Effects Of Climate Variability Research Articles

Climate change and economic growth: Evidence for European countries

AbstractClimate change may affect economies and the welfare of people around the world. To design appropriate policy responses, the economic effects of climate change should be known. One strand in the literature empirically estimates the growth effects of climatic variations. However, those studies often neglect economic variables that have proven to be robust in explaining economic growth. Further, often they fail to check for the robustness of their results. The main aim of this study is to detect whether there exists a statistically significant robust relation between climate change and economic growth by estimating different model specifications. To do so panel estimation techniques for 24 European economies for the period from 2002 to 2019 are applied whereby panel fixed effects estimations and dynamic Generalized Methods of Moments estimations are resorted to. No statistically significant robust relationship between the temperature change and economic growth is found just as for precipitation that does not exert a significant effect on growth. As regards the institutional and macroeconomic control variables the rule of law, the fiscal variable, and the output gap are statistically significant and robust. It is argued that far‐reaching policy measures, such as the net zero goal of the European Union, should be given only based on robust results. Otherwise, economic policy may turn out to be inadequate and can lead to welfare losses. Hence, the conclusion is that the net zero goal of the European Green Deal is to be seen skeptical.

Uneven changes in air and crown temperatures associated with snowpack changes affect the phenology of overwintering cereals

Time series analysis of overwintering cereals in snowy areas has revealed several phenological patterns associated with climate changes in winter. Herein, to investigate the recent effect of climatic variations on overwintering cereals, we investigated the phenology over multiple decades at three snowy region sites with an air temperature (Tair) increase trend of 0.48–1.09 °C/decade. Our findings were as follows: heading trends differed within the same cultivar at different sites; phenology was promoted with increasing temperatures in cooler regions and decreasing snow duration in regions with heavy snow; crown temperature (Tcrown) was a more direct determinant than Tair in phenology estimation model in regions with heavy snow. A thermal gap of more than a few degrees Celsius between Tair and Tcrown, owing to the insulation effect of snowpack, affected the phenology of overwintering cereals. A shorter snow cover period promoted phenology in locations with temperatures >0 °C. Subsequently, we found that when the thermal gap was >0 °C of the growing temperature range, Tcrown directly helped determine the phenology of overwintering cereals, and irrespective of the warming trend, the periodic inflow of cold air into the northern mid-latitudes of the Northern Hemisphere and associated snow cover changes dominated Tcrown, resulting in annual phenological anomalies with a range of fluctuations of approximately 1 month. The trend of increasing Tair during spring in northern Japan is consistent with the global trend, with a pronounced trend of advancing phenology reaching >4 days/decade in a typical cooler location experiencing snowmelt in March.

The influence of climate variability events on the mesoscale eddies in the Bay of Bengal

This study investigates the temporal variability of mesoscale eddies in the Bay of Bengal (BoB) over a 29-year period (1993–2021) using satellite altimeters. High-resolution daily sea level anomaly data are considered to identify the mesoscale eddies in the BoB utilizing py-eddy-tracker, an automated eddy detection and tracking method. Wavelet coherence analysis was conducted to find a statistically significant relation between eddy properties and climate indices. The findings indicate that anti-cyclonic eddies are more susceptible to the consequence of the Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO) than cyclonic eddies. Additionally, the joined impact of ENSO and IOD conceivably alters eddy activities across the BoB, as the second downwelling coastal Kelvin wave (dCKW) were absent. The mesoscale eddies exhibit correlations with climate indicators, suggesting that eddies get stronger during La Niña and negative IOD years and get weaker during El Niño and positive IOD years. This is because La Niña and negative IOD events intensify the second dCKW, while it weakens or becomes completely absent during El Niño and positive IOD years. Random Forest model was used to compare the influence of ENSO and IOD on the forecasting performance of the eddy properties. It was demonstrated that a unique positive IOD (+IOD) negatively affects the forecasting of eddy properties when using Sea Surface Temperature (SST) and SST anomalies. The findings bear importance in verifying and confirming the interactions between the ocean and climate.

The impact of climate change upon intestinal parasites in central Europe during the 4th millennium BCE

The Neolithic period in Europe was subject to marked climatic variations during the fourth millennium BCE in the Alpine arc, marking the transition between the recent Atlantic and the Subboreal. This phase is characterized by falling temperatures and rising humidity in the Northern Hemisphere. Within this phase, between 3700 and 3250 BCE, a more intense phase takes place, known as Rootmoos 2 or Piora 2. This phase is characterized by a significant drop in lake water levels. This climatic change had repercussions on lakeside dwellers, notably through the modification and adaptation of their diet and subsistence modes. Intestinal parasites (helminths), found by human and animals via parasitic markers, seem to respond over time to these climatic variations. At first sight, low lake level phases are characterized by significant proportions of Trichuris at the expense of Diphyllobothrium, as well as an increase in Fasciola. These phases therefore seem to favour parasites indicative of agropastoral activities. During periods of high lake levels, Diphyllobothrium increase in number, pointing to a higher frequency of fishing practices. In sum, during periods of cooler/wetter climate, Neolithic lakeside populations seem to focus more on fishing produce, which may be a response to a destabilization of previously established agropastoral systems, marking a return to more opportunistic behaviour with the exploitation of products from the direct environment. This pilot study tends to evaluate if the evolution of parasitic communities in the 4th millennium BCE could therefore be used to complete our understanding of the effects of climatic variations on societies, both as a direct consequence of environmental destabilization (effect on the hosts) and the result of the behavioural adaptation of the inhabitants, even if it is still difficult to determine the importance of the influence of each factor on these variations. Despite some remaining challenges in the current study, the integration of paleoparasitic data into broader paleoenvironmental models appears promising. Future research can continue to develop along this path.

Predicting the potential distribution of Dendrolimus punctatus and its host Pinus massoniana in China under climate change conditions

IntroductionDendrolimus punctatus, a major pest endemic to the native Pinus massoniana forests in China, displays major outbreak characteristics and causes severe destructiveness. In the context of global climate change, this study aims to investigate the effects of climatic variations on the distribution of D. punctatus and its host, P. massoniana. MethodsWe predict their potential suitable distribution areas in the future, thereby offering a theoretical basis for monitoring and controlling D. punctatus, as well as conserving P. massoniana forest resources. By utilizing existing distribution data on D. punctatus and P. massoniana, coupled with relevant climatic variables, this study employs an optimized maximum entropy (MaxEnt) model for predictions. With feature combinations set as linear and product (LP) and the regularization multiplier at 0.1, the model strikes an optimal balance between complexity and accuracy.ResultsThe results indicate that the primary climatic factors influencing the distribution of D. punctatus and P. massoniana include the minimum temperature of the coldest month, annual temperature range, and annual precipitation. Under the influence of climate change, the distribution areas of P. massoniana and its pests exhibit a high degree of similarity, primarily concentrated in the region south of the Qinling−Huaihe line in China. In various climate scenarios, the suitable habitat areas for these two species may expand to varying degrees, exhibiting a tendency to shift toward higher latitude regions. Particularly under the high emission scenario (SSP5-8.5), D. punctatus is projected to expand northwards at the fastest rate. DiscussionBy 2050, its migration direction is expected to closely align with that of P. massoniana, indicating that the pine forests will continue to be affected by the pest. These findings provide crucial empirical references for region-specific prevention of D. punctatus infestations and for the rational utilization and management of P. massoniana resources.

Climatic Variations and Indoor Environmental Quality Performance of Houses in Selected Cities in Oyo State, Nigeria

Understanding how climatic variations influence Indoor Environmental Quality (IEQ) becomes crucial for designing sustainable and comfortable living spaces in this specific region. This study therefore investigates the effect of climatic variations on IEQ performance of houses in selected cities within Oyo State, Nigeria. The types of data collected for the study were numeric and ordinal. The numeric data of air temperature, relative humidity, air velocity and noise level, were gotten through objective measurements and IEQ through IEQ Calculator. The ordinal data were gotten through observation and questionnaire. Control Potential Zone technique on psychometric chat was used to analyze climate of Ibadan, Ogbomoso and Kisi. The physical measurements were conducted in the living, bedroom and kitchen spaces of the sampled houses in the low, medium and high residential density zones of the selected cities. A sample size of 581 houses from 3,490 were selected across each of the three residential density zones in the selected cities. The indoor temperature and relative humidity in the three cities were higher during the afternoon period with average thermal stress index of 39.40C, 36.90C and 38.40C respectively for Ibadan, Ogbomoso and Kisi respectively. None of the spaces satisfied the effective indoor ventilation comfort criteria of between 0.5m/s -1.5 m/s. All the spaces except the bedroom space in the compound impluvium house type satisfied the illumination range of between 50 – 60 lux. The maximum indoor noise level during the morning, afternoon and evening periods in study area were 58db, 59db and 58db respectively. Result from the IEQ calculator indicated that majority of the houses (83.6%) were star 2 in the IEQ performance. The implication was that these houses were below average in terms of IEQ performance.

Contrasting responses of forest phenological guilds to complex floodplain change

Abstract Understanding the seasonal dynamics of the forest herb layer and the factors that influence it is essential for predicting how the forest ecosystem, including mutualistic interactions, will respond to global change. However, to date, no research has investigated how understorey phenological guilds respond to major environmental threats and forest interventions. We showed the marked changes in the phenological structure of floodplain forest plant communities over half a century at a multi‐regional scale in Central Europe. Unlike previous studies focusing on individual species' responses to climate change, we examined shifts in species richness, frequency and abundance between phenological guilds within the plant community. We examined the effects of temporal variation in climate, hydrology, soil conditions and canopy structure, and assessed the effects of non‐intervention and intervention management on phenological guild responses. Our results show a significant loss of local species richness and a decline in species frequency in the forest understorey vegetation, associated with species exhibiting summer phenology. In contrast, an increase in abundance and richness of spring flowering species was observed, attributed to high nutrient loads and reduced flooding, respectively. The abundance of spring species increased only in stands where canopy cover increased over time, probably due to the suppression of summer flowering species, allowing spring flowering species to spread on open, bare ground. The community experienced a shift in maximum flowering plant richness from June to May. Despite management interventions such as clearcutting and tree planting, our data show similar temporal trajectories in intervention and non‐intervention forests, indicating that changes in phenological structure are largely independent of recent management activities. Synthesis. We propose that a complex interplay of environmental factors, rather than climate change alone, is shaping shifts towards earlier phenological guilds in floodplain forests. This study highlights the importance of considering a comprehensive view of phenological guild dynamics and the impact of environmental factors on forest plant community structure in the face of global change.

Influence of Climatic Variables on the Stem Growth Rate in Trees of a Tropical Wet Forest

The growth of tropical wet forests has a significant relationship with the climate; aspects such as temperature and precipitation affect the species; however, few studies have characterized the stem growth rate of tropical tree species. This study’s objective was to characterize the effects of climatic variation on the interannual stem growth rate of eight species in tropical wet forest. Six trees per species were selected (n = 48 trees), and a dendrometer was installed to measure diametric growth bi-monthly between 2015 and 2018 (3 years), complemented with environmental measurements, to determine their growth equations from environmental variables and, finally, to define the relationship between the wood density and the stem growth rate. The results showed an average stem growth from 0.45 to 4.35 mm year−1, and 40 to 70% growth occurred in the months with the highest rainfall. Also, species with higher wood densities were found to have lower stem growth rates. Finally, the analysis of stem growth rate showed a significant relationship in all species between the variables of temperature and precipitation (R2 adj 0.88 to 0.96). Our results suggest that species with greater stem growth rates in wet tropical forests are more susceptible to climate changes, which may affect their dynamics in the face of potential drought scenarios and heat waves associated with climate change.

Global relevance of Argentinean rainfed crops in a climatic variability context: A water footprint assessment in Buenos Aires province

Argentina has a relevant international role as a producer of agricultural commodities. Buenos Aires is the province with the largest cultivated area of cereals and oilseeds of the country. Rainfed crops depend exclusively on green water, meaning a comparative advantage for Buenos Aires province. The green virtual water content in the crops produced in Buenos Aires has implications for water allocation at international level. A great amount of countries depends on the Argentinean rainfed agriculture. Therefore, it is important to understand the effects of climate variations on Argentinean crop production at local level and the role of rainfed crops in regional and international trade. We analysed the temporal and territorial variations of crops green water demand in a climatic variability context and their influence on the water footprint. The green water footprint of the main crops of Buenos Aires was assessed, including soybeans, maize, sunflower, wheat and barley, in different climatic conditions: for the period 2008–2018, which include a dry year, a humid year and an ordinary year. A dataset about the green water footprint at municipality level was provided, and the results were presented on maps for each crop and for the different climatic conditions. The relevance of green water of main crops in the world water-dependent supply chains was shown. This comprehensive green water footprint assessment provides a useful database for researchers, companies and policy makers in Argentina and beyond.

Effects of Climatic Variations and Changing Land Use/Land Cover on Flooding in Southern Nigeria

The prevalence of flooding in Nigeria in the past few years (with its devastating consequences) has become a source of concern for policymakers and researchers alike. Scholars have attributed the high frequency of flooding, particularly in the southern region of Nigeria, to several factors; climatic variation and land use/land cover changes are themes that fall under the domain of natural and anthropogenic causes of flooding, respectively. This study examined climatic variations and changing land use/land cover in southern Nigeria with the view of determining their synergistic effects on flooding. We adopted a mixed approach for data collection with the use of Geographic Information System (GIS), retrieval of primary data from meteorological stations in the region, and field surveys. Findings show a significant decrease in rural land uses like arable lands, wetlands, and undisturbed forests; while there was a corresponding increase in urban/peri-urban land uses like settlements and tree-crop plantations over the period from 1999 to 2019. The land use/land cover changes have manifested in the destabilization of the microclimate, distortion of the carbon circle, loss of biodiversity, reduction of ecosystem services of the natural areas, and flooding. The decadal rainfall trends over the past three decades show consistent extremities with mean rainfall duration decreasing while the mean intensity increases; aggravating soil erosion, urban runoff challenges, and flooding. Climatic variations (mainly extreme rainfall patterns) synergize with inefficient land use management to exacerbate flooding in southern Nigeria. While policymakers in this region may not have the standalone capacity to significantly control climate change and the consequential variations in the local microclimate, they can re engineer land use policies to eliminate or substantially degrade anthropogenic factors that exacerbate flooding.

Global malaria predictors at a localized scale

Malaria is a life-threatening disease caused by Plasmodium parasites transmitted by Anopheles mosquitoes. In 2022, more than 249 million cases of malaria were reported worldwide, with an estimated 608,000 deaths. While malaria incidence has decreased globally in recent decades, some public health gains have plateaued, and many endemic hotspots still face high transmission rates. Understanding local drivers of malaria transmission is crucial but challenging due to the complex interactions between climate, entomological and human variables, and land use. This study focuses on highly climatically suitable and endemic areas in Côte d’Ivoire to assess the explanatory power of coarse climatic predictors of malaria transmission at a fine scale. Using data from 40 villages participating in a randomized controlled trial of a household malaria intervention, the study examines the effects of climate variation over time on malaria transmission. Through panel regressions and statistical modeling, the study investigates which variable (temperature, precipitation, or entomological inoculation rate) and its form (linear or unimodal) best explains seasonal malaria transmission and the factors predicting spatial variation in transmission. The results highlight the importance of temperature and rainfall, with quadratic temperature and all precipitation models performing well, but the causal influence of each driver remains unclear due to their strong correlation. Further, an independent, mechanistic temperature-dependent R0 model based on laboratory data, which predicts that malaria transmission peaks at 25°C and declines at lower and higher temperatures, aligns well with observed malaria incidence rates, emphasizing the significance and predictability of temperature suitability across scales. By contrast, entomological variables, such as entomological inoculation rate, were not strong predictors of human incidence in this context. Finally, the study explores the predictors of spatial variation in malaria, considering land use, intervention, and entomological variables. The findings contribute to a better understanding of malaria transmission dynamics at local scales, aiding in the development of effective control strategies in endemic regions.

Remote sensing assessment of anthropogenic and climate variation effects on river channel morphology and vegetation: Impact of dry periods on a European piedmont river

AbstractRivers are subject to increasing human pressure, resulting in a loss of their natural characteristics, further enhanced by climate change. The present study focuses on a piedmont reach of the Italian Po River and combines Landsat satellite information with hydrological records to investigate changes in sandbars exposure and riparian vegetation coverage, considering the summer period of 1984–2022. Satellite data were handled via Google Earth Engine, looking at common indexes such as the Modified Normalized Difference Water Index, which was used to identify temporal variations in wetted channel area, and the Normalized Difference Vegetation Index, considered as a proxy of vegetation coverage variations. Changes in the river hydrology were analysed by looking at the annual minimum water levels, the discharge duration curve, the stage–discharge relationship and the yearly annual water volume. Results suggest that a process of oversimplification is affecting this reach of the Po River, showing how climate change can affect piedmont European watercourses. Indeed, after an initial period where bars tended to be barer and somehow stable over time, in the most recent decade a different trend appeared, with vegetation able to colonize the exposed sandbars more. Using the Po River as an exemplary case study, this work suggests that prolonged dry periods, which are more common in recent decades, might impact large and medium rivers located in temperate climates, favouring the development of vegetation on exposed sandbars, eventually resulting in a less dynamic active channel.

Cross-habitat utilization of fish in a tropical deltaic system as a function of climate variability and body size: Are mangroves fish nurseries in a tropical delta?

The temporal variability of fish habitat utilization is poorly understood in tropical deltaic systems due to high water turbidity, which limits visual censuses, and to the lack of long-term data incorporating climate variability events. We aimed to assess the influence of body size and El Niño Southern Oscillation (ENSO) variability on the cross-habitat utilization rate of 14 fish species of commercial relevance in the Ciénaga Grande de Santa Marta (CGSM). We estimated the utilization of mangroves and coastal lagoons based on relative catch frequencies from encircling gillnets used within a long-term catch monitoring program, and then tested for significant changes in each species' habitat utilization as a function of body size and climate variability. Six species showed a high dependence on mangroves and four on coastal lagoons for most body size classes (including juveniles) and ENSO conditions. One species (Elops smithi) showed a high utilization of mangroves in some ENSO phases and body size classes, while three species showed a high utilization of both mangroves and coastal lagoons. Mangrove utilization by six species (Megalops atlanticus, E. smithi, Centropomus undecimalis, Mugil incilis, Mugil liza, and Ariopsis canteri) increased in larger body sizes at low depths, which usually occurs under dry ENSO conditions, when predatory risk is higher in coastal lagoons. Another species (Caquetaia kraussi) increased its mangrove utilization from the body size at which its feeding habits change. Mangroves and coastal lagoons are important nurseries and habitats for adults of the main commercial fish species in the CGSM. Seascape habitats and fringe/riverine mangroves must be conserved in tropical deltas to promote not only nurseries but also fish lifecycles.

The heterogeneous impacts of climate finance on environmental sustainability and social welfare in developing countries

PurposeDue to their limited capacity for adaptation and dependence on natural resources for economic growth, developing countries (DCs) tend to be more prone to climate change. It is argued that climate finance (CF) is a significant financial innovation to mitigate the negative effects of climate variation. However, the heterogeneous impacts of CF on environmental sustainability (ES) and social welfare (SW) have been masked. Thus, this study aims to investigate the heterogeneous effects of CF on ES and SW in 80 CF receipt DCs from 2002 to 2018. This study also aims to investigate the effects of CF on ES and SW based on population size, income heterogeneity and the type of CF.Design/methodology/approachThe method of moments quantile regression (MMQR) with fixed effects is utilized. Alternatively, the fully modified least square (FMOLS) and dynamic least square (DOLS) estimators are used for the robustness test.FindingsThe findings revealed that DCs with the lowest and middle quantiles of EF, carbon dioxide (CO2) emissions and human development exhibit large beneficial impacts of CF on ES and SW. In contrast, the positive effects of CF on ES breakdown for countries with the largest distributions of EF and CO2 emissions. Besides, the impacts of CF on ES and SW depend on income heterogeneity, population size and the type of CF.Practical implicationsThis study calls for a framework to integrate CF into all economic development decisions to strengthen climate-resilient SW and ES in DCs.Originality/valueTo the best of the authors’ knowledge, this is the first study to investigate the effects of CF on ES and SW in a wide range of DCs. Thus, it complements existing related literature focusing on the effects of CF on ES and SW.

Perception of Adaptation Strategies to Climate Variability in Machakos County, Kenya

The study was designed to assess climate variability trends on rainfall and temperature data between 1990 and 2020, analyse community perception to climate variability, evaluate adaptation strategies and their effectiveness and examined the challenges of adaptation to climate variability. Farmers were randomly selected and questionnaires administered, while focused group discussions were conducted to obtain farmer’s perceptions of climate variability. Rainfall and temperature data was statistically analysed using Mann Kendall test and Sen’s slope estimator (p<0.05. The study found out there was a significant variation in the amount of annual rainfall received of (p< 0.004) (S= -53) which showed a decreasing trend, while temperature showed a warming trend of (p>0.099) (S=29). Also, farmers perceived that climate variability events were real with (71.1%) and (68.0%) noticing a change in rainfall and temperature respectively over the same period. The study established that community perceptions on rainfall and temperature trends agreed with meteorological data on observed climatic trends. Planting of drought resistant crops was most popular with (89.8%) (n=255) agreeing, while (79.2%) said it was the most effective strategy. The study found that although some farmers have adopted some adaptation strategies, they were constrained with (82.4%) agreeing that age was a great challenge to adaptation and had a moderate negative correlation with adaptation of (0.097) with labour and (25.5%) saying it was not a challenge. The study recommends farmers use the study findings on rainfall and temperature trends and data recordings on local agricultural performances to enhance their ability to adapt. To researchers and academic community the study recommends the intensification of research on ecosystem-based adaptation and the use of the results in mainstreaming policy making, planning and implementation of climate related decisions. The results reveal important knowledge that if effectively applied will inform the county government in climate management decisions and reduce farmer’s vulnerability.

Synergistic evolution and attribution analysis of water-sediment in the middle and lower reaches of the Yangtze River

Study area: The Yangtze RiverStudy focus: Climatic variation and anthropogenic factors have a far-reaching impact on the evolution of runoff and sediment in the middle and lower Yangtze River. We introduced IHA-RVA and Copula functions, and used Budyko and sediment decomposition method. Under the effect of climatic variation and anthropogenic factors, the co-evaluation system and attribution analysis of runoff and sediment change are established. This study clarified the synergistic evolution law of water-sediment.New hydrological insights for the area: We found that the interannual variation trends of sediment transport at various stations in the middle and lower reaches of the Yangtze River during the period from 1954 to 2019 were more pronounced compared to the variations in runoff. Moreover, the degree of changes in water-sediment consistency varied among these stations, with water-sediment consistency gradually recovering with an increase in distance from the upstream cascade reservoirs. Human factors contributed 52.68–74.16% to the changes in runoff and 89.40–94.15% to the changes in sediment transport. Variation of water-sediment and its consistency in the middle and lower reaches of the Yangtze River are mainly related to human factors. The research results can provide some assistance to decision-makers in formulating regional water-sediment regulation planning frameworks.

Mathematical analysis of a time-delayed model for cocoa yield

Abstract Cocoa is an important crop that is predominantly grown in the western part of Africa. However, there have been fluctuations and declining trends in production and several factors have been identified to be responsible for this. A significant factor is the effect of climate variation, which could result in a low farm-level yield. Therefore, to understand the contribution of climate variability on the farm-level yield, we construct and analyse a time-delayed model to capture the effect of rainfall on cocoa production. This work uses a system of differential equations to model the crop transition from the flowering stage to pod formation, pod ripening and then to harvesting. We introduce a periodic forcing function into the model of flowering to account for the impact of seasonal rainfall variations. This leads to a novel nonlinear parametrically forced ODE for the flowering with periodically varying coefficients, which is coupled to a time-delayed model for the ripened pod formation and then harvesting. We perform an analysis of all parts of the system proving that it has a periodic solution when (parametrically) forced periodically, and we then conduct an asymptotic analysis on this periodic solution to show how its rich behaviour depends on the parameters of the climatic forcing in the model.

Effect of Climatic Variations in the Floral Phenology of Berberis microphylla and Its Pollinator Insects

Berberis microphylla (calafate) is an evergreen shrub that grows spontaneously in the Argentinean and Chilean Patagonia with a very harsh climate. This Sub-Antarctic zone is affected by the “El Niño” and “La Niña” pattern, which is measured using the Oceanic Niño Index (ONI). The objective of this study was to analyze the floral phenology and its pollinator insects, in relation to the climatic conditions observed. This work was developed in Ushuaia (Argentina) during 2010, 2014, 2015, and 2016. Significant differences were observed for the development of flower bud and floral phenology between the four years studied. On 26 October, between 84 and 100% of flower buds was recorded in the shrubs tested during the years 2010, 2014, and 2015 and then decreased abruptly in 2010 and more slowly in 2014 and 2015. However, in 2016 on the same date, it was recorded 70% of button flowers increasing to 90% on 5 November and then slowly evolving towards the anthesis phase. On the other hand, the anthesis phase was developed rapidly for 2010 and 2015 and slower for 2014 and 2016. A peak in anthesis occurred on 2 November in 2010, while in the other years, it was observed later in 16 November. The hoverflies of the genus Carposcalis and Allograpta, both insects verified to be responsible for the pollination of calafate, were registered between 2014 and 2016. Carposcalis was significantly more present in 2014, while in 2015 and 2016, Allograpta was predominant. The insect activity was also related with the climatic conditions, i.e., air temperature, air relative humidity, wind speed, and gust of wind along the day during the anthesis phase, and which also modified its life cycle. So, it was observed in 2016, the year with winter temperatures higher than normal, that adult hoverflies ended their hibernation period earlier and began to lay eggs on the juvenile calafate sprouts; hence, the emerging larvae ate the pollen grain of button flowers, causing a decrease in future fruits harvested. The results presented show that the “La Niña” and “El Niño” effects in these latitudes are the opposite of those expected. Spring 2016 developed under a strong “La Niña” effect, as occurred in 2010 with temperatures warmer than in 2014 and 2015, where both years developed under the “El Niño” effect. This study showed how climatic conditions can modify the floral phenology of B. microphylla and its pollinator insect frequency, their activity, and their life cycle.

Effects of freezing temperatures on early life stages of native trees of different elevational origin: implications for tree recruitment in seasonally dry mountain forests.

In mountain forests, tree regeneration is limited by increasingly frequent frosts with increasing elevation. We investigated the effects of exposure to freezing temperature on early life stages of two native trees of different elevational origin in a seasonally dry mountain forest. We hypothesized that the negative effects of freezing exposure on performance of early life stages increases as freezing temperature decreases, and that frost resistance increases in plants of high elevational origin. We collected seeds of two tree species (Kageneckia lanceolata and Lithraea molleoides) from populations located at different elevations and grew seedlings and saplings in a greenhouse. Dry seeds, imbibed seeds and 1-month-old seedlings were exposed to seven temperature treatments ranging from 4 °C to -20 °C, while 12-month-old saplings were exposed to four temperature treatments from -8 °C to -20 °C. After freezing exposure in a climate chamber, we monitored seed germination and seedling and sapling survival. Germination of K. lanceolata decreased with decreasing temperature only for imbibed seeds from mid- and high elevations, whereas germination of L. molleoides slightly increased with decreasing temperature only for imbibed seeds from high elevations. For both species, seedling survival decreased with decreasing temperature. For K. lanceolata, the negative effects of freezing temperatures were weaker as elevational origin of seeds increased, whereas L. molleoides showed the opposite pattern. For both species, saplings only survived at the mildest applied freezing temperature (-8 °C). We conclude that effects of climatic variation associated with elevation depend on the study species and life stage. The observed patterns could be caused by maternal effects, which are absent at the sapling stage. Moreover, temperatures below -8 °C can limit recruitment since partial mortality of seedlings and saplings occurred at such values.

Dynamic of Grassland Degradation and Its Driving Forces from Climate Variation and Human Activities in Central Asia

Central Asia is one of the most sensitive regions to climate changes in the world and the grassland degradation of this region has attracted considerable concern. Quantifying the driving force of grassland degradation is important for understanding the effects of climate variation and human activities on grassland. In this study, net primary productivity (NPP) was selected as an indicator to quantitatively evaluate the relative role of climate variation and human activities in Central Asia from 2000 to 2020. This study used the global NPP product MOD17A3 as actual NPP and estimated the potential NPP using the Thornthwaite memorial model. The potential NPP and the difference between the potential NPP and actual NPP were used to represent the influence of climate variation and human activities. The grassland degradation or restoration can be demonstrated by the slope of actual NPP (SA). A positive slope value (SA) suggested that restoration occurs, whereas a negative slope value suggested that degradation occurred. The results showed that 23.08% of the total grassland area experienced grassland degradation, whereas 2.51% of the whole grassland underwent grassland restoration. Furthermore, 53.8% of the degraded grassland areas were influenced by climate variation, and 14.5% were caused by human activities. By contrast, the relative roles of climate variation and human activities in grassland restoration were 25% and 47.9%, respectively. The NPP variation also could be calculated by assessing the effects of these factors and the results showed that 55.7% of the NPP decrease was caused by climate variation, whereas 9.6% was a result of human activities. On the contrary, climate variation and human activities resulted in 19.8% and 37.3% of grassland restoration, respectively. Therefore, climate variation was the dominant factor of grassland degradation, and human activities were the main driver of grassland restoration in Central Asia.