N₂-fixing species play a crucial role in mixed-plantations as they improve stand productivity. To quantify the N transfer from N₂-fixing species to Eucalyptus (Eucalyptus urophylla × E. grandis) in N₂-fixing species/Eucalyptus plantations, we established a pot experiment and confirmed the occurrence of this process under natural conditions. The ¹⁵N was traced in labeled species as well as in neighboring tree species after labeling, and the growth was evaluated in short-term natural trials. Our results showed that a bidirectional N transfer occurred. The amount of net N transfer was 21.8–127.0 mg N plant⁻¹, which was equal to 1.5–21.2% of the total nitrogen (TN) that accumulated in Eucalyptus plants under pot conditions, was transferred from Dalbergia odorifera to Eucalyptus. The amount of N transferred significantly decreased with the increasing N application rate but increased with time after labeling. Compared with the results for the Eucalyptus monocrop, the soil N concentration (including NO₃⁻-N and NH₄⁺-N) greatly improved when D. odorifera was introduced together with Eucalyptus under both field and pot conditions. Furthermore, the results under field conditions were consistent with the results of the pot experiment. The dry matter (DM) yield (14.5–16.4%) and the N content (5.1–9.6%) in Eucalyptus increased when mixed together with D. odorifera, but the N content in and DM yield of D. odorifera slightly decreased. It is concluded that the N transfer between Eucalyptus and D. odorifera is a much more important dynamic process than previously recognized, and Eucalyptus and legume intercropping is a successful management practice because N transfer provides a significant amount of N required for Eucalyptus productivity.

Urbanization presents significant challenges to biodiversity but also offers opportunities for its protection and development. While uncontrolled urban expansion has a destructive impact on biodiversity, effective urban planning can play a positive role in protecting and maintaining urban biodiversity. The positive role of human factors, such as urban planning, can protect and maintain the healthy development of urban biodiversity. This study conducted an in-depth analysis of the evolution of various wildlife migration corridors throughout the full-cycle construction of Xiong’an New Area (Xiong’an) in China, revealing the impact of urbanization on these networks. Habitats for species like Sus scrofa, Bufo gargarizans, and Parus minor have notably increased. Between 2016 and 2023, Sus scrofa habitats grew from 35 to 44, large-toed frog habitats from 24 to 35, and Chinese tit habitats remained stable. By the planning phase, Sus scrofa habitats expanded to 87, large-toed frog habitats to 97, and Chinese tit habitats to 58. Habitat areas also grew significantly, especially for Sus scrofa, which increased from 2873.84 hectares in 2016 to 7527.97 hectares in the planning phase. Large-toed frog habitats grew from 2136.86 hectares to 6982.78 hectares, while Chinese tit habitats expanded from 1894.25 hectares to 3679.71 hectares. These changes suggest that urban parks and green spaces have provided more extensive habitats for these species. In terms of migration networks, the number of dispersal routes increased considerably. In 2016, Sus scrofa had 77 routes, large-toed frogs had 16, and Chinese tits had 77. By 2023, Sus scrofa and large-toed frog routes increased to 91 and 49, respectively, while Chinese tit routes remained stable. In the planning phase, Sus scrofa routes surged to 232, large-toed frogs to 249, and Chinese tits to 152, indicating a denser migration network. The distribution of ecological pinchpoints also changed significantly. By 2023 and in the planning phase, pinchpoints were concentrated in densely built areas, reflecting urbanization’s impact on the ecological network. The ecological resilience, assessed through network performance, showed a gradual recovery. The ecological connectivity index decreased from 8.25 in 2016 to 7.29 in 2023, then rebounded to 11.37 in the planning phase, indicating that the ecosystem had adapted after initial urbanization pressures.

The Qinghai–Tibet Plateau ecosystem is fragile, experiencing rapid changes in land cover driven by both climate change and human activities, leading to habitat fragmentation and loss and resulting in biodiversity decline. Habitat ecological networks (HA-ENs) are considered effective solutions for habitat connectivity and biodiversity conservation in response to these dual drivers. However, HA-EN studies typically rely on current or historical landscape data, which hinders the formulation of future conservation strategies. This study proposes three future scenarios—improvement, deterioration, and baseline scenarios—focused on the southeastern Qinghai–Tibet Plateau (SE-QPT). The habitats of 10 species across three classes are extracted, integrating land use and climate change data into habitat ecological network modeling to assess the long-term dynamics of HA-ENs in the SE-QPT. Finally, conservation management strategies are proposed based on regional heterogeneity. The results show the following: Climate change and human activities are expected to reduce the suitable habitat area for species, intensifying resource competition among multiple species. By 2030, under all scenarios, the forest structure will become more fragmented, and grassland degradation will be primarily concentrated in the southeastern and western parts of the study area. Compared to 1985 (71,891.3 km²), the habitat area by 2030 is projected to decrease by 12.9% (62,629.3 km²). The overlap rate of species habitats increases from 25.4% in 1985 to 30.9% by 2030. Compared to the HA-EN control in 1985, all scenarios show a decrease in connectivity and complexity, with only the improvement scenario showing some signs of recovery towards the control network, albeit limited. Finally, based on regional heterogeneity, a conservation management strategy of “two points, two cores, two corridors, and two regions” is proposed. This strategy aims to provide a framework for future conservation efforts in response to climate change and human activities.