Effects of Different Pre-Heating Welding Methods on the Temperature Field, Residual Stress and Deformation of a Q345C Steel Butt-Welded Joint.

Heavy plate welding has been widely used in the construction of large projects and structures, in which the residual stress and deformation caused by the welding process are the key problems to address to reduce the stability and safety of the whole structure. Strengthening before welding is an important method to reduce the temperature gradient, control the residual stress and reduce the deformation of welds. Based on the ABAQUS software, the thermal elastoplastic finite element method (FEM) was used to simulate the welding thermal cycle, residual stress and deformation of low-alloy, high-strength steel joints. Based on the finite element simulation, the influences of flame heating and ceramic heating on the temperature field, residual stress distribution and deformation of a Q345C steel butt-welded joint were studied. The results showed that the thermal cycle of the ceramic sheet before welding had little influence on the whole weldment, but had great influence on the residual stress of the weldment. The results show that the maximum temperature and residual stress of the welded parts are obviously weakened under the heating of ceramic pieces, and the residual stress of the selected feature points is reduced by 5.88%, and the maximum temperature of the thermal cycle curve is reduced by 22.67%. At the same time, it was concluded that the weld shapes of the two were basically the same, but the weld seams heated by ceramic pieces had a better weld quality and microstructures through comparing the macro- and micro-structures between the welded parts heated by ceramic pieces and the simulated weld. Heating before welding, therefore, is an effective method to obtain a high weld quality with less residual stress and deformation.

Interspecific association of sika deer in terrestrial animal communities of Liancheng National Nature Reserve, China.

The prevention and control of invasive of alien species is an important work for nature reserves. This study analyzes the development trend of the alien species sika deer in Liancheng National Nature Reserve. From October 2019 to June 2020, 3523 valid photos and videos of terrestrial animals were acquired from 130 camera traps, and sika deer were recorded in 21 photos from 13 traps. The survival of the sika deer population was investigated by means of morphological identification, population structure analysis, species relative abundance indices, and species spatial association analysis. A total of 13 sika deer individuals were identified by camera trapping, including two kids and three subadults representing the reproductive capacity of the population. Spatially, sika deer is not associated with any local species and was outside the spatial association network of terrestrial animals in Liancheng National Nature Reserve, indicating that the sika deer population has not been integrated into the local community and has failed to perform its ecological function. It is worth noting that the reserve provides habitat suitable for sika deer and that the population has adequate reproductive capacity. Due to the lack of large apex predators in the reserve, the population size of ungulates such as sika deer, red deer, and Siberian roe deer may expand and lead to population outbreaks and the associated problems for the ecosystem. To restore large- and medium-sized carnivores and avoid the population outbreak of the species, the present challenges require immediate attention in Liancheng National Nature Reserve.

The Ecological Roles of Medium and Small Carnivores in the Terrestrial Animal Community in Liancheng National Nature Reserve, China.

It is vitally important to understand the ecological roles of medium and small carnivores in the context of the massive decline in the number of large carnivores around the world. Based on a spatial association network of terrestrial birds and mammals, this study analyzed the ecological roles of medium and small carnivores in the community in Liancheng National Nature Reserve. From October 2019 to June 2020, we obtained 3559 independent detections of 20 terrestrial birds and mammals from 112 camera traps. There are seven species that are medium and small carnivores present in the study area, including red fox (Vulpes vulpes), leopard cat (Prionailurus bengalensis), Chinese mountain cat (Felis bieti), stone marten (Martes foina), Asian badger (Meles leucurus), Siberian weasel (Mustela sibirica) and mountain weasel (Mustela altaica). By calculating the Phi coefficient of all species pairs, a spatial association network composed of twelve species was constructed. We analyzed the characterization of spatial associations by the Shannon-Wiener index and Lambda statistic. The results showed that: (1) the status of the network reflects the changes of community composition and structure after the decline in large carnivores and other species; (2) with the exception of the Chinese mountain cat and stone marten, the other five medium and small carnivores were located in the network, which played an important role in the complexity of the network and the maintenance of the community; (3) the medium and small carnivores could not take the place of the large carnivores in order to control the population of herbivores, such as Siberian roe deer (Capreolus pygargus) and Himalayan marmot (Marmota himalayana). The results of this study provide guidance for determining the direction and focus of conservation efforts.

Establishment of nature reserves in administrative regions of mainland China.

Nature reserves are widely considered as one available strategy for protecting biodiversity, which is threatened by habitat fragmentation, and wildlife extinction. The Chinese government has established a goal of protecting 15% of its land area by 2015. We quantitated the characteristics and distribution of nature reserves in mainland China and evaluated the expansion process for national nature reserves. National nature reserves occupy 64.15% of the total area of nature reserves. Steppe and meadow ecosystem, ocean and seacoast ecosystem, and wild plant nature reserves represent lower percentages, particularly in national nature reserves, in which they comprised 0.76%, 0.54%, and 0.69%, respectively, of the area. Furthermore, medium and small nature reserves compose 92.32% of all nature reserves. The land area under any legal protection has reached 14.80%, although only 9.78% is strictly protected. However, if 9 super-large national nature reserves, located in Southwest and Northwest China were removed, the percentage of strictly protected area decreases to 2.66% of the land area of China. The areas contained in nature reserves in each province are not proportional to the areas of the provinces, particularly for national nature reserves, with higher protection rates in Southwest and Northwest China than in other regions. Of the 31 provinces, 22 provinces feature strict protection of less than 4% of their areas by national nature reserves; these provinces are mainly located in East, Central, South, and North China. Moreover, the unevenness indexes of the distribution of nature reserves and national nature reserves are 0.39 and 0.58, respectively. The construction of nature reserves has entered a steady development stage after a period of rapid expansion in mainland China. In recent years, the total area of national nature reserves has increased slowly, while the total area of nature reserves has not increased, although the number of nature reserves continues increase.

The efficacy of landscape-level conservation in Changbai Mountain Biosphere Reserve, China.

Anthropogenic landscape alteration is rather common in many protected areas (PAs), jeopardizing the efficacy of PAs conservation. However, the general consensus is that PAs still remain effective in habitat conservation. To assess the efficacy of landscape-level conservation, we examined landscape alterations in the Changbai Mountain Biosphere Reserve (CMBR), which was established in 1960 as a "flagship" protected area in China. Based on analyses of high-resolution satellite images and data of forest inventory, field survey and interview, we developed two new indexes to assess the efficacy of landscape conservation, i.e. the quality index of protected landscape and the interference index of anthropogenic landscape. From 1993 to 2012, the quality index increased from 74.48 to 75.50, and the interference index decreased from 0.49 to 0.06, suggesting that the overall quality of protected landscape improved and the degree of anthropogenic interference decreased in CMBR. The increase in landscape quality was mainly due to the progressive vegetation recovery of previous cutover land in the windthrow area, the cease of the use of the cultivated land, and the amelioration of spatial pattern of protected landscape. We conclude that the current landscape conservation methods used in CMBR are effective, and the method we developed has the potential to be used to assess the efficacy of landscape-level conservation in nature reserves worldwide.

[Structure characteristics of natural nests and its implication to artificial nest frame design for Ciconia boyciana].

Artificial nest can improve the breeding success of birds in the field, and it has been proved to be more effective to endangered species. We surveyed the structure characteristics of natural nest and the status of the use of artificial nests for oriental white stork, Ciconia boyciana, in Honghe National Nature Reserve, Heilongjiang Province. Differences were investigated among the structure characteristics of the used and unused artificial nests, and natural nests based on one-way ANOVA. It was observed that significant differences in the diameter of nest branch, the vertical an- gle between nest branch, the height of the jointthe height of the nest above ground exited in different nest types. On account of the structure characteristics of the natural nests of C. boyciana, the suitable diameter of nest pillar for artificial nest frame should be 15.0-25.0 cm with the height of 5.0-12.0 m, which would be better if they were constructed by some acid-resistant materials, e.g., cement. The number of nest stands should be 3-4 individuals with the diameter of 9.0-12.0 cm, the vertical angle of 45 degrees-60 degrees, and the length of 90.0-140.0 cm.

Anthropogenic halo disturbances alter landscape and plant richness: a ripple effect.

Although anthropogenic landscape fragmentation is often considered as the primary threat to biodiversity, other factors such as immediate human disturbances may also simultaneously threaten species persistence in various ways. In this paper, we introduce a conceptual framework applied to recreation landscapes (RLs), with an aim to provide insight into the composite influences of landscape alteration accompanying immediate human disturbances on plant richness dynamics. These impacts largely occur at patch-edges. They can not only alter patch-edge structure and environment, but also permeate into surrounding natural matrices/patches affecting species persistence-here we term these "Halo disturbance effects" (HDEs). We categorized species into groups based on seed or pollen dispersal mode (animal- vs. wind-dispersed) as they can be associated with species richness dynamics. We evaluated the richness of the two groups and total species in our experimental landscapes by considering the distance from patch-edge, the size of RLs and the intensity of human use over a six-year period. Our results show that animal-dispersed species decreased considerably, whereas wind-dispersed species increased while their richness presented diverse dynamics at different distances from patch-edges. Our findings clearly demonstrate that anthropogenic HDEs produce ripple effects on plant, providing an experimental interpretation for the diverse responses of species to anthropogenic disturbances. This study highlights the importance of incorporating these composite threats into conservation and management strategies.

Sleeping site selection of Francois's langur (Trachypithecus francoisi) in two habitats in Mayanghe National Nature Reserve, Guizhou, China.

Sleeping site selection is an important aspect of the behavioral biology of primates. Comparison of different habitats for the same species in this context enhances understanding of their adaptation to altered environments. We collected data on sleep-related behaviors for 6 groups of Francois's langur (Trachypithecus francoisi) in two habitats, in Mayanghe National Nature Reserve, Guizhou, China. Regardless of habitat, all sleeping sites were located in areas of steep terrain of ≥60°. In undisturbed habitat, sleeping sites were located only in evergreen broadleaf forest with rock caves and crevices surrounded mainly by a vegetation layer of shrub + rock. In disturbed habitat, sleeping sites were also located in mixed evergreen and deciduous broadleaf forest and in grassland, including rock caves, crevices, and pits, surrounded mainly by arbor + shrub and shrub + rock. Wild food availability was higher in undisturbed habitat than disturbed habitat, but food abundance around sleeping sites was lower. Water sources included river and seasonal gully or pond. There was strong positive correlation between use of sleeping sites away from the river valley and occurrence of seasonal water sources. The number of sleeping sites varied across groups, numbering 6, 7, and 10 for three specific groups. Few sleeping sites were used all year round. Six consecutive nights was the longest recorded run. Francois's langurs' sleeping habits differed between two habitats. In undisturbed habitat, minimizing predation risk appeared to predominate, expressed by choosing steep terrain, open visual field, and inconspicuous presleeping behavior. In disturbed habitat, along with predation avoidance, food resources may strongly influence sleeping site selection, as demonstrated by the richer food abundance and greater foraging activity around the site. Finally, water resources may influence choice of sites distant from the river; such sites were used less frequently during water shortages.

[A new category system of China nature reserves based on their attributes].

Based on the numeric attributes of 114 typical nature reserves in China, a new category system was established by using cluster analysis method. Compared with the China national category system of nature reserves, the new category system was simpler and more applicable. The 4 categories in the new system matched well to the categories I , II , IV, and V in IUCN category system, respectively. The new category system, characterized by the consistency of category criteria and scale, could avoid the deviation caused by subjective category to some degree, and provide a quantitative standard for the classification of nature reserves in China.

[Conservation priorities for plant species of forest-meadow ecotone in Sanjiangyuan Nature Reserve].

Based on field survey, information collection and experts consultation, the quantitative grading index system and assessment standards for preference conservation of rare and endangered plant species of forest-meadow ecotone in Sanjiangyuan Nature Reserve were established by using the methods and principles of systematical analysis. The quantitative grading index system included endangered coefficient, genetic coefficient, and useful value coefficient. In addition, 10 indicators used to evaluate endangered grading and conservation priorities sequenc, were also included in 3 subsystems respectively. Furthermore, the weights of 3 subsystem and 10 indicators were given through experts consultation and analytic hierarchy process. Endangered coefficient and conservation priorities coefficient, which respectively described the endangered grading, and preferential conservation of plant species were calculated by mathematic models and computer program. Contrasting to the standards of endangered grading and conservation priorities for plant species, we quantitatively evaluated the status of endangered and conservation priorities of plant species. The results showed that the number of endangered species was 4, vulnerable species 68, lower risk species 179, safety species 695; the number of the first class species was 8, the second class species 78, the third class species 164, and the delayed conservation species 696. Finally, we discussed the problems of indicator system and its weight, the relationship between endangered grading and conservation priorities sequence, and the spatial scale problem of plant species assessment.