Open-pit mining generates airborne particulate matter that can accumulate on vegetation and potentially influence herbivore foraging behaviour. However, the relative importance of foliar particulate deposition compared with habitat quality in driving habitat selection remains poorly understood in arid ecosystems. We investigated whether semi-quantitative foliar particulate indicators derived from scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS) were associated with habitat patch selection by cattle (Bos taurus), sheep (Ovis aries), goats (Capra hircus), and springbok (Antidorcas marsupialis) in an arid shrub–grass savanna adjacent to an operational iron-ore mine in South Africa. Leaf-surface particulate signatures were quantified as elemental weight percentages (wt%) of aluminium (Al), magnesium (Mg), and silicon (Si), and compared between preferred and avoided habitat patches using stratified Wilcoxon (van Elteren) tests with animal identity treated as the stratification variable. Habitat-quality variables were subsequently evaluated alongside the measured foliar particulate indicators. Elemental signatures showed substantial overlap between preferred and avoided habitat patches. Although three element-by-growth-form comparisons were statistically significant, preferred patches consistently exhibited equal or higher elemental values than avoided patches, providing no evidence that the measured foliar particulate indicators were associated with habitat avoidance. In contrast, vegetation height and greenness showed stronger and more consistent relationships with habitat selection across species. These findings indicate that habitat quality outweighed the measured foliar particulate indicators in explaining grazer patch selection within this arid mining landscape. Because the SEM–EDS-derived elemental signatures cannot distinguish mine-derived particulates from natural background dust, these results should not be interpreted as evidence that mining-derived dust has no ecological effects. Rather, they demonstrate that the specific foliar particulate indicators measured in this study were poor predictors of observed habitat use, highlighting the need for future studies incorporating source-resolved dust measurements and quantitative particulate loading.

Clarifying the grazing effects on the carbon sink function on the Tibetan Plateau is highly important under climate change. Based on parallel carbon flux and meteorological observations in nearby grazing and grazing-excluded alpine meadows, the effects of grazing were studied. The results indicated that gross primary productivity (GPP) was dominated by soil temperature (TS) and soil water content (SWC) in both the grazing and grazing-excluded meadows. During the whole growing season, in both meadows, TS exerted the strongest control effects on GPP, whereas the dominant factor shifted to SWC during the peak growing season. During the early and late stages of the growing season, the dominant factor for GPP shifted from SWC to TS in the grazing meadow, whereas the dominant factor remained SWC in the grazing-excluded meadow. The grazing-excluded meadow showed improved temperature conditions, resulting in a lower sensitivity of GPP to TS. In contrast, the grazing meadow showed better water conditions, leading to a lower sensitivity of GPP to SWC, which might result in stronger resistance to droughts. Proper grazing could improve GPP and shift the sensitivity of GPP to environmental factors, providing implications for the sustainable management of alpine meadows.

Under global climate change, extreme climate events are important factors for vegetation dynamics in arid and semi-arid regions. However, a systematic understanding of the response patterns and nonlinear characteristics of vegetation to extreme climate across multi-temporal scales and geomorphic subregions remains lacking. Taking the Yellow River's 'Ji Zi Bend' as the study area, we used 23-year MODIS NDVI data and station-based extreme climate indices (2000–2022), combined with trend analysis, correlation analysis, lag analysis, and the interpretable machine learning model XGBoost-SHAP, to systematically analyze vegetation response characteristics at annual, seasonal, and monthly time scales, including lagged responses across seven geomorphic subregions. The results showed that: (1) NDVI in the study area increased at a rate of 0.004 a−1 from 2000 to 2022, with significant increases in 69.65% of the area and significant decreases in only 7.85%; the regional climate concurrently exhibited warming-drying and intensifying extremes, with both Consecutive dry days (CDD) and Maximum five-day precipitation (RX5day) showing upward trends. (2) Vegetation responses to extreme climate exhibited significant temporal scale dependence: annual responses showed stronger associations with extreme precipitation, monthly responses displayed significant associations with combined water and temperature conditions, together with lagged responses. (3) XGBoost-SHAP indicated that CDD and RX5day had the largest negative and positive contributions, respectively, to model-predicted vegetation variation, with both showing clear predictive nonlinear relationships and model-derived response turning points of approximately 69.91 days and 78.63 mm, respectively. These findings improve our understanding of vegetation sensitivity to climate extremes across multiple temporal scales in dryland ecotones.

Clarifying the grazing effects on the carbon sink function on the Tibetan Plateau is highly important under climate change. Based on parallel carbon flux and meteorological observations in nearby grazing and grazing-excluded alpine meadows, the effects of grazing were studied. The results indicated that gross primary productivity (GPP) was dominated by soil temperature (TS) and soil water content (SWC) in both the grazing and grazing-excluded meadows. During the whole growing season, in both meadows, TS exerted the strongest control effects on GPP, whereas the dominant factor shifted to SWC during the peak growing season. During the early and late stages of the growing season, the dominant factor for GPP shifted from SWC to TS in the grazing meadow, whereas the dominant factor remained SWC in the grazing-excluded meadow. The grazing-excluded meadow showed improved temperature conditions, resulting in a lower sensitivity of GPP to TS. In contrast, the grazing meadow showed better water conditions, leading to a lower sensitivity of GPP to SWC, which might result in stronger resistance to droughts. Proper grazing could improve GPP and shift the sensitivity of GPP to environmental factors, providing implications for the sustainable management of alpine meadows.

Under global climate change, extreme climate events are important factors for vegetation dynamics in arid and semi-arid regions. However, a systematic understanding of the response patterns and nonlinear characteristics of vegetation to extreme climate across multi-temporal scales and geomorphic subregions remains lacking. Taking the Yellow River's 'Ji Zi Bend' as the study area, we used 23-year MODIS NDVI data and station-based extreme climate indices (2000–2022), combined with trend analysis, correlation analysis, lag analysis, and the interpretable machine learning model XGBoost-SHAP, to systematically analyze vegetation response characteristics at annual, seasonal, and monthly time scales, including lagged responses across seven geomorphic subregions. The results showed that: (1) NDVI in the study area increased at a rate of 0.004 a−1 from 2000 to 2022, with significant increases in 69.65% of the area and significant decreases in only 7.85%; the regional climate concurrently exhibited warming-drying and intensifying extremes, with both Consecutive dry days (CDD) and Maximum five-day precipitation (RX5day) showing upward trends. (2) Vegetation responses to extreme climate exhibited significant temporal scale dependence: annual responses showed stronger associations with extreme precipitation, monthly responses displayed significant associations with combined water and temperature conditions, together with lagged responses. (3) XGBoost-SHAP indicated that CDD and RX5day had the largest negative and positive contributions, respectively, to model-predicted vegetation variation, with both showing clear predictive nonlinear relationships and model-derived response turning points of approximately 69.91 days and 78.63 mm, respectively. These findings improve our understanding of vegetation sensitivity to climate extremes across multiple temporal scales in dryland ecotones.

Terrestrial carbon cycling plays an important role in land–atmosphere interactions, yet carbon dynamics in dryland ecosystems across different aridity levels remain poorly understood. Using multi-year eddy-covariance observations from four desert ecosystems along a regional precipitation gradient in the Hexi Corridor, northwestern China, we investigated growing-season carbon fluxes and their environmental controls. All sites acted as weak net carbon sinks during the growing season (−43.73 to −64.26 g C m−2 growing season−1), with carbon uptake generally increasing with long-term mean annual precipitation. Weekly carbon fluxes (7-day moving averages) showed nonlinear responses to soil water content (SWC), with site-specific thresholds ranging from 1.87% to 14.44%. Below these thresholds, gross primary productivity (GPP) and ecosystem respiration (Reco) increased rapidly with increasing SWC, whereas responses weakened above the thresholds. Environmental controls differed among sites: carbon fluxes at the Huangmo site (HMo) were primarily regulated by soil moisture and vegetation activity, whereas fluxes at the Bajitan site (BJT) and Shenshawo site (SSW) were jointly controlled by soil moisture, soil temperature, and normalized difference vegetation index (NDVI). At the Linze site (LZe), both air and soil temperatures showed significant relationships with carbon fluxes, indicating stronger thermal constraints at this site. Soil temperature generally exhibited stronger associations with carbon exchange than air temperature. These results highlight the coupled roles of water availability and temperature in regulating carbon exchange across dryland desert ecosystems and provide insights into a better representation of dryland carbon cycle processes in land-surface and Earth system models.

Cenozoic rift basins encompass prolific petroleum systems worldwide. This study investigates the key controls on thermal maturity evolution and hydrocarbon potential in Cenozoic rift basins through comparative analysis of the Gulf of Suez Rift Basin (GOSRB, Egypt) and the Dongpu Rift Basin (DRB, China). Basin modeling of the Lower Rudeis Formation in the central and southern GOSRB integrates subsidence history, erosion, stratigraphic thicknesses, and kinetic models to reconstruct burial, thermal, generation, and expulsion histories. The Lower Rudeis source rock exhibits pronounced spatiotemporal variability in maturity, with the central province achieving early, mid, and late mature stages, high transformation ratios, and predominantly oil-prone systems, while the southern province is characterized by lower transformation ratios, thinner source and overburden successions, and gas-prone charge. These differences are primarily governed by burial depth at the onset of maturity, subsidence and negative subsidence rates, and associated variations in heat flow. Comparison with the DRB shows that both basins share similar crustal thicknesses, rift-related subsidence magnitudes, and high heat flows sufficient to generate efficient petroleum systems from marine source rocks in the Gulf of Suez and lacustrine source rocks in the Dongpu Sag, but differ in rifting duration, structural style, and kerogen assemblages. The results indicate that the principal factors controlling maturity evolution and hydrocarbon potential in Cenozoic rift basins are burial depth to the onset of early maturity, the magnitude of negative subsidence, subsidence rate, thermal regime, source-rock quality, structural architecture, and seal effectiveness. These factors collectively dictate whether rift basins evolve predominantly oil- or gas-prone petroleum systems and provide a predictive framework for exploration in frontier Cenozoic rifts.

Cenozoic rift basins encompass prolific petroleum systems worldwide. This study investigates the key controls on thermal maturity evolution and hydrocarbon potential in Cenozoic rift basins through comparative analysis of the Gulf of Suez Rift Basin (GOSRB, Egypt) and the Dongpu Rift Basin (DRB, China). Basin modeling of the Lower Rudeis Formation in the central and southern GOSRB integrates subsidence history, erosion, stratigraphic thicknesses, and kinetic models to reconstruct burial, thermal, generation, and expulsion histories. The Lower Rudeis source rock exhibits pronounced spatiotemporal variability in maturity, with the central province achieving early, mid, and late mature stages, high transformation ratios, and predominantly oil-prone systems, while the southern province is characterized by lower transformation ratios, thinner source and overburden successions, and gas-prone charge. These differences are primarily governed by burial depth at the onset of maturity, subsidence and negative subsidence rates, and associated variations in heat flow. Comparison with the DRB shows that both basins share similar crustal thicknesses, rift-related subsidence magnitudes, and high heat flows sufficient to generate efficient petroleum systems from marine source rocks in the Gulf of Suez and lacustrine source rocks in the Dongpu Sag, but differ in rifting duration, structural style, and kerogen assemblages. The results indicate that the principal factors controlling maturity evolution and hydrocarbon potential in Cenozoic rift basins are burial depth to the onset of early maturity, the magnitude of negative subsidence, subsidence rate, thermal regime, source-rock quality, structural architecture, and seal effectiveness. These factors collectively dictate whether rift basins evolve predominantly oil- or gas-prone petroleum systems and provide a predictive framework for exploration in frontier Cenozoic rifts.

The Upper Jurassic–Lower Cretaceous Chia Gara Formation is a major marine source rock in the Middle East. However, its early-stage maturation dynamics often remain underestimated by bulk geochemical parameters. This study provides a comprehensive organic petrographic and palynofacies characterization of the Chia Gara Formation in the Hr-1 well (Hamrin Field, Northern Iraq). This study calibrates its generative potential and clarifies the nature of its organo-mineral fabric. The palynofacies results record a dominance of marine-derived amorphous organic matter (AOM) and alginite. This assemblage indicates a distal, anoxic basinal setting. However, reflected-light microscopy reveals a notable scarcity of thick bituminite lenses, despite the high AOM abundance in acid-digested residues. This difference is attributed to fine-scale organo-mineral mixing. The AOM is adsorbed onto clay and micrite surfaces as a dispersed organo-clay complex rather than forming segregated maceral layers. Moreover, the study identifies evidence of early hydrocarbon generation. This is presented as thin, solid bitumen in microfractures and as liquid, fluorescent oil droplets isolated within foraminiferal tests. The comparative analysis with more thermally mature occurrences of Chia Gara formations establishes a regional maturity gradient. This research highlights the need for integrated microscopy to identify transitional phases of petroleum systems, as active generation and micromigration precede traditional bulk maturity thresholds.

The Upper Jurassic–Lower Cretaceous Chia Gara Formation is a major marine source rock in the Middle East. However, its early-stage maturation dynamics often remain underestimated by bulk geochemical parameters. This study provides a comprehensive organic petrographic and palynofacies characterization of the Chia Gara Formation in the Hr-1 well (Hamrin Field, Northern Iraq). This study calibrates its generative potential and clarifies the nature of its organo-mineral fabric. The palynofacies results record a dominance of marine-derived amorphous organic matter (AOM) and alginite. This assemblage indicates a distal, anoxic basinal setting. However, reflected-light microscopy reveals a notable scarcity of thick bituminite lenses, despite the high AOM abundance in acid-digested residues. This difference is attributed to fine-scale organo-mineral mixing. The AOM is adsorbed onto clay and micrite surfaces as a dispersed organo-clay complex rather than forming segregated maceral layers. Moreover, the study identifies evidence of early hydrocarbon generation. This is presented as thin, solid bitumen in microfractures and as liquid, fluorescent oil droplets isolated within foraminiferal tests. The comparative analysis with more thermally mature occurrences of Chia Gara formations establishes a regional maturity gradient. This research highlights the need for integrated microscopy to identify transitional phases of petroleum systems, as active generation and micromigration precede traditional bulk maturity thresholds.