The variation and correlation among desert plant traits are helpful to understanding the adaptation strategies of plants to the environment and the mechanism of community assembly. However, the diversity and covariation among fine root traits of desert plants and their phylogenetic relationships remain unclear. Principal component analysis, Pearson’s correlations, phylogenetic independent comparison, mixed linear model, and variance decomposition were used to investigate the variation and correlation among 10 fine root traits of 25 common desert plants in arid areas. The results are as follows: (1) We found that all fine root traits varied more among interspecific variation, with the coefficient of variation ranging from 21.83% to 105.79%. Most traits were predominantly shaped by interspecific variation, whereas root phosphorus content (RPC) and intraspecific variation in root carbon/nitrogen ratio (RCN) were more important. (2) Root traits were correlated with four axes of variation. Root nitrogen content (RNC) correlated positively with root diameter (AD) and tissue density (RTD) but negatively with specific root length (SRL), which was inconsistent with the inference of the root economics spectrum (RES). (3) Covariance and trade-off strategies of fine root traits in different life forms of plants were different. Herb RNC was negatively correlated with SRL and positively correlated with AD, while this relationship did not exist in shrubs. Moreover, shrub AD was negatively correlated with RTD, but herbs showed no significant correlation. (4) Influenced by phylogenetic factors, fine root traits exhibited a covariant or trade-off pattern. Taken together, fine root traits were predominantly shaped by interspecific variation, but intraspecific variation also played a significant role. Concurrently, distinct patterns in fine root covariation and trade-off strategies among different life forms of plants were also observed. Future studies should explore the variation and correlation among traits at different scales within and between species from the perspective of life form.

Forest plantations play a critical role in mitigating climate change, with their carbon storage and sequestration capacity significantly influenced by planting patterns. This study focuses on Picea crassifolia plantations in the shallow mountainous region of the Qilian Mountains, aiming to investigate the effects of five planting patterns (pure forests, mixed forests, and uneven-aged forests) on vegetation and soil organic carbon (SOC) dynamics. The research provides a scientific basis for optimizing forest management strategies in arid and semi-arid regions. Fifteen sample plots were established in the Qilian Mountains, Gansu Province, covering five planting patterns: pure forests with 1.5 × 1.5 m (P1.5) and 2 × 2 m (P2) spacing, uneven-aged pure forests (PX), mixed forests of P. crassifolia and Pinus sylvestris var. mongholica (PC), and mixed forests of P. crassifolia, P. sylvestris, and Caragana korshinskii (PPC). Vegetation biomass (tree height, DBH, crown width) and soil samples (0 – 80 cm depth) were collected. Carbon content was determined using the potassium dichromate oxidation method, and carbon stocks were estimated using national biomass models. Statistical analyses (one-way ANOVA) and membership function evaluation were applied to assess carbon sink potential. Results showed that: 1. Planting spacing: The 2 × 2 m pure forest (P2) exhibited higher vegetation-layer carbon storage (10 t·ha⁻¹) compared to the 1.5 × 1.5 m pure forest (P1.5, 5 t·ha⁻¹). 2. Age heterogeneity: The uneven-aged pure forest (PX) showed the highest vegetation-layer carbon storage (6.61 t·ha⁻¹), but its total carbon stock (106.98 t·ha⁻¹) was slightly lower than P2 (111.08 t·ha⁻¹) due to P2’s superior SOC content in deeper soil layers (13.64 g·kg⁻¹ at 60–80 cm). 3. Pure vs. mixed forests: Pure forests (P2) outperformed mixed forests (PC, PPC) in total carbon storage, driven by soil-layer contributions (>95% of total stocks). The 2 × 2 m pure forest (P2) demonstrated optimal carbon sequestration potential in the Qilian Mountains, with soil carbon dominance highlighting the importance of deep-layer SOC accumulation. While uneven-aged forests (PX) showed strong vegetation carbon storage, long-term carbon sinks require integrated soil management. These findings provide critical insights for arid-region plantation configurations. Future studies should combine remote sensing for dynamic carbon monitoring and explore diversified mixed-species systems to enhance ecosystem stability.

Drought-induced plant mortality, resulting from either hydraulic failure or carbon starvation, is hypothesized to be modulated by the drought intensity. However, there is a paucity of research investigating the response strategies in desert shrubs under drought stress with different intensities. We transplanted potted Reaumuria soongorica (Pall.) Maxim. and Salsola passerina Bunge seedlings in the rain-out shelter, and implemented three water treatments: a control (well-watered, CK), a chronic drought (gradually less watered, CD), and a flash drought (not watered, FD). We then quantified plant physiological traits associated with water use and carbon assimilation. Both R. soongorica and S. passerina showed similar changes in water use and carbon characteristics under different drought treatments. Water use efficiency was not significantly changed, but embolism resistance was significantly lower in CD, and leaf specific conductivity and embolism resistance were significantly lower in FD compared to CK. Under the drought treatment, both shrubs had significantly lower hydraulic safety margins than CK, with FD being significantly lower than CD. Notably, FD had lower carbon assimilation and a lower leaf non-structural carbon concentration, but higher stem non-structural carbon concentration. The results of a principal component analysis showed that net photosynthetic rate, sapwood specific conductivity, embolism resistance, midday water potential, and leaf and stem soluble sugar concentration were the main axes of variation for R. soongorica traits. CK had the highest water use efficiency, net photosynthetic rate, and gas exchange rate, while FD had the lowest embolism resistance and highest osmoregulation. Midday water potential, leaf and stem soluble sugar concentration were the main axes of variation for S. passerina traits, and individual distribution under three water treatments was associated with drought tolerance traits. The findings suggest that species exhibit different response strategies for resistance to drought stress, with R. soongorica being drought-avoidant and S. passerina being drought-tolerant. These findings highlight the adaptive capacity of desert shrubs to water deficit and provide insights for assessing hydraulic failure and carbon starvation in desert shrubs.

The Zuli River is in the northwest of the Loess Plateau. As an important center of production and domestic water source, variations in the water quality of this basin and their influencing factors are important considerations for improving the river water environment. In order to identify and predict changes in the water quality of the watershed, the following water quality indicators, namely, dissolved oxygen content (DO), five-day biological oxygen demand (BOD₅), ammonia nitrogen concentration (NH₃-N), the high-manganese salt index (COD_Mn), volatile phenol concentration (VP), total phosphorus (TP), fluoride concentration (F⁻), and nitrite nitrogen concentration (NO₃-N), were studied together with their change trends, influencing factors, and main variation cycles in the basin from 2001 to 2021. The results were as follows: (1) All the water quality indicators except for DO and F- showed an increasing trend before 2011, and DO showed an extreme, significant downward trend. There was an increase in the content of pollutants in the water caused by chemical fertilizer and aquaculture, resulting in a decrease in the DO content. (2) There was an extreme, significant upward trend in DO after 2011, while a significant downward trend was observed in the other water quality indicators except for NO₃-N. (3) According to the main variation cycle of the other water quality indicators, the DO will remain in its peak period, while the other water quality indicators except for NO₃-N will remain in a trough period (which began in 2021). The increase in precipitation and runoff reduced the content of pollutants in the water. Therefore, the overall water quality of the Zuli River Basin gradually improved after 2011. This may be due to (1) increased precipitation and runoff, thereby diluting the concentration of pollutants in the river, or (2) a decreased concentration of pollutants entering the river with the decrease in soil erosion.

Phenotypic variation analysis and comprehensive evaluation are important tools for selecting provenances of forest trees, which, in turn, is crucial for genetic improvement of forest trees. The study analyzed eight needle-leaf and fourteen tracheid trait indexes of ten provenances of Qinghai spruce forest stands. Multiple comparisons, correlation analysis, cluster analysis, and principal component analysis were used to evaluate the differences in needle-leaf and tracheid traits among the different provenances. The study found significant differences in the needle-leaf and tracheid traits among the provenances. All traits included 50 pairs of positive and 26 pairs of negative correlations. The coefficient of variation for the tracheid trait (18.86%) was higher than that for the needle-leaf trait (17.20%). A comprehensive evaluation of needle-leaf and tracheid traits was conducted using principal component analysis. The study demonstrated that the degree of variation in needle-leaf and tracheid traits among the provenances of Qinghai spruce was extensive, with a multitude of sources of variation. Therefore, it is crucial to strengthen the selection of good provenances in the early seed selection process. The results of the comprehensive evaluation can be utilized as a foundation for the selection of good provenances for carbon sequestration and timber properties.