The aim of this study was to explore the effects of grazing on the formation of the spatial pattern of elm growth in a sparse woodland steppe. We used a point pattern method to analyze the elm trees within different diameter at breast height (DBH) classes in both grazed and fenced plots, which were established in Horqin Sandy Land of northeastern China. The results showed that, in the grazed plot, the distances where transformation between random and clustered patterns occurred in class 1 (10 cm ≤ DBH ≤ 15 cm) and class 2 (15 cm < DBH ≤ 20 cm) were 2.27 and 2.37 m, respectively. Meanwhile, in the fenced plot, the distances between random and aggregated patterns that occurred in classes 1, 2 and 3 (DBH > 20 cm) were 3.13, 3.13 and 7.85 m, respectively. In the fenced plot, at distances larger than 67.72 m there was a negative association between classes 1 and 2, which was also the case between classes 2 and 3 and between classes 1 and 3 for distances greater than 104.09 and 128.54 m, respectively. Meanwhile, negative associations occurred only at distances larger than 29.38 m in the grazed plot. These findings suggest that grazing reduced the competition intensity between elm trees; and therefore, grazing management could be an effective strategy used to regulate the elm population in the degraded sandy land of northern China.

Effects of exclosure management on the plant recruitment are not clear yet. To assess the effects of exclosure management on the recruitment of elm, population structure, seed production, and densities of seeds and seedlings of elm were investigated in fenced and grazed pastures in Horqin Sandy Land, northeastern China. The results showed that seed biomass per branch of elm in the grazed plot was significantly higher than in fenced pasture (0.85 ± 0.27 g vs. 0.55 ± 0.36 g, p < 0.05), and seed density was higher in grazed pasture (845 ± 370 seedsm⁻²) than that in fenced pasture (558 ± 241 seedsm⁻²), indicating that grazing would improve reproductive allocation of elm. However, there was no significant difference of seedling density between grazed and fenced pastures. More important, the elm trees with a height less than 0.5 m appeared in the fenced pasture but disappeared in the grazed pasture, indicating the positive effects of exclosure management on the elm recruitment. Our results suggested that the exclosure would favor recruitment of elm through its protection of saplings instead of through increased seed production. This study improves our understanding of the effects of grazing on population dynamics of elm and would contribute to the restoration of degraded sandy land in northern China.

Leveraging circular regression, this study analyzed phenological data from China spanning the period 2003 to 2015, meticulously examining the effects of temperature, precipitation, and CO₂ concentrations on the phenological patterns of woody and herbaceous plants. For woody plants, the results showed that rising temperatures and increased precipitation notably advanced early growth phases, such as budburst, leaf unfolding, and first flowering (p < 0.001). Specifically, CO₂ concentrations had a pronounced impact on the leaf unfolding phase (p < 0.001). In contrast, autumnal events, particularly fruit maturity, autumn coloring, and leaf fall, were delayed by warmer temperatures and higher precipitation (p < 0.001), Of these events, only fruit maturity demonstrated sensitivity to CO₂ concentration variations. In the realm of herbaceous plants, elevated temperatures and precipitation collectively hastened the budburst phase (p < 0.001), which is an effect further accentuated by high CO₂ levels (p < 0.001). Moreover, rising temperatures and augmented precipitation were instrumental in advancing the flowering phase (p < 0.001). Conversely, warmer conditions slowed down the fruiting process (p < 0.001), with this delay somewhat mitigated by the effects of increased precipitation. Interestingly, while CO₂ concentrations had negligible influence on the flowering and fruiting stages, they noticeably delayed seed dispersal and the initiation of senescence (p < 0.001). Overall, the prevailing trend suggests that plants, whether woody or herbaceous in nature, tend to prolong their growth season under warmer and more humid conditions. The influence of CO₂ concentration, however, is contingent upon the specific phenological phase and plant type. Our findings emphasize the nuanced and stage-specific responses of plant phenology to temperature, precipitation, and CO₂, highlighting the value of using circular regression in ecological studies.

The conflict between economic development and ecological protection continues to intensify, highlighting the necessity for constructing regional ecological security patterns (ESPs) to reconcile the relationship between development and protection effectively. This study used the GMOP and PLUS model to simulate future land use changes by 2030 under the following three scenarios: natural development (ND), ecological protection (EP), and economic development (ED). Employing the MSPA model and circuit theory, it identified ecological source areas and constructed the ESP for the Beijing–Tianjin–Hebei urban agglomeration (BTH) from 2000 to 2030. The results indicate that the proportion of ecological source areas increased from 22.24% in 2000 to 23.09% in 2020, the EP scenario showing the highest proportion of ecological source areas compared with the other two scenarios. These areas are densely distributed in the northern and western mountainous regions, with sparse distributions in the southern plains. The number of ecological corridors grew from 603 in 2000 to 616 in 2020, with the EP scenario having more corridors than the other two scenarios. From 2000 to 2030, corridors in the northern and western mountainous areas were denser, shorter, and more variable, while those in the southern plains were less dense, longer, and relatively stable. Over two decades, habitat areas for species in BTH increased, while landscape connectivity decreased. Compared with 2020 and the other two scenarios, the EP scenario saw an increase in habitat areas and improved landscape connectivity. The impact on ecological corridors and improvement areas primarily arose from a combination of socio-ecological drivers (e.g., elevation, slope, population), while the influence on restoration and key areas mainly stemmed from ecological factors (e.g., elevation, temperature, NDVI, precipitation). The findings demonstrate that distinguishing different geomorphological units to improve and restore the regional environment, while considering socio-ecological drivers, is crucial for restoring the overall ESP and landscape connectivity of BTH.