Increase In Mean Annual Temperature Research Articles

Impact of climate change-induced challenges on fisheries in the North Eastern Region of India and the way ahead

Abstract India's North Eastern Region comprises eight land-locked states and has a total population approaching 46 million, made up of approximately 220 ethnic communities. A high demand for fish prevails in the region as 90–100% of the population prefers fish in their daily diet. The region faces climate change-related issues at various levels and with a range of impacts on the inland fisheries sector. The period 1951 to 2010 saw a significant increase in annual mean temperature in several states of the region (Arunachal Pradesh, Assam, Manipur, Sikkim, Mizoram, and Tripura). The highest increase in annual mean temperature was recorded in Sikkim (+0.05 °C yr-1) followed by Manipur (+0.03 °C yr-1). Significant changes in annual rainfall pattern were also recorded during the same time period in the region: four of the eight states (Assam, Arunachal Pradesh, Sikkim, and Nagaland) experienced a decreasing trend, and the remaining four (Meghalaya, Manipur, Tripura, and Mizoram) an increasing trend. The highest increase in annual rainfall was recorded in Meghalaya (+14.68 mm yr-1) during this period. The change in seasonal trend of mean temperature and the erratic rainfall pattern in the region have had profound impacts on the traditional fisheries of the region. This study outlines these impacts and suggests potential adaptation actions that may be implemented to cope with climate change.

Long‐term resilience in microcrustacean communities despite environmental changes

AbstractThe ability of communities to withstand stress or maintain their species composition over extended periods of environmental changes is a matter of major concern. Here, we utilize a dataset where microcrustacean communities were related to water chemistry in 82 boreal‐alpine lakes over a 50‐yr time span (1968 and 2016), with the same person involved in sampling both times ensuring identical sites and sampling protocols. Over this time span, there has been a 1–2°C increase in mean annual temperatures and prolonged growing seasons. Also, the strong changes in SO4 deposition and acidification, peaking in the early 1980s, followed by a recovery period, have caused not only an increase in pH but also a pronounced browning (elevated DOC) and reduced levels of Ca over the past three decades. Despite this, the microcrustacean diversity and community composition have remained remarkably stable, and this holds both for the species‐rich larger, boreal sites and the species‐poor alpine sites. While likely there are interannual fluctuations in species abundance, and perhaps species may also be missing for certain periods, a combination of local refugia, resting egg seed‐banks and a regional recolonization that may occur at the meta‐population level, aims at maintaining a strong stability in community composition.

Regional evaluation of satellite‐based methods for identifying end of vegetation growing season

AbstractAutumn phenology plays an important role in regulating ecosystem carbon and water cycling, but it has received less attention than spring phenology. Satellite‐based methods have been widely applied in monitoring autumn phenology at large spatial scales. However, few studies have evaluated and compared the performance of different satellite‐based methods in autumn phenology identification. Here, we compared the spatiotemporal variations of end of vegetation growing season dates (EOS) as determined from eight prevailing satellite‐based methods against long‐term field observations at 31 sites in China. We found that field‐based observations in forest and grassland sites, respectively, had rates of EOS delay of 2.11 and 3.85 days per 1°C increase in mean annual temperature (MAT) during 2001–2014. However, nearly all the eight satellite‐based methods underestimated these delay rates compared with the ground observations over all sites. We also found that the eight methods weakly agreed with the field‐observed interannual variations of EOS. At the regional scale, the identified average EOS differed up to 38 and 40 days among the investigated satellite‐based methods in forest and grassland ecosystems respectively. The delayed rate of identified EOS with the increase of MAT ranged from 0.77 to 3.51 days °C−1 for forests and from 0.41 to 2.95 days °C−1 for grasslands. The identified EOS by most of the eight methods had delayed temporal trends in forests during 2001–2014 while we found advanced trends in grassland ecosystems. The large discrepancy in EOS identification among the prevailing satellite‐based methods highlight the need for more accurate satellite‐based methods in data gap‐filling and phenometrics detection, and more extensive, multi‐species based field observations that can be used to constrain and validate the satellite‐based methods.

Altitudinal variation of leaf carbon isotope for Dendrosenecio keniensis and Lobelia gregoriana in Mount Kenya alpine zone

AbstractAbiotic factors vary along altitudinal gradients, and this may influence plant morphology, physiology and function. This study aimed to test the hypothesis that leaf δ13C—a common proxy for water use efficiency—was indirectly influenced by morphological adjustments with changing climatic factors along an altitudinal gradient on Mount Kenya. We sampled leaves of Dendrosenecio keniensis and Lobelia gregoriana using seventy‐two 10 × 10 m plots situated every 100 m starting from 3600 to 4300 m. We determined leaf δ13C using stable isotope mass spectrometry. We also quantified the following morphological factors; leaf area, leaf mass per area, specific leaf area and leaf thickness. Climate data included mean annual temperature and precipitation, diurnal temperature range and water vapor pressure. Our results revealed that there was a leaf δ13C enrichment of 1.76 ‰ km−1 and 1.62 ‰ km−1 with altitude for D. keniensis and L. gregoriana, respectively. Leaf δ13C was enrichment by 0.01 ‰ mm−1 with mean annual precipitation along the altitude gradient for D. keniensis and 0.02 ‰ mm−1 for L. gregoriana. D. keniensis and L. gregoriana have high‐water use efficiency, an adaptation for surviving near freezing alpine temperatures and high‐diurnal range. Leaf δ13C exhibited a depletion of −0.37 ‰ per °C increase of mean annual temperature along the altitude gradient for D. keniensis and −0.34 ‰ per °C increase for L. gregoriana. Our results also showed a negative relationship between pCO2 and leaf δ13C and positive relationship between pCO2 and ∆13C for both species. Low temperatures led to the increase in leaf thickness and specific leaf area for these two species, factors that influenced leaf δ13C and ∆13C.Abstract in Chinese is available with online material.

Herbarium records demonstrate changes in flowering phenology associated with climate change over the past century within the Cape Floristic Region, South Africa

Climate change is affecting species composition and diversity across the globe. Phenological changes provide a sensitive indicator of biological responses to changes in climate. Recent studies using herbarium records in Europe and North America have shown changes in flowering time and other phenological events in response to changing climate conditions, such as warming temperatures and chilling winters, but few studies have been carried out in the southern hemisphere. We examined changes in flowering time from 1901–2009 in South Africa in the widespread, diverse genus Pelargonium. We combined records from more than 6,200 herbarium specimens of 129 species with historical weather data on temperature to examine the impact of climate change on flowering phenology. Data from over 464 weather stations in South Africa was used to estimate historical climate conditions for each of the 4,600 geographic sites included in our sample. During this time period there was a 2.9 ± 0.53 °C increase in mean annual temperature across South Africa. Flowering date advanced by nearly two weeks (11.6 days), with nearly all of the advance associated with the increase in temperature during this time. Thus, Pelargonium species are showing similar phenological responses when compared to species in the northern hemisphere. This study adds more evidence to the limited number of studies of climate change responses within Mediterranean climate regions that assess large-scale climate and phenological patterns. It also illustrates that herbarium records provide an effective method for detecting effects of climate change on flowering phenology across large geographic scales.

Temporal change in the molluscan assemblages (bivalves and gastropods) of Frobisher Bay, Nunavut, Canada, over 50 years

Long-term studies provide an effective way to assess the ecological impacts of decades-long environmental change in Arctic coastal benthic environments, but are rarely undertaken in the Canadian Arctic. In light of this, historical datasets can be compared with modern samples to examine temporal differences in benthic community structure. Frobisher Bay, Nunavut, provides a unique opportunity to use a historical census to examine the impacts that long-term environmental changes have had on the marine benthos. Between 1967 and 1976, and in 2016, infaunal samples were collected in inner Frobisher Bay and were compared to determine how the molluscan assemblages have changed between the two time periods. Molluscan assemblages in two regions of inner Frobisher Bay (Iqaluit and Cairn Island) were examined to minimize sampling discrepancies between the two time periods. A long-term increase in mean annual air temperature and a decline in the length of the ice cover season were observed. Both regions exhibited some change in sediment composition and quality as well as in molluscan assemblage between the two time periods, and species diversity indices also indicated some change between these time periods. Both the 1967–1976 and 2016 molluscan datasets provide a baseline for future long-term studies in a changing Arctic.

Impact of climate change on the hydrochemistry of Debaga unconfined aquifer, Kurdistan region, Iraq

The available climate parameters data of the rainfall and temperature for the Iraqi meteorological stations: Mosul, Kirkuk, Baiji, Tuz, Tikrit, and Debaga were investigated. The findings indicate profound document of changein climateshowed by the noticeable increase of the average mean annual temperature with the remarkable decrease of the yearly precipitation in the investigated meteorological locations.The impact of the climatic change on the hydrochemistry of Debaga unconfined aquifer was noticeable in increasing the water salinity as studied during the year 2014 and compared with the years before 2001. The Debaga unconfined aquifer water has indicated two groups’sulphate (79%) and chloride (21%) for the year 2014. It is clear that the climate change conditions increase the sulphate group in Debaga basin during 2014. It is recommended to overcome the water shortage by choosing an economical method of irrigation rather than the local traditional methods.

Joint control of plant ecological strategy by climate, regeneration mode,and ontogeny in Northeastern Chinese forests.

Research on how plant ecological strategies (competitive, stress‐tolerant, or ruderal) vary within species may improve our understanding of plant and community responses to climate warming and also successional changes. With increasing temperature, the importance of ruderal (R) and stress tolerance (S) components is hypothesized to decrease, while the strength of the competitive (C) component should increase. Offshoots and younger plants are predicted to have greater R and smaller S components.Leaf area, leaf dry matter content, and specific leaf area were measured for 1,344 forest plants belonging to 134 species in Liangshui and Fenglin Nature Reserves in Northeastern China, and C, R, and S scores calculated for each. Linear mixed effect models were used to assess how these indicators differed among study sites (n = 2), regeneration types, ontogenetic stages, and plant life forms. The two study sites have an average annual temperature difference of 0.675°C, simulating a temperature increase of 0.630°C due to climate warming.Higher temperatures reduce low‐temperature stress and frost damage, which may explain the observed decrease in R and S scores; at the same time, plant competitive ability increased, as manifested by higher C scores. This effect was most pronounced for herbaceous plants, but nearly negligible as compared to the effect of regeneration type for trees and of ontogeny for woody species. Resprouting trees and younger woody plants had higher R scores and lower S scores, a sign of adaptation to high disturbance.In this study, a small increase in mean annual temperature led to shifts in CSR strategy components for herbaceous species, without altering the vegetation type or community composition. Offshoots and younger plants had higher R and lower S scores, shedding light on similar changes in the ecological strategies of tree communities during secondary succession, such as the transition of Quercus mongolica coppices to forest and age‐related changes in Populus davidiana–Betula platyphylla forests.

The Properties of Annually Laminated Stalagmites‐A Global Synthesis

AbstractAnnually laminated speleothems have the potential to provide information on high‐frequency climate variability and, simultaneously, provide good chronological constraints. However, there are distinct types of speleothem annual laminae, from physical to chemical, and a common mechanism that links their formation has yet to be found. Here, we analyzed annually laminated stalagmites from 23 caves and 6 continents with the aim to find if there are common mechanisms underlying their development. Annually laminated stalagmites are least common in arid and semiarid climates, and most common in regions with a seasonality of precipitation. At a global scale, we observe faster growth rates with increasing mean annual temperature and decreasing latitude. Changepoints in average growth rates are infrequent and age‐depth relationships demonstrate that growth rates can be approximated to be constant. In general, annually laminated stalagmites are characterized by centennial‐scale stability in calcite precipitation due to a sufficiently large and well‐mixed water source, a time series spectrum showing first‐order autoregression due to mixing of stored water and annual recharged water, and an inter‐annual flickering of growth acceleration, bringing growth rates back to the long‐term mean. Climate forcing of growth rate variations is observed where a multi‐year climate signal is strong enough to be the dominant control on calcite growth rate variability, such that it retains a climate imprint after smoothing of this signal by mixing of stored water. In contrast, long‐term constant growth rate of laminated stalagmites adds further robustness to their unparalleled capacity to improve accuracy of chronology building.

Effect of Air Temperature Increase on Changes in Thermal Regime of the Oder and Neman Rivers Flowing into the Baltic Sea

The paper presents long-term changes in water temperature in two rivers, Oder and Neman, with catchments showing different climatic conditions (with dominance of marine climate in the case of the Oder and continental climate in the case of the Neman River). A statistically significant increase in mean annual water temperature was recorded for four observation stations, ranging from 0.17 to 0.39 °C dec−1. At the seasonal scale, for the winter half-year, water temperature increase varied from 0.17 to 0.26 °C dec−1, and for the summer half-year from 0.17 to 0.50 °C dec−1. In three cases (Odra-Brzeg, Odra-Słubice, Niemen-Grodno), the recorded changes referred to the scale of changes in air temperature. For the fourth station on Neman (Smalininkai), an increase in water temperature in the river was considerably slower than air temperature increase. It should be associated with the substantial role of local conditions (non-climatic) affecting the thermal regime in that profile. Short-term forecast of changes in water temperature showed its further successive increase, a situation unfavorable for the functioning of these ecosystems.

An approach to quantify climate-productivity relationships: an example from a widespread Nothofagus forest.

Unique combinations of geographic and environmental conditions make quantifying the importance of factors that influence forest productivity difficult. I aimed to model the height growth of dominant Nothofagus alpina trees in temperate forests of Chile, as a proxy for forest productivity, by building a dynamic model that accounts for topography, habitat type, and climate conditions. Using stem analysis data of 169 dominant trees sampled throughout south-central Chile (35°50' and 41°30' S), I estimated growth model parameters using a nonlinear mixed-effects framework that takes into account the hierarchical structure of the data. Based on the proposed model, I used a system-dynamics approach to analyze growth rates as a function of topographic, habitat type, and climatic variability. I found that the interaction between aspect, slope, and elevation, as well as the effect of habitat type, play an essential role in determining tree height growth rates of N. alpina. Furthermore, the precipitation in the warmest quarter, precipitation seasonality, and annual mean temperature are critical climatic drivers of forest productivity. Given a forecasted climate condition for the region by 2100, where precipitation seasonality and mean annual temperature increase by 10% and 1°C, respectively, and precipitation in the warmest quarter decreases by 10mm, I predict a reduction of 1.4m in height growth of 100-yr-old dominant trees. This study shows that the sensitivity of N. alpina-dominated forests to precipitation and temperature patterns could lead to a reduction of tree height growth rates as a result of climate change, suggesting a decrease in carbon sequestration too. By implementing a system dynamics approach, I provide a new perspective on climate-productivity relationships, bettering the quantitative understanding of forest ecosystem dynamics under climate change. The results highlight that while temperature rising might favor forest growth, the decreasing in both amount and distribution within a year of precipitation can be even more critical to reduce forest productivity.

Land conversion regulates the effects of long-term climate warming on soil micro-food web communities

Climate models forecast an intensification of the global temperature cycle. However, the mechanisms by which belowground biota respond to global warming remain elusive, especially when climate change interacts with land conversion. To better understand how climate warming affects soil micro-food web components with land conversion, a mesocosm experiment was set up with soil transplants to a temperate gradient region to stimulate climate warming in both cropland and abandoned land (restored following abandonment from cropland). After 8-year of experiment, the soil micro-food web shifted from a bacterial-dominated channel to a fungal-dominated one after land conversion. Climate warming weakened top-down effects in bacterial channel in both land use types. Relative abundance of soil microbes and nematodes changed with climate warming in both land use types. However, nematode diversity and C flux decreased with increasing mean annual temperature only in cropland. Structural equation modeling analysis suggested that the land conversion affected ecosystem multifunction by stimulating nematode abundance, while climate warming affected ecosystem multifunction through diversity and C flow among the soil faunal communities. Our findings indicate that the effects of climate warming on soil micro-food web communities depend on land use types. Therefore, understanding the effects of climate warming and land conversion on soil fauna helps in predicting the effects of long term warming on ecosystem processes.

Numerical Study on Thermal Insulation of a Roadway Tunnel at Southeast Edge of the Qinghai-Tibet Plateau

Tunnels in seasonal frost regions are heavily affected by damage related to icing problem and cyclic freeze-thaw of surrounding rock. To mitigate frost related damage, thermal insulation is widely used at entrance and exit section of tunnels. In thermal insulation design, length of the insulated section and thickness of the thermal insulation layer (TIL) are two important parameters. In this study, a coupled mathematical model of heat and moisture transfer was built for tunnels in cold regions. Then, field observed air temperatures at entrance section of a roadway tunnel at Altun Mountain, southeast edge of the Qinghai-Tibet Plateau, were collected and analysed. Based on the mathematical model and field observed inside air temperatures, seasonal freeze-thaw of surrounding rocks of the tunnel entrance was numerically investigated with consideration of the thicknesses and thermal conductivities of insulation layer. The results showed that, within the tunnel, the air has its mean annual temperature increase and the its amplitude decrease with increase in the distance from the entrance. The significant variations mainly occurred within the section 375 m from the entrance. Without the TIL, the maximum seasonal freeze depth of surrounding rocks at the entrance can reach to 1.5 m. To ensure that the surrounding rocks do not experience freezing, the minimum thickness of the TIL with a thermal conductivity of 0.037 W/(m·°C) should be 7 cm. While when the thickness of the TIL is 5 cm, its thermal conductivity should be not greater than 0.014 W/(m·°C).

Hydrological trends and the evolution of catchment research in the Alptal valley, central Switzerland

AbstractWhen the observation of small headwater catchments in the pre‐Alpine Alptal valley (central Switzerland) started in the late 1960s, the researchers were mainly interested in questions related to floods and forest management. Investigations of geomorphological processes in the steep torrent channels followed in the 1980s, along with detailed observations of biogeochemical and ecohydrological processes in individual forest stands. More recently, research in the Alptal has addressed the impacts of climate change on water supply and runoff generation. In this article, we describe, for the first time, the evolution of catchment research at Alptal, and present new analyses of long‐term trends and short‐term hydrologic behaviour. Hydrometeorological time series from the past 50 years show substantial interannual variability, but only minimal long‐term trends, except for the ~2°C increase in mean annual air temperature over the 50‐year period, and a corresponding shift towards earlier snowmelt. Similar to previous studies in larger Alpine catchments, the decadal variations in mean annual runoff in Alptal's small research catchments reflect the long‐term variability in annual precipitation. In the Alptal valley, the most evident hydrological trends were observed in late spring and are related to the substantial change in the duration of the snow cover. Streamflow and water quality are highly variable within and between hydrological events, suggesting rapid shifts in flow pathways and mixing, as well as changing connectivity of runoff‐generating areas. This overview illustrates how catchment research in the Alptal has evolved in response to changing societal concerns and emerging scientific questions.

Exposure of mammal genetic diversity to mid‐21st century global change

Accelerating climate and land‐use change are rapidly transforming Earth's biodiversity. While there is substantial evidence on the exposure and vulnerability of biodiversity to global change at the species level, the global exposure of intraspecific genetic diversity (GD) is still unknown. Here, we assess the exposure of mitochondrial GD to mid‐21st century climate and land‐use change in terrestrial mammal assemblages at grid‐cell and bioclimatic region scales under alternative narratives of future societal development. We used global predictions of mammal GD distribution based on thousands of georeferenced mitochondrial genes for hundreds of mammal species, the latest generation of global climate models from the ongoing sixth phase of the Coupled Model Intercomparison Project (CMIP6), and global future projections of land‐use prepared for CMIP6. We found that more than 50% of the genetically poorest geographic areas (grid‐cells), primarily distributed in tundra, boreal forests/taiga and temperate bioclimatic regions, will be exposed to mean annual temperature rise that exceeds 2°C compared to the baseline period under all considered future scenarios. We also show that at least 30% of the most genetically rich areas in tropical, subtropical and montane regions will be exposed to an increase of mean annual temperature > 2°C under less optimal scenarios. Genetic diversity in these rich regions is also predicted to be exposed to severe reductions of primary vegetation area and increasing human activities (an average loss of 5–10% of their total area under the less sustainable land‐use scenarios). Our findings reveal a substantial exposure of mammal GD to the combined effects of global climate and land‐use change. Meanwhile the post‐2020 conservation goals are overlooking genetic diversity, our study identifies both genetically poor and highly diverse areas severely exposed to global change, paving the road to better estimate the geography of biodiversity vulnerability to global change.

Regional evaluation of satellite-based methods for identifying leaf unfolding date

Satellite-based methods have been widely used to identify the critical phenophases of terrestrial vegetation and detect responses of phenophases to climate change. However, few studies have been conducted to evaluate the performance of satellite-based methods for identifying the spatial and temporal changes of phenophases based on site-based phenophase observations. This study used the ground observations of leaf unfolding date (LUD) of woody and herbaceous plants over 31 sites in China to evaluate the accuracy of LUDs modeled by eight satellite-based methods using Moderate resolution imaging spectroradiometer (MODIS) vegetation index product. Our results showed an observed 2.62 and 2.45 days advance of LUD over the spatial scale with an increased mean annual temperature of 1 °C over the forest and grassland ecosystems respectively, but almost all eight methods underestimated the advance rates. In addition, the trends for the observed LUD varied from site to site, and the eight methods showed the poor performance in capturing the long-term trends, mostly because low temporal resolution of satellite data. Most methods tended to overestimate the trend of LUD over more than 40% forest sites. Our results highlight that there is a need for further improvements in the methods and satellite datasets used for identifying LUD.

SSP‐Based Land‐Use Change Scenarios: A Critical Uncertainty in Future Regional Climate Change Projections

AbstractTo better understand the role projected land‐use changes (LUCs) may play in future regional climate projections, we assess the combined effects of greenhouse‐gas (GHG)‐forced climate change and LUCs in regional climate model (RCM) simulations. To do so, we produced RCM simulations that are complementary to the North‐American Coordinated Regional Downscaling Experiment (NA‐CORDEX) simulations, but with future LUCs that are consistent with particular Shared Socioeconomic Pathways (SSPs) and related to a specific Representative Concentration Pathway (RCP). We examine the state of the climate at the end of the 21st century with and without two urban and agricultural LUC scenarios that follow SSP3 and SSP5 using the Weather Research and Forecasting (WRF) model forced by one global climate model, the MPI‐ESM, under the RCP8.5 scenario. We find that LUCs following different societal trends under the SSPs can significantly affect climate projections in different ways. In regions of significant cropland expansion over previously forested area, projected annual mean temperature increases are diminished by around 0.5°C–1.0°C. Across all seasons, where urbanization is high, projected temperature increases are magnified. In particular, summer mean temperature projections are up to 4°C–5°C greater and minimum and maximum temperature projections are increased by 2.5°C–6°C, amounts that are on par with the warming due to GHG‐forced climate change. Warming is also enhanced in the urban surroundings. Future urbanization also has a large influence on precipitation projections during summer, increasing storm intensity, event length, and the overall amount over urbanized areas, and decreasing precipitation in surrounding areas.

Multi-year eddy covariance measurements of net ecosystem exchange in tropical dry deciduous forest of India

Tropical deciduous forests are unique in terms of their geographical distribution, strong seasonality and their contribution to global carbon dynamics, but yet their carbon sequestration potential is poorly sampled. In the current study, we report the carbon balance of 65-year-old tropical dry deciduous forest in central India using the multi-year eddy covariance measurements from November 2011 to May 2019. Over the study period, the forest site was observed to be a net sink of atmospheric CO2 with a mean annual net ecosystem productivity (NEP) of 524 (± 40; ±1 SD across different years) g C m−2 yr−1 with a 233 (±15) day growing season. The NEP was partitioned into gross primary productivity (GPP) of 3358 (± 167) g C m−2 yr−1 and annual carbon loss due to respiration and decomposition (Reco) of 2834 (± 157) g C m−2 yr−1. The ecosystem showed a strong seasonality as a source of carbon during the leaf-off season (March to June), and as a carbon sink during the rest of the year with significant sequestration during the winter season (October to December). The intra-annual analysis suggested that CO2 flux is primarily controlled by canopy greenness with mean Reco/GPP ratio varying from 1.90 (± 0.12) to 0.79 (± 0.04) during leaf-off to leaf-on seasons. The monthly C fluxes in the growing season are found to be strongly correlated to the environmental variables rather than in the leaf-off season, while variability in monthly ecosystem respiration was better explained by air temperature during the leaf-off season than the growing season. Further, the inter-annual variability of NEP was mainly dependent on growing season length and mean annual temperature. The variations in annual GPP and Reco were directly dependent on the increase in mean annual temperature. The eddy covariance-based NEP was complemented by close independent biometric estimates, imparting confidence in our measurements. In conclusion, this tropical dry deciduous forest site is a substantial carbon sink and would add crucial information regarding carbon budgeting of tropical forests in global carbon balance models.

Central Asian rivers under climate change: Impacts assessment in eight representative catchments

Study regionEight river catchments within Central Asia. Study focusThe limited amount of water resources is already an issue in the Central Asian region, and climate change may be crucial for water availability and development of countries in the region. This study investigates potential climate change impacts on water resources in Central Asia to the end of the century by focusing on eight river catchments with diverse natural conditions located in different countries. The eco-hydrological model SWIM was setup, calibrated and validated for all selected catchments under study. Scenarios from five bias-corrected GCMs under Representative Concentration Pathways 4.5 and 8.5 were used to drive the hydrological model. New hydrological insights for the regionThe results show an increase of mean annual temperature in all catchments for both RCPs to the end of the century. The projected changes in annual precipitation indicate a clear trend to increase in the Zhabay and to decrease in the Murghab catchments, and for other catchments, they were smaller.The projected trends for river discharge are similar to those of precipitation, with an increase in the north and decrease in the south of the study region. Seasonal changes are characterized by a shift in the peak of river discharge up to one month, shortage of snow accumulation period, and reduction of discharge in summer months.

Changes in Community Composition Induced by Experimental Warming in an Alpine Meadow: Beyond Plant Functional Type

Climate warming exerts profound effects on plant community composition. However, responses to climate warming are often reported at the community and functional type levels, but not at the species level. To test whether warming-induced changes are consistent among community, functional type, and species levels, we examined the warming-induced changes at different levels in an alpine meadow from 2015 to 2018. The warming was achieved by deploying six (open top) chambers [including three non-warmed chambers and three warmed chambers; 15 × 15 × 2.5 m (height) for each] that resulted in a small increase in mean annual temperature (0.3–0.5°C, varying with years) with a higher increase during the non-growing season (0.4–0.6°C) than in the growing season (0.03–0.47°C). The results show that warming increased plant aboveground biomass but did not change species richness, or Shannon diversity and evenness at the community level. At the functional type level, warming increased the relative abundance of grasses from 3 to 16%, but decreased the relative abundance of forbs from 89 to 79%; relative abundances of sedges and legumes were unchanged. However, for a given functional type, warming could result in contrasting effects on the relative abundance among species, e.g., the abundances of the forb species Geranium pylzowianum, Potentilla anserine, Euphrasia pectinate, and the sedge species Carex atrofusca increased in the warmed (compared to the non-warmed) chambers. More importantly, the difference in species identity between warmed and non-warmed chambers revealed warming-induced species loss. Specifically, four forb species were lost in both types of chambers, one additional forb species (Angelica apaensis) was lost in the non-warmed chambers, and two additional species (one forb species Saussurea stella and one sedge species Blysmus sinocompressus) were lost in the warmed chambers. Consequently, changes at the species level could not be deduced from the results at the community or functional type levels. These data indicate that species-level responses to climate changes must be more intensively studied. This work also highlights the importance of examining species identity (and not only species number) to study changes of community composition in response to climate warming.