Use of aerial imagery to assess habitat suitability and predict site occupancy for a declining wetland-dependent bird

Remote sensing is a valuable tool for wetland habitat quantification, monitoring and assessment. Here we show that habitat assessment via aerial image inspection is useful in predicting wetland site occupancy by black terns (Chlidonias niger), an imperiled and declining species throughout much of North America. We used Google Earth^® images and National Wetlands Inventory maps to rank 390 candidate wetlands throughout Wisconsin (USA) according to their apparent suitability as nesting habitat for black terns and quantified habitat features associated with the suitability rankings. We then conducted ground-based suitability assessments and point counts of terns at most wetlands from May to July 2010. Pre-survey assessment resulted in 123 wetlands classified as suitable, 81 as marginal, and 186 as unsuitable. Wetlands ranked as suitable were more likely to be in the hemi-marsh stage, part of a wetland complex and relatively undisturbed. Black terns were present at 47 % of the wetlands considered suitable but only 11 % of the sites considered marginal or unsuitable. Of the 42 sites where nesting was confirmed, 79 % were at wetlands classified as suitable; no nesting was recorded in any wetlands deemed unsuitable. We found strong concordance in wetland suitability rankings between the two assessment methods (remote sensing, site surveys). We propose that remote sensing is an efficient and inexpensive way to predict site occupancy by wetland birds, such as black terns, that prefer a specific kind of habitat discernible from aerial imagery. This method may be particularly useful in areas, such as the Prairie Pothole region of North America, where ground surveys of all wetlands are not feasible.     

Climate Change Impacts on the Future Distribution of Date Palms: A Modeling Exercise Using CLIMEX

Climate is changing and, as a consequence, some areas that are climatically suitable for date palm (Phoenix dactylifera L.) cultivation at the present time will become unsuitable in the future. In contrast, some areas that are unsuitable under the current climate will become suitable in the future. Consequently, countries that are dependent on date fruit export will experience economic decline, while other countries’ economies could improve. Knowledge of the likely potential distribution of this economically important crop under current and future climate scenarios will be useful in planning better strategies to manage such issues. This study used CLIMEX to estimate potential date palm distribution under current and future climate models by using one emission scenario (A2) with two different global climate models (GCMs), CSIRO-Mk3.0 (CS) and MIROC-H (MR). The results indicate that in North Africa, many areas with a suitable climate for this species are projected to become climatically unsuitable by 2100. In North and South America, locations such as south-eastern Bolivia and northern Venezuela will become climatically more suitable. By 2070, Saudi Arabia, Iraq and western Iran are projected to have a reduction in climate suitability. The results indicate that cold and dry stresses will play an important role in date palm distribution in the future. These results can inform strategic planning by government and agricultural organizations by identifying new areas in which to cultivate this economically important crop in the future and those areas that will need greater attention due to becoming marginal regions for continued date palm cultivation.     

Climatic responses of tree-ring width and δ13C signatures of sessile oak (Quercus petraea Liebl.) on soils with contrasting water supply

We investigated climate–growth relationships (in terms of tree-ring width, basal area increment (BAI), and tree-ring δ¹³C signatures) of Quercus petraea in Central Europe (Luxembourg). Tree responses were assessed for 160 years and compared for sites with contrasting water supply (i.e. Cambisols vs. Regosols with 175 and 42 mm available water capacity, respectively). Oak trees displayed very low climate sensitivity, and climatic variables explained only 24 and 21 % of variance in tree-ring width (TRW) (Cambisol and Regosol sites, respectively). Contrary to our expectations, site-related differences in growth responses (i.e. BAI, δ¹³C signatures) to climate shifts were not significant. This finding suggests a high plasticity of oak trees in the study area. Despite a distinct growth depression found for all trees in the decade 1988–1997 (attributable to increasing annual mean temperatures by 1.1 °C), oak trees completely recovered in subsequent years. This indicates a high resilience of sessile oak to climate change. Shifts in δ¹³C_corr signatures were mainly affected by temperature, and peaks in δ¹³C_corr values (corrected for the anthropogenic increase in atmospheric CO₂) coincided with decadal maximum temperatures. Correlations between δ¹³C signatures and TRW (mainly affected by precipitation) were not significant. This finding suggests that wood growth often was disconnected from carbon assimilation (e.g. due to carbon storage in the trunk or allocation to seeds). Since the selection of drought-resistant tree species gains importance within the context of adaptive forest management strategies, Q. petraea proves to be an adaptive tree species in Central Europe’s forests under shifting climatic conditions.     

Predicting how adaptation to climate change could affect ecological conservation: secondary impacts of shifting agricultural suitability

Aim:  Ecosystems face numerous well‐documented threats from climate change. The well‐being of people also is threatened by climate change, most prominently by reduced food security. Human adaptation to food scarcity, including shifting agricultural zones, will create new threats for natural ecosystems. We investigated how shifts in crop suitability because of climate change may overlap currently protected areas (PAs) and priority sites for PA expansion in South Africa. Predicting the locations of suitable climate conditions for crop growth will assist conservationists and decision‐makers in planning for climate change. Location:  South Africa. Methods:  We modelled climatic suitability in 2055 for maize and wheat cultivation, two extensively planted, staple crops, and overlaid projected changes with PAs and PA expansion priorities. Results:  Changes in winter climate could make an additional 2 million ha of land suitable for wheat cultivation, while changes in summer climate could expand maize suitability by up to 3.5 million ha. Conversely, 3 million ha of lands currently suitable for wheat production are predicted to become climatically unsuitable, along with 13 million ha for maize. At least 328 of 834 (39%) PAs are projected to be affected by altered wheat or maize suitability in their buffer zones. Main conclusions:  Reduced crop suitability and food scarcity in subsistence areas may lead to the exploitation of PAs for food and fuel. However, if reduced crop suitability leads to agricultural abandonment, this may afford opportunities for ecological restoration. Expanded crop suitability in PA buffer zones could lead to additional isolation of PAs if portions of newly suitable land are converted to agriculture. These results suggest that altered crop suitability will be widespread throughout South Africa, including within and around lands identified as conservation priorities. Assessing how climate change will affect crop suitability near PAs is a first step towards proactively identifying potential conflicts between human adaptation and conservation planning.     

A phyloclimatic study of Cyclamen

Background

The impact of global climate change on plant distribution, speciation and extinction is of current concern. Examining species climatic preferences via bioclimatic niche modelling is a key tool to study this impact. There is an established link between bioclimatic niche models and phylogenetic diversification. A next step is to examine future distribution predictions from a phylogenetic perspective. We present such a study using Cyclamen (Myrsinaceae), a group which demonstrates morphological and phenological adaptations to its seasonal Mediterranean-type climate. How will the predicted climate change affect future distribution of this popular genus of garden plants?

Results

We demonstrate phylogenetic structure for some climatic characteristics, and show that most Cyclamen have distinct climatic niches, with the exception of several wide-ranging, geographically expansive, species. We reconstruct climate preferences for hypothetical ancestral Cyclamen. The ancestral Cyclamen lineage has a preference for the seasonal Mediterranean climate characteristic of dry summers and wet winters. Future bioclimatic niches, based on BIOCLIM and Maxent models, are examined with reference to a future climate scenario for the 2050s. Over the next 50 years we predict a northward shift in the area of climatic suitability, with many areas of current distribution becoming climatically unsuitable. The area of climatic suitability for every Cyclamen species is predicted to decrease. For many species, there may be no areas with a suitable climate regardless of dispersal ability, these species are considered to be at high risk of extinction. This risk is examined from a phylogenetic perspective.

Conclusion

Examining bioclimatic niches from a phylogenetic perspective permits novel interpretations of these models. In particular, reconstruction of ancestral niches can provide testable hypothesis about the historical development of lineages. In the future we can expect a northwards shift in climatic suitability for the genus Cyclamen. If this proves to be the case then dispersal is the best chance of survival, which seems highly unlikely for ant-dispersed Cyclamen. Human-assisted establishment of Cyclamen species well outside their native ranges offers hope and could provide the only means of dispersal to potentially suitable future environments. Even without human intervention the phylogenetic perspective demonstrates that major lineages could survive climate change even if many species are lost.     

Differences in the heat stress associated with white sportswear and being semi-nude in exercising humans under conditions of radiant heat and wind at a wet bulb globe temperature of greater than 28 °C

This study investigated whether wearing common white sportswear can reduce heat stress more than being semi-nude during exercise of different intensities performed under radiant heat and wind conditions, such as a hot summer day. After a 20-min rest period, eight male subjects performed three 20 min sessions of cycling exercise at a load intensity of 20 % or 50 % of their peak oxygen uptake (VO_2peak) in a room maintained at a wet bulb globe temperature (WBGT) of 28.7?±?0.1 °C using two spot lights and a fan (0.8 m/s airflow). Subjects wore common white sportswear (WS) consisting of a long-sleeved shirt (45 % cotton and 55 % polyester) and short pants (100 % polyester), or only swimming pants (SP) under the semi-nude condition. The mean skin temperature \( \left(\overline{T} sk\right) \) was greater when subjects wore SP than WS under both the 20 % and 50 % exercise conditions. During the 50 % exercise, the rating of perceived exertion (RPE) and thermal sensation (TS), and the increases in esophageal temperature (ΔTes) and heart rate were significantly higher (P?<?0.001–0.05), or tended to be higher (P?<?0.07), in the WS than SP trials at the end of the third 20-min exercise session. The total sweat loss (m _sw,tot) was also significantly higher in the WS than in the SP trials (P?<?0.05). However, during the 20 % exercise, the m _sw,tot during exercise, and the ΔTes, RPE and TS at the end of the second and third sessions of exercise did not differ significant between conditions. The heat storage (S), calculated from the changes in the mean body temperature (0.9Tes + 0.1 \( \overline{T} sk \) ), was significantly lower in the WS trials than in the SP trials during the 20 min resting period before exercise session. However, S was similar between conditions during the 20 % exercise, but was greater in the WS than in the SP trials during 50 % exercise. These results suggest that, under conditions of radiant heat and wind at a WBGT greater than 28 °C, the heat stress associated with wearing common WS is similar to that of being semi-nude during light exercise, but was greater during moderate exercise, and the storage of body heat can be reduced by wearing WS during rest periods.     

Potential Suitability and Viability of Selected Biodiesel Crops in Australian Marginal Agricultural Lands Under Current and Future Climates

The potential environmental suitability and economic viability of growing two biodiesel crops in marginal regions of Australia were explored. Firstly, we used spatial analysis techniques to identify marginal agricultural regions suitable for growing pongam (Pongamia pinnata) and Indian mustard (Brassica juncea), and determined the base socioeconomic viability of investments for the production of biodiesel in the identified areas. Secondly, we used climate change projections (target years 2020 to 2070) from the Commonwealth Scientific, Industrial and Research Organization Mk3.0 global circulation model generated for two emission scenarios (A1B and A1FI) to determine the shift in potential areas for these crops. Under the climate change scenarios tested, the total area suitable for growing pongam between 2040 and 2070 is substantially different from the suitable area under current climate, indicating that long-term investments in this perennial tree crop may not be viable in all regions, especially in southern Australia. There is a greater variation in suitability projections for Indian mustard, although there is more flexibility for cropping options given that it is an annual crop. However, future economic viability is likely to depend on the ability to receive renewable energy certificates for both crops and, in the case of pongam, the certified emission reductions. Opportunities exist for sustainable pongam agroforestry to supply biodiesel to regional towns, cattle stations and mines in northern Australia.     

Understanding the role of climatic and environmental variables in gonadal maturation and spawning periodicity of spotted snakehead, <Emphasis Type="Italic">Channa punctata</Emphasis> (Bloch, 1793) in a tropical floodplain wetland,India

Temperature and seasonal rainfall along with other environmental variables are important in regulating the reproductive cycles in teleost fishes. Certain environmental variables may act as cues for reproduction and changes in these may affect seasonality and success of reproduction, as fishes are known to integrate their physiological functions with environmental cycles. Wetlands are sensitive to climate change due to their shallow and confined nature. Since wetlands are important spawning and nursery grounds for many fishes, changes in the environmental variables may have direct consequences for the spawning and survival of fish. In the present study, we have assessed climatic and water chemistry variables capable of influencing seasonality in environmental variables as well as gonadal maturation of spotted snakehead Channa punctata, to predict threshold values of Gonado Somatic Index in females and a favourable range of identified climatic and water chemistry variables for breeding success. Among the climatic and water chemistry variables studied, seasonal variation in rainfall was found to have the most profound effect on gonadal maturation and breeding in C. punctata, followed by water temperature. The favourable range of rainfall obtained varied between 800 mm to 1400 mm, corresponding to the water temperature range between 29 °C and 31 °C. An overall significant warming trend with a reduction in total rainfall has been observed with changes in seasonal trends in temperature and rainfall in the study area. The rainfall being the major climatic factors influencing water chemistry in the wetlands during the spawning season, changes in rainfall pattern may influence breeding periodicity of C. punctata in wetlands in climate change scenario.     

The Sweet Passion Fruit (<Emphasis Type="Italic">Passiflora alata</Emphasis>) Crop: Genetic and Phenotypic Parameter Estimates and QTL Mapping for Fruit Traits

Despite their economic importance, some tropical crop species are largely neglected when it comes to conducting genetic studies characterizing target traits for breeding. Herein, genetic and phenotypic parameters as well quantitative trait loci (QTL) are described for the first time in a full-sib progeny of sweet passion fruit (Passiflora alata). A hundred F₁ individuals were evaluated in two locations for seven fruit traits: diameter of fruit (DF, in mm), length of fruit (LF, in mm), weight of fruit (WF, in g), thickness of fruit skin (TS, in mm), weight of fruit skin (WS, in g), weight of fruit pulp (WP, in g) and soluble solids (SS, in °Brix). Mixed models fitted complex, unstructured genetic variance-covariance matrices for all traits in phenotypic analysis. Because of important genetic correlations among skin and pulp traits, multiplicative index selection to select the most promising individuals was successfully applied. A previously reported integrated map supported composite interval mapping (CIM) analyses. In total, we found 22 QTLs mapped in seven out of nine linkage groups. Heritabilities (from 59.8 % to 82.7 %) and proportion of phenotypic variance explained by the QTLs (from 42.0 % to 64.3 %) were comparable for each trait. Principal component analysis on TS, WS and WP showed that the first two principal components (PCs) accounted for 93.6 % of the total variability. CIM analyses on these two PCs revealed five putative QTLs controlling variation for these three traits simultaneously. Thus, genetic improvement for sweet passion fruit should be based on correlations between traits and QTL-related information can be a useful tool.     

Global warming may freeze the invasion of big-headed ants

Climate change and invasive species are two of the most serious threats of biodiversity. A general concern is that these threats interact, and that a globally warming climate could favour invasive species. In this study we investigate the invasive potential of one of the “100 of the world’s worst invasive species”, the big-headed ant Pheidole megacephala. Using ecological niche models, we estimated the species’ potential suitable habitat in 2020, 2050 and 2080. With an ensemble forecast obtained from five different modelling techniques, 3 Global Circulation Models and 2 CO₂ emission scenarios, we generated world maps with suitable climatic conditions and assessed changes, both qualitatively and quantitatively. Almost one-fifth (18.5 %) of the landmass currently presents suitable climatic conditions for P. megacephala. Surprisingly, our results also indicate that the invasion of big-headed ants is not only unlikely to benefit from climate change, but may even suffer from it. Our projections show a global decrease in the invasive potential of big-headed ants as early as 2020 and becoming even stronger by 2080 reaching a global loss of 19.4 % of area with favourable climate. The decrease is observable in all 6 broad regions, being greatest in the Oceania and lowest in Europe.     

Integrating genetics and suitability modelling to bolster climate change adaptation planning in Patagonian <Emphasis Type="Italic">Nothofagus</Emphasis> forests

We investigated the impact of past changes in habitat suitability on the current patterns of genetic diversity of two southern beeches (Nothofagus nervosa and Nothofagus obliqua) in their eastern fragmented range in Patagonian Argentina, and model likely future threats to their population genetic structure. Our goal was to develop a spatially-explicit strategy for guiding conservation and management interventions in light of climate change. We combined suitability modelling under current, past (Last Glacial Maximum ~ 21,000 bp), and future (2050s) climatic conditions with genetic characterization data based on chloroplast DNA, isozymes, and microsatellites. We show the complementary usefulness of the distribution of chloroplast haplotypes and locally common allelic richness calculated from microsatellite data for identifying the locations of putative glacial refugia. Our findings suggest that contemporary hotspots of genetic diversity correspond to convergence zones of different expansion routes, most likely as a consequence of admixture processes. Future suitability predictions suggest that climate change might differentially affect both species. All genetically most diverse populations of N. nervosa and several of N. obliqua are located in areas that may be most severely impacted by climate change, calling for forward-looking conservation interventions. We propose a practical spatially- explicit strategy to target conservation interventions distinguishing priority populations for (1) in situ conservation (hotspots of genetic diversity likely to remain suitable under climate change), (2) ex situ conservation in areas where high genetic diversity overlaps with high likelihood of drastic climate change, (3) vulnerable populations (areas expected to be negatively affected by climate change), and (4) potential expansion areas under climate change.     

Influence of Drought,High Temperature,and Carbamide Cytokinin 4-PU-30 on Photosynthetic Activity of Bean Plants. 1. Changes in Chlorophyll Fluorescence Quenching

Fifteen-day-old bean plants (Phaseolus vulgaris L.) grown in a climatic chamber were exposed to water deficit (WD) and high temperature (HT) stresses applied separately or in combination. Changes in chlorophyll fluorescence quenching were investigated. Bean plants that endured mild (42 °C, 5 h for 2 d) WD separately or in combination with HT did not change their q_P and q_N quenching (measured at 25 °C) compared with those of the control. After 5 min testing at 45 °C, q_P in control and droughted plants strongly decreased, while q_P of plants that experienced combined WD+HT stress was insignificantly influenced, suggesting the acclimation effect of HT treatments. At more severe stresses (after 3 d-treatment), q_P measured at 25 °C was the lowest in WD+HT plants and q_N values were the highest. But when measured at 45 °C, q_P of WD+HT plants had practically the same values as at 25 °C. Under these conditions q_P of WD plants also showed an adaptation to HT. Twenty-four hours after recovery, the unfavourable effects of the stresses were strongly reduced when measured at 25 °C, but they were still present when measured at 45 °C. Positive effect of the carbamide cytokinin 4-PU-30 was well expressed only in droughted plants. This revised version was published online in June 2006 with corrections to the Cover Date.     

Water flux of Eucalyptus regnans: defying summer drought and a record heatwave in 2009

Making predictions as to how heatwaves will affect forests in the future is a major challenge in ecosystem science, not the least because we have few documented examples of how they respond now. We captured the effects of drought and a record-breaking heatwave on whole-tree water use (Q) in Eucalyptus regnans during the summer drought of 2008/2009 in southeastern Australia. While air temperatures steadily increased, average maximum sap flow (J _Smax) declined with progression of the drought prior to the heatwave. In the period approaching the heatwave, Q during daytime (Q _d) steadily declined, while nighttime Q (Q _n) increased. This pattern was particularly pronounced during nights that followed hot days (>32 °C) where Q _n was frequently 20–30 % of Q _d. We found clear trends in the relation of Q _d to Q _n that point to the increasing importance of refilling depleted stem water stores following hot days. On the day the heatwave climaxed (7 February 2009), sap flow (J _S) was dramatically low, and declined as weather conditions became increasingly arid (air temperature > 42 °C, vapor pressure deficit >7 kPa). Almost immediately after the heatwave passed J _S resumed its common diurnal hysteresis, albeit at slightly slower rates. In the context of prognosticated effects of future climate, our data highlight that depletion and refill of stored water in E. regnans are likely important features for the tree to endure drought- and heat-related climatic extremes. We suggest that elucidating the peculiarity of capacitance and defining its threshold for keystone tree species, such as E. regnans, can add to our understanding of how climatic extremes may affect forests.     

Understanding how lake populations of arctic char are structured and function with special consideration of the potential effects of climate change: a multi-faceted approach

Size dimorphism in fish populations, both its causes and consequences, has been an area of considerable focus; however, uncertainty remains whether size dimorphism is dynamic or stabilizing and about the role of exogenous factors. Here, we explored patterns among empirical vital rates, population structure, abundance and trend, and predicted the effects of climate change on populations of arctic char (Salvelinus alpinus) in two lakes. Both populations cycle dramatically between dominance by small (≤300 mm) and large (>300 mm) char. Apparent survival (Φ) and specific growth rates (SGR) were relatively high (40–96 %; SGR range 0.03–1.5 %) and comparable to those of conspecifics at lower latitudes. Climate change scenarios mimicked observed patterns of warming and resulted in temperatures closer to optimal for char growth (15.15 °C) and a longer growing season. An increase in consumption rates (28–34 %) under climate change scenarios led to much greater growth rates (23–34 %). Higher growth rates predicted under climate change resulted in an even greater predicted amplitude of cycles in population structure as well as an increase in reproductive output (R _o) and decrease in generation time (G _o). Collectively, these results indicate arctic char populations (not just individuals) are extremely sensitive to small changes in the number of ice-free days. We hypothesize years with a longer growing season, predicted to occur more often under climate change, produce elevated growth rates of small char and act in a manner similar to a “resource pulse,” allowing a sub-set of small char to “break through,” thus setting the cycle in population structure.     

Germination et croissance des plantules de hêtre (Fagus sylvatica) sous contraintes climatiques et allélopathiques

Recruitment is a key process for forest sustainability, especially in warm margin of distribution area. The influence of climate (temperate or warm), of soil water availability, and of allelopathic interactions from different forest species have been tested on the germination of Fagus sylvatica in controlled climatic conditions. Germination rates of non-dormant Fagus seeds were improved by relatively warm temperatures (20 °C), but reversibly stopped under heat constraint (27 °C). The relative growth rate of Fagus seedlings was better under temperate climatic conditions. Foliar extracts of Hedera helix showed the highest allelopathic effect on Fagus recruitment, especially in temperate conditions. Our results suggest a limitation of Fagus recruitment in warm margin of its distribution area, and a modulation of recruitment success according to the identity of plant neighbourhood.     

Projected Shifts in Coffea arabica Suitability among Major Global Producing Regions Due to Climate Change

Regional studies have shown that climate change will affect climatic suitability for Arabica coffee (Coffea arabica) within current regions of production. Increases in temperature and changes in precipitation patterns will decrease yield, reduce quality and increase pest and disease pressure. This is the first global study on the impact of climate change on suitability to grow Arabica coffee. We modeled the global distribution of Arabica coffee under changes in climatic suitability by 2050s as projected by 21 global circulation models. The results suggest decreased areas suitable for Arabica coffee in Mesoamerica at lower altitudes. In South America close to the equator higher elevations could benefit, but higher latitudes lose suitability. Coffee regions in Ethiopia and Kenya are projected to become more suitable but those in India and Vietnam to become less suitable. Globally, we predict decreases in climatic suitability at lower altitudes and high latitudes, which may shift production among the major regions that produce Arabica coffee.     

Future Risks of Pest Species under Changing Climatic Conditions

Most agricultural pests are poikilothermic species expected to respond to climate change. Currently, they are a tremendous burden because of the high losses they inflict on crops and livestock. Smallholder farmers in developing countries of Africa are likely to suffer more under these changes than farmers in the developed world because more severe climatic changes are projected in these areas. African countries further have a lower ability to cope with impacts of climate change through the lack of suitable adapted management strategies and financial constraints. In this study we are predicting current and future habitat suitability under changing climatic conditions for Tuta absoluta, Ceratitis cosyra, and Bactrocera invadens, three important insect pests that are common across some parts of Africa and responsible for immense agricultural losses. We use presence records from different sources and bioclimatic variables to predict their habitat suitability using the maximum entropy modelling approach. We find that habitat suitability for B. invadens, C. cosyra and T. absoluta is partially increasing across the continent, especially in those areas already overlapping with or close to most suitable sites under current climate conditions. Assuming a habitat suitability at three different threshold levels we assessed where each species is likely to be present under future climatic conditions and if this is likely to have an impact on productive agricultural areas. Our results can be used by African policy makers, extensionists and farmers for agricultural adaptation measures to cope with the impacts of climate change.     

Sustainability potential for Ginkgo biloba L. plantations under climate change uncertainty: An ex-situ conservation perspective

G. biloba is native to China and one of the oldest living species. It has high economic value and has been used for medicinal, ornamental and other purposes. The current study sought to assess the potential sustainability of the plantations of the endangered species under climate change scenarios. The sustainability of the existing small wild population and plantations of the species worldwide were evaluated by assessing the changes in the climatic suitability of the areas to be used for the species plantations under different emission scenarios. A survey for the species distribution worldwide showed that it is currently planted in 29 botanic gardens. In Egypt only 31 trees exist in private and public botanic gardens. Propagation and germination experiments have been tested in 4 successive years to assess the effect of climate changes on germination requirements and phenology of the species. Propagation trials showed that seeds that were grown in soil media for 5 months under 25 °C attained high germination rate (>60%). Propagation trials in the nursery by stem cuttings gave promising results (100%) in 2015–2016. Using SDMs approach for assessing the change in the potential climatically suitable areas for the plantations and ex situ conservation of G. biloba under different climate change and emission scenarios, revealed that overall G. biloba is predicted to gain more climatically suitable areas under the four representative concentration pathway scenarios (RCP 2.6, 4.5, 6.0 and 8.5), however, a gain in the climatically suitable areas for the species is expected under the low and moderate emission scenarios and a decline is expected under the more warming scenarios. Also, a northwards shift is predicted in the climatic suitability for the plantations of the species. The projected latitudinal shift needs to be considered by mangers of G. biloba plantations. The provided predictions can guide the managers in developing short- and long-term plans for sustaining the plantations of the species under a precipitously changing climate.     

Dissecting the nonlinear response of maize yield to high temperature stress with model‐data integration

Evidence suggests that global maize yield declines with a warming climate, particularly with extreme heat events. However, the degree to which important maize processes such as biomass growth rate, growing season length (GSL) and grain formation are impacted by an increase in temperature is uncertain. Such knowledge is necessary to understand yield responses and develop crop adaptation strategies under warmer climate. Here crop models, satellite observations, survey, and field data were integrated to investigate how high temperature stress influences maize yield in the U.S. Midwest. We showed that both observational evidence and crop model ensemble mean (MEM) suggests the nonlinear sensitivity in yield was driven by the intensified sensitivity of harvest index (HI), but MEM underestimated the warming effects through HI and overstated the effects through GSL. Further analysis showed that the intensified sensitivity in HI mainly results from a greater sensitivity of yield to high temperature stress during the grain filling period, which explained more than half of the yield reduction. When warming effects were decomposed into direct heat stress and indirect water stress (WS), observational data suggest that yield is more reduced by direct heat stress (?4.6 ± 1.0%/°C) than by WS (?1.7 ± 0.65%/°C), whereas MEM gives opposite results. This discrepancy implies that yield reduction by heat stress is underestimated, whereas the yield benefit of increasing atmospheric CO₂ might be overestimated in crop models, because elevated CO₂ brings yield benefit through water conservation effect but produces limited benefit over heat stress. Our analysis through integrating data and crop models suggests that future adaptation strategies should be targeted at the heat stress during grain formation and changes in agricultural management need to be better accounted for to adequately estimate the effects of heat stress.     

Genetic engineering of polyamine metabolism changes <Emphasis Type="Italic">Medicago truncatula</Emphasis> responses to water deficit

In the current scenario of climate change and increasing water scarcity there is an increased need to combine research efforts for the development of abiotic stress resistant crops, specifically plants able to support water deficit (WD). Polyamines (PAs) have been described as being involved in the regulation of many physiological processes and a variety of stress responses in plants. Arginine decarboxylase (ADC) is considered a key enzyme of the polyamine (PA) biosynthetic pathway. In this study, a T₂ transgenic homozygous line of Medicago truncatula expressing the oat Adc under the control of CaMV 35S was obtained and was shown to have higher leaf accumulation of putrescine, spermidine and norspermidine compared to wild type plants. The photosynthetic parameters, leaf internal CO₂ concentration (Ci), net CO₂ assimilation rate (A), transpiration (E) and stomatal conductance (gs) of transformed and untransformed lines during WD and water deficit recovery experiments were measured by IRGA (infrared gas analyzer) and compared over time. Two light intensities were used, growth light intensity (391 μmol m^?2 s^?1) and saturating light intensity (1044 μmol m^?2 s^?1). Independently of the light intensity, and under WD, the transgenic line stood out with increased Ci, A, E and gs; suggesting a possible benefit of the augmented PAs under such disturbing environmental conditions. We showed that the constitutive expression of the oat Adc gene improve the physiological responses to WD and that WD recovered transgenic plants had higher seed yield, suggesting a possible benefit of PA metabolism manipulation in legumes.