Island biogeography theory and the habitat heterogeneity jointly explain global patterns of Rhododendron diversity

Mountain biodiversity is of great importance to biogeography and ecology. However, it is unclear what ecological and evolutionary processes best explain the generation and maintenance of its high levels of species diversity. In this study, we determined which of six common hypotheses (e.g., climate hypotheses, habitat heterogeneity hypothesis and island biogeography theory) best explain global patterns of species diversity in Rhododendron. We found that Rhododendron diversity patterns were most strongly explained by proxies of island biogeography theory (i.e., mountain area) and habitat heterogeneity (i.e., elevation range). When we examined other relationships important to island biogeography theory, we found that the planimetric area and the volume of mountains were positively correlated with the Rhododendron diversity, whereas the ‘mountains-to-mainland’ distance was negatively correlated with Rhododendron diversity and shared species. Our findings demonstrate that Rhododendron diversity can be explained by island biogeography theory and habitat heterogeneity, and mountains can be regarded as islands which supported island biogeography theory

A Review on the Application of 3D Printing Technology in Pavement Maintenance

To examine the application and significance of 3D printing technology in pavement maintenance engineering, a review of the current developments in principles, types, materials, and equipment for 3D printing was conducted. A comparison and analysis of traditional methods and 3D printing for asphalt pavement maintenance led to an investigation of 3D asphalt printing technologies and equipment. As a result, the following suggestions and conclusions are proposed: 3D printing technology can increase the level of automation and standardization of pavement maintenance engineering, leading to effective improvements in worker safety, climate adaptability, repair accuracy, etc. For on-site repair of cracks and minor potholes, utilizing material extrusion technology a mobile 3D asphalt printing robot with a screw extrusion device can be used for accuracy and flexibility. For efficient repair of varying cracks, material jetting technology with a UAV equipped with a 3D printing air-feeding device can be employed

Climatic niche breadth can explain variation in geographical range size of alpine and subalpine plants

Understanding the environmental factors determining the distribution of species with different range sizes can provide valuable insights for evolutionary ecology and conservation biology in the face of expected climate change. However, little is known about what determines the variation in geographical and elevational ranges of alpine and subalpine plant species. Here, we examined the relationship between geographical and elevational range sizes for 80 endemic rhododendron species in China using Spearman’s rank-order correlation. We ran the species distribution model – maximum entropy modelling (MaxEnt) – with 27 environmental variables. The importance of each variable to the model prediction was compared for species groups with different geographical and elevational range sizes. Our results showed that the correlation between geographical and elevational range sizes of rhododendron species was not significant. Climate-related variables were found to be the most important factors in shaping the distributional ranges of alpine and subalpine plant species across China. Species with geographically and elevationally narrow ranges had distinct niche requirements. For geographical ranges, the narrow-ranged species showed less tolerance to niche conditions than the wide-ranged species. For elevational ranges, compared with the wide-ranged species, the narrow-ranged species showed an equivalent niche breadth, but occurred at different niche position along the environmental gradient. Our findings suggest that over large spatial extents the elevational range size can be a complementary trait of alpine and subalpine plant species to geographical range size. Climatic niche breadth, especially the range of seasonal variability, can explain species’ geographical range sizes. Changes in climate may influence the distribution of rhododendrons, with the effects likely being felt most by species with either a narrow geographical or narrow elevational range

Quantitative analysis of local microcirculation changes in early osteonecrosis of femoral head: DCE-MRI findings

AimThis study aims to quantitatively analyze the changes in local microcirculation in early osteonecrosis of the femoral head (ONFH) by dynamic contrast-enhanced (DCE) MRI and to explore the pathophysiological mechanisms of early ONFH.Patients and MethodsWe selected 49 patients (98 hips) aged 21–59 years who were clinically diagnosed with early ONFH. A total of 77 femoral heads were diagnosed with different degrees of necrosis according to the Association Research Circulation Osseous (ARCO) staging system, and 21 femoral heads were judged to be completely healthy. All patients underwent DCE-MRI scanning. Pseudocolor images and time-signal intensity curves were generated by Tissue 4D processing software. The volume transfer constant (Ktrans), extracellular extravascular space, also known as vascular leakage (Ve), and transfer rate constant (Kep) of healthy and different areas of necrotic femoral heads were measured on perfusion parameter maps. The differences and characteristics of these parameters in healthy and different areas of necrotic femoral heads were analyzed.ResultsThe signal accumulation in healthy femoral heads is lower than that of necrotic femoral heads in pseudocolor images. The time-signal intensity curve of healthy femoral heads is along the horizontal direction, while they all have upward trends for different areas of necrotic femoral heads. The mean value of Ktrans of healthy femoral heads was lower than the integration of necrotic, boundary, and other areas (F = 3.133, P = .036). The Kep value of healthy femoral heads was higher than the integration of lesion areas (F = 6.273, P = .001). The mean Ve value of healthy femoral heads was smaller than that of the lesion areas (F = 3.872, P = .016). The comparisons of parameters between different areas and comparisons among healthy areas and lesion areas showed different results.ConclusionONFH is a complex ischemic lesion caused by changes in local microcirculation. It mainly manifests as increased permeability of the vascular wall, blood stasis in the posterior circulation, high intraosseous pressure in the femoral head, and decreased arterial blood flow. The application of DCE-MRI scanning to quantitatively analyze the visual manifestations of microcirculation after early ONFH is an ideal method to study the microcirculation changes of necrotic femoral heads

Tree plantations displacing native forests: The nature and drivers of apparent forest recovery on former croplands in Southwestern China from 2000 to 2015

China is credited with undertaking some of the world's most ambitious policies to protect and restore forests, which could serve as a role model for other countries. However, the actual environmental consequences of these policies are poorly known. Here, we combine remote-sensing analysis with household interviews to assess the nature and drivers of land-cover change in southwestern China between 2000–2015, after China's major forest protection and reforestation policies came into effect. We found that while the region's gross tree cover grew by 32%, this increase was entirely due to the conversion of croplands to tree plantations, particularly monocultures. Native forests, in turn, suffered a net loss of 6.6%. Thus, instead of truly recovering forested landscapes and generating concomitant environmental benefits, the region's apparent forest recovery has effectively displaced native forests, including those that could have naturally regenerated on land freed up from agriculture. The pursuit of profit from agricultural or forestry production along with governmental encouragement and mobilization for certain land uses – including tree planting – were the dominant drivers of the observed land-cover change. An additional driver was the desire of many households to conform with the land-use decisions of their neighbors. We also found that households' lack of labor or financial resources, rather than any policy safeguards, was the primary constraint on further conversion of native forests. We conclude that to achieve genuine forest recovery along with the resulting environmental benefits, China's policies must more strongly protect existing native forests and facilitate native forest restoration. Natural regeneration, which thus far has been grossly neglected in China's forest policies, should be recognized as a legitimate means of forest restoration. In addition, social factors operating at the household level, notably the pursuit of profit and conformation to social norms, should be harnessed to promote better land-cover, biodiversity, and environmental outcomes. More generally, for China and other countries to succeed in recovering forests, policies must clearly distinguish between native forests and tree plantations