Northeastern Qinghai-Tibetan Plateau Research Articles

Effects of the freeze–thaw process on sources and pathways of subsurface flow in an alpine hillslope on the northeastern Qinghai-Tibet Plateau

The impact of the freeze–thaw process on the active layer is reflected in the changed subsurface flow (SSF) process in cold alpine regions. Identifying sources and pathways of SSF in the freeze–thaw process is critical but difficult, and the related dominant factors and mechanisms are still unknown. In this paper, the effective identification and analysis of SSF are promoted based on field sampling data from the thawing (June) to freezing (September) period of 2022 in the Qinghai Lake basin on the northeastern Qinghai-Tibetan Plateau. By the proposed method with a high sampling frequency and refined sampling spatial scale, the sources and pathways of SSF are clearly identified. The results are as follows: (1) The soil temperature is considered the most fundamental factor affecting the SSF pathways, it influences water infiltration to the deep layer and the effect is extended to the saprolite and weathered bedrock layers. (2) Thawing promotes water to infiltrating into deep layer. 30 cm soil water contributes the most to SSF (2 %–86 %) in the thawing period, while the contribution difference of the water from the 30 cm, 60 cm, and 90 cm layers is small (ranging from 32 %–33 %, 24 %–26 %, and 32 %–35 %, respectively) in the thawed period. (3) Meanwhile, the soil water from different slope positions contribute differently to SSF, and the SSF from deep soil layer is transit in prolong paths and depths. It is caused by the out-of-sync water transit process in the hillslope. With continuing climate warming, we propose that the differences in the water sources of SSF across soil layers may decrease, while the differences in the transit processes of SSF across soil layers may increase.

Estimation of Phytoplankton Primary Productivity in Qinghai Lake Using Ocean Color Satellite Data: Seasonal and Interannual Variations

Estimation of primary production in Qinghai Lake is crucial for the aquatic ecosystem management in the northeastern Qinghai–Tibet Plateau. This study used the Vertically Generalized Production Model (VGPM) with ocean color satellite data to estimate phytoplankton primary productivity (PP) in Qinghai Lake during the non-freezing period from 2002 to 2023. Field data from 2018 and 2023 were used to calibrate and verify the model. The results showed a seasonal trend in chlorophyll-a and PP, with the lowest values in May and peaks from June to September. Qinghai Lake was identified as oligotrophic, with annual mean chlorophyl-a of 0.24–0.40 µg/L and PP of 40–369 mg C/m2/day. The spatial distribution of PP was low in the center of the lake and high near the shores and estuaries. An interesting periodic increasing trend in PP every 2 to 4 years was observed from 2002 to 2023. This study established a remote sensing method for PP assessment in Qinghai Lake, revealing seasonal and interannual variations and providing a useful example for monitoring large saline mountain lakes.

Quantifying the contribution of climate change and human activities to surface drought in Qinghai, northeastern Qinghai-Tibetan Plateau

Quantifying the contribution of climate change and human activities to surface drought in Qinghai, northeastern Qinghai-Tibetan Plateau

Prediction of soil organic carbon stock combining Sentinel-1 and Sentinel-2 images in the Zoige Plateau, the northeastern Qinghai-Tibet Plateau

Prediction of soil organic carbon stock combining Sentinel-1 and Sentinel-2 images in the Zoige Plateau, the northeastern Qinghai-Tibet Plateau

An observational network of ground surface temperature under different land-cover types on the northeastern Qinghai–Tibet Plateau

Abstract. Ground surface temperature (GST), measured at approximately 5 cm in depth, is a key controlling parameter for subsurface biophysical processes at the land–atmosphere boundary. This work presents a valuable dataset of GST observations at various spatial scales in the Headwater Area of the Yellow River (HAYR), a representative area of high-plateau permafrost on the northeastern Qinghai–Tibet Plateau (QTP). GST was measured every 3 h using 72 iButton temperature loggers (DS1922L) at 39 sites from 2019 to 2020. At each site, GST was recorded in two plots at distances from 2 to 16 m under similar and different land-cover conditions (steppe, meadow, swamp meadow, and bare ground). These sensors proved their reliability in harsh environments because there were only 165 biased measurements from a total of 210 816. A high significant correlation (>0.96, p<0.001) was observed between plots, with a mean absolute error (MAE) of 0.2 to 1.2 °C. The daily intra-plot differences in GST were mainly <2 °C for sites with similar land cover in both plots and >2 °C when GST of bare ground was compared to that of sites with vegetation. From autumn to spring, the differences in GST could increase to 4–5 °C for up to 15 d. The values of the frost number (FN) were quite similar between the plots with differences in FN <0.05 for most of the sites. This dataset complements the sparse observations of GST on the QTP and helps to identify the permafrost distribution and degradation at high resolution as well as to validate and calibrate the permafrost distribution models. The datasets are openly available in the National Tibetan Plateau/Third Pole Environment Data Center (https://doi.org/10.11888/Cryos.tpdc.272945, Şerban and Jin, 2022).

Comparative skin histological and transcriptomic analysis of Rana kukunoris with two different skin colors

This study compares the skin structures of Rana kukunoris with two different skin colors living in the same area of Haibei in the Northeastern Qinghai-Tibet Plateau. The skin thickness of the khaki R. kukunoris was significantly greater than that of the brown R. kukunoris (P < 0.01), and significantly more mucous and granular glands were present on the dorsal skin of the khaki frog (P < 0.05). Meanwhile, the melanocytes on the dorsal skin of the brown frog were significantly larger than those on the khaki one (P < 0.05). Morphological changes in the expansion and aggregation of melanocytes seemed to deepen the skin color of R. kukunoris. Moreover, transcriptome sequencing identified tyrosine metabolism, melanogenesis, and riboflavin metabolism as the main pathways involved in melanin formation and metabolism in brown R. kukunoris. TYR, MC1R was upregulated as the skin color of R. kukunoris was deepened and contributed to melanin production and metabolism. In contrast, the khaki frog had significantly more upregulated genes and metabolic pathways related to autoimmunity. The khaki frog appeared to defend against ultraviolet (UV) radiation-induced damage by secreting mucus and small molecular peptides, whereas the brown frog protected itself by distributing a large amount of melanin. Hence, the different skin colors of R. kukunoris might represent different adaptation strategies for survival in the intense UV radiation environment of the Qinghai-Tibet Plateau.

Spatiotemporal Distributions of the Thunderstorm and Lightning Structures over the Qinghai–Tibet Plateau

Utilizing data from the Tropical Rainfall Measuring Mission (TRMM) satellite’s precipitation radar (PR) and lightning imaging sensor (LIS), this study explores the spatiotemporal distributions of thunderstorm and lightning structures over the Qinghai–Tibet Plateau (QTP), an aspect that has not been explored previously. The structural aspects are crucial when considering the impact of thunderstorm and lightning activity in the atmospheric processes. Thunderstorms over the QTP show clear spatial variations in both vertical height and horizontal extension. In the southern region, the average heights of 20 dBZ and 30 dBZ echo tops typically exceed 11.2 and 9.3 km, respectively. Meanwhile, in the eastern part, the average coverage areas for reflectivity greater than 20 dBZ and 30 dBZ consistently surpass 1000 and 180 km2, respectively. The spatial distribution of thunderstorm vertical development height relative to the surface aligns more closely with the horizontal extension, indicating stronger convection in the eastern QTP. The thunderstorm flash rate shows an eastward and northward prevalence, while the thunderstorm flash density peaks in the western and northeastern QTP, with a minimum in the southeast. Furthermore, in the eastern QTP, lightning duration, spatial expansion, and radiance are more pronounced, with the average values typically exceeding 0.22 s, 14.5 km, and 0.50 J m−2 sr−1 μm−1, respectively. Monthly variations reveal heightened values during the summer season for thunderstorm vertical extension, areas with reflectivity greater than 30 dBZ, and lightning frequency. Diurnal variations highlight an afternoon increase in thunderstorm vertical and horizontal extension, lightning frequency, duration, and spatial scale. From a statistical perspective, under weak convective conditions, lightning length exhibits a positive correlation with thunderstorm convection intensity, contrasting with the opposite relationship suggested by previous studies. This article further analyzes and discusses the correlations between various thunderstorm and lightning structural parameters, enhancing our understanding of the distinctive features of thunderstorm and lightning activities in the QTP.

Jurassic–cretaceous exhumation history of the Northern Qaidam Basin and its implications for Northeastern Qinghai–Tibet plateau tectonism: evidences from zircon fission track thermochronology

ABSTRACT Reconstructing the growth model of the Northeastern Qinghai–Tibet Plateau is of significant importance in understanding its tectonic evolution through time. We present 20 new zircon fission track data on samples collected from the Chakabeishan-Shaliuquan district in the North Qaidam Tectonic Belt (NQTB) to constrain its Mesozoic mineralization and exhumation history. Sample ages and characteristics are differentiated by regional thrust fault systems. The mineralized pegmatite ages with high U concentrations can be divided into two groups of 170–168 Ma and 149–137 Ma, recording exhumation and hydrothermal mineralization events, with average cooling and exhumation rates of 0.074 mm/y and 2.305°C/Ma, respectively. Two ZFT ages groups characterized by low U concentrations at the deposit periphery of 125–106 Ma and 99–80 Ma, respectively, are associated with accelerated cooling and exhumation, with mean values of 7.662°C/Ma and 0.245 mm/y. We suggest that the NQTB was positioned in the high background thermal field in the Triassic, and subsequent tectonic extension resulted in the unroofing, cooling and mineralization of the region. The transition from extensional to contractional deformation in the Cretaceous tectonic setting has reactivated regional thrust fault systems and reset the Jurassic ZFT ages, and this exhumation event was influenced by the closure of the Middle-Tethys and Mongol-Okhotsk Oceans, consistent with the double-sided subduction model.

Soil properties and fungal community jointly explain N2O emissions following N and P enrichment in an alpine meadow

Nutrient enrichment, such as nitrogen (N) and phosphorus (P), typically affects nitrous oxide (N2O) emissions in terrestrial ecosystems, predominantly via microbial nitrification and denitrification processes in the soil. However, the specific impact of soil property and microbial community alterations under N and P enrichment on grassland N2O emissions remains unclear. To address this, a field experiment was conducted in an alpine meadow of the northeastern Qinghai-Tibetan Plateau. This study aimed to unravel the mechanisms underlying N and P enrichment effects on N2O emissions by monitoring N2O fluxes, along with analyzing associated microbial communities and soil physicochemical properties. We observed that N enrichment individually or in combination with P enrichment, escalated N2O emissions. P enrichment dampened the stimulatory effect of N enrichment on N2O emissions, indicative of an antagonistic effect. Structural equation modeling (SEM) revealed that N enrichment enhanced N2O emissions through alterations in fungal community composition and key soil physicochemical properties such as pH, ammonium nitrogen (NH4+-N), available phosphorus (AP), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN)). Notably, our findings demonstrated that N2O emissions were significantly more influenced by fungal activities, particularly genera like Fusarium, rather than bacterial processes in response to N enrichment. Overall, the study highlights that N enrichment intensifies the role of fungal attributes and soil properties in driving N2O emissions. In contrast, P enrichment exhibited a non-significant effect on N2O emissions, which highlights the critical role of the fungal community in N2O emissions responses to nutrient enrichments in alpine grassland ecosystems.

Hearth Residue Analysis Reveals Human Adaptation to the Younger Dryas on the Northeastern Qinghai-Tibetan Plateau

ABSTRACT Human adaptation to the extreme environment of the Qinghai-Tibetan Plateau (QTP) has drawn widespread attention as a case study on how to successfully deal with environmental changes. However, little is known about the human subsistence strategy on the QTP during the Younger Dryas (YD) cold event due to limited findings on bioarcheological remains. In this study, animal exploitation during the YD on the northeastern QTP (NEQTP) was explored through hearth sediment analysis at the Bronze Wire site. The results support the food preparation function of these hearths and indicate the preservation of fuel plant lipids as well as terrestrial non-ruminant animal fat. The absence of ruminant herbivorous fats and freshwater resources implies a hostile surrounding environment during the YD, where small-sized animals with higher tolerance may have dominated and could have thus been the main source of non-ruminant animal fat in the hearths. Although the shift to a broadspectrum pattern was not thought to be the direct result of environmental change, it could have greatly influenced such a process in certain areas. Lipid residue analysis has been applied for the first time for hearth study on the NEQTP, showing great potential in understanding human behaviour regarding subsistence strategies in the Paleolithic Age.

Effect of organic amendments on soil structure, microbial community and water transport in the Qinghai Lake watershed, North-Eastern Qinghai–Tibet Plateau

ABSTRACT The effect of organic amendments on soil structure, microbial community and water transport in alpine ecosystems remains uncertain. Six fertilization regimes from a 2-year field experiment were selected to study this mechanism, i.e. plant litter (PL), organic fertilizer (OF), low concentration of glucose (LCG), medium concentration of glucose (MCG), high concentration of glucose (HCG) and the control (CT). Our results indicated that the soil macroporosity, branch density, length density and node density of soil macropores treated with OF, PL, HCG, MCG and LCG were larger than those of soils treated with CT. The phospholipid fatty acids (PLFAs), bacteria, fungi, actinomycetes, gram-positive bacteria (G+) and gram-negative bacteria (G−) of soils treated with OF, PL, HCG and MCG were larger than those of soils treated with LCG and CT. In contrast, the dyed area ratio and the maximum wetting depth of soils treated with OF, PL, LCG, HCG and MCG were smaller than those treated with CT. There were significant positive correlations between soil organic matter (SOM) and connectivity of soil macropores. Therefore, SOM accumulation significantly improved the soil pore structure, induced the development of the soil microbial community, increased the soil water retention ability and decreased the generation of preferential flow.

Effect of grazing management strategies on the vegetation parameters and soil nutrients in alpine Kobresia pygmaea meadow on the northeastern Qinghai–Tibetan Plateau

Understanding the impact of grazing management strategies on alpine meadow is of fundamental importance for grassland conservation. However, the vegetation and soil properties in response to the different grazing management strategies implemented on Kobresia pygmaea meadow remains elusive. In this study, a medium-term field experiment with three grazing management strategies (free grazing, FG; no grazing, NG; and reduced grazing, RG) was conducted. The results revealed that the total aboveground biomass (AGB), vegetation cover and litter biomass increased significantly under NG treatment, whereas the total belowground biomass (BGB) decreased significantly in NG plot. Furthermore, the responses of plant functional groups to different grazing management strategies were varied. The AGB of grass increased remarkably under NG treatment compared to FG plot, whereas there were no obvious change in AGB of the sedge, legume, and forb groups. The concentrations of the soil available phosphorus (AP) and ammonia nitrogen (NH4+-N) of RG and FG were considerably different at the 0–5 cm soil layers. In contrast, the soil C:N ratios in all soil layers were similar among the three grazing management strategies. It is worth noting that the soil AP concentration was positively correlated with the total AGB. More importantly, the results supported the functional equilibrium hypothesis for AGB versus BGB, which is based on the unique biological characteristics of K. pygmaea meadow. Our study provides valuable insights into the response of alpine meadow to grazing management strategies and can thus provide guidance for designing management strategies for degraded alpine meadow.

Mesozoic–Cenozoic cooling, exhumation and tectonic implications of Chaqiabeishan–Shaliuquan Li[sbnd]Be ore district in the northeastern Qinghai–Tibet Plateau

The Mesozoic-Cenozoic exhumation and deformation of the northeastern Qinghai–Tibetan Plateau generated extensive regional rugged mountains. We aimed to explore the prolonged kinematic evolutionary history since the Mesozoic. We collected Mesozoic magmatic rock samples from the Chaqiabeishan-Shaliuquan lithium‑beryllium ore district in the Northern Qaidam tectonic belt (NQTB) to constrain the cooling exhumation history using apatite fission track (AFT) thermochronology. Twenty samples yielded AFT ages from 111 to 11 Ma, including four age groups:111–103, 89–75, 71–47, and 30–11 Ma, with mean track lengths of 12.5–11.2 μm. Four thermal history phases of 120–90, 90–50, 50–20, and 20–0 Ma were established based on the inverse thermal model and isostatic adjustment of the lithosphere. Additionally, the average cooling rates of the four phases were 1.67 ± 0.17, 1.25 ± 0.13, 0.33, and 1.75 ± 0.5 °C/Myr, with a corresponding exhumation amount of 1.15 ± 0.07 km, 0.98 ± 0.06 km, 0.86 ± 0.05 km, and 1.09 ± 0.06 km respectively, and the maximum exhumation was 6.021–6.787 km since 120 Ma. In the first phase, the far-field effects of Mid-Tethys Ocean subduction and closure drove the rapid exhumation of the research area. The closure of the Neo-Tethys Oceans and the continuing collision of the India-Asia plate disturbed the northeastern plateau, inducing regional backlash fault events in the NQTB, demonstrated in the second phase of thermal history. The third phase of the stable tectonic setting is consistent with previous research results, suggesting a similar cooling history for the NQTB and Qilian Mountains, evidenced by the widespread absence of Eocene to Miocene cooling signals. The rapid exhumation and reactivation of the NQTB and Qilian thrust fault system since 20 Ma represents the final stage of growth and expansion of the northeastern Qinghai–Tibet Plateau.

Vegetation cover dynamics on the northeastern Qinghai-Tibet Plateau since late Marine Isotope Stage 3

Knowledge of long-term changes in vegetation cover is essential for paleoenvironmental reconstruction and Earth system modeling. The vegetation on the northeastern Qinghai-Tibet Plateau (QTP) is highly sensitive to climatic changes, but studies of long-term changes in the vegetation cover of this region are lacking. To better understand the changes in the regional vegetation cover since late Marine Isotope Stage (MIS) 3, we obtained a pollen record from Luanhaizi Lake and used it to quantitatively reconstruct changes in the cover of trees and grasses using the random forest method. The pollen spectra show that the vegetation of the Luanhaizi Lake area was probably alpine tundra from late MIS3 to the Last Glacial Maximum, after which it changed to alpine steppe with alpine shrub and sparse forest at lower elevations during the last deglaciation. Alpine steppe and alpine meadow dominated the vegetation during the Holocene, with sparse forest in the surrounding low-elevation areas. The quantitative vegetation cover reconstruction suggests that the vegetation cover of the Luanhaizi Lake area was low (20–30%) during 47.0–20.0 ka. The tree cover then increased from ∼3% to ∼10%, and the grass cover increased from ∼20% to ∼45% during the last deglaciation (20.0–11.9 ka). The increasing Northern Hemisphere summer insolation caused increases in the regional temperature, meltwater supply, and monsoon precipitation, which promoted the development of steppe vegetation. The continued increases in insolation and monsoonal precipitation during the Holocene further increased the tree cover, which reached a maximum of 17.4% at ∼7.2 ka. Vegetation cover reconstructions from two other sites on the eastern QTP for the last deglaciation indicate contrasting patterns of changes, likely due to contrasts in elevation, climate, and environment.

Driving factors for soil C:N ratio in woody plant communities across northeastern Qinghai-Tibetan Plateau

Soil carbon: nitrogen ratio (Soil C:N ratio) is a crucial and stable indicator of soil organic matter quality, but little is known about how it is driven in woody plant communities on the northeastern Qinghai-Tibetan Plateau (QTP). For addressing the gap, we sampled 92 tree field plots and 200 shrub field plots during the plants’ growing seasons based on Vegetation Map of the People's Republic of China (1:1,000,000) to investigate the vegetations and soils. Our results showed that soil C:N ratios in tree communities were higher than those in shrub communities, with values of 14.58 ± 1.85 and 13.16 ± 1.66, respectively. Random forest (RF) algorithm and multiple comparison analysis further suggested that soil C:N ratios varied significantly among lifeforms and community types. Interestingly, our findings challenged the long-held view that climate had the most important impact on soil C:N ratios at the regional scale, as the hierarchy of importance for integrated factors was found to be soil > topography > biology > climate > lifeform for all woody plants. Pearson correlation analysis and ordinary least squares (OLS) regression analysis revealed that dissolved organic nitrogen (DON), ectomycorrhizal fungi (EcM) species proportion and downward shortwave radiation (Shwara) had significant positive correlations with soil C:N ratios in both lifeforms. The variation partitioning analyses (VPA) results showed that edaphic properties solely explained most of the variance. Multiple linear regression (MLR) models exhibited that dissolved total nitrogen (DTN) and DON were the main attributes influencing soil C:N ratios in tree communities while DON had the largest positive effect in shrub communities. Overall, these findings provide new insights into the regulatory mechanisms of C and N cycling in the woody plant communities of the northeastern QTP and shed light on the controlling factors of soil C:N ratios in this region.

Autumn migration of black-necked crane (Grus nigricollis) on the Qinghai-Tibetan and Yunnan-Guizhou plateaus.

Despite previous research efforts, the majority migration routes of the black-necked cranes (Grus nigricollis) have remained veiled. In this study, we utilized satellite telemetry data from 45 cranes between 2015 and 2021 to unveil critical insights. Our results revealed 11 distinct autumn migration routes and one sedentary flock, of which eight routes and the sedentary flock were previously undocumented. Our findings highlighted the remarkable diversity in the migration routes of black-necked cranes, especially in terms of migration orientations, spatial-temporal patterns, and altitudinal movement patterns. Cranes breeding on the eastern, northern, and central Qinghai-Tibetan Plateau migrated southward, while those on the northern slopes of the Himalayas migrated eastward, westward, northward, or opted to remain sedentary. Moreover, we expanded the known range of migration distances to 84-1520 km at both ends (excluding sedentary individuals) and identified two long-term (Da Qaidam and Chaka) and one short-term (Gyatong grassland) stopover sites. Furthermore, our study revealed that the breeding colonies in the Qilian Mountains on the northeastern Qinghai-Tibetan Plateau utilized long-term stopover sites before embarking on significant altitude ascent, while other flocks displayed more urgent migration patterns, preferring to roost only at night. By unveiling the near-complete autumn migration routes of black-necked cranes, our research has contributed to discovering the critical habitats and connectivity among various breeding colonies, which is instrumental in developing effective seasonal conservation plans.

Climate and environmental changes recorded by aeolian sediment during the last glaciation in the western Qaidam Basin

Aeolian sediments are widely distributed in the Qaidam Basin (QB) on the northeastern Qinghai-Tibet Plateau (QTP) and are ideal carriers of information for studying the environmental evolution of the basin. However, due to factors such as dry denudation and glacier erosion, there is a lack of palaeo-aeolian sediment records in the late glacial period. This study applied quartz optically stimulated luminescence (OSL) dating to fluvial-aeolian sequences in the TLH profile, which were exposed by river downcutting in the Tora River. In addition, OSL ages were combined with grain size and chemical elements to explore the sedimentary and environmental changes in the late glacial period recorded by palaeo-aeolian sediments in the QB. The results show that aeolian sediment accumulated earlier than the last glacial period in the QB and that the QB experienced multiple alternations of drying and wetting during this period. From approximately 70.45 ka BP to 60.87 ka BP, thick aeolian sediment with noticeable cross-bedding developed in this location, suggesting relatively dry environmental conditions and intense sand activities. From 60.87 ka BP to 58.56 ka BP, the environmental proxies revealed two distinct layers of fluvial deposits, with relatively coarse average grain sizes and weak chemical weathering, indicating wetter conditions. This region experienced alternations of drying and wetting between 58.56 ka BP and 41.09 ka BP, resulting in an aeolian sand layer and a freeze-thaw folded layer. This research is a good supporter of climate and environmental changes in the last glaciation.

Differential responses of CO2 and latent heat fluxes to climatic anomalies on two alpine grasslands on the northeastern Qinghai–Tibetan Plateau

Discrete extreme heat events, deluges, and droughts will become more frequent and disproportionately affect the processes and functions of grassland ecosystems. Here, we compared the responses of CO2 and heat fluxes to natural extreme events in 2016 in a lower alpine meadow and neighboring upper shrubland on the northeastern Qinghai–Tibetan Plateau. Unlike insensitive sensible heat flux, latent heat flux (LE) increased by 21.8 % in the meadow and by 56.4 % in the shrubland during a dry period and subsequent compound hot-dry period in August. Changes (Δ, data for 2016 minus the corresponding means from other years) in the heat flux at both sites were determined by changes in solar radiation (ΔSwin), as sufficient soil moisture was available. ΔLE was more sensitive to ΔSwin in the open-canopy shrubland, reflecting its greater capacity for evaporative cooling to buffer climate anomalies. CO2 fluxes responded weakly to extreme wet or dry events but strongly when those events were accompanied by exceptional heat. During single or compound hot events, the mean changes in total ecosystem respiration (ΔTER) increased by about 30 % in both grasslands, although ΔTER was more sensitive to changes in the topsoil temperature in the more productive meadow than in the shrubland. The mean changes in gross primary productivity (ΔGPP) fluctuated by <10 % in the warmer meadow but increased by 29.3 % in the cooler shrubland relative to the respective baseline, probably because of the differences in canopy structure and root depth and the consequent high-temperature stress on vegetation photosynthesis. The changes in net ecosystem CO2 exchange (ΔNEE) were significantly related to ΔTER in the meadow and increased by 55.8 %, whereas ΔNEE was controlled mainly by ΔGPP in the shrubland and decreased by 22.4 %. Overall, both alpine grasslands were resistant to rainfall anomalies but susceptible to exceptional warmth, with the differential responses being ascribed to canopy structure and root depth. Our results provide helpful insights based on which the carbon sequestration and water-holding functions of alpine grasslands during future climate change can be predicted.

In situ observations of soil hydraulic properties and soil moisture in a high, cold mountainous area of the northeastern Qinghai-Tibet Plateau

In situ observations of soil hydraulic properties and soil moisture in a high, cold mountainous area of the northeastern Qinghai-Tibet Plateau

Plant drought adaptation strategies regulate alpine grassland water yield in the Qinghai Lake Basin, northeastern Qinghai-Tibet Plateau

Study regionThe Qinghai Lake Basin, northeast Qinghai-Tibetan Plateau. Study focusVegetation dynamic induced change on catchment water yield (including surface runoff and groundwater runoff) is one of the research hotspots in the field of hydrology and ecology. However, few studies have explored the underlying biological mechanism by which plant regulate water yield. In this study, we examined the impact of different plant drought adaptation strategies on watershed water yield in the Qinghai Lake Basin, using both the ecohydrological model, water balance method and surface runoff experiments. New hydrological insightswe defined two type of plant drought adaptation strategies: drought-avoiding strategy can maximize the soil moisture and therefore minimize vegetation water stress, while drought-tolerating strategy tends to increase productivity by tolerating a certain degree of water stress. The result shows that plants employing drought-avoiding strategy have significantly higher water yield and water yield coefficient (the ratio of water yield to precipitation) than plants adopting drought-tolerating strategy, regardless of meadow or steppe species. Meanwhile, for all grassland species in the study region, plants with drought-avoiding strategy have less vegetation cover and net primary productivity than plants with drought-tolerating strategy, which reflect the trade-off between avoiding water stress and achieving competitive advantages. Our findings offer insights into the biological mechanism by which vegetation regulates water yield, and provide vital guidance for watershed management.