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Substantial evidence suggests a widespread increase in global vegetation gross primary production (GPP) since the 1980s. If the increasing trend of GPP remains unchanged in the future, it is considered to be the persistence of increasing GPP. However, it is still unknown whether the vegetation increasing GPP is persistent under the interactive effects of climate change and land use changes in Northwest China. Using the Mann-Kendall and boosted regression tree models, we constructed the relationship between the increasing GPP and environmental variables, and further explored its persistence under the interactions between climate change and land use changes under SSP245 and SSP585 scenarios. The results indicated that: (1) Land use change (8.01%) was the most important variable for the increasing GPP. The surface net solar radiation (6.79%), and maximum temperature of the warmest month (6.78%) were also very important. Moreover, mean temperature of the warmest quarter had strong interactions with mean precipitation of the warmest quarter (9.82%) and land use change (8.24%). (2) Under the SSP245 scenario, the persistence of increasing GPP accounted for 65.06% of the area in 2100, mainly located in Qinghai, Ningxia, and Shaanxi, while it only accounted for 19.50% under the SSP585 scenario. (3) The SSP245 scenario moderate warming leads to a slight ecosystem benefit, with more areas developing an increase in GPP due to climate and land use change factors. On the other hand, under SSP585 scenario, there are widespread losses of increasing GPP, driven largely by climate change, while ecological engineering is conducive to the persistence of increasing GPP in southern Qinghai. The results highlight the importance of the interactive effects of climate change and land use changes for predicting the persistence of vegetation change., Competing Interests: Declaration of competing interest This manuscript entitled “Persistence of Increasing Vegetation Gross Primary Production under the Interactions of Climate Change and Land Use Changes in Northwest China” has not been published or presented elsewhere in part or in entirety, and is not under consideration by another journal. All the authors have approved the manuscript and agree with submission to your esteemed journal. There are no conflicts of interest to declare., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Managed and natural vegetation restorations are two vital measures of land restoration; however, their effects on soil microbial communities at a large scale are not clearly understood. Hence, changes in the microbial community composition after 15 years of vegetation restoration along a climatic gradient in the subtropical karst region of Southwest China were assessed based on phospholipid fatty acids (PLFAs) profiles. Managed (plantation forest) and natural (naturally recovered to shrubbery) vegetation restoration types were compared, with cropland and mature forest serving as controls. Soil microbial community abundance was significantly higher under the two vegetation restoration types than in the cropland; however, it was lower than in the mature forest. The abundance, composition, and structure of soil microbial communities did not differ significantly between plantation forest and shrubbery. Soil organic carbon or total nitrogen was the primary factor positively affecting soil microbial abundance, whereas the mean annual temperature (MAT) was recognized as the primary factor contributing to the variation in the soil microbial community structure. Moreover, temperature had opposite effects on different indicators of microbial community structure. That is, it positively and negatively affected the ratios of gram-positive to gram-negative bacterial PLFAs (GP:GN) and fungal to bacterial PLFAs (F:B), respectively. Our results show that both vegetation restoration types have the ability to improve soil productivity in karst areas. Furthermore, shifts in soil microbial community structure (GP:GN and F:B ratios) induced by warming are likely to lead to a higher proportion of labile carbon, which is sensitive to soil tillage. Hence, more attention should be paid to ecological restoration in warmer karst areas to alleviate the severe loss of soil carbon in croplands. [ABSTRACT FROM AUTHOR]

Purpose: Changes in climate and land use may disrupt the soil carbon (C), nitrogen (N), and phosphorus (P) cycles, which affect the availability of essential nutrients differently, including soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP). Nevertheless, lithologic impact on soil C:N:P stoichiometry over a broad climatic gradient remains largely unknown. We aimed to determine the variation in nutrient limitations between karst and non-karst forests and croplands across a climate gradient. Materials and methods: This study investigated soil C:N:P stoichiometry in mature forest (MF) and nearby cropland rotation (CR) (as a control) soils on limestone (karst) and clastic rock (non-karst) throughout a climatic gradient in southwest China through analysis of soil samples. Result and discussion: The SOC and TN contents in the karst MF were 1.3 and 1.6 times greater, respectively, than that in the non-karst MF. Consequently, the karst MF had a lower C:N ratio than did the non-karst MF. The SOC and TN contents were considerably higher in the MF than they were in the CR under both lithologies, leading to higher C:P and N:P ratios in the MF compared to those in the CR. The increasing temperature resulted in a shift from TN and TP to SOC limitation, due to the increased decomposition of SOC by microbes with an increase in temperature. Soil pH and Ca content are controlled by the lithology, and they were closely related to C:N:P stoichiometry in this study, whereas a combination of lithology and temperature controlled soil microbial activity and plant growth. Importantly, the magnitude of lithology-induced changes in the stoichiometry was greater as temperature increased, which was more pronounced in the non-karst than it was in the karst. Conclusions: These findings highlight the responses of soil C, N, and P to climate warming in relation to stoichiometry, and soil-microorganism-plant response strategies may be the key to the mitigating the effect of temperature increase on nutrient cycles in karst ecosystems. [ABSTRACT FROM AUTHOR]

The karst area in southwest China is, in recent decades, one of the world's regions with the fastest vegetation growth and increase in aboveground biomass. The improvement in the ecological conditions within this region can, to a large extent, be attributed to ecological protection projects. However, it remains unclear whether the observed increase in vegetation cover could mitigate rocky desertification at large scale. In this study, we utilized information from large field campaigns in the years 2005, 2011, and 2016, supported by satellite imagery interpretation and statistics on ecological protection projects, to explore the impact of restoration efforts on rocky desertification mitigation and vegetation resilience/resistance. The results show that restoration efforts caused a net decrease of 26.14% in areas affected by rocky desertification from 2005 to 2016. The larger the restoration efforts, the stronger the decrease in rocky desertification areas, and also the vulnerability of landscapes towards desertification; the probability of rocky desertification occurring decreased almost linearly with increased restoration efforts. In addition, both vegetation resilience and resistance against climate variations increased with restoration efforts. Restoration efforts were mainly responsible for the recovery of the ecosystem, showing that human impact is the main driver for the reversal of rocky desertification. Our study provides scientific evidence on rocky desertification control being an important step towards a sustainable development of the landscapes of Southwest China. [ABSTRACT FROM AUTHOR]

The vegetation is known to be sensitive to both climate change and anthropogenic disturbance. However, the relationship between changes in vegetation and climate is unclear in karst regions. The nonlinear characteristics of vegetation change and its possible relationships with driving factors in the karst region of southwest China are revealed, using methods of Ensemble Empirical Mode Decomposition, Mann-Kendall, and Partial Least Squares Regression. The results show that: (1) vegetation changes demonstrate an increasing trend with an abrupt change in 2002. Multiple time scales of 3, 6, 10, and 25-year are observed in vegetation variations, dominated by long-term trend and the short time scale of 3-year with variance contributions of 58.10% and 28.63%. (2) The relationship of climate indexes with vegetation changes shows r 2 = 0.78 (p < 0.01) based on the reconstruction of characteristic scales, indicating significant great relationship. In space, the area percentage with relationship of climate to vegetation is more than 50%, and the impact is much greater after the abrupt change of vegetation in 2002 (r 2 are 0.24–0.91 and 0.42–0.99, respectively). In addition, the correlation between vegetation change and ecological engineering is 0.15 (p < 0.01). The results indicate that climate change is the main impact factor of vegetation change, ecological engineering has positive influences in improving vegetation condition, and methods of scales decomposition and abrupt detection could reveal some hidden information for better understanding ecosystems in karst regions. [ABSTRACT FROM AUTHOR]

Potential evapotranspiration (PET) is a key input to hydrologic models simulating the atmospheric water demand. Thus, uncertainties in PET would result in considerable uncertainty in model outputs. Among numerous PET algorithms, the Penman‐Monteith equation (PM equation) is most widely used because of its clear physical basis and acceptable estimation. However, PM equation has a physical limitation resulting from the linear approximation of the saturation water vapor pressure differences between the evaporation surface and the surrounding air, which can affect markedly the responses of PET to air warming. By considering a modified PM‐type evaporation model, we revisited the global drying trends based on the widely used Palmer Drought Severity Index (PDSI). We demonstrate that the studies, which based on the classic PM equation, often overestimate the effects of air warming on global drying trends. Particularly, the PET_PM (PET calculated using the classic PM equation) driven PDSI, overestimates global mean drought‐affected areas by 60%, drought intensity by 65%, and drought duration by 35% on average over the globe, and tends to overestimate drying trends in areas that are drying and underestimate wetting trends in areas that are becoming wetter. Key Points: Modifying PM evaporation model by introducing the nonlinear relationship between water vapor and temperaturePM evaporation model overestimates the effects of air warming on potential evapotranspirationThe drought index driven by PM‐type PET overestimates the global drying trends considerably [ABSTRACT FROM AUTHOR]

Context: The karst region of southwestern China, one of the largest continuous karsts in the world, is known for its unique landscapes and rich biodiversity. This region has suffered severe environmental degradation (e.g., vegetation cover loss, soil erosion and biodiversity loss). In recent decades, Chinese governments at different levels have initiated several ecological programs (e.g., Green for Grain, Mountain Closure) to restore the degraded environment and to alleviate poverty. Objectives: This study summarizes landscape studies of karst landscapes patterns, their dynamics and interactions among landscape pattern, hydrological processes and ecosystem services (ES). Methods: We conducted a systematic literature review of science and land use policy to identify knowledge gaps and recommend future research and policy directions. Results: Karst landscapes have experienced rapid turnover in recent decades due largely to the overlap of intense human activity on the fragile karst ecosystems. Many studies have comprehensively examined hydrology, soil processes and ecosystem services (ES) and their relationships with landscape pattern. Most of these studies have found that karst ecosystems recover with improved ES. However, the importance of epikarst in hydrological and soil processes, intense anthropogenic disturbance and landscape heterogeneity in landscape models remains elusive. Conclusions: Future research should focus on in-depth examination and modelling of karst specific hydrological and soil processes, investigating relationships between climatic change, landscape change, ecological processes, and region-specific ES assessments. Results from such research should provide the necessary scientific support for a comprehensive, national karst rocky desertification treatment project (Stage II) and poverty alleviation initiatives. [ABSTRACT FROM AUTHOR]

[Display omitted] • Vegetation change dominated by inter-annual variation and long-term trend. • Variation increases with increasing relief, decreases with increasing timescale. • Vegetation change is positive for maximum, negative for minimum temperature. • Maximum temperature mainly controls inter-annual vegetation variation. Despite numerous studies on the response of vegetation change to climate variation, they have mainly been based on annual mean temperature and annual mean precipitation, and have failed to reveal the impact of climate on the inter-annual variation of vegetation in different geomorphic zones based on non-linear methods and considering daily low and high temperature. In this study, the effect of climate variation on the inter-annual variation of vegetation in different geomorphic zones along the area of t the Yangtze River Basin, China from 1982 to 2015 is revealed using Ensemble Empirical Mode Decomposition method. The results show that the inter-annual variation of vegetation is frequently fluctuating, mainly on a short time scale (3-year time scale), and its contribution gradually increases from 62.35% to 73.57% with increasing relief (from plain to high undulating mountain). The vegetation change of more than 75% of the areas is dominated by inter-annual variations, moreover, the vegetation change of the low relief areas is dominated by the 3-year timescale along with the long-term trend, while that of the other geomorphic zones is dominated by the 3-year timescale only. Inter-annual vegetation variation is positively related to precipitation and maximum temperature, but negatively related to mean temperature and minimum temperature in most areas, with area percentages of 67.20%, 86.55%, 65.38% and 75.02%. Inter-annual variation is mainly controlled by maximum temperature in most areas (54.77%). These results will deepen our understanding of the vegetation-climate relationship, suggesting that the responses of inter-annual variation in vegetation to climate vary not only on different time scales, but also in indifferent geomorphic zones. [ABSTRACT FROM AUTHOR]

Highlights • The difference of biomass growth rates in natural forests and plantation forests. • Stand characteristics explained more growth rates than did climatic variables. • Forest growth rates varied with climate, stand characteristics, and forest origin. Abstract Comparing the growth rate of natural forest and plantation forest may be useful to better understand rates of carbon sequestration and carbon turnover. However, the large-scale patterns of biomass growth rates in China's forests are still not well defined. We analyzed the growth rates of forest leaves, branches, stems, and roots across forest communities in China by using data collection, collation, and systematic analysis of published research and our unpublished data. The biomass growth rates in all forests exhibited negative latitudinal trends and negative altitudinal trends, with significant influence from climatic variables and stand characteristics. Stand characteristics explained more variation in growth rates of forest biomass than did climatic variables, and growth rates of forest leaves, branches, stems, and roots varied in relation to climate, stand characteristics, and forest origin. The cross-validated results of stepwise multiple regression (SMR) models and neural network models (NNM) indicated that the prediction accuracy of growth rate of forest biomass by NNM was better than that of the SMR models. Our results improve understanding of the environmental factors affecting Chinese forest growth and inform efforts to model dynamics of carbon accumulation in China's forests. [ABSTRACT FROM AUTHOR]

• As high as 30.04% of the monotonically increasing vegetation NPP (41.08%) can maintain the increasing trend. • Soil moisture and land-use changes interacted with other variables to affect NPP increment. • The coupling and shared effects had greater influences than the pure effects on NPP increment. • The shared and coupling effects dominated the persistent and non-persistent NPP increment, respectively. In the framework of ecological engineering, vegetation net primary productivity (NPP) has grown dramatically in the Three-north Shelter Forest Program area (TSFPA), which is influenced by both human activities and climate change, as well as their interaction. However, it remains unclear how the individual (pure effects) and interactive (shared and coupling effects) impacts affect and maintain the growing vegetation NPP trend. In this study, the monotonically increasing NPP trend from nonlinear trends was detected using Ensemble empirical mode decomposition (EEMD), and its persistence was investigated using boosted regression tree (BRT) models. We investigated the relative contributions of environmental factors and variable interactions, as well as spatially identified the multiple effects of climate change and human activities on the increasing trend and its persistence over TSFPA. The results indicated that: (1) The vegetation NPP was dominated by the monotonically increasing trend (41.08 %), and 30.04 % of all pixels can still maintain NPP increment. (2) Although soil moisture exhibited the highest interaction with the precipitation seasonality (32.21 %) on the monotonically increasing NPP trend, land-use change substantially interacted with soil moisture (26.97 %), snowmelt (23.34 %), and net solar radiation (13.43 %). (3) The monotonically increasing vegetation NPP was caused not only by the pure effects of climate change (23.57 %) and human activities (11.69 %) directly but also by their coupling effects (26.64 %) or shared effects (38.10 %) interactively. (4) The shared effects (50.94 %) dominated the persistently increasing NPP trend, whereas the coupling effects (78.78 %) dominated the non-persistently increasing NPP trend. The findings highlight the importance of the pure, shared, and coupling effects of human activities and climate change interactively for elucidating the driving of the vegetation NPP increment and its persistence over ecological engineering areas. [ABSTRACT FROM AUTHOR]

This study proposes a hydrological drought index, the standardized wetness index (SWI), by combining the structure of the Standardized Precipitation-Evapotranspiration Index and actual-evaporation-based residual water-energy ratio, in which actual evaporation is estimated using the Budyko hypothesis. The SWI requires three parameters-precipitation, potential evaporation, and parameter [ABSTRACT FROM AUTHOR]

An intensified hydrologic cycle and a large amount of monitoring flow data in the latter half of the 20th century attracted a lot of research on the continental U.S. hydrologic change. However, most previous studies are based on HCDN (Hydro-Climate Data Network) dataset with a period of ~1950s −1988. This study analyzed hydrologic change in continental U.S. based on MOPEX (international Model Parameter Estimation Experiment) hydrology dataset with a period of ~1950s −2000 for 302 watersheds (gages) across diverse climate, vegetation and soil conditions. This dataset is more representative of the latter half of the 20th century than HCDN. In contrast with previous studies, this study shows that only 20-30 % of watersheds present increasing trends in flow (streamflow, Q; baseflow, Q; baseflow index, BFI), and most (> 65 %) watersheds presents non-significant trends. Similar to previous studies, the watersheds with increasing trends in Q and Q are concentrated in Midwest and high plain (North-Central area) of USA. Climate contributes more to Q change (61 ± 25 % vs. 39 ± 25 %) but slightly less to Q change than human activity (49 ± 26 % vs. 51 ± 26 %) and much less to BFI change than human activity (−5 ± 61 % vs. 105 ± 61 %). A step change at ~1971 in Q and Q was found for 35-45 % but not for a large proportion of watersheds (50 % or more was reported by previous studies). This study provides new insights on the latter half of the 20th century's hydrologic cycle for the continental U.S. with a more representative dataset of this period. [ABSTRACT FROM AUTHOR]

Water quality is essential for lake systems, which are not only influenced by climate change and human activities but are also controlled by high-frequency hydrological rhythms. However, the differences in water quality during different hydrological periods have not been addressed in detail. Here, a 15-year water quality dataset (2004–2018) was selected to explore the variation trends and their relationship with water level in different hydrological periods in Dongting Lake, a typical river-connected lake in China. The hydrological periods were classified into hydrological years and hydrological phases based on the characteristics of water level fluctuations. The results showed that annual variation in the water level in Dongting Lake fluctuated between 23.63 and 25.81 m from 2004 to 2018, and also displayed considerable water level differences ranging from 7.66 m (dry years) to 9.97 m (wet years) within a year. The water level of the lake phase showed significant differences among the different hydrological years. The concentration of TP, COD Mn , and NH 3 -N showed significant decreasing trends, whereas that of TN showed a significant increasing trend from 2004 to 2018. The TN concentration in wet years was significantly higher than that in dry years, which could be attributed to sewage discharge and hydrological conditions. The contributions of the lake phase to the total sewage discharge successively decreased from 64.54% in wet years to 59.47% in dry years, while the river phase showed the opposite trends, ranging from 35.46% to 40.53%, reflecting the strong relationship between water regimes and pollutant fluxes. A regression analysis indicated the different responses of water quality to water level fluctuations over hydrological years, and water quality in different hydrological phases clearly separated the lake and river phases, highlighting the influence of water level fluctuations on water quality within a year. To maintain the water quality of Dongting Lake, the control of external load should not be relaxed, and hydrological regulation should be actively carried out within each year. [ABSTRACT FROM AUTHOR]

• AMF richness increased at high temperature levels in shrubland and mature forest. • AMF community was more sensitive to climatic levels than that of diazotrophs. • High temperature and precipitation strengthened AMF-diazotroph interactions. • Glomus and Bradyrhizobium contributed to the most correlation links in co-occurrence patterns. Arbuscular mycorrhizal fungi (AMF) and diazotrophs have the potential for nutrient transfer and biological nitrogen fixation in ecosystems, respectively. However, their response to vegetation restoration remains unclear, especially under varying temperature and precipitation levels in karst ecosystems. This study aimed to understand the effects of three climatic levels within four natural and managed vegetation restoration types on the diversity and community composition of AMF and diazotrophs. The interactive effects of temperature, precipitation, and vegetation types affected AMF diversity, while diazotroph diversity was not affected. Under conditions of natural vegetation restoration, there was an increase in AMF diversity in response to increasing temperature and precipitation. AMF richness was higher in shrubland and mature forest than in cropland when temperatures were over 20 ℃ and precipitation was high. Thus, in terms of diversity, AMF were more responsive to changes in climatic conditions and vegetation recovery than diazotrophs. Both AMF and diazotroph community compositions were affected by temperature and vegetation type. The relative abundances of AMF groups (e.g., Gigaspora , Glomus , and Septoglomus) and diazotroph taxa (e.g., Frankia) increased at temperatures above 18 ℃. The relative abundances of the AMF genus Glomus and the diazotroph genus Bradyrhizobium in shrubland and mature forest were higher than those in cropland, while abundances of the AMF genus Septoglomus and diazotroph genus Anabaena increased in cropland. Network complexity increased with increasing temperature and precipitation between AMF and diazotroph taxa. Glomus and Bradyrhizobium showed the most links with other groups, confirming that the dominant genera perform well in the co-occurrence network. These results suggested high hydrothermal regions resist rapid nutrient decomposition by strengthening the interactions between AMF and diazotrophs, especially between the abundant groups Glomus and Bradyrhizobium. Management to increase AMF and diazotroph abundance during vegetation recovery in high climate level may stimulate nutrient absorption and transport. [ABSTRACT FROM AUTHOR]

Tree biomass and it's allocation pattern may respond to the environmental conditions and are quite important for understanding the global carbon cycling, climate change, and forest management. However, how stand characteristics (e.g. tree age, density) and environmental factor (e.g. climate, site conditions, and soil chemistry) influence the biomass and biomass allocation in southwest of China has not been well investigated. We analyzed 318 field measurements of forest biomass in this region, which 62 sites were obtained from our field measurements and the others from the national forest inventory. The results showed that the average above-ground biomass (AGB) and below-ground biomass (BGB) were 134 Mg/ha and 28 Mg/ha, respectively. The root/shoot biomass ratio (R/S) ranged between 0.06 and 0.81, with an average of 0.22. Forest stand characteristics explained 43% and 21% of the variation in AGB and BGB, respectively, while climate only explained 2–4%, reflecting the strong effect of forest features on biomass. However, only 5% of the R/S ratio was explained by climate, soil chemistry, and stand characteristics, suggesting that these factors had no significant effect on biomass allocation. In addition, the scaling exponents between AGB and BGB did not differ significantly from 1, and did not vary with mean annual temperature, mean annual precipitation, longitude, latitude, altitude, soil pH, soil total nitrogen concentration, and stand age, but did vary with soil total phosphorus concentration, stand density, and forest type. Our findings suggest that stand characteristics have a marked impact on forest biomass, and root biomass scales isometrically with above-ground biomass in southwest China. [ABSTRACT FROM AUTHOR]

Highlights • A dynamic Budyko model was improved by linking climate and vegetation. • Catchments with larger portion of karst landform (POK) have lower vegetation available water. • Evapotranspiration in catchments with larger POK rely more on precipitation. Abstract Karst landscape, covers more than 10% of the global land surface and plays an important role in supporting ecosystems and human society, may be strongly influenced by climate change. Vegetation available water (VAW) is a key variable impacting the sensitivity of ecosystems to a changing environment. However, VAW in karst region is difficult to determine and remains uncertain. This study improved a dynamic Budyko-type water balance model, by introducing a nonlinear equation linking climate, vegetation and Budyko-type water balance. This model was calibrated using evolutionary algorithm based on monthly runoff. Comparison results in the Pearl, Yangtze and 12 karst catchments in south China, suggested high effectiveness of this improved model in simulating monthly runoff and evapotranspiration. Furthermore, in the 12 karst catchments, the max VAW was negatively correlated to the portion of karst landscape of the catchment (POK, r = −0.63, α = 0.027) and the elasticity of evapotranspiration to precipitation (r = −0.60, α = 0.04). These implied that karst catchments with higher POK had lower VAW, making the ecosystems rely more on precipitation. [ABSTRACT FROM AUTHOR]

Nitrogen (N) deposition may change carbon (C) or nutrient limitation of soil microbes, but whether such change can be reflected by ecoenzymatic stoichiometry has not been well studied. Here, we synthesized data from 36 published studies to evaluate the responses of ecoenzymatic stoichiometry to N addition. Results showed that N addition did not change the enzyme ratio (1:1:1) of C, N, and phosphorus (P) acquisition, and also did not change vector angle of ecoenzymatic stoichiometry which is an indicator of microbial P limitation. However, N addition increased two indicators of C-limitation significantly (i.e., activity of β- D -glucosidase and vector length), both of which indicated that N addition aggravated microbial C-limitation. The aggravated C-limitation may be partly due to the reduced decomposition of recalcitrant organic C. Our study extends our understanding of the effects of N deposition on C cycling from a new perspective. [ABSTRACT FROM AUTHOR]

Free-living biological N 2 fixation (BNF) in soil, litter and moss is an important pathway for external nitrogen (N) inputs to unmanaged terrestrial ecosystems. However, how free-living BNF responses to temperature, moisture and their interaction have not been well understood, especially in the subtropical regions. Here we investigated the responses of BNF in soil, litter and moss to temperature (15, 25 and 35 °C) and moisture (low, intermediate and high levels) over a one-week period under laboratory conditions. The samples were collected in a subtropical karst forest, southwest China. We found that the responses of BNF in moss, litter and soil to temperature and moisture were divergent. Litter and soil BNF rates increased with temperature under the three moisture levels. However, moss BNF rates were decreased, not changed or increased by warming under low, intermediate and high moisture levels, respectively. At each temperature, the BNF rates increased with moisture for moss and litter. However, the patterns of moisture responses were different at the three temperatures for soil BNF, which was not changed and increased by moisture at 15 °C and 25 °C, respectively; and was greatest under intermediate moisture, but lowest under low moisture at 35 °C. The temperature sensitivity of BNF was generally highest for litter, intermediate for soil and lowest for moss. In contrast, the moisture sensitivity of BNF was generally highest for moss, intermediate for soil, and lowest for litter. Our findings suggest that different temperature or moisture sensitivities of BNF for the three substrates should be integrated into terrestrial ecosystem models in order to better predict N inputs via BNF under climate change. [ABSTRACT FROM AUTHOR]

Soil hydrologic functions are important for karst landscapes where soil water loss is significant. The largest global ecological restoration engineering project, namely the “Grain for Green” program, is being implemented since 2000 in karst landscapes across southwestern China. However, its effects on soil hydrologic functions are still unknown. Using data acquired in field investigations and a generalized linear model (GLM), this study examines the effects of different vegetation restoration types on soil field saturated-hydraulic conductivity ( K fs ) in karst landscapes of southwest China. The results indicate that the K fs of artificial grassland (napiergrass) was higher than in other vegetation restoration types (zenia insignis, toona sinensis, orchard, and natural restoration shrubland) and cropland at both the surface and 10 cm depths. The K fs of vegetation restoration lands was lower than that of Mulun nature reserve (primary forest) at both the surface and 30 cm depths. We found significant differences of K fs in different depths of vegetation restoration lands but not significant for primary forest. The GLM model explains 64.75% of the total variation in K fs . Among the input variables, vegetation type explained the largest proportion (11.29%) of the variation, followed by bulk density (BD), soil organic carbon, and BD and vegetation type interactions. The factors above were significantly related to K fs . This study suggests that the implementation of different vegetation restoration types can alter soil hydrologic functions and provides useful knowledge for ecological restoration practices and management in karst landscapes. [ABSTRACT FROM AUTHOR]

Quantifying the impacts of climate and human activities on water and sediment discharge has become a central topic in climate and hydrologic research. This issue, however, has so far received little attention in karst regions around the world. Seven karst catchments located in southwest China were chosen to explore water and sediment discharge responses to different driving factors during the period from the 1950s to 2011. The non-parametric Mann-Kendall test was used to detect both the trends and abrupt changes in water and sediment discharge. The double mass curve method was used to quantify the effects of climate and human activities on water and sediment discharge. Results indicated that the annual water discharge showed a decreasing trend in all catchments (−0.21 to −3.68 × 10 8 m 3 yr −1 ), and the sediment discharge exhibited a significant decreasing trend (−7 to −101 × 10 4 t yr −1 ) for six out of the seven catchments. A rapid decline (abrupt change) in sediment discharge occurred since 2000 for all except Liujiang catchment where the sediment discharge has a slight increase since 1983 as no large dams were constructed in this catchment. Specifically, the magnitude of reduction in sediment discharge (%) significantly increases with the extent of flow regulation as measured by the ratio of the area upstream the dam to the total catchment area for the seven catchments ( R 2 = 0.98, P < 0.01). This study demonstrated that water discharge was mainly influenced by precipitation, while sediment discharge was mainly influenced by human activities (relative contribution 70–111%, regardless of whether the effect is negative or positive). Ecological restoration played somehow important roles in the decrease in sediment discharge (negative relationships of sediment discharge with the Normalized Differential Vegetation Index (NDVI)), but dam construction was likely to be the principal cause of the significant decrease in sediment discharge. This study is of use for better catchment management in karst regions in southwest of China. [ABSTRACT FROM AUTHOR]

Summary Karst landform represents about 10% of the continental area and plays key roles in water supplies for almost a quarter of the global population. Knowledge of ecohydrological responses of karst landform to climate change is critical for both water resources management and ecological protection in these regions. This study investigated the effects of karst landform on the elasticity of actual evapotranspiration (derived by the Budyko equation), estimated the contribution of climate change and evaluated the implications, on the basis of 13 typical catchments that have different karst landform coverages in southwest China. Catchment properties, including the vegetation coverage, portion of karst landform (POK), drainage area, surface roughness, mean topographic wetness index, mean slope, and mean aspect, were selected to test the influencing factors for the elasticity of actual evapotranspiration. Results indicate that POK is the most influencing factor for the elasticity of actual evapotranspiration in this region. Moreover, the actual evapotranspiration in karst catchments is more sensitive to precipitation change and less sensitive to the potential evapotranspiration change than that in the non-karst catchments. On the other hand, the contribution of climate change to actual evapotranspiration was generally negative in this region. Furthermore, relatively large negative contributions mainly occurred in the karst-dominated catchments, suggesting that the karst catchments were exposed to higher degradation stress brought by the climate change than that in non-karst catchments. [ABSTRACT FROM AUTHOR]

• Annual precipitation and runoff showed similar changes with turning points in 2002. • Ecological restoration had a great impact on runoff in karst basins. • Increases in NDVI negatively related to the proportions of karst landscape. • Revegetation decreased flood season runoff and increased non-flood season runoffs. Ecological restoration changes land cover types and management practices. However, understanding of their hydrological response is limited, especially in karst ecosystems, which are vulnerable to environmental changes. This study aimed to identify the spatial variability of the hydrological response in a mesoscale karst basin to climate change and ecological restoration. We examined changes in hydrological variables and normalized difference vegetation index (NDVI) from 1985 to 2015 in Longjiang River Basin (LRB) and its three main sub-basins, namely Huanjiang (HJB), Zhongzhouxiaojiang (ZZB), and Dongxiaojiang (DXB) sub-basins. The proportions of karst landscapes (POK) were 81, 66, 61, and 26%, respectively. Three independent quantitative methods were employed to distinguish the relative contributions of climate change and human activity. Annual runoff showed a good linear correlation with precipitation in all the basins, with insignificantly lower average values during 2003–2015 than during 1985–2002. The relative contribution of precipitation to annual runoff change varied from 17.5 to 52.9%. At a seasonal scale, flood season precipitation and runoff decreased with similar patterns of annual variation, whereas non-flood season values increased from 1985–2007 to 2008–2015. The quantitative results showed that the relative contribution rates of human activity to non-flood season runoff change were strongly linked to POK values and related vegetation changes. Annual NDVI improved after the implementation of ecological restoration projects, with change rates negatively related to POK values. Human activity was the dominant cause of increased non-flood season runoff in the LRB and HJB (accounting for 57 and 78%, respectively), whereas increases in non-flood season runoff in the ZZB and DXB were mainly caused by precipitation changes (accounting for 84 and 172%, respectively). These findings highlighted the facts that ecological restoration had changed hydrological processes and seasonal-scale analyses might therefore facilitate a better understanding of runoff changes in karst basins. [ABSTRACT FROM AUTHOR]