Climate-related Variables Research Articles

Nonlinear relationship of greening and shifts from greening to browning in vegetation with nature and human factors along the Silk Road Economic Belt

Understanding the trends in vegetation evolution and their driving factors is critical to revealing changes in ecosystem's structure and function. However, less is known about the nonlinear relationship between greening trends and greening to browning shifts in vegetation and its driving factors. Based on ensemble empirical mode decomposition (EEMD) and Boosted Regression Tree (BRT) methods, we investigated the nonlinear relationships of the greening trends and greening to browning shifts in vegetation to climate change, elevation, and human activities along the Silk Road Economic Belt (SREB). Results indicated that: (1) For vegetation with greening trends, although the total importance of climate-related variables was greater than human activities (59.57% and 35.33%, respectively), Land use changes (14.91%) and CO2 (9.41%) were more important than the other nature-related variables. In addition, volumetric soil moisture (8.72%), precipitation of warmest quarter (6.50%), and daily snow water equivalent (5.75%) were also very important. For vegetation with greening to browning shifts, the total contributions of climate-related variables were also larger than human activities (69.10% and 19.36%, respectively). Moreover, elevation (11.54%), vapor pressure deficit (9.85%), annual mean temperature (6.84%), min temperature of the coldest month (5.98%), soil moisture (5.16%), and annual precipitation (5.11%) might be the main reasons. (2) Increased cropland and grassland, along with the land conversions from shrub land/sparse vegetated to forest could promote vegetation greening. Increased rates of CO2, volumetric soil moisture, warmest quarter precipitation, and daily snow water equivalent could also promote it. For vegetation with greening to browning shifts, low-altitude areas, increased vapor pressure deficit, decreased cold temperature, and drought could promote vegetation shift greening to browning. The nonlinear analysis can correctly reveal the actual trends in vegetation and its responses to driving factors, which will further provide adaptation strategies to protect ecology.

Maximum entropy modeling for the conservation of Hopea odorata in riparian forests, central Thailand

Abstract. Asanok L, Kamyo T, Marod D. 2020. Maximum entropy modeling for the conservation of Hopea odorata in riparian forests, central Thailand. Biodiversitas 21: 4663-4670. Hopea odorata plays a dominant role in both ecologically and economically in Thailand. We analyzed potentially suitable areas for H. odorata in the riparian zone of the Chao Phraya River using the software MaxEnt. Modeling included 164 occurrence records along with 19 climate-related variables, slope, aspect, and elevation. Precipitation was the key climatic variable influencing the distribution of H. odorata. Riparian areas along the Chao Phraya that were predicted to be highly suitable for this species were located in the provinces of Nakhon Sawan, Ang Thong, Phra Nakhon Si Ayutthaya, Pathum Thani, Nonthaburi, and Bangkok. The ROC AUC score was 0.891, indicating that MaxEnt is an excellent tool for predicting suitable regions for the restoration or cultivation of commercially and ecologically valuable species such as H. odorata. Models such as what we have presented here can facilitate habitat conservation and sustainable resource use for rare and important plants.

Are smallholder farmers’ perceptions of climate variability supported by climatological evidence? Case study of a semi-arid region in South Africa

Purpose Literature contends that not much is known about smallholder farmers’ perceptions of climate variability and the impacts thereof on agricultural practices in Sub-Saharan Africa and South Africa in particular. The purpose of this study is to examine the perceptions of smallholder farmers from Botlokwa (a semi-arid region in South Africa) on climate variability in relation to climatological evidence. Design/methodology/approach The study area is in proximity to a meteorological station and comprises mainly rural farmers, involved in rain-fed subsistence agriculture. Focus group discussions and closed-ended questionnaires covering demographics and perceptions were administered to 125 purposely sampled farmers. To assess farmers’ perceptions of climate variability, their responses were compared with linear trend and variability of historical temperature and rainfall data (1985-2015). Descriptive statistics were used to provide insights into respondents’ perceptions. Findings About 64% of the farmers perceived climate variability that was consistent with the meteorological data, whereas 36% either held contrary observations or were unable to discern. Age, level of education, farming experience and accessibility to information influenced the likelihood of farmers to correctly perceive climate variability. No significant differences in perception based on gender were observed. This study concludes that coping and adaption strategies of over one-third of the farmers could be negatively impacted by wrong perceptions of climate variability. Originality/value This study highlights discrepancies in perceptions among farmers with similar demographic characteristics. To guarantee sustainability of the sector, intervention by government and other key stakeholders to address underlying factors responsible for observed discrepancies is recommended.

Alpine tundra species phenology is mostly driven by climate-related variables rather than by photoperiod

The study of plant phenology has frequently been used to link phenological events to various factors, such as temperature or photoperiod. In the high-alpine environment, proper timing of the phenological cycle has always been crucial to overcome harsh conditions and potential extreme events (i.e. spring frosts) but little is known about the response dynamics of the vegetation, which could shape the alpine landscape in a future of changing climate. Alpine tundra vegetation is composed by an array of species belonging to different phytosociological optima and with various survival strategies, and snowbed communities are a relevant expression of such an extreme-climate adapted flora. We set eight permanent plots with each one in a snowbed located on the Cimalegna plateau in Northwestern Italy and then we selected 10 most recurring species among our plots, all typical of the alpine tundra environment and classified in 3 different pools: snowbed specialists, grassland species and rocky debris species. For 3 years we registered the phenophases of each species during the whole growing season using an adaptation of the BBCH scale. We later focused on the three most biologically relevant phenophases, i.e., flower buds visible, full flowering, and beginning of seed dispersion. Three important season-related variables were chosen to investigate their relationship with the phenological cycle of the studied species: (i) the Day Of Year (DOY), the progressive number of days starting from the 1st of January, used as a proxy of photoperiod, (ii) Days From Snow Melt (DFSM), selected to include the relevance of the snow dynamics, and (iii) Growing Degree Days (GDD), computed as a thermal sum. Our analysis highlighted that phenological development correlated better with DFSM and GDD than with DOY. Indeed, models showed that DOY was always a worse predictor since it failed to overcome interannual variations, while DFSM and marginally GDD were better suited to predict the phenological development of most of the species, despite differences in temperature and snowmelt date among the three years. Even if the response pattern to the three variables was mainly consistent for all the species, the timing of their phenological response was different. Indeed, species such as Salix herbacea and Ranunculus glacialis were always earlier in the achievement of the phenophases, while Agrostis rupestris and Euphrasia minima developed later and the remaining species showed an intermediate behavior. However, we did not detect significant differences among the three functional pools of species.

Using Apparent Electrical Conductivity as Indicator for Investigating Potential Spatial Variation of Soil Salinity across Seven Oases along Tarim River in Southern Xinjiang, China

Soil salinization is a major soil health issue globally. Over the past 40 years, extreme weather and increasing human activity have profoundly changed the spatial distribution of land use and water resources across seven oases in southern Xinjiang, China. However, knowledge of the spatial distribution of soil salinization in this region has not been updated since a land survey in the 1970s to 1980s (the harmonized world soil database, HWSD) due to scarce observational data. Now, given the uncertainty raised by near future climate change, it is important to develop quick, reliable and accurate estimates of soil salinity at larger scales for a better manage strategy to the local fragile ecosystem that with limited land and water resources. This study collected electromagnetic induction (EMI) readings near surface soil to update on the spatial distribution and changes of water and salt in the region and to map apparent electrical conductivity (ECa, mS·m−1), in four coil configurations: vertical dipole in 1.50 m (ECav01) and 0.75 m (ECav05), so as the horizontal dipole in 0.75 m (ECah01) and 0.37 m (ECah05), then all the ECa coil configurations were modeled with random forest algorithm. The validation results showed an R2 range of 0.77–0.84 and an RMSE range of 115.17–142.76 mS·m−1. The validation accuracy of deep ECa dipole (ECah01, ECav05, and ECav01) was greater than that of shallow ECa (ECah05), as the former integrated a thicker portion of the subsurface. The range of EC spatial variability that can be explained by ECa is 0.19–0.36 (farmland, mean value is 0.28), grassland is 0.16–0.49 (shrub/grassland, mean value is 0.34), and bare land is 0.28–0.70 (bare land, mean value is 0.56). Among them, ECav01 has the best predictive ability. As the depth increased, the influence of soil-related variables decreased, and the contribution of climate-related variables increased. The main factor affecting ECa variation was climate-related variables, followed by vegetation-related variables and soil-related variables. Scatter plot show ECa was significantly correlated with ECe_HWSD_030 (0–30 cm, r = 0.482, p < 0.01) and ECe_HWSD_30100 (30–100 cm, r = 0.556, p < 0.01). The predicted spatial ECa maps were similar to the ECe values from HWSD, but also implies that the distribution of soil water and salt has undergone tremendous changes since 1980s. The study demonstrates that EMI data provide a reliable and cost-effective tool for obtaining high-resolution soil maps that can be used for better land evaluation and soil improvement at larger scales.

Comparing podzolization under different bioclimatic conditions

Silicate weathering and within soil redistribution of released metals are a near universal process believed to drive the formation of Podzols in various bioclimatic zones, ranging from tropical forest to Arctic environments. Yet the importance of climate and the fractionation of Al, Fe and Si in Podzols remains largely unknown. The aim of this study was to increase our understanding of climate-related variability in the podzolization mechanisms by conducting high-resolution chemical probing of seven soils in different bioclimatic zones and under different hydrological regimes: one well drained and one seasonally hydromorphic from the boreal zone (Sweden), two well-drained Podzols from a mild and humid area (NW Spain) and three, two poorly drained and one well drained soils, from the tropics (Brazil). The analytical strategy included seven selective dissolution techniques, in order to understand the distribution of Fe, Al and Si in organic (high, medium and low stability metal-OM complexes) and inorganic secondary compounds (short-range order and crystalline forms) in relation to their bioclimatic setting. Results indicate that the translocation of metals is coupled to the soil organic matter (SOM) mobilization in all three bioclimatic zones. The accumulation of metals and organic matter in the spodic horizons, in contrast, is contingent upon temperature, as well as on the local hydrological conditions and pH. Multivariate statistics allowed to identify the effect of climate, of soil hydrological conditions and of parent material in the soil vertical development. The high vertical resolution sampling and the extended fractionation employed were key for detecting the differences in Al, Fe and SOM dynamics in the studied soils, and revealed that different podzolization mechanisms are active in each bioclimatic zone.

Climate warming moderates the impacts of introduced sportfish on multiple dimensions of prey biodiversity.

Human-assisted introductions of exotic species are a leading cause of anthropogenic change in biodiversity; however, context dependencies and interactions with co-occurring stressors impede our ability to predict their ecological impacts. The legacy of historical sportfish stocking in mountainous regions of western North America creates a unique, natural quasiexperiment to investigate factors moderating invasion impacts on native communities across broad geographic and environmental gradients. Here we synthesize fish stocking records and zooplankton relative abundance for 685 mountain lakes and ponds in the Cascade and Canadian Rocky Mountain Ranges, to reveal the effects of predatory sportfish introduction on multiple taxonomic, functional and phylogenetic dimensions of prey biodiversity. We demonstrate an innovative analytical approach, combining exploratory random forest machine learning with confirmatory multigroup analysis using multivariate partial least-squares structural equation models, to generate and test hypotheses concerning environmental moderation of stocking impacts. We discovered distinct effects of stocking across different dimensions of diversity, including negligible (nonsignificant) impacts on local taxonomic richness (i.e. alpha diversity) and trophic structure, in contrast to significant declines in compositional uniqueness (i.e. beta diversity) and body size. Furthermore, we found that stocking impacts were moderated by cross-scale interactions with climate and climate-related land-cover variables (e.g. factors linked to treeline position and glaciers). Interactions with physical morphometric and lithological factors were generally of lesser importance, though catchment slope and habitat size constraints were relevant in certain dimensions. Finally, applying space-for-time substitution, a strong antagonistic (i.e. dampening) interaction between sportfish predation and warmer temperatures suggests redundancy of their size-selective effects, meaning that warming will lessen the consequences of introductions in the future and stocked lakes may be less impacted by subsequent warming. While both stressors drive biotic homogenization, our results have important implications for fisheries managers weighing the costs/benefits of stocking-or removing established non-native populations-under a rapidly changing climate.

The effects of climate change variability on rural livelihoods in Madre de Dios, Peru

Studies of the effects of droughts and fires on the livelihoods of resource-dependent rural smallholders have been reported for the Brazilian Amazon, but less so for other Amazonian countries. To bridge this gap in the literature, our research analyzes how climate-related variability affects different livelihood activities involving management of natural resources in Madre de Dios in Peru, located in the southwestern Amazon. Madre de Dios fell within the epicenters of both the 2005 and 2010 Amazon droughts. We examine one key question: What are the effects of extreme climatic events on different livelihood activities in communities located across Madre de Dios? We apply the key concepts of livelihood vulnerability to guide our conceptual framework. This concept organized our field inquiry, which consisted of survey questionnaires applied to rural producers and workshops with diverse stakeholders. Results show that climatic variability has affected many local livelihood activities and thereby increased the vulnerability of rural communities in Madre de Dios. The greatest impacts were felt in agriculture due to increased temperatures and fires followed by high winds and heavy rains. Our findings bear implications for science communication for policy. Climate politics will advance action on climate change if the tactic is to focus on how climate change means extreme climatic events that will cause damage to people, property, and livelihoods.

Biogeographical characterisation of Egypt based on environmental features and endemic vascular plants distribution

Biogeographical studies are considered effective for investigations on macroecology and evolution, as well as for delineating patterns of endemism and identifying the key drivers influencing the historical distribution of species. Clustering techniques, based on environmental datasets and distribution of endemic species, have been largely used in biogeography and for the definition of endemic-rich regions where conservation actions should be implemented. Despite several earlier studies have dealt with the biogeographical territories in Egypt, none of them have provided a replicable method to support such regionalisation. We proposed a two-step procedure for the biogeographical regionalisation of Egypt consisting in (1) the definition of environmental clusters (based on 24 climatic, three topographic, two soil organic carbon content and pH, and four habitat heterogeneity variables) by using the k-nearest neighbours algorithm and (2) the spatial clustering of such clusters according to the distribution of 140 endemic vascular plants. The hierarchical clustering and indicator values analyses, based on the presence-absence matrix of endemic taxa in each cluster were performed to define two cut-off levels of biogeographical sectors and subsectors. A total of six sectors and nine subsectors were identified. Climatic-related variables, elevation and soil organic carbon were the most important determinants for environmental clustering of Egypt. The highest endemic richness was recorded in the Marioutico-Arishian (71 species), Sinaico-Arabian (62 species) and Nilotic (16 species) sectors, and in Sinaic (54 species), Arishian (45 species) and Marioutic (40 species) subsectors. Nonetheless, the most protected sectors were Elbanian and Suezian (62.73 and 29.05%, respectively) while the lowest sectors were Nilotic and Marioutico-Arishian (9.86 and 13.26%, respectively). The already established protected areas in Egypt are not sufficient for conserving the representation of the identified endemic rich plant sectors. This two-step procedure confirms the usefulness of environmental attributes together with the spatial distribution of endemic vascular plants to define the biogeographical units in Egypt. Our regionalisation method could be replicated for other species’ groups, with the ultimate goal of integration all species of interest in a single biogeographical system. Furthermore, the presented regionalisation will help to identify weaknesses in current protection actions and to understand biogeographical processes.

Environmental and anthropogenic drivers of coniferous species distribution in Mediterranean drylands from North West Algeria

Understanding the influence of environmental and anthropogenic factors on the distribution of species is essential for developing management in endangered ecosystems. We studied the current abundance and distribution patterns of vegetation along environmental and anthropogenic gradients in North West Algeria. We focused on the four dominant coniferous species (Pinus halepensis, Tetraclinis articulata, Juniperus oxycedrus and Juniperus phoenicea). We compiled inventories of species composition, together with 12 environmental variables in 177 sampling plots throughout the study area. Multivariate (detrended correspondence analysis) and univariate (Huisman–Olf–Fresco models) analyses were applied to predict the presence of coniferous species and to explore species-environment relationships with ecological and anthropogenic variables. We found that species segregated along environmental gradients, mainly altitude and related climatic variables (temperatures). Anthropogenic variables, like fire frequency and overgrazing, were secondary, but also significant. Juniperus phoenicea was located exclusively in coastal areas. Tetraclinis articulata had a wide distribution and was linked to coastal and inland areas, but did not arrive at more continental areas (colder and drier), where it was replaced with J. oxycedrus. P. halepensis displayed the widest distribution and was practically present throughout the study area, but its maximum abundance was in continental areas. These results indicate a possible shift of species’ potential distribution in future climatic change. Species like J. oxycedrus would be seriously threatened by niche narrowing, while Pinus halepensis and T. articulata could expand to a certain extent. Our results provide important inputs for optimizing the management plans of coniferous species by considering environmental factors key modulators of vegetation distribution.

Multidecadal modulations of key metrics of global climate change

Widespread public and scientific interest in the recent global warming hiatus and related multidecadal climate variability stimulated a surge in our understanding of key metrics of global climate change. While seeking explanations for the nearly steady global mean temperature from late 1990s through the early 2010s, the scientific community also grappled with concomitant and seemingly inconsistent changes in other metrics. For example, over that period, Arctic sea ice experienced a rapid decline but Antarctic sea ice expanded slightly, summertime warm extremes continued to rise without evidence of a pause, and the expanding Hadley cell trend maintained its course. In this article, we review recent advances in understanding the multidecadal variability of these metrics of global climate change, focusing on how internal multidecadal variability may reconcile differences between projected and recently observed trends and apparent inconsistencies between recent trends in some metrics. We emphasize that the impacts of global scale, naturally occurring patterns on multidecadal timescales, most notably the Pacific and Atlantic Multidecadal Variability, tend to be more regionally heterogeneous than those of radiatively forced change, which weakens the relationship between local climate impacts and global mean temperature on multidecadal timescales. We conclude this review with a summary of current challenges and opportunities for progress.

Remote sensing: generation of long-term kelp bed data sets for evaluation of impacts of climatic variation.

A critical tool in assessing ecosystem change is the analysis of long-term data sets, yet such information is generally sparse and often unavailable for many habitats. Kelp forests are an example of rapidly changing ecosystems that are in most cases data poor. Because kelp forests are highly dynamic and have high intrinsic interannual variability, understanding how regional-scale drivers are driving kelp populations-and particularly how kelp populations are responding to climate change-requires long-term data sets. However, much of the work on kelp responses to climate change has focused on just a few, relatively long-lived, perennial, canopy-forming species. To understand how kelp populations with different life history traits are responding to climate-related variability, we leverage 35yr of Landsat satellite imagery to track the population size of an annual, ruderal kelp, Nereocystis luetkeana, across Oregon. We found high levels of interannual variability in Nereocystis canopy area and varying population trajectories over the last 35yr. Surprisingly, Oregon Nereocystis population sizes were unresponsive to a 2014 marine heat wave accompanied by increases in urchin densities that decimated northern California Nereocystis populations. Some Oregon Nereocystis populations have even increased in area relative to pre-2014 levels. Analysis of environmental drivers found that Nereocystis population size was negatively correlated with estimated nitrate levels and positively correlated with winter wave height. This pattern is the inverse of the predicted relationship based on extensive prior work on the perennial kelp Macrocystis pyrifera and may be related to the annual life cycle of Nereocystis. This article demonstrates (1) the value of novel remote sensing tools to create long-term data sets that may challenge our understanding of nearshore marine species and (2) the need to incorporate life history traits into our theory of how climate change will shape the ocean of the future.

Long-term surface water trends and relationship with open water evaporation losses in the Namoi catchment, Australia

Economic pressures on natural resources have led to a modification of natural surface water patterns. This has affected the hydrologic cycle at a global scale with multiple environmental and socioeconomic implications. This study evaluates long-term trends in surface water occurrence and related climate variables in a large agricultural catchment of Australia to understand trends in evaporative water losses from open water bodies. Surface water detection was based on a supervised classification of Landsat images between 1988 and 2018 to obtain inundation and surface water frequencies across the catchment, which were compared with other surface water products. Climate trends were based on monthly SILO gridded datasets. Open water evaporation was estimated using the FAO56 methodology and compared with the Penman-Monteith-Leuning Evapotranspiration V2 (PML_V2) product. Evaporation trends were analysed using the Mann Kendall (MK) test and the Sen’s slope (SS). Generally, open water frequencies showed significant negative trends, though these varied spatially. The number of dams, on the other hand, had an increasing trend. Temperatures are increasing in the catchment, while rainfall and relative humidity are decreasing, resulting in an overall positive trend for reference evapotranspiration (ETr) across 90% of the catchment. Even though ETr and evaporation per unit area of water show positive trends, lumped open water evaporation showed a negative trend, possibly associated with an average decrease in surface water frequencies. Annual evaporative losses averaged 201.9 GL, exceeding annual total account usage of surface water in the catchment. All the studied changes imply a loss of blue and green water in the catchment, and provide evidence of an overall intensification of the hydrologic cycle as predicted under climate change.

A sandwich smoother for spatio-temporal functional data

Statistical analysis of spatio-temporal data has been evolving to handle increasingly large data sets. For example, the North American CORDEX program is producing daily values of climate-related variables on spatial grids with approximately 100,000 locations over 150 years. Smoothing of such massive and noisy data is essential to understanding their spatio-temporal features. It also reduces the size of the data by representing them in terms of suitable basis functions, which facilitates further computations and statistical analysis. Traditional tensor-based methods break down under the size of such massive data. We develop a penalized spline method for representing such data using a generalization of the sandwich smoother proposed by Xiao et al. (2013). Unlike the original method, our generalization treats the spatial and temporal dimensions distinctly and allows the methodology to be directly applied to non-gridded data. We demonstrate the practicality of the methodology using both simulated and real data. The new smoother, as well as the original sandwich smoother, is implemented in the hero R package.

Perceptions of climate variability and change in relation to observed data among two east coast communities in Zanzibar, East Africa

ABSTRACT This paper seeks to understand the perceptions of local communities to climate variability and change in relation to observed climatic data. A perception survey, historical timeline and analysis of sea level and meteorological data from the study area were used to achieve this objective. As perceptions regarding different types of climate stimuli are likely to trigger response actions, this study highlights the importance of integrating local perceptions into planning for adaptation. The study suggests that climate change is happening in Zanzibar and is set to intensify as it is directly linked to regional and global events such as ENSO. The perceptions of local communities regarding variability in rainfall, temperature and sea level are highly influenced by the relationship between these elements and their livelihood activities, namely fishing, farming and seaweed farming; their direct experience of shifts in weather patterns; and their recall of past climate. While variability and changes were recognized, the majority of respondents linked this to God’s doing, and most had little exposure to the phenomenon of global climate change. Furthermore, while local people's perceptions of rainfall and temperature changes showed some relationship with observed data, their perceptions on sea level rise did not.

Afforestation driving long-term surface water browning.

Increase in surface water color (browning), caused by rising dissolved organic carbon (DOC) and iron concentrations, has been widely reported and studied in the last couple of decades. This phenomenon has implications to aquatic ecosystem function and biogeochemical carbon cycling. While recovery from acidification and changes in climate‐related variables, such as precipitation and length of growing season, are recognized as drivers behind browning, land‐use change has received less attention. In this study, we include all of the above factors and aim to discern their individual and combined contribution to water color variation in an unprecedentedly long (1940–2016) and highly resolved dataset (~20 times per month), from a river in southern Sweden. Water color showed high seasonal variability and a marked long‐term increase, particularly in the latter half of the dataset (~1980). Short‐term and seasonal variations were best explained by precipitation, with temperature playing a secondary role. All explanatory variables (precipitation, temperature, S deposition, and land‐use change) contributed significantly and together predicted 75% of the long‐term variation in water color. Long‐term change was best explained by a pronounced increase in Norway spruce (Picea abies Karst) volume—a measure of land‐use change and a proxy for buildup of organic soil layers—and by change in atmospheric S deposition. When modeling water color with a combination of explanatory variables, Norway spruce showed the highest contribution to explaining long‐term variability. This study highlights the importance of considering land‐use change as a factor behind browning and combining multiple factors when making predictions in water color and DOC.

Weather and climate in the assessment of tourism-related walkability.

Walking is an important outdoor recreational and tourism activity, both in natural surroundings and in urban settings. Walkability is the extent to which the built environment promotes walking, and addresses issues such as comfort, connectivity, safety and aesthetic values. The paper explores a relatively overlooked domain of recreation- and tourism-related walkability: the extent to which weather and climatic conditions are incorporated into assessments of walkability and their influence on walking behaviour. Following a discussion of the assessment of walkability, the results of a scoping review of weather- and climate-related variables in walkability articles published up to June 2018 are presented. The review indicates there is little research on walkability from a tourist perspective, although there is substantial interest in walking for leisure and recreation. Four major themes were identified. The descriptive theme focuses on the general importance of weather and climate to walkability; the passive analyses the weather and climate conditions as barriers to, or as promoters of, walking; proactive studies refer to adapting to and managing weather, such as provision of shade or snow-clearing. The proactive perspective gains less attention than the passive analysis. Finally, statistical controlling was only employed by a minority of studies that adjusted their results to the impacts of weather conditions. The work concludes that the sub-field has been poorly served with respect to concept and variable definition and consistency of use mean that present knowledge is of limited scientific value. Strategies for future research are suggested.

Trends of actual and potential evapotranspiration based on Bouchet’s complementary concept in a cold and arid steppe site of Northeastern Asia

Due to complex natural water flux processes and the ambiguous explanation of Bouchet’s complementary theory, site-level investigations on evapotranspiration (ET) and related climate variables assist in understanding the regional hydrological response to climate change. In this study, site specific empirical parameters were incorporated in the Bouchet’s complementary relationship (CR) and potential and actual ET were estimated by CR method and subsequently validated by 6 years of ground-based vapor flux observations. Time series analysis, correlation analysis and principal regression analysis were conducted to reveal the characteristics of climate change and the controlling factor(s) of the variations of potential ET and actual ET. The results show that this region is exhibiting a combined warming and drying trend over the past decades with two change points that occurred in 1993 and in 2000. Potential ET was predominantly influenced by temperature and vapor pressure deficit, while actual ET was mostly influenced by vegetation activity. Potential ET was found to be increasing concurrently with declining actual ET to constitute nearly a symmetric complementary relationship over the past decades. This study help to enhance our understanding of the regional hydrological response to climate change. Further studies are needed to partition the actual ET into transpiration and other components and to reveal the role of vegetation activity in determining regional ET as well as water balance.

Adaptation of mangrove trees to different salinity areas in the Ayeyarwaddy Delta Coastal Zone, Myanmar

Mangroves in the Ayeyarwaddy Coastal Delta Zone (ADCZ) of Myanmar are well known for their rich biodiversity and their enormous ecosystem services. However, as recently evident from the adverse impacts of Cyclone Nargis in 2008, they are increasingly threatened by the impacts of climate change and variability. This study was aimed to understand mangrove species composition and their characteristics driven by climate-related variables such as salinity. Transect survey method to investigate the species composition and mangrove quality including tree density, canopy height, and diameter at breast height and species distribution were used. The study was conducted during 2015–2017 in Laputta and Bogalay Townships of ADCZ. Individual transects of 500 m which included six sample plots of 15 m × 15 m along each transect line were investigated. Salinity was significantly higher in Laputta (14.4 ± 3.0 PSU in November - 28.8 ± 0.5 PSU in May) than in Bogalay (0.5 ± 0.2 PSU in November - 14.4 ± 3.0 PSU in May). Six species were confirmed to grown only in the high salinity area at Laputta. Nine species showed a preference for low salinity area at Bogalay. Among the thirty species, fifteen species were documented as the highest salt tolerant species as observed in both low and high salinity areas.

Community Responses to Climate-Related Variability and Disease: The Critical Importance of Long-Term Research

Community Responses to Climate-Related Variability and Disease: The Critical Importance of Long-Term Research