSL responses against air temperature were significantly negative. The response of leaf phenology and GSL to air temperature at lower latitudes was larger than that at higher latitudes. The findings indicate that GSL extension should be considered with regards to latitude and climate change. [ABSTRACT FROM AUTHOR]