The effects of elevated CO₂ concentration on photosynthetic gas exchange parameters and chlorophyll fluorescence parameters in leaves of Calamagrostis angustifolia seedlings under drought stress were studied through control of different CO₂ concentrations (370 and 700 μmol·mol⁻¹) with an artificial OTC climate chamber. The results demonstrated that: Under non-drought conditions, although the stomatal conductance (G_s) and transpiration rate (T_r) decreased slightly as the CO₂ concentration increased, while the net photosynthetic rate (P_n) increased significantly, resulting in a significant increase in leaf water use efficiency (WUE). However, the effect of elevated CO₂ concentration on PSII reaction center activity was insignificant under non drought conditions. Under severe drought stress, the amount of active reaction centers per unit area and the proportion of PSII absorbed light energy for photosynthetic electron transfer increased, while the proportion of PSII absorbed light energy for heat dissipation decreased, providing energy guarantee for effective fixation of CO₂ as dark reaction. In conclusion, elevated CO₂ concentration could improve the water use efficiency of C. angustifolia seedlings under normal water and drought stress, and the elevated CO₂ concentration could improve the drought resistance ability of C. angustifolia seedlings through PSII function improvement under severe drought stress.

Hunchun, a typical area suffering wild boar (Sus scrofa) damage, is an important region for the Siberian Tiger (Panthera tigris) in China. By incorporating the maximum entropy model with 22 variables in the home range scale (12 variables) and in the feeding site scale (10 variables), we predicted wild boar damage risks in this area of China and analyzed how spatial factors influence damage risk. Damage risk was found to be high in areas close to the forest edge, areas with a higher forest cover and lower to medium deciduous forest proportion, low road density, and a medium river density and farmland proportion. The proportion of farmland which was identified as being in the high damage risk zone was 23.55%, of which 38.68% was within the habitat area of the Siberian Tiger. Finally, we propose wild boar damage prevention based on different management goals.