Willows are suitable candidates for phytoremediation projects. A pot experiment was conducted to evaluate the potential of using Salix unrooted cuttings for the phytoremediation of lead/zinc (Pb/Zn) and copper (Cu) mine tailings. Cuttings of 14 Salix clones were directly rooted into pots containing mine tailings. The 14 clones showed different levels of tolerance to tailing treatments. A total of 71.40% and 85.70% of the S. jiangsuensis ‘172’ cuttings either grown in Pb/Zn or Cu tailings survived, respectively. However, the other clones had lower survival rates, and the values were no more than 40%. Usually, all clones produce less biomass in an extremely contaminated environment. Clonal variation in biomass yield was observed in this research. The surviving clones, such as S. integra ‘WSH’, S. matsudana ‘14’, S. chaenomeloides ‘3’, S. chaenomeloides ‘4’, and S. chaenomeloides ‘5’ (Pb/Zn tailing), S. integra ‘HY’, S. integra ‘WSH’, S. matsudana ‘14’, S. matsudana ‘19’, and S. matsudana ‘34’ (Cu tailing) produced relatively more biomass in this study. In general, all the clones presented lower bioconcentration factor values for the tailings of heavy metals. In principle, all clones could easily take up and translocate Zn and Cd from the tailings to aboveground parts, especially S. integra. All clones exhibited a huge variation in their heavy metal accumulation capacity. As stated above, the direct utilization of cuttings for phytoremediation is a viable option. S. jiangsuensis ‘172’ had a high tolerance capacity and would be a recommended candidate for future phytoremediation projects in soils containing tailings with an extremely high concentration of heavy metals. These results provide crucial information about willow growth and metal accumulation capacity in extremely adverse environments.

The short legacy effects of growing season nitrogen (N) addition and reduced precipitation on nongrowing season soil respiration (Rs), autotrophic respiration (Ra), and heterotrophic respiration (Rh) are still unclear. Therefore, a field manipulative experiment to determine the responses of nongrowing season Rs and its components to growing season N addition and reduced precipitation was conducted in a temperate forest. The results show that growing season N addition and reduced precipitation significantly increased nongrowing season Rs by regulating the response of Ra and Rh. The combination of N addition and reduced precipitation also showed a much stronger effect on Rs and its components, but the magnitude and direction largely depended on the snowpack thickness. The effects of growing season N addition and reduced precipitation on nongrowing season Rs and its components were mediated by different sampling periods. N addition significantly decreased Rs by decreasing Rh in early winter and significantly increased Rs by increasing Ra in deep winter and late winter. All treatments decreased temperature sensitivity (Q₁₀) of Rs and Rh. Our findings contribute to a better understanding of how nongrowing season Rs and its components will change under growing season N addition and reduced precipitation and could improve predictions of the future states of the soil C cycle in response to climate change.

(1) Background: Understanding how forest management practices regulate hydrological cycles is critical for sustainable water resource management and addressing global water crises. However, the effects of light-felling (selective thinning) on hydrological processes in temperate mixed forests remain poorly understood. This study comprehensively evaluated the impacts of light-felling intensity levels on three hydrological layers (canopy, litter, and soil) in mid-rotation Korean pine (Pinus koraiensis) forests managed under the “planting conifer and preserving broadleaved trees” (PCPBT) system on Changbai Mountain, China. (2) Methods: Hydrological processes—including canopy interception, throughfall, stemflow, litter interception, soil water absorption, runoff, and evapotranspiration—were measured across five light-felling intensity levels (control, low, medium, heavy, and clear-cutting) during the growing season. The stand structure and precipitation characteristics were analyzed to elucidate the driving mechanisms. (3) Results: (1) Low and heavy light-felling significantly increased the canopy interception by 18.9%~57.0% (p < 0.05), while medium-intensity light-felling reduced it by 20.6%. The throughfall was significantly decreased 10.7% at low intensity but increased 5.3% at medium intensity. The stemflow rates declined by 15.8%~42.7% across all treatments. (2) The litter interception was reduced by 22.1% under heavy-intensity light-felling (p < 0.05). (3) The soil runoff rates decreased by 56.3%, 16.1%, and 6.5% under the low, heavy, and clear-cutting intensity levels, respectively, although increased by 27.1% under medium-intensity activity (p < 0.05). (4) The monthly hydrological dynamics shifted from bimodal (control) to unimodal patterns under most treatments. (5) The canopy processes were primarily driven by precipitation, while litter interception was influenced by throughfall and tree diversity. The soil processes correlated strongly with throughfall. (4) Conclusions: Low and heavy light-felling led to enhanced canopy interception and reduced soil runoff and mitigated flood risks, whereas medium-intensity light-felling supports water supply during droughts by increasing the throughfall and runoff. These findings provide critical insights for balancing carbon sequestration and hydrological regulation in forest management.

As a major driver of global change, increasing nitrogen deposition is affecting community structure and biodiversity in forest ecosystems. However, the responses of different plant life forms to long-term nitrogen inputs and their associations with environmental changes remain poorly understood. In this study, we investigated the effects of long-term nitrogen addition on α- and β-diversity and their components (species turnover and nestedness) across different plant life forms in a cold-temperate coniferous forest, based on a 14-year nitrogen addition experiment. We further examined the relationships between plant diversity changes and soil environmental variables. The results showed that long-term nitrogen addition had limited effects on tree-layer α-diversity, whereas shrub- and herb-layer α-diversity decreased. Nitrogen addition significantly altered shrub-layer β-diversity, whereas no significant changes were detected in tree- and herb-layer β-diversity. β-diversity partitioning indicated that nestedness contributed more to shrub-layer compositional differences, whereas species turnover contributed more to herb-layer compositional dissimilarity among plots. Changes in understory plant diversity were associated with soil pH and inorganic nitrogen concentrations. These findings demonstrate contrasting responses of plant diversity among vegetation layers under long-term nitrogen enrichment and highlight the importance of considering life-form-specific responses when assessing the impacts of atmospheric nitrogen deposition on forest biodiversity.