Enriching nitrogen and phosphorus severely threaten ecological health, and accurately identifying their sources is the basis for watershed management. However, analyzing the spatial-temporal distribution of pollution sources in rivers has become challenging due to the complex interaction of natural and human factors. Taking the Mihe River, which has significant hydrological regime variation as the case study, the spatial-temporal characteristics of nitrogen and phosphorus sources were analyzed based on two methods: receptor model and emission inventory. The results showed that: (1) the average nitrogen and phosphorus loading in the river from 2015 to 2021 was 13.08×103 t·a-1 and 38.03 t·a-1, with significant fluctuations influenced by flow changes; (2) the LAM results indicated that NPS (non-point source) are the primary pollution sources to nitrogen and phosphorus loading, accounting for 81.7% and 99.6%, respectively; (3) The ECM results indicated that the nitrogen and phosphorus loading are concentrated in the middle and lower reaches, which are highly consistent with the distribution of cropland and urban land. (4) The results from the two methods on the pollution source structure are consistent. Still, there are significant differences in the total amount of pollutant loading. The LAM and ECM model have the problem of underestimating and overestimating pollutant loading, respectively. However, combining the two methods is beneficial to accurately identify the spatial-temporal distribution of pollution sources in the high-flow variable river.
Summary Increasingly, ecologists are using functional and phylogenetic approaches to quantify the relative importance of stochastic, abiotic filtering and biotic filtering processes shaping the pattern of species co‐occurrence. A remaining challenge in functional and phylogenetic analyses of tropical tree communities is to successfully integrate the functional and phylogenetic structure of tree communities across spatial and size scales and habitats in a single analysis. We analysed the functional and phylogenetic structure of tree assemblages in a 20‐ha tropical forest dynamics plot in south‐west China. Because the influence of biotic interactions may become more apparent as cohorts age, on local scales, and in resource‐rich environments, we perform our analyses across three size classes, six spatial scales and six distinct habitat types, using 10 plant functional traits and a molecular phylogeny for the >400 tree taxa found in the plot. All traits, except leaf area and stem‐specific resistance, had significant, albeit weak phylogenetic signal. For canopy species, phylogenetic clustering in small and medium size classes turned to phylogenetic overdispersion in the largest size class and this change in dispersion with size was found in each habitat type and across all spatial scales. On fine spatial scales, functional dispersion changed from clustering to overdispersion with increasing size classes. However, on larger spatial scales assemblages were functionally clustered for all size classes and habitats. Phylogenetic and functional structure across spatial and size scales and habitats gave strong support for a deterministic model of species co‐occurrence rather than for a neutral model. The results also support the hypothesis that abiotic determinism is more important at larger scales, while biotic determinism is more important on smaller scales within habitats.
By taking the agent-based simulation of Lushan visitors' tour route as example,some key technical problems are solved in the micro individual level of tourist agent.For example,how to build the spatial database about Lushan tour route,building the conceptual model of visitor agents tour routes simulation,the quantification of the tourist agent's behavior rules,the realization of the visitors tour route simulation.These results indicated that the dynamic simulation of tourist visit course can directly reflect the tour routes.By combing Agent and GIS,the spatial behavior model of tourist agent based on Repast actualizes the dynamic simulation of visitors' tour route course and effectively improves the function of spatial behavior simulation in GIS,which provides a reasonable reference to make a better choice for visitors' tour route.
The seven-year medical program is oriented through wide-base , spacious-pathand then up to specific professional direction. The solution to the challenge on how to connect the wide-base to narrow-professional naturally is very important for the program development.This paper is aimed to introduce the seven-year medical program of optometry & ophthalmology in Wenzhou Medical College. It is summarized here that its critical points for efficient connection between wide-baseof basic and clinical courses and very specific profession direction in eye clinic and vision science.
Key words:
Seven-year medical program; Optometry and ophthalmology; Wide-base; Specific professional direction
Abstract One of the few rules in ecology is that communities are composed of many rare and few common species. Trait‐based investigations of abundance distributions have generally focused on species‐mean trait values with mixed success. Here, using large tropical tree seedling datasets in China and Puerto Rico, we take an alternative approach that considers the magnitude of intraspecific variation in traits and growth as it relates to species abundance. We find that common species are less variable in their traits and growth. Common species also occupy core positions within community trait space indicating that they are finely tuned for the available conditions. Rare species are functionally peripheral and are likely transients struggling for success in the given environment. The work highlights the importance of considering intraspecific variation in trait‐based ecology and demonstrates asymmetry in the magnitude of intraspecific variation among species is critical for understanding of how traits are related to abundance.
ABSTRACT Xishuangbanna of southern Yunnan is biogeographically located at a transitional zone from tropical Southeast (SE) Asia to subtropical East Asia, and is at the junction of the Indian and Burmese plates of Gondwana and the Eurasian plate of Laurasia. The flora of the region consists of a recorded 3336 native seed plant species, belonging to 1140 genera in 197 families, among which 83.5 percent are tropical genera and 32.8 percent are endemic to tropical Asia, suggesting a strong affinity to tropical Asian flora. The vegetation of Xishuangbanna is organized into four forest types: tropical rain forest, tropical seasonal moist forest, tropical montane evergreen broad‐leaved forest, and tropical monsoon forest. The tropical rain forest in Xishuangbanna has the same floristic composition of families and genera as some lowland equatorial rain forests in SE Asia, and is dominated (with a few exceptions) by the same families both in species richness and stem dominance. The exceptions include some deciduous trees in the canopy layer, fewer megaphanerophytes and epiphytes, and a higher abundance of lianas and microphyllic plants. We consider the tropical rain forest of Xishuangbanna as a type of tropical Asian rain forest, based on their conspicuous similarities in ecological and floristic characteristics.
As global energy demand continues to rise and traditional energy sources increasingly fail to meet sustainability targets, conventional domestic hot water systems that rely exclusively on either geothermal or solar energy face inefficiencies and seasonal limitations. To tackle these issues, this study introduces an innovative domestic hot water supply system combining MDBHE with a PV/T heat pump and investigates its thermal performance. This system utilizes thermal energy to elevate the temperature of water extracted from the MDBHE, while supplying power through photovoltaic electricity. The results indicate that increasing the circulating water flow rate improves the heat extraction capacity of the MDBHE. However, this also leads to higher flow resistance and an increased power requirement for the circulating water pump. Additionally, at a circulating water flow rate of 32 m3/h, the system fails to extract heat from geothermal energy when the inlet temperature exceeds 34.5°C. Furthermore, with a PV/T module area of 2000 m2, solar radiation intensity of 600 W/m2, and MDBHE depth of 2000 m, the system can attain a maximum water supply temperature of 50.9°C, with solar energy contributing 63%. Moreover, the coefficient of performance (COP) of the system can reach 5.8, outperforming conventional systems.
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