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• A new method to estimate the C-factor for various LULCC scenarios. • Combined changes of climate and LULC leads to increased water erosion in the future. • Impoverished countries are increasingly vulnerable to erosion compared to wealthier nations. • Soil erosion rates are rising faster in lower-middle-income countries due to greater vulnerability. • Significant increase in global soil water erosion is projected after the 2050s. Soil water erosion presents a significant challenge to the sustainable productivity of agriculture, making the precise prediction of its future patterns essential for ensuring global food security. However, there is a notable scarcity of global-scale explorations of soil water erosion and its anticipated future changes. This study proposes a method for calculating the C-factor using the fraction of land use/land cover change (LULCC) scenario data. Subsequently, we conduct an extensive evaluation of global water erosion from the 2010 s to the 2090 s under various climate change and LULCC scenarios, providing a comprehensive analysis of historical and projected erosion patterns. Predictions indicate a rapid increase in total soil erosion, but the rate of increase may decelerate after the 2050 s, with projected average increases of 6.8 %, 9.3 % and 11.3 % per 20-year interval under the SSP1-RCP2.6, SSP2-RCP4.5 and SSP5-RCP8.5 scenarios, respectively. The most rapid increase in soil erosion rates is observed in lower-middle-income countries such as India and Tanzania, which are more sensitive to changes in climate and land use, whereas many high-income countries, predominantly in Europe, are likely to experience a reduction in erosion rates. We emphasize the roles of both climate change and LULCC in shaping future erosion dynamics. Specifically, while LULCC is the dominant factor under the SSP1-RCP2.6 and SSP2-RCP4.5 scenarios, climate change emerges as the chief influencer in the SSP5-RCP8.5 scenario, particularly after the 2050 s. This highlights the importance of devising regional and scenario-specific mitigation approaches, especially for more vulnerable nations. The findings highlight the need for enhanced international cooperation and increased support from low- to middle-income countries to address the challenges of water erosion and promote global sustainability. [ABSTRACT FROM AUTHOR]

• The warming trend of climate is more than twice in the RS region than in the entire DP. • TWS decreased significantly due to the reduced rate of climate moistening after 2009. • GWSA has the longest response time to rainfall among all constituent components of TWS. • SMSA and GWSA were two major contributors to the TWSA in both the DP and RS regions. • SWSA played a vital role in TWS variability, particularly in the RS region. Inter-state river water disputes are frequent over the rain shadow (RS) region of the Western Ghats (WG), where the annual rainfall is much lower (75.2 cm) than that of overall India (118 cm). This study investigated the TWS (Terrestrial Water Storage) dynamics of the entire Deccan plateau (DP) and RS regions, located at the leeward side of the WG mountain range, with the help of Gravity Recovery and Climate Experiment (GRACE) based TWS anomalies (TWSA) data. Here, the latest TRMM (Tropical Rainfall Measuring Mission) rainfall product was evaluated at different time scales against gauge-based measurements to check its applicability as an alternative to gauge-based observed data. Trends in climate variables and TWSA were estimated to understand their variations during 2003–2016 in both regions. The response of GRACE-based TWSA and its constituent components to rainfall was determined using time-lagged correlation analysis. The contribution of constituent variables to TWSA was estimated using the component contribution ratio (CCR) method. It was observed that the TRMM-3B43 data captured the rainfall pattern over the entire DP with great accuracy. Results showed that the increasing trend of TWS in 2003–2009 had reversed in 2010–2016 due to the reduction of climate moistening in both regions. The warming trend of climate is more than twice in the RS region than that found in the DP, leading to a higher decreasing rate of TWS in this region than in DP. For both DP and RS regions, the time lags of groundwater storage anomalies (GWSA), total runoff anomalies (RA), canopy water storage anomalies (CWSA), and soil moisture storage anomalies (SMSA) to rainfall can be arranged as CWSA ≤ RA ≤ SMSA ≤ GWSA. SMSA and GWSA are the main contributors to the TWSA in both areas. However, SWSA also played a vital role in TWS variability, particularly in the RS region. [ABSTRACT FROM AUTHOR]

• The relationship between gross N turnover and temperature and moisture varies on annual and seasonal scales. • The gross N turnover under the influence of temperature and water is different between field and laboratory conditions. • Soil temperature has more influence on soil gross nitrogen turnover than moisture. Understanding how soil nitrogen (N) turnover responds to temperature and soil moisture alterations is important for accurately predicting responses of soil N availability and plant productivity to global climate change. However, few studies had explored such questions under natural conditions. We investigated effects of temperature and moisture on soil gross N turnover with an annual scale field experiment in an Inner Mongolian grassland and a laboratory incubation experiment. In the field experiment, on the annual scale both gross ammonification and nitrification rates showed a hump-shaped response to temperature, with maximum rates occurring around 10 °C and 5 °C, respectively. Gross ammonification rates did not respond to soil moisture, and gross nitrification rates decreased first and then increasing with soil moisture, which the threshold was 35% water holding capacity (WHC). Totally, soil temperature explained more variation than moisture in gross ammonification (0.30 VS 0.04) and nitrification (0.24 VS 0.14) rates. On the seasonal scale, both soil temperature and moisture showed generally significant effects on gross N turnover. Grazing had no effects on soil temperature and moisture sensitivity of gross N turnover on the annual scale, but increased the sensitivity of gross ammonification to soil moisture during the spring freeze–thaw period. In the laboratory incubation experiment, gross ammonification and nitrification rates increased with the increase of temperature, although there was no difference between 20 °C and 30 °C. Gross ammonification rates reached a maximum at 50% WHC, while gross nitrification rates did not respond to soil moisture until 100% WHC. Soil temperature explained more variation than moisture in gross ammonification (0.71 VS 0.01) and nitrification (0.37 VS 0.25) rates. Our results imply that climate warming may have greater impact on gross nitrogen turnover compared to changes in rainfall, however it remains great uncertainty due to the low explanation of soil temperature and moisture. [ABSTRACT FROM AUTHOR]

• Artificial restored shrub and grass aggravated soil deficit but they got replenished better under large rainfall. • The effects of revegetation and topography on SWS varied greatly with rainfall. • Water-intensive vegetation species should be used cautiously for revegetation. The Chinese Loess Plateau (CLP) rose to prominence for its fragmented terrain and fragile ecosystems. Large-scale revegetation was applied to control soil and water loss there. However, revegetation resulted in unexpected water shortages. In this study, we investigated the temporal-spatial distribution of soil water in the northern CLP based on 13-year soil water content (SWC) data of four different revegetation types on a loessial slope and 4-year data of a gully system to study the response of soil water to long-term revegetation, topography, and precipitation. Results showed that in the 0–400 cm soil depth under shrub, grass, natural fallow, and millet, soil water storage (SWS) was –102.8, –129.3, 54.9, and 39.3 mm higher after 13-year of restoration, respectively. Although soil water under shrubs- and grasslands became more replenished under high precipitation, planting these water-intensive vegetation types aggravated soil desiccation. The gully intensified soil water spatial heterogeneity, with mean SWS within 0–480 cm soil depth of 902, 712, and 746 mm at the gully bottom, edge, and bank, respectively. The deviation index among the four revegetation types and among gully bottom, edge, and bank were 0.43 and 0.26, respectively, which indicated that revegetation types had a more obvious effect on SWS. Given that more concentrated rainfall under global climate change, both revegetation type and topography should be considered during ecological restoration in semi-arid areas. These findings can deepen our comprehension of the hydrological processes on the CLP and provide a reference for the development of ecological restoration policies under future climate change. [ABSTRACT FROM AUTHOR]

[Display omitted] • Droughts and floods are increasing worldwide. • Changes in soil moisture affect the soil microbiome. • Climate change affects the soil environment. • Changes in the soil environment affect crop production. • Drought and floods have a negative impact on agriculture. Climate change is progressing and is already visible to the naked eye around the world. Hydrological events associated with climate change, i.e. floods and droughts, have reached extreme levels in recent years. Researchers warn that these phenomena will continue to intensify. According to recent reports, the number of extreme weather events, including hydrological phenomena, has increased by 60% in Europe over the last three decades. Both water shortages and water surpluses affect the soil environment and its functions. This in turn has a direct impact on crops and agriculture. For example, in the US alone, droughts and floods were responsible for more than 70% of the decline in cereal yields in 2011 alone. However, the soil environment is a complex ecosystem that is not yet fully understood, making it difficult to predict the impact of climate change on its quality and functioning. In this paper, we discuss the effects of floods and droughts on the soil microbiome and the implications of these changes for agriculture. We suggest that changes in soil moisture are an important factor affecting crop growth and yield, which is of great importance for global food security. [ABSTRACT FROM AUTHOR]

Abstract The conversion of extreme xeromorphic vegetation (natural desert forest) to agricultural lands is one of the largest land-use changes in the arid desert region of China over the past 30 years, which may substantially influence soil respiration, and hence may largely determine local climate change. However, few studies have considered the change in soil respiration across natural desert forest and agricultural lands in the arid desert region. In this study, soil respiration and its influencing factors, i.e., soil moisture content, soil salinity, microbial quantity, soil temperature, fine-root biomass, soil organic matter (SOM), air temperature, p H and relative air humidity, were determined across natural desert forest and three chronosequential fields where forests have been converted to agricultural lands having varying length of cultivation period (i.e., 5, 10 and 30 years of cultivation) in an arid desert region. We used two-way repeated measure ANOVA for evaluating significant differences in soil respiration and its influencing factors between natural desert forest and agricultural lands, and then employed structural equation model (SEM) with the support of stepwise regressions analyses to test for the direct and indirect effects of influencing factors on soil respiration. The results showed that soil respiration significantly increased along the years of cultivation in agricultural lands (P < 0.05). Soil respiration was higher in all agricultural lands than that in natural desert forest (P < 0.05). Stepwise regressions and SEM showed that soil moisture content and soil salinity had explained 75% of the variation in soil respiration through direct and indirect effects via abiotic and biotic factors. Soil respiration was significantly affected by the sum of the direct and indirect effects of soil salinity (β = −0.46) and soil moisture content (β = 0.49) via microbial quantity, soil temperature, fine-root biomass and SOM. This study suggests that deforestation and subsequent agricultural activities might alter the soil moisture and salinity contents, and as a consequence influence soil respiration across natural desert forest and agricultural lands in an arid desert region. Graphical abstract Unlabelled Image Highlights • Soil respiration increases along the years of cultivation. • Soil respiration was higher in agricultural lands than that in natural desert forest. • Deforestation and agricultural activities alter the soil moisture and salinity. • Soil moisture content and salinity drive the variation in soil respiration. [ABSTRACT FROM AUTHOR]

Climate change has different manifestations in various regions all over the world. Such changes strongly affect ecosystem services, environmental and agricultural stability. Soils play a crucial role in the complex system that generates climate change. However, the nature and structure of response of different soils to climate change is still distant to be interpreted. Bearing in mind that climate simulations can help us to comprehend soil balance in the future, we defined the purpose of this study: to project temporal and spatial changes of temperature and moisture in four different soils under A1B scenario for the periods 2021–2050 and 2071–2100 with respect to the period 1961–1990. For this analysis climate data obtained by the ECHAM5 model simulations, dynamically downscaled by the coupled regional climate model EBU-POM (Eta Belgrade University-Princeton Ocean Model), were used. The 43 sites in Vojvodina region (Serbia) were analyzed for pedological parameters and climate elements. The projected changes at the end of 21st century (2071–2100) can be summarized as follows: (i) increase in the mean annual soil temperature up to 3.5 °C in the surface layer 0–10 cm and up to 1.8 °C in average for 0–200 cm depth and decrease in the mean soil moisture up to 0.039 kg kg − 1 in the subsurface layer 40–100 cm and up to 0.019 kg kg − 1 in average for 0–200 cm depth, which corresponds to decrease of 16% and 7%, respectively; (ii) Chernozerms proved to be more sensitive to temperature increase in contrast to water affected soils (Fluvisols, Gleysols and Vertisols) that showed the lowest susceptibility; (iii) Chernozems also showed higher sensitivity to moisture loss than Cambisols, Arenosols and Umbrisols that showed the lowest susceptibility; and (iv) it was assumed that predicted changes in soil temperature and moisture will cause significant changes in soil respiration, release of CO 2 , soil processes, agriculture, biodiversity and ecosystem functioning. [ABSTRACT FROM AUTHOR]

• Land use and land cover classes homogenize within-class differences in vegetation density, type and other characteristics that influence surface erosion. • When these classes are used to estimate current and projected future RUSLE C-factor for native vegetation, this introduces significant error. • Remote sensing methods can be used to assess intra-class variation in C-factor, improving the soil loss estimate. • A strong, predictive relationship exists between remotely-sensed C-factor values and climate. • Current and projected changes in climate can be used to directly estimate C-factor, improving the estimate of current and future soil loss rates. This new method provides a low-cost, efficient and reliable estimate of future C. Understanding how reservoir sedimentation rates may evolve due to climate change is essential for projecting future changes in reservoir water storage capacity. The Revised Universal Soil Loss Equation (RUSLE) is commonly used to assess regional soil loss rates because of its suitability for working with the coarse temporal and spatial scale of climate model outputs. Application of the RUSLE for projecting future erosion rates is constrained by the relatively limited number of classes used in projected changes of native vegetation: this typically reduces a wide range of variation in RUSLE cover (C) factors to a single value per class, and these classes may be insensitive to changes in species composition and canopy density with time and space. This paper develops a low-cost, efficient, and objective approach to projecting future C values directly based on widely available Landsat data, downscaled climate model data, and a limited number of terrain variables. Observed C is estimated from Landsat-derived Normalized Difference Vegetation Index (NDVI) and Modified Soil-Adjusted Vegetation Index (MSAVI) values using standard methods. A linear relationship is established between the observed C values and average annual antecedent temperature, average annual antecedent precipitation, latitude, and percent sand (adjusted R2 = 0.75604, 0.7543, and RMSE = 0.09448, 0.07043, respectively). A proof of principal study demonstrates that, unlike when land cover classes are used to estimates C, a RUSLE model driven by the regression-based C provides a correct order-of-magnitude estimate of observed long-term erosion and sediment yield rates (e.g., an estimate of 2.9–3.2 t ha−1 y-1 is obtained where observed rates range from 1.2 to 3.9 t ha−1 y-1 for the same time period, and up to 8 t ha−1 y-1 historically, while standard formulations of RUSLE yield 16.1 and 0.3 t ha−1 y-1). Using climate model data to estimate both precipitation intensity (R factor) and C in the RUSLE model results in basin wide projected end 21st century soil erosion rates for relative concentration pathway 8.5 of 5.5–7.5 t ha−1 y-1, consistent with expectations for accelerated soil loss in the study area as climate change reduces soil moisture while increasing precipitation intensity. The same model driven by land cover class estimates of C produces soil loss rates an order of magnitude smaller (0.3–0.4 t ha−1 y-1), consistent with a much more heavily vegetated landscape than could be supported under the increasingly arid projected climate. [ABSTRACT FROM AUTHOR]

As a hidden resource, our understanding and knowledge on the distribution of groundwater and its quantity is limited. In areas where such data is scarce, geo-observatory products such as the Gravity Recovery and Climate Experiment (GRACE) can provide an accurate estimate of changes in total terrestrial water storage at a coarser, regional resolution. However, in the Lake Tana basin, Ethiopia, groundwater is stored in localized aquifers, and its flow is controlled by physical variables (local geology, soil cover, slope, elevation difference, topographic index and drainage density) and climate (rainfall). The objective of this study is to utilize GRACE (CSR RL05) for the evaluation of spatial and temporal changes of soil moisture and groundwater storage at watershed scale. A geographic information system (GIS) based multi-layer analysis of the physical variables is implemented to delineate aquifer potential zones. The aquifer potential zone of the basin is combined with the GRACE (CSR RL05) based change in total terrestrial water storage data. Accordingly, the very high and high potential aquifer zone classes demarcate hot spots of high groundwater storage fluctuations recorded by the satellite data. The change in storage fluctuation of the 11-year monthly data, from 2003 to 2013, reveals that the total terrestrial water storage of the basin has declined by 18.37 cm. This is equivalent to the loss of 2.21 BCM of water within 11 years. Groundwater and soil moisture gains are a response of recharge, hence it is highly recommended to promote groundwater recharge, soil moisture harvesting, and sustainable use. On the other hand, the study highlights the possibility of application of the regional GRACE (CSR RL05) product for watershed-scale evaluations. [ABSTRACT FROM AUTHOR]

In this work, we investigated how the reindeer grazing in subarctic boreal Scots pine forests and climate (air temperature and the amount of precipitation) affects soil temperature, soil water content, and ultimately the CO 2 efflux from forest soils. The study was carried out in years 2013 and 2014, where 2013 was an extremely dry year (especially the summer), while 2014 was a “normal” year. Our work showed that in subarctic mature pine forests, soil temperatures were higher, and soil water content was fluctuating more on grazed areas compared to non-grazed areas in both years. On both years, the soil water content on the grazed area was higher in June and the situation changed in the second half of July when the moisture content in the non-grazed area remained higher. There was a negative correlation between soil water content and soil temperature. The soil CO 2 effluxes were mostly affected by the year of measurement, time of measurement (different months through growing season), soil temperature and also by the management (grazed or non-grazed) resulting in higher CO 2 emissions on the grazed areas. Soil moisture content was not affecting the soil CO 2 efflux. The average soil CO 2 efflux values were significantly higher in the year 2014 compared to the year 2013 mainly due to differences in soil temperature at the beginning of season. [ABSTRACT FROM AUTHOR]

[Display omitted] • Salinity varied with time, space, topography and land use activities. • Salinity decreased with increasing distance from the coastline of the Bay of Bengal. • Polder restricts direct salinization of coastal soils. • Landsat imagery based salinity indexes can reliably predict soil salinity. • A large coastal area turned into saline in the last few decades. Salinity in soils and water of coastal tracts in Bangladesh, one of the major challenges for agriculture, varies significantly due to multiple stressors, including the consequences of rapid changes in the climate pattern. However, their dynamics has not been studied in detail accentuating its importance for the management of agriculture. Here, we examined such changes along zones - defined by spatial proximity from the seafront towards inland in the south-central coast of Bangladesh. Samples of soil and water were collected at single-month intervals between November 2020 and June 2021. In April, a comprehensive soil sampling was conducted to examine spatial variability in relation to soil type and land use. Moreover, Landsat imagery-based salinity index was calculated. Our results showed that soil and water salinity gradually increased from January onwards and peaked during May. It decreased gradually from the seafront to inland, suggesting direct and indirect intrusion of salinity from the sea. A significant non-linear relationship was found between Landsat imagery-based salinity index and measures values (r2 = 0.79, p < 0.01), indicating the Landsat imagery- based estimate could potentially be used for agriculture. Our observation also showed that salinity to soil and water was significantly low in highlands, croplands, and interior of polders as compared respectively to that of low land, fallow land, and exterior of polders. Our estimation of salinity in soil and water of the south-central coast of Bangladesh was significantly higher than that of historical records. This study, thus, would contribute to contemporary policy issues on cropland management along coastal Bangladesh. [ABSTRACT FROM AUTHOR]

• There was no significant correlation between soil fungal and bacterial a-diversity and elevation. • Soil temperature (ST), soil water content (SWC), and total phosphorus (TP) were the driving factors affecting the elevation distribution pattern of soil fungal communities. • Soil fungi were more sensitive than bacteria in response to elevation changes. • The network complexity of soil bacteria is higher than that of fungi. The Qinghai-Tibet Plateau is one of the most sensitive regions in response to global climate change. Because soil bacteria have a considerable influence on ecosystem function, it is essential to understand their responses to different climates. We investigated the effects of elevation change on soil microbial diversity and community structure in the Abies georgei var. smithii forest of the Sygera Mountains in southeastern Tibet. We sampled soils from 0 to 10 cm depth at 3500 m, 3900 m and 4300 m asl, and examined changes in fungal and bacterial communities using Illumina MiSeq sequencing. The results showed that 1) fungal and bacterial diversity (Shannon index) did not change significantly (P > 0.05) with increasing elevation, and 2) elevation had no effect on the community structure of bacteria but had a significant effect on the community structure of fungi. Redundancy analysis showed that elevation, soil temperature (ST), soil water content (SWC), and total phosphorus (TP) were drivers of changes in fungal community structure. 3) Elevation had no significant effect (P > 0.05) on the relative abundance of the dominant bacterial phylum in the soil but had a significant effect (P < 0.05) on the relative abundance of the dominant fungal phylum. The dominant bacterial phyla were Proteobacteria, Actinobacteria, Acidobacteria, and Choroflexi, whereas the dominant fungal phyla were Basidiomycota, Ascomycota and Mortierllomycota. The relative abundance of Basidiomycota at 3900 m was significantly higher (P < 0.05) than that of Ascomycota at 3500 m and 4300 m, while the relative abundance of Ascomycota at 4300 m was significantly lower (P < 0.05) than that of Basidiomycota at 3500 m and 4300 m. and 4) the complexity of the bacterial network was the lowest at 3900 m elevation, while the most complex at 3500 m elevation. The fungal network complexity was lower than that of the bacteria. In conclusion, soil fungal communities are more sensitive to changes in elevation than are bacterial communities. [ABSTRACT FROM AUTHOR]

Plant litter can be incorporated into topsoil under natural circumstances by soil splash, sediment deposition, and soil-dwelling animal activities. The incorporated litter can change the mechanical properties of soil and the decomposition of the incorporated litter can improve soil structural stability. Those changes likely influence soil detachment process by overland flow. This study was undertaken to quantify the effects of incorporated plant litters into topsoil on the temporal variation in soil resistance to detachment by overland flow using natural soil samples collected from four different plots (one control and three litter incorporation treatments) and then scoured under six different flow shear stresses in a hydraulic flume. The experiment started from April 19 to October 5, 2015 for 10 times at approximately 20 days sampling intervals. Soil properties and environmental parameters were also measured at each sampling time to explain the temporal variations in rill erodibility and critical shear stress. The results showed that the incorporated plant litter was effective to enhance soil resistance to flowing water erosion. Compared to bare soil, rill erodibilities of litter incorporated soils of black locust, sea buckthorn, and green bristle grass decreased by 24.3%, 33.5%, and 34.8%. The temporal variations in rill erodibility of bare and litter incorporated soils were similar. Rill erodibility decreased significantly over time as an exponential function for both bare and litter incorporated soils. The relative rill erodibility of three litter incorporated soils increased over time as a power function. The fitted critical shear stress increased exponentially over time. The temporal variations in rill erodibility could be explained by the temporal variations in soil consolidation, water stable aggregate, and litter decomposition. Rill erodibility could be well estimated by soil bulk density, water stable aggregate, and litter mass density ( r 2 = 0.92). [ABSTRACT FROM AUTHOR]

Drylands are important ecosystems that are facing severe challenges under a changing climate. The relationships between soil moisture and vegetation have garnered international interest because of their significant impact on ecosystem restoration in semi-arid and arid regions. Grasslands are among the largest ecosystems in the world and are very important to dryland ecosystems. The Loess Plateau in China is an important example of drylands, and grasslands occupy more than 1/3 of its area. Water is the primary limiting factor of vegetation restoration, so understanding the relationship between grasslands and soil moisture on the Loess Plateau is imperative. The processes of precipitation, soil surface infiltration and evaporation, root water uptake and leaf transpiration are important for the relationship between grasslands and soil moisture. This paper found the following research topics that were related to the Loess Plateau based on 283 references of local studies from CNKI, ScienceDirect and Springer: (1) the effects of grasslands on soil moisture, including the influence of precipitation, geography, grassland type, grass age and growth stage on soil moisture and soil moisture determination methods; (2) the influence of soil moisture on grasslands, including the influence of soil moisture stress on grass growth and the methods for determining the physiological and ecological characteristics of grass; and (3) models of the relationships between grasslands and soil moisture. International references were used to explain certain processes and were compared with studies on Loess Plateau. Existing studies on the Loess Plateau paid more attention to these phenomena compared to water transport processes. Additional process-based studies with greater accuracy, longer time series, and larger spatial scales are needed to achieve ecosystem sustainability on the Loess Plateau. This summary of studies on the Loess Plateau may provide examples for research on arid and semi-arid areas in other countries. [ABSTRACT FROM AUTHOR]

In this study eight temperate grassland sites were monitored for soil CO 2 efflux (R s ) and the spatial covariate soil water content (SWC) and soil temperature (T s ) at fine scale in over 77 measurement campaigns. The goals of this multisite study were to explore the correlations between environmental gradients and spatial patterns of R s , SWC and T s , which are not site-specific and to quantify the relevance of biotic and abiotic controls over spatial patterns along increasing vegetation structural complexity. These patterns in water-limited ecosystems in East-Central Europe are likely to be influenced by summer droughts caused by the changing climate. A consistent experimental setup was applied at the study sites including 75 sampling locations along 15 m circular transects. Spatial data processing was mainly based on variography. Two proxy variables were introduced to relate the site characteristics in terms of soils, water status and vegetation. Normalised SWC (SWCn) reconciled site-specific soil water regimes while normalised day of year integrated temperature and vegetation phenology. A principal component analysis revealed that the progressing closure of vegetation in combination with large R s and SWCn values, as well as low T s and R s variability support the detectability of spatial patterns found in both the abiotic and biotic variables. Our results showed that apart from SWC the pattern of soil temperature also had an effect on spatial structures. We detected that when the spatially structured variability of T s was low, a strong negative correlation existed between SWCn and the spatial autocorrelation length of R s with r = 0.66 (p < 0.001). However, for high spatially structured variability of T s , occurring presumably at low T s in spring and autumn, the correlation did not exist and it was difficult to quantify the spatial autocorrelation of R s . Our results are indicative of a potential shift from homogeneity and dominance of biotic processes to an increased heterogeneity and abiotic regulation in drought prone ecosystems under conditions of decreasing soil moisture. [ABSTRACT FROM AUTHOR]

Soil microbial communities play an important role in regulating land–atmosphere CO 2 exchange in terrestrial ecosystems. However, their responses to climate change are unclear. We explored the effects of water and nitrogen addition and their interaction on soil microbes and the resulting impacts on soil carbon emissions in the Gurbantunggut Desert, northwestern China. A manipulative 30% increase in precipitation and 5 gN m − 2 year − 1 deposition alone and in combination was applied across three years from 2011 to 2013. Water addition significantly increased microbial biomass and respiration, metabolic quotient, and the utilization of carbohydrates, carboxylic acids and amino acids. Water addition did not change the microbial community composition. Nitrogen addition only significantly increased soil bacterial PLFAs, while exerting no significant impacts on soil fungal PLFAs, microbial respiration and soil respiration. Moreover, nitrogen addition had no significant impacts on microbial community composition. Water and nitrogen addition in combination did not generate synergistic effects on microbial communities and soil respiration. Across treatments in three years, soil respiration and microbial respiration were positively correlated with microbial total PLFAs, microbial carbon utilization profiles, while being independent of microbial community structure. This study suggests water addition can increase soil carbon emission through increasing microbial utilization of labile carbon, and water plus nitrogen addition had no synergistic effects on soil microbial communities and soil respiration, demonstrating nitrogen is not a limiting factor for soil microbial communities in the scenario of increasing precipitation in this desert ecosystem. [ABSTRACT FROM AUTHOR]

The fourth palaeosol (S 4 ) of the Brunhes Epoch (780,000–0 years B.P.) at Shuangzhu, Tianjiapo, and Hejiacun in the Guanzhong Plain developed over about 40 ka and varies in thickness from 3.6 to 4.0 m. It consists of four horizons: the first (uppermost) is a well developed red–brown clay horizon (Bts), the second is a dark yellowish-brown weathering-cracked loess horizon (Cs) with red ferruginous argillans, the third is a yellowish-brown weathering-cracked loess horizon (Cl) without red ferruginous argillans, and the fourth consists of CaCO 3 nodules (Ck). The two weathering-cracked loess horizons, which are a major feature differentiating a pedocomplex from a palaeosol, have not been found previously in Chinese palaeosol. The ferruginous clay argillans are composed of montmorillonite–illite with some kaolinite minerals. The pedocomplex suggests that a moist subtropical climate prevailed between 420,000 and 360,000 years in the southern parts of the Chinese Loess Plateau. Its profile is Bts–Cs–Cl–Ck–Co. When the pedocomplex was developed, the mean annual temperature and precipitation were about 16 °C and 1000 mm respectively, about 3 °C higher and 400 mm more than at present in the Guanzhong Plain. The removal depth of CaCO 3 and the weathering-cracked loess layer indicate that the gravitational water reached a depth of at least 3.2 m, and the moisture content in S 4 would have been sufficient to sustain forest development at that time. In the typical interglacial in which S 4 was developed, the Qinling Mountains lost their function as the boundary between the subtropical and temperate zones of China, and water-bearing air masses resulting in rich rainfall could frequently reach the southern Loess Plateau. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biocrusts increase evaporation rate by 10% on average in laboratory experiments. • All types of biocrusts increase evaporation rate by >42% in field experiments. • Biocrusts increase soil moisture (θ) by 9–44% compared with bare soil at 0–10 cm. • Biocrusts decrease soil temperature by 4.7–4.9 °C at 0–10 cm depth after rainfalls. • Reshaped soil properties and increased θ of biocrusts are key factors of increasing E. Soil evaporation is a three-stage process and plays a vital role in soil physical, chemical, and biological processes, as well as global climate change. As an important living skin, biocrusts strongly influence most soil properties and support fundamental ecosystem functions. Although there are many studies concerning biocrust effects on surface soil hydrological processes, it still remains unclear how biocrusts impact soil evaporation and their potential effects on the water budget in drylands. In this study, we selected aeolian sandy soil (bare soil) and three types of biocrusts, specifically cyanobacteria (cyano), cyanobacteria and moss mixed crusts (cyano-moss), and moss crusts (moss), on the northern Chinese Loess Plateau. By utilizing weighing micro-lysimeters in simulated and ∼4 months in-situ field evaporation experiments, we investigated all evaporation stages containing stages I–II and III, as well as the soil evaporation rate (E) of all treatments. The soil moisture (θ) and temperature (T) at 2 cm and 10 cm depths were also measured in field. Our results showed that biocrust types strongly influenced E in the ranked order of moss > cyano-moss > cyano > bare soil. The cumulative evaporation amount (E c) of all types of biocrusts was significantly higher than that of bare soil in simulated experiments. Particularly, moss increased E c by 15.7% compared with bare soil. The results of in-situ field measurements illustrated that the E of cyano, cyano-moss, and moss was increased by 42.4%, 55.5%, and 46.9%, respectively, compared with the bare soil, and these increasing effects became more pronounced after rainfall events. Additionally, all types of biocrusts markedly increased θ and decreased T at 0–10 cm depth of soil, but cyano and cyano-moss increased T (by up to 5.7 °C) at 2 cm depth during the non-rainfall periods. The increasing effects of biocrusts on E were reasonably attributed to their higher contents of fine particles and organic matter, as well as their higher field capacity in contrast to bare soil. All these regulations of biocrusts on soil properties further reshaped soil water and temperature regimes and finally changed soil evaporation. In conclusion, biocrusts may greatly intensify surface soil water loss due to their higher E. However, their greater θ and lower T in comparison to bare soil may partially offset these negative effects in return, and they may have feedback impacts on surface soil water and heat balances in drylands. [ABSTRACT FROM AUTHOR]

[Display omitted] • A GBCM is developed for multivariate drought risk analysis. • It can reveal the impact of multivariate interaction on drought risk. • GBCM is applied to the Aral Sea Basin (ASB), Central Asia. • Droughts with high risk would expect to move from the south to the north in ASB. • In 2020–2050, drought risk would increase 1.6%∼4.1% under climate change. As one of the most pressing issues in the world, climate change has brought significant impacts on natural and human systems, where drought events are likely to be frequent and severe under climate change impact. In this study, a multi-GCMs Bayesian copula (MGBC) method is developed for assessing the impact of climate change on drought risk, through integrating multi-GCMs, Bayesian, and copula function into a general framework. MGBC can tackle uncertainties existing in copula parameters and global climate models (GCMs), as well as provide ensemble projections for drought risk. MGBC is applied to the Aral Sea basin for assessing multivariate drought risk (i.e., duration-severity, duration-peak, and severity-peak) during 1901–2017 and 2021–2050, where climate data are derived from multi-GCMs (CMCC-CM, GFDL-CM3, MRI-CGCM3) under RCP4.5 and RCP8.5. Some major findings can be summarized: (1) in the historical period (1901–2017), the basin suffered 119 drought events, where drought risks of middle and lower reaches are higher than that in the upstream; (2) in the future (2021–2050), the basin's drought risk level will increase (1.5%∼8.6%), particularly for middle and lower reaches due to climate change impact; (3) as the impacts of climate change intensify, drought risk would increase (i.e., RCP8.5 > RCP4.5), and drought events in association with high-risk level would move from the basin's south to north; (4) the main factors that bring the drought risk are meteorological condition (e.g., precipitation and evapotranspiration) and human activity (e.g., soil moisture and texture). The findings suggest that droughts in the Aral Sea basin are affected significantly by climatic factors and drought risk would intensify with climate change. [ABSTRACT FROM AUTHOR]

• We selected Tibetan Plateau to examine net primary production during 2000–2018. • The NPP in permafrost region had a steadier and faster increasing rate. • Soil water and temperature were the main reasons for NPP changes. • The NPP values will show greater interannual changes in the future. Permafrost affects soil water and soil temperature regimes; however, its effects on net primary production (NPP) remain unknown. Here, we examined temporal-spatial changes in grassland NPP during 2000–2018 in permafrost and permafrost-free areas on the Qinghai–Tibetan Plateau using the random forest (RF) and radial basis function artificial neural network (RBF-ANN). Our results indicated that the areas that showed increasing, decreasing, and non-significant trends for NPP accounted for 13.88%, 1.90%, and 84.22% of the permafrost area, respectively. For the permafrost-free areas, these NPP trends accounted for 22.25%, 2.68%, and 75.07% of the permafrost-free area, respectively. The mean NPP in the permafrost regions showed a faster and steadier (1.520 g C/m2/yr, p < 0.05) increase than in non-permafrost regions (1.224 g C/m2/yr, p < 0.05). The Biome-BGC model confirmed that these spatial NPP patterns could be attributed to differences in soil water and soil temperature between permafrost and permafrost-free areas. Both the soil temperature and soil water content in permafrost sites exhibited relatively lower variance than in permafrost-free sites. Although many factors may be attributed to these patterns, our results suggest that there is a possibility that the relatively stable change in permafrost NPP can be explained by the fact that permafrost can regulate soil water and temperature regimes. Therefore, climate warming can increase NPP in cold regions, and permafrost degradation may destabilize the grassland ecosystem, which may cause NPP values to exhibit greater interannual changes in the future. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to discuss the range of temperature and moisture differences and variability in tundra vegetation and Arctic soils in the context of weather changes during the growing season. Research was carried out in Wedel Jarlsberg Land (SW Spitsbergen) in a small non-glaciated catchment in the vicinity of the Polish Polar Station in Hornsund. Measurements of air and soil temperature and changes in volumetric soil water content were carried out between June 24 and September 9 of 2008. The studied sites represented: (1) Turbic Cryosol, poorly covered by vegetation and exhibiting evidences of strong cryogenic processes; (2) Hyperskeletic Cryosol covered by a community of wet moss tundra vegetation with variable moisture which evolves under the influence of water flowing from the adjacent mountain slopes occupied by Little Auk colonies; and (3) Haplic Cryosol covered by lichen–herb–heath tundra vegetation, located on a raised marine terrace. Hyperskeletic Cryosol is the wettest of all the soil profiles studied. This profile shows the largest fluctuations in water content, related to the rate of snow melting on mountain slopes and the outflow of ablation water. The volumetric soil water content in Hyperskeletic Cryosol varies from 29% to 71%, with an average value of 49%. The mean volumetric soil water content in the driest Haplic Cryosol is 6% and ranges from 3% to 10% throughout the growing season. This is related to its sandy texture and a large number of stones, which leads to fast infiltration of snowmelt water and rainfall. Turbic Cryosol shows an intermediate volumetric water content ranging from 21% to 38%, with a mean value of 30%. The thermal regimes of the soils studied are also variable. The warmest soil was the driest Haplic Cryosol, as no influence of cold thawing water was observed. During the measurement period, the mean soil temperature at a depth of 10cm in Haplic Cryosol was 6.3°C. Turbic Cryosol was ca. 1.2°C–1.5°C colder than Haplic Cryosol. Hyperskeletic Cryosol was the coldest in comparison with the other soils studied because of the moss cover having insulating capacity. The temperatures recorded in this profile at a depth of 10cm reached a mean value of 3.2°C. The results indicate that cold water inflow from melting snow cover greatly affects soil temperature in the first part of summer (ablation season). This is related to an increase in solar radiation and air temperature leading to more intensive snow melting. This relationship is particularly evident in the first ten days of July. The highest soil surface temperatures (>20°C) were recorded in the beginning of July under intense solar radiation (25–27MJ/m2 d−1). In the second part of August, thermal gradients were weaker and soil temperatures in all the pedons studied were almost the same, ranging between +3°C and +6°C. This was due to limited solar energy inflow and heat migration into the soil transported with rainfall. [ABSTRACT FROM AUTHOR]

Abstract: Characterizing the inherent spatial variability of soil water is intensive in terms of sampling effort and therefore costly. The objectives of this study were to examine time stability of the spatial pattern of soil water storage (SWS) at different seasons and depths, to identify representative monitoring locations (RMLs) that consistently reflect field average SWS, and to recommend efficient ways to identify these locations. Soil water was measured down to 1.4m at 0.20-m vertical depth intervals using time domain reflectometry and neutron backscattering along a hummocky transect in semiarid central Canada. Strong Spearman rank correlation coefficients between SWS spatial series indicated similarity of spatial patterns, which showed strong seasonal dependence: intra-season time stability was stronger than inter-annual time stability, which was stronger than inter-season time stability. The observed time stability was used to identify an RML. The RML for the surface layer (0–0.20m) was different from the root zone (0–0.60m) and the total active soil profile (0–1.20m), the latter two having adjacent RMLs. The bias (~3%–10% maximum) associated with using an RML to predict field-averaged SWS was examined using regression. However, the prediction of field-averaged SWS using an RML was better compared to the prediction using field extreme locations in terms of error associated with the prediction. Predictions using more than one RML yielded better results than when a single RML was used. Successful and rapid identification of RMLs greatly reduced the number of observations needed to characterize the average soil water behaviour of a field. The measurement of SWS through representative monitoring location(s) may be used for environmental monitoring and modelling, irrigation scheduling, nutrient recommendations, and predicting greenhouse gas emissions. [Copyright &y& Elsevier]

• Warming effects increased with warming duration and magnitudes. • Warming effects on C and N concentrations remain globally invariant. • [C] and [N] responded inconsistently to warming between above- and belowground. • Warming effects on [C] and [N] are linked to soil moisture and soil pH. Global warming has significantly affected the terrestrial C and N cycling processes. Whereas, it is unclear how global warming impacts the C and N concentrations in the above- and belowground ecosystems. We performed a meta-analysis with the results presented in 136 papers and 1886 observations. The data reveals that global warming increased C concentrations in leaf, shoot, and microbial biomass and N concentrations in the shoot. The C:N ratios of microbial biomass also increased under conditions of warming. However, the soil C concentration and soil C:N ratios decreased. Furthermore, these responses are more evident with longer warming duration and elevated warming magnitudes. The warming effects on C and N concentrations and C:N ratios never changed with warming methods, ecosystem types, or background climates. Also, in response to warming, soil moisture was negatively correlated with leaf C concentration as well as C:N ratio in microbial biomass. Soil pH response to warming was in a negative correlation with those of soil C concentration, soil C:N ratio, and microbial biomass C concentration. Our analysis has identified some key ecosystem processes that can be potentially implemented into the ecosystem models for predicting how warming affects future terrestrial C and N dynamics. [ABSTRACT FROM AUTHOR]

Abstract: Soil moisture plays a significant role in determining the amount of energy exchange between the atmosphere and the earth''s surface and is highly variable in space and time. Temporal stability analysis (TSA) is a statistical approach for describing the persistence of spatial patterns and characteristic behavior of soil moisture. Using TSA, this study is aimed at determining the adequacy of long term point-scale surface and subsurface soil moisture (θv) measurements in representing field and watershed scale averages that serve as in situ ground truth locations for remotely sensed soil moisture calibration and validation programs, as well as applications for hydrologic modeling. In two agricultural fields, twenty temporary frequency-domain reflectometry (FDR) soil moisture sensors, spaced 70m apart, were installed at depths of 5 and 20cm in each field with measurements transmitted every 30min from June 29 through September 21, 2010. Soil moisture data were also obtained from FDR sensors permanently installed at depths of 5 and 20cm at seven sites located within the USDA, Upper Cedar Creek Watershed (UCCW) monitoring network in northeastern Indiana. Additionally, meteorological data (i.e., rainfall, air temperature, humidity) were obtained from existing UCCW network weather stations. Spatiotemporal analysis revealed persistent patterns in surface soil moisture and identified sites that were temporally stable at both study scales. However, soil water patterns differed between preferred states (wet/dry) and were primarily controlled by lateral and vertical fluxes. At the field scale, locations that were optimal for estimating the area-average water contents were different from the permanent sensor locations. However, minimum offset values could be applied to the permanent sensor data to obtain representative field average values of surface θv. TSA of 20cm θv showed little correlation with surface θv TSA results in terms of comparable stable sites or vertical transferability at either scale. The results are of relevance for the interpretation, scaling, or in describing the variability of coarser resolution soil moisture data such as that retrieved from remotely sensed active and passive microwave platforms and in terms of modeling field and watershed scale soil moisture based on point measurements. [Copyright &y& Elsevier]

Abstract: Drylands are regarded as highly sensitive to climatic change. The putative positive relationship between average annual rainfall and runoff, assumed for areas between 100 and 300mm ignores the fact that climatic change in drylands is not limited to climatic factors alone, but is often accompanied by a parallel change in surface properties. Data on rainfall, runoff and soil moisture regime were collected at five monitoring sites in a sandy area, along a rainfall gradient from 86 to 160mm. Despite the uniform sandy substratum the frequency and magnitude of runoff declined with increasing annual rainfall. Under wetter conditions a thick topsoil biological crust develops. This crust is able to absorb and retain large rain amounts, limiting the depth to which water can penetrate, and therefore water availability for the perennial vegetation. In the drier area, the thin crust can absorb only limited rain amounts, resulting in surface runoff and deeper water infiltration at run-on areas. Our findings demonstrate the important role played by different types of biological soil crusts along the rainfall gradient considered, and question the generally held belief that higher rainfall necessarily leads to deeper water infiltration in sandy arid areas; and higher water availability for the perennial vegetation. [Copyright &y& Elsevier]

Abstract: Soils are the third biggest sink of carbon on the earth. Hence, suitable land uses for a climatic condition are expected to sequester optimum atmospheric carbon in soils. But, information on how climatic conditions and land uses influence carbon accumulation in the soils on the Himalayan Mountains is not known. This study reports the impact of four climatic conditions (sub-tropical, altitude: 500–1200m; temperate 1200–2000m; lower alpine 2000–3000m; upper alpine, 3000–3500m) and four land uses (forest, grassland, horticulture, agriculture) on the concentrations and stocks of soil organic carbon (SOC) in upper (0–30cm) and deeper (30–100cm) soil depths on the western Himalayan Mountains of India. The study also explored the drivers which influenced the SOC stock build up on the mountains. Rainfall and soil moisture showed quadratic relations, whereas temperature declined linearly with the altitude. SOC stock as well as concentration was the highest (101.8Mgha−1 in 0–30cm, 227.97Mgha−1 in 0–100cm) in temperate and the lowest in sub-tropical climate (37Mgha−1 in 0–30cm, 107.04Mgha−1 in 0–100cm). Pattern of SOC stock build up across the altitude was: temperate>lower alpine>upper alpine>sub-tropical. SOC stocks in all land uses across the climatic conditions, except agriculture in lower alpine, was higher (0.7 to 41.6%) in the deeper than upper soil depth. SOC stocks in both the depths showed quadratic relations with soil temperature and soil moisture. Other factors like fine soil particles, land-use factor and altitude influenced positively whereas slope and pH, negatively to the SOC stocks. In all climatic conditions, other than temperate, SOC stocks were greater in natural ecosystems like forests and pastures (112.5 to 247.5Mgha−1) than agriculture (63 to 120.4Mgha−1). In temperate climate, SOC stock in agriculture (253.6Mgha−1) on well formed terraces was a little higher than forest (231.3Mgha−1) on natural slope. These observations, suggest that land uses on temperate climate may be treated as potential sinks for sequestration of the atmospheric carbon. However, agriculture in subtropical climate need to be pursued with due SOC protection measures like the temperate climate for greater sequestration of the atmospheric carbon. [Copyright &y& Elsevier]

Abstract: The importance of bioturbation as an agent of soil and geomorphological change is well known but few observations have been made of spatial and temporal variations in bioturbation rates. We quantified variations in surface bioturbation by ants (particularly Aphaenogaster longiceps) and vertebrates in the sandstone terrain of the Blue Mountains, southeast Australia. Following wildfire during the period late 2001–early 2002, we monitored thirty-three 5m2 plots positioned in six different slope units and in two catchments affected by different wildfire severities. Measurements were made seasonally for six years. Overall, mean rates of ant mounding and surface scraping by vertebrates were similar (246±339g m−2 yr−1 and 274±179g m−2 yr−1, respectively). However, rates varied substantially according to slope unit, showing a marked maximum for both ant mounding and total bioturbation on footslopes. Possible reasons for this spatial variation are discussed. A complex response to various soil and ecological factors such as soil texture, soil moisture and vegetation patterns is the most likely explanation. Associated estimates of topsoil (0–30cm depth) turnover times, based on ant mounding rates alone, ranged from 300 to 100,000years for different slope units. In contrast to previous findings, wildfire severity did not seem to affect bioturbation, possibly because of ant survival in deep nests and spatial patchiness of fire severity. There was likewise no clear link between temporal changes in bioturbation and fire severity; high rates in the first two years after wildfire were followed by lower rates for all burn severity types. There was also seasonal variability that was not directly related to rainfall. The results substantiate the importance of bioturbation in modifying soil characteristics and influencing soil erosion, especially following a major disturbance event like wildfire. [Copyright &y& Elsevier]

Abstract: The demographic pressure decrease in Southern Spanish Mediterranean mountainous areas in the mid twentieth century led to the abandonment of agriculture and rupture in the geo-ecosystem balance which had existed until then. Since then, different phases of recovery have been put into action to return the landscape to its earlier natural condition according to climate and soil degradation state after the abandon. In Mediterranean climatic conditions (between subhumid and semi-arid regimes), degraded soil recovery has followed different tendencies rendering the landscape in heterogenic and complex one. This heterogeneity has manifested in the vegetation pattern of abandoned fields. In this paper, we analyze the state of three abandoned fields situated under different Mediterranean climatic conditions from the recovery point of view by means of monitoring the effects of spatial and temporal variability of soil moisture in the vegetation pattern over a period of two years sampling (Nov. 2002–Nov. 2004). The results showed that: i) more annual rainfall volume did not guarantee success in the biological recovery of the system due to the influence of other factors such as the degradation state of the soil post-abandonment or the steep slope gradient; ii) soil moisture variability tended to play a more important role in affecting vegetal cover in semi-arid conditions; and iii) in dry climatic conditions the system demonstrated greater signs of recovery (greater biodiversity). [Copyright &y& Elsevier]

[Display omitted] • Altitude and season jointly affect microbial necromass and its contribution to SOC. • Microbial necromass shows linear or quadratic patterns with elevation. • Microbial necromass and its contribution to SOC are higher in the dry season. • Soil micro-climate and nutrient directly regulate microbial necromass accumulation. The sequestration of soil organic carbon (SOC) in terrestrial ecosystems is determined by the balance between plant- and microbial-derived carbon inputs and losses through soil respiration. However, a consensus on the elevational patterns of soil microbial necromass and its contribution to SOC is rare, and the information on how climatic and edaphic factors affect the accumulation of microbial necromass remains limited. In this study, soil samples were collected with a 50-m interval along an elevational gradient (200–950 m above sea level) to investigate the effects of climatic and edaphic variability associated with elevation and season on microbial necromass in subtropical forests. The concentration of soil amino sugar was measured by high-performance liquid chromatography (HPLC) to characterize soil microbial necromass. Partial least squares path modeling (PLS-PM) was used for testing climatic and edaphic controls over the elevational pattern of microbial necromass. The concentration of soil microbial necromass and its contribution to SOC were affected by elevation and season, with lower concentration and contribution in the wet season than in the dry season. Soil microbial necromass linearly increased or followed a quadratic pattern with elevation, and accounted for 18.9% of SOC on average with a greater contribution from fungal necromass (13.2%) than from bacterial necromass (5.7%). Soil temperature, soil nitrogen and moisture content directly influenced the accumulation of soil microbial necromass with varied effects on fungal and bacterial necromass. Warmer and nutrient-impoverished environments were linked with the depletion of fungal necromass, whereas higher soil moisture and nutrient availability were positively associated with the accumulation of bacterial necromass. Our findings demonstrate that less microbial necromass, especially fungal necromass will accumulate in SOC in response to future climate warming in subtropical forests. Such information is valuable for improving our understanding of the potential impacts of future climatic change on soil carbon cycling in subtropical regions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Soil water contents on the Tibetan Plateau during 1986–2016 were analyzed. • Soil water in permafrost areas had smaller changes than non-permafrost areas. • Climate factors could not explain the different soil water content patterns. • Permafrost favors the stability of soil water regimes. Permafrost is an important factor affecting soil hydrology in cold regions, while the effects of permafrost on temporal changes in soil water content largely remain unknown. Here, based on the calibrated Climate Change Initiative (CCI) soil moisture products using field observation soil water data at 5 cm depth from 8 representative sites, we examined changing trends of climate conditions and soil water contents during 1986–2016 between the permafrost and permafrost-free sites on the Qinghai-Tibetan Plateau (QTP). We found that all the sites have been experienced continuous warming during this period. Soil water contents showed significant increasing or decreasing trends at three of the four permafrost-free sites, but there were no significant increasing or decreasing changes at all the four permafrost sites. In addition, the Mann-Kendall (M−K) test showed that there were 2 change-points in soil water content for the sites with the active layer thickness was about 2 m, while the sites with active layer thickness larger than 3 m and permafrost-free sites showed 3–5 change-points, indicating that the soil water contents in areas with shallower active layer showed smaller changes. The different changing trends and change-points between permafrost and permafrost-free sites were associated with the existence of permafrost and active layer thickness. Although soil water contents can be affected by many factors, our results suggested that permafrost existence can affect interannual changes in soil water contents, and permafrost degradation including increasing active layer thickness and disappearance of permafrost may decrease ecosystem resilience in the face of climate change. [ABSTRACT FROM AUTHOR]

• Fire-induced hydrological impacts were assessed using the OpenLISEM model. • Rainfall dominated the catchment hydro-sedimentary responses before and after fire. • Fire led to a mean increase of 57% in peak discharge and up to 31% in sediment yield. • Sediment sources partly changed from croplands to burnt areas. Wildfires can have strong negative effects on soil and water resources, especially in headwater areas. The spatially explicit OpenLISEM model was applied to a burned catchment in southern Portugal to quantify the individual and combined impacts of wildfire and rainfall on hydrological and erosion processes. The companion paper has calibrated and assessed model performance in this area before and after a fire. In this study, the model was applied with design storms of six different return periods (0.2, 0.5, 1, 2, 5, and 10 years) to simulate and evaluate pre- and post-wildfire hydrological and erosion responses at the catchment scale. Our results show that rainfall amount and intensity played a more important role than fire occurrence in the catchment discharge and sediment yields. Fire occurrence was found to be an important factor for peak discharge, indicating that high post-fire hydro-sedimentary responses are frequently related to extreme rainfall events. The results also suggest a partial shift from runoff to splash erosion after fire, especially for higher return periods. This can be explained by increased splash erosion in burned upstream areas saturating the sediment transport capacity of surface runoff, limiting runoff erosion in downstream areas. Therefore, the pre-fire erosion risk in the croplands of this catchment was partly shifted to a post-fire erosion risk in upper slope forest and natural areas, especially for storms with lower return periods, although erosion risks in croplands were important both before and after fires. These findings have significant implications to identify areas for post-wildfire stabilization and rehabilitation, which is particularly important given the predicted increase in the occurrence of fires and extreme rainfall events with climate change. [ABSTRACT FROM AUTHOR]

• Microbial resource limitation varied in different season and peatland type of Zoige. • Abiotic factors affected soil organic carbon more than biotic factors in Zoige soils. • Total nitrogen might be the most critical factor affecting soil organic carbon. • Soil properties directly and indirectly affected soil carbon by affecting microbes. A large quantity of carbon (C) storage in peatland soils plays an important role in global C cycling. Microbial resource limitation and environmental factors can drive C cycling. However, the microbial resource limitation and regulator of C cycling in such an ecosystem are debated and still unclear. Therefore, this study chose Zoige, the largest peatland in the Qinghai-Tibet Plateau of China, to identify microbial resource limitation by analyzing ecoenzymatic stoichiometry and the regulation of soil organic C (SOC) through the interrelationships correlating SOC to abiotic (soil properties) and biotic factors (ecoenzyme activities, microbial communities, and abundance). The results demonstrated that soil microbial resource limitation varied in different seasons, across peatland types, and with depths; SOC content was more affected by abiotic factors (total nitrogen, total phosphorus, Olsen-phosphorus, moisture content) than biotic factors at the regional scale, and the factors driving C cycling differed among peatland types at the subregional scale. The path analysis further emphasized the importance of abiotic factors in C cycling, especially total nitrogen. This study provides important information for the understanding regulator of C cycling in peatland soils, which may help mitigate global climate change. [ABSTRACT FROM AUTHOR]

Abstract: Drylands are regarded as highly sensitive to climatic changes. A positive relationship between rainfall and environmental factors (water availability for plants, productivity, species diversity, etc.) is often assumed for areas with an annual rainfall of 100–300 mm. This assumption disregards the fact that a climatic change in arid and semi-arid areas is not limited to climatic factors. This change is often accompanied by a parallel change in surface properties. The alteration of surface properties may have opposite effects on the water regime and ecosystem characteristics. Data on rainfall, runoff, soil moisture regime, and vegetation cover were collected at five monitoring sites in a sandy area along the Israeli–Egyptian border, where average annual rainfall varies from 86 to 160 mm. Data obtained show a decrease in water availability for perennial plants with increasing annual rainfall, clearly expressed by a lower survival of perennial plants in the wetter area. Results obtained cast doubt of the prevailing idea regarding the positive relationship between average annual rainfall and ecosystem characteristics. The findings are attributed to the decisive role played by the non-uniform properties of the topsoil biological crusts along the rainfall gradient considered. Under wetter conditions a thick topsoil biological crust develops. This crust is able to absorb large rain amounts, limiting thus the depth of rainwater infiltration and water availability for the perennial vegetation. A better water regime was found in the drier area, where a thin crust allows deeper water infiltration and water concentration by surface runoff. The process described may be regarded as a desertification process with increasing annual rainfall. [Copyright &y& Elsevier]

• Warming significantly increased CH 4 emission by 52%. • N addition reduced the positive effect of warming on CH 4 flux. • Warming and N addition together did not significantly change CH 4 flux. • CH 4 flux positively correlated with GPP. • Soil T, soil moisture, DOC and TN were the main controls for CH 4 flux. Methane (CH 4) fluxes in boreal peatlands could be impacted by global warming and N deposition. However, the interaction of these factors remains poorly understood and has not been considered in coupled climate-carbon models. In this study, manipulated warming and N deposition (ammonium nitrate) were conducted for five years in a coastal bog in western Newfoundland, Canada. Consistent with previous studies, warming significantly increased CH 4 emission by 52%, which might be due to the increase of microbial activity and vegetation growth. Although N addition alone did not alter CH 4 emissions, it significantly reduced the positive effect of warming on CH 4 fluxes. We attributed this finding to three possible reasons: (1) N addition caused a shift in root allocation from deep to shallow roots, which decreased labile substrates for CH 4 production under warming; (2) warming promoted vegetation uptake of ammonium (NH 4 +), which alleviated the inhibition of NH 4 + to methanotrophs and subsequently increased CH 4 oxidation under N addition; and (3) the combination of warming and N addition increased maintenance respiration of vascular plants compared with warming alone, thus reducing net primary production and root exudates for CH 4 production. In addition, we found that soil temperature, soil moisture, DOC and TN were the main controls on CH 4 fluxes. Our results indicate that the combined effect of N deposition and warming should not be ignored. Otherwise, the emission of CH 4 in bogs will be overestimated under future scenarios of climate warming and N deposition increase. Our study can be further applied as empirical evidence for the parameterization of temperature-dependence and nutrient-dependence of CH 4 fluxes in biogeochemical models of boreal peatlands. [ABSTRACT FROM AUTHOR]

• Delayed and wetter wet season were manipulated to study precipitation effects. • Delayed wet season significantly increased soil CH 4 uptake by 164%. • Wetter wet season increased the soil CH 4 uptake during the dry season. • The optimum soil moisture for the soil CH 4 uptake was ~16%. • This study helps to better predict CH 4 flux in tropical forests. Tropical monsoon forest soils have the potential to mitigate global warming by removing methane (CH 4) from the atmosphere, yet whether this function would be altered under future precipitation regimes remains unclear. In this study, we conducted two rainfall manipulation treatments, including the delayed wet season (DW) and wetter wet season (WW), since 2012 in a tropical monsoon forest in southern China to investigate the impact of changing precipitation patterns on soil CH 4 uptake over two measurement years between 2018 and 2019. We found that DW significantly increased the annual average soil CH 4 uptake by 164%, mainly due to a significant increase during the dry season via enhancing soil moisture and soil enzyme activities. Although WW exerted a limited impact on the annual average soil CH 4 uptake, it remarkably increased CH 4 uptake during the dry season due to the alteration of soil temperature, nutrient conditions, and enzyme activities. Furthermore, we found that methanotrophic abundance increased and decreased with soil moisture during the dry and wet seasons, respectively. The optimum air-filled soil porosity for CH 4 uptake was 0.45 m3 m−3. Our results suggested that the role of tropical monsoon forests as CH 4 sinks would be enhanced under delayed wet season, which should not be overlooked for determining the global CH 4 uptake capacity of forest soils in the future. [ABSTRACT FROM AUTHOR]

• Soil erosion is caused by erosive rainfall with a low frequency and high intensity. • Extreme rainfall affects obviously the monthly distribution of rainfall erosivity. • Intra-annual variation of runoff & sediment relates to erosion-sensitive period. • Changes of monthly runoff & sediment are consistent to monthly rainfall erosivity. • Changes in annual soil loss are synchronous with interannual rainfall erosivity. More variable or extreme rainfall caused by global climate change is likely to cause much uncertainty in soil erosion. Exploring the effects of changes in the timing and magnitude of rainfall erosivity on soil erosion allows to better understand the sensitivity of soil erosion to rainfall. The aim of this study was to investigate the relationships between the periodicity of soil and water loss and erosion-sensitive periods based on the temporal distributions of rainfall erosivity in the Three Gorges Reservoir Region, China. A daily rainfall erosivity model and field runoff plot monitoring were used to achieve these goals. We found that extreme rainfall has a great effect on the distributions of rainfall erosivity. The average annual erosive rainfall frequency accounts for only 21.2% of the average annual total rainfall frequency, but the average annual erosive rainfall amount accounts for 70.4% of the average annual total rainfall amount. The monthly runoff yields and sediment yields show synchronization with variations in rainfall erosivity to some extent, but the former are closer to the changes in monthly rainfall erosivity. The annual runoff yields and soil loss rates do not show synchronization, but the changes in annual soil loss rates are closer to the interannual variations of rainfall erosivity. The annual soil erosion in the study area can be divided into three periods, namely, highly sensitive periods, moderately sensitive periods and slightly sensitive periods, which indicate the erosion risks from high to low, respectively. Additionally, low vegetation coverage in highly sensitive periods and human activities in moderately sensitive periods can aggravate soil erosion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Predicting the impacts of climate change on streamflow in MRB. • Future climate data are generated by 34 GCMs with three RCPs. • The streamflow will increase by 10.5%–23.2% during 2020–2093. • Increased temperature causes the decrease of dry season streamflow. • Precipitation highly contributed to yearly streamflow change. The typical warm and wet regions of Southeast Asia have significant water resource issues. Deep insight of the future streamflow in the region is therefore necessary for effective water resource management and prediction. We coupled the Soil and Water Assessment Tool (SWAT) with a downscaling method (Delta) and global circulation models (GCMs) in the Mun River Basin (MRB), in Thailand under three Representative Concentration Pathways (RCPs). The results show that the calibrated SWAT model can accurately characterize the hydrological process on the daily, monthly, and yearly terms. The future monthly minimum temperature would rise by >1.5 °C, >2 °C, and >3 °C in the 2030s, 2060s, and 2080s respectively, under all RCPs (2.6, 4.5, and 8.5), which would also occur at the maximum temperature. The temperature increase in dry season was more significant than that of the wet season. The average annual precipitation decreased in the 2030s, and increased by 8.9%, 12.8%, and 13.9% in the 2060s under the three climate scenarios, respectively. Moreover, precipitation from June to September in wet season markedly increased. The streamflow was projected to increase by 10.5%, 20.1%, and 23.2% during 2020–2093 under three climate scenarios, respectively. Monthly average streamflow increased from June to September and decreased from February to May, and the dry seasonal streamflow decreased by 1.1%-37.2%. These changes in flow were closely related to climate change. Monthly flow changes were negatively related to temperature (p < 0.05) in dry season and positively linked to precipitation (p < 0.01) in wet season. The results of this study highlight the impact of climate change on streamflow in the Southeast Asia and provide scientific basis for adaptive management. [ABSTRACT FROM AUTHOR]

• Increased frequency and prolonged duration lead to rise in drought severity. • The eastern part of Yunnan Province was most sensitive to drought. • The southwestern part of Yunnan Province was vulnerable to long drought. • A significant increase in drought severity in the last decade. • Regional SM changes cannot be only attributed to "dry to dryer, wet to wetter" Droughts in humid regions may have more severe consequences owing to a lack of drought-resistant measures and awareness. The Yunnan Province, in the humid southwestern part of China, experienced an extreme drought from 2009 to 2010. However, few studies have systematically explored agricultural droughts in this region. Based on revised global multi-source microwave-based SM products, the European Space Agency's Climate Change Initiative Soil Moisture (ESA CCI SM) data, the 10-day-scale soil moisture (SM) series was constructed and applied to detect droughts and analyze changes in drought characteristics, including duration, area, frequency, intensity, and severity. The results suggest that the intensity of agricultural drought in the Yunnan Province decreased, while the drought frequency increased. Drought duration increased by 20 days, collectively leading to a significant increase in drought severity in the last decade. Qujing in the east was most sensitive to agricultural drought, followed by Kunming and Chuxiong in the central area. The southwest region was prone to long drought and maintained an upward trend in terms of drought area. Regional SM with complicated temporal-spatial change patterns cannot be attributed to a single trend of "dry to dryer, wet to wetter". This study may provide insights into drought analysis in other humid regions. [ABSTRACT FROM AUTHOR]

• NFGs were attenuated along the soil profiles in desert ecosystems. • Soil pH and available phosphorus contributed to the highest variations in NFGs. • The enhanced genes (nifH + chiA) contribute to the soil increased available N. • N-fixation gene noticeably increased as the desertification processed. With ongoing global climate change and human activities, increasing desertification plays a predominant role in increasing soil nutrient losses. Soil nitrogen (N) is the essential limiting nutrient supporting plant growth and evaluating soil nutrient content, especially in desert ecosystems. N microbial processes will ultimately restore and maintain the balance in the soil N cycle, but the damage caused by desertification to soil N functional microorganisms associated with N supply, transformation, and loss is poorly understood. We examined changes in soil N and N functional gene (NFG) abundances within vertical profiles (i.e., soil depths of 0–100 cm) throughout the desertification process. We found that the abundance of N functional genes (NFGs) (except the N-fixation gene) decreased during the desertification process, almost all NFGs were attenuated along the vertical profiles, and available phosphorus (AP), soil water content (SWC) and pH were the best explanatory variables. The sums of (AOA + AOB) (associated with available N transformation) and (nirK + nirS + qnorB + nosZ) (associated with N loss) significantly decreased as desertification progressed, leading to decreased N transformation and loss potential. The (nifH + chiA) associated with available N supply increased along the desertification process gradient, suggesting enhanced potential for the acquisition available N. The increased ratio of (nifH + chiA + AOA + AOB)/(nirK + nirS + qnorB + nosZ) (associated with available N storage) collaboratively contributed to enhanced available N storage potential throughout the desertification process. Our results lay the foundation for better understanding the distinct responses of NFGs to desertification and the process through which they ultimately regulate available N storage in the degraded soils of desert ecosystems. [ABSTRACT FROM AUTHOR]

Understanding vegetation dynamics and its response to climate changes is important for revealing the mechanisms of terrestrial ecosystem behaviour, predicting future vegetation growth, and thus guiding environmental management. The Jing River Basin (JRB) and the Beiluo River Basin (BLRB), two typical ecoenvironmentally vulnerable regions on the Loess Plateau in China, were selected as case study regions. Based on long-term Normalized Difference Vegetation Index (NDVI) datasets, the time-lag relationships between NDVI and climatic factors (precipitation/temperature) as well as teleconnection factors (large-scale modes of climate variability and solar activity) were revealed. Additionally, ridge regression models were established to quantitatively explore the response of vegetation dynamics to climate change. Results indicate that: (1) NDVI in autumn showed significantly increasing trend (p < 0.01), whereas that in spring and summer was insignificant; (2) there was a time-lag of more than one month between spring/winter NDVI and precipitation/temperature behaviour, and summer NDVI exhibited no lag with temperature but a one month lag with precipitation; (3) regarding the time-lag effects, precipitation was the driving factor of NDVI variations in spring, whereas sunspots dominated NDVI variations in autumn; (4) when time-lagged teleconnection factors were considered, the explanation of the climate effect on the vegetation dynamics in three seasons all relatively increased by >95%, which indicates that the prediction accuracy of NDVI was significantly improved; (5) in summer, time-lagged climatic and teleconnection factors explained <20% of NDVI variations, whereas when soil moisture and base flow were considered, the explanation of NDVI changes in the JRB and BLRB relatively increased by 37.4% and 65.1%, respectively. These findings highlight that considering the time-lag effect of climatic and teleconnection factors has important significance for the accurate monitoring of underlying surface dynamics under changing environment. [ABSTRACT FROM AUTHOR]

• SOC increased with increasing precipitation, but the reverse for SIC in alpine steppe. • SOC density decreased with soil depth, but SIC density increased with depth. • Biological processes drive SOC profiles, while abiotic factors determine SIC patterns. • SIC comprises about 10% of C storage in alpine steppe soils of the Tibetan Plateau. Both soil organic carbon (SOC) and inorganic carbon (SIC) are important components of soil carbon storage. However, few studies have attempted to estimate the magnitude and patterns of SIC in arid areas. We measured the concentrations of SOC and SIC in alpine steppe grasslands along a climate gradient in the Tibetan Plateau. At all sites, an opposing trend was found in the distribution of SOC compared with SIC. SOC increased with increasing precipitation, while SIC decreased. Within sites, SOC decreased with soil depth, while SIC increased. Among the variables considered, soil total nitrogen (TN) and soil water content explained the most variability in SOC (r2 = 0.95 for TN, r2 = 0.93 for soil water content), and soil pH had the highest correlation with SIC (r2 = 0.90). This finding indicates that SOC is closely related to biological processes, such as biomass input and litter accumulation, while SIC is determined by abiotic factors such as chemical and physical processes of soil formation. SOC and SIC densities showed that the SOC pool comprised 91% of total carbon (TC) storage in these alpine steppe soils. A decrease in SOC density occurred with depth, but this pattern was the opposite for SIC density in all soil profiles. These findings help to characterize the C cycle in the alpine steppe of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]